Rmbridgee Modguide

RM Bridge Professional Engineering Software for Bridges of all Types

MODELER USER GUIDE

RM Bridge V8i

August 2012

RM Bridge

M o d e l e r U s e r G u i d e

© Bentley Systems Austria

This document is an integral part of the program package RM Bridge. Duplication and

dissemination is only allowed with explicit permission of Bentley Systems,

Incorporated.

© 2012, Bentley Systems, Incorporated. All Rights Reserved.

http://www.bentley.com/

RM Bridge Contents

M o d e l e r U s e r G u i d e I


Contents

1 General Information ............................................................................................... 1-1

1.1 Introduction .................................................................................................... 1-1

1.2 Program Start ................................................................................................. 1-1

1.3 Input Conventions .......................................................................................... 1-2

1.4 Definitions ..................................................................................................... 1-3

1.4.1 Bridge Axes ............................................................................................... 1-3

1.4.2 Segments .................................................................................................... 1-3

1.4.3 Cross-Sections ........................................................................................... 1-5

1.4.4 Parts ........................................................................................................... 1-5

1.4.5 Variables .................................................................................................... 1-8

2 Main Input Window ............................................................................................... 2-1

2.1 Program Version, Project Directory .............................................................. 2-2

2.2 General Toolbar ............................................................................................. 2-2

2.3 Navigation Panel ............................................................................................ 2-3

2.4 Unit Control ................................................................................................... 2-3

2.5 Axis, Cross-Section and Segment List Windows .......................................... 2-3

2.6 Edit Functions ................................................................................................ 2-4

2.7 Zoom functions .............................................................................................. 2-4

2.7.1 Icons ........................................................................................................... 2-5

2.7.2 Free-Hand Symbols ................................................................................... 2-5

2.8 Modeling Functions ....................................................................................... 2-6

2.9 Recalculation Functions ................................................................................. 2-7

2.10 File Functions ................................................................................................ 2-7

3 Plan View Geometry .............................................................................................. 3-1

3.1 Introduction .................................................................................................... 3-1

3.2 Toolbar for Horizontal Axis Construction ..................................................... 3-1

3.3 3D Points ........................................................................................................ 3-2

RM Bridge Contents

M o d e l e r U s e r G u i d e I I


4 Vertical View Geometry ........................................................................................ 4-1

4.1 Introduction .................................................................................................... 4-1

4.2 Toolbar for Vertical Axis Construction ......................................................... 4-2

5 Cross-Section Definition ........................................................................................ 5-1

5.1 Introduction .................................................................................................... 5-1

5.2 Construction Line (CL) Toolbar .................................................................... 5-3

5.3 Variables and Cross-Section Input ................................................................ 5-6

5.4 Part, Formula and Point Lists ........................................................................ 5-6

5.5 Layers ............................................................................................................. 5-6

5.6 Cross-Section Lock ........................................................................................ 5-7

5.7 Element Definition ......................................................................................... 5-7

5.7.1 Icons ........................................................................................................... 5-7

5.7.2 Individual Mesh Refinement ..................................................................... 5-9

5.7.3 Copying Elements ...................................................................................... 5-9

5.8 Link Segments ............................................................................................. 5-11

5.8.1 Principles ................................................................................................. 5-11

5.8.2 Link Segment Cross-Section ................................................................... 5-12

5.9 Reference Points .......................................................................................... 5-13

5.9.1 Icons ......................................................................................................... 5-13

5.9.2 Local Mesh Refinement ........................................................................... 5-13

5.10 Dimension Line ............................................................................................ 5-15

5.11 Import and Management of Cross-Sections ................................................. 5-15

6 Formulas ................................................................................................................ 6-1

6.1 Introduction .................................................................................................... 6-1

6.2 Expressions and Tables .................................................................................. 6-1

6.3 Formula Input Window .................................................................................. 6-3

7 Segment Definition ................................................................................................ 7-1

7.1 Introduction .................................................................................................... 7-1

7.2 Further Functions in the “Segment Management Window” .......................... 7-3

7.2.1 Connections between two nodes ................................................................ 7-4

7.2.2 Modelling Supports with Spring Elements ................................................ 7-7

RM Bridge Contents

M o d e l e r U s e r G u i d e I I I


7.2.3 Cross members ......................................................................................... 7-10

7.3 Copying Segments or Sequences ................................................................. 7-14

7.3.1 Copying Complete Segments ................................................................... 7-14

7.3.2 Copying Sequences of a Segment ............................................................ 7-14

7.4 Existing FE-Cross-Sections at the Segment Points ..................................... 7-16

7.5 Active Segment Point Details ...................................................................... 7-16

7.6 Stay cable input ............................................................................................ 7-17

7.7 Segment Type „Free Pier“ ........................................................................... 7-17

7.8 Link Segments ............................................................................................. 7-17

8 Creating the RmBridge Analysis Model ................................................................ 8-1

RM Bridge General Information

M o d e l e r U s e r G u i d e 1 - 1


1 General Information

1.1 Introduction

Every structural analysis is based on mathematical models. The quality of the answers

gained from such models depends strongly on the quality of the approximations and

generalizations that underlie each particular model.

Such approximations are necessary to describe geometric properties and the resistance

behavior of structures among others.

The Modeler of RmBridge (formerly geometric preprocessor GP) was invented in order

to achieve high accuracy in describing the geometry of bridges.

The RmBridge Modeler is a geometric pre-processor for the definition of structural

bridge systems. It supports the construction of road axes in both plan view and elevation

and generates structural information for bridges along such road axes. Powerful

interactive tools allow the definition of cross-sections for these bridges. The Modeler

transforms the individual axes together with the associated cross-sections into a

structural database and makes this information available for analysis in RmBridge.

Describing general concepts and the basic program functions is the aim of this ‘Modeler

User Guide’. Detailed input descriptions are given through online help texts by pressing

the <F1> -button. They are not repeated in this book.

The input follows some basic rules, which comply with most Windows applications.

The database of the Modeler is part of the RmBridge database. However, it consists of

files (gpdata*.gp9) which are separate from the actual analysis database (db-*.rm9) of

RmBridge. The Modeler database is stored in the RmBridge project directory in parallel

tot he analysis database. The file management is either done by respective functions in

the Modeler or by Windows applications such as the Windows Explorer.

General bridge modeling concepts are discussed in the “RmBridge Analysis User

Guide”.

1.2 Program Start

The Modeler is started in the main menu of RmBridge, either by selecting the main

menu function Modeler, or by selecting the respective function <Modeler in the

navigation tree.

The main input window with presentation of the axes in plan is presented on selecting

the Modeler (see Figure 8 - Main input window). In this window, new axes can be input

and existing axes modified. The main graphic presentation window of the Modeler

overlaps the main graphics window of RmBridge. The small RmBridge graphics

window beneath the navigation tree remains related to the RmBridge analysis database




and shows the current calculation model. The navigation window remains unchanged,

only the sub-functions of the Modeler are presented in addition to the RmBridge

analysis functions.

Any already defined axes are directly presented in the graphics window when the

Modeler is started. An empty window appears if no axes have yet been defined. The

respective icons for defining or modifying axes are arranged at the left edge of the

graphics window. The user can switch to the other functions of the Modeler, e.g. cross-

section definition or segment definition, by selecting the respective function in the

navigation tree.

On selecting the exit button ( -Icon) or any other RmBridge function outside the

modeler, the program leaves the Modeler level and returns to the RmBridge analysis

level (without automatic update of the RmBridge analysis model). The analysis model

update is performed by pressing the Remodel button replacing in the Modeler the

RmBridge Recalc button (see section 2.1 and chapter 8).

1.3 Input Conventions

All communication between the user and the Modeler is done interactively and all

modifications to the model are updated immediately in the representations on the

graphic screen. A special input sequence is not required – any part of the structure can

be defined independently - and default values are usually provided for information that

is not explicitly entered. The structural data can be passed on to the analysis database of

RmBridge at any point, and more information can be added to the analysis model at a

later stage with using the input functions provided directly in the RmBridge GUI.

Two types of input windows are used in the Modeler: Multi-tasking windows and

single-tasking windows. Multi tasking windows can be opened and worked on

simultaneously. They are not active when a single-tasking window is open. Single-

tasking windows are used for the definition of objects and must be closed by clicking on

<Ok> or <Cancel> .

Input fields within such input windows provide the means to enter numbers or strings,

so-called radio buttons offer choices of alternative options and check-boxes (or option

fields) allow the activation or de-activation of program options which do not exclude

each other. Buttons are used to trigger actions such as <Ok> or <Calculate> while

icons or symbols call whole program sequences which usually require additional input

through input windows.

Existing objects are often represented in selective lists which are usually accessed by

clicking the arrow next to an input window (Figure 1), or by double clicking on the

corresponding line.




Icon or Button

Radio button

Input field

Button Selective

list

Check box

Arrow

Figure 1 – RmBridge Modeler Input

1.4 Definitions

1.4.1 Bridge Axes

In many instances the precise geometry of a bridge must be derived from a known road

or railway axis. The RmBridge Modeler provides all the necessary functions to enter

such axes and to use them as a basis for all ensuing modeling operations. The distance

measured along an axis is called station. An axis in plan view is defined by straight

lines and arcs which can be connected by spiral-shaped curves called spirals. In

elevation, an axis is given by a series of straight lines, arcs and parabolas. The

combination of the information from the two views defines the three-dimensional

position of the axis.

1.4.2 Segments

Segments identify components of a bridge and group logical units together within a

bridge (e.g. bridge girders, piers, cross beams). Segments are partitioned by segment-

points. Segments are either related to an axis (master segments) or depend on the

geometry and position of specified segment-points in other segments (slave segments)

(Figure 2).




Axis

Bridge

Main

girders

Piers

Cross

beams

Axis Structural

points

Master segment (main girders)

Slave

origin

Slave

reference

line

Reference

line for pier

Supports Pylon

Figure 2 - Master segments and slave segments

Segments are connected at segment-points. The slave origin specifies the position of

the reference line for the slave segment. The connection point(s) specify the position of

the physical connection between segments. These connections in the structural model

are usually made with eccentric spring elements with a physical length of zero. Each

segment-point becomes a node in RmBridge and structural elements are generated

between each two neighboring nodes within a segment for the analysis in RmBridge.




Slave reference line

Segment points Segment point

(master)

Slave origin

Segment point

slave

Eccentric

connections

Spring

elements Connection

points

Figure 3 - Connection between master segment and slave segment

1.4.3 Cross-Sections

Cross-sections of segments are modeled with cross-section elements (Figure 4). These

three and four-sided elements are used in RmBridge to compute all relevant cross-

section properties.

Certain reference points within the cross-section such as reinforcement-points, stress

check points, connection points, temperature points or geometry points can be identified

during the cross-section input sequence in the Modeler.

1 1 1 1 1 1 1 1

2 2

2 2

2 2

2 2

1 1 1 1 1 1 1 1

1 1

1 1 1 1 Part

numbers

Segment points

Figure 4 - Cross-sections and Cross-section elements.

1.4.4 Parts

Cross-sections can be split into parts. Each part consists of a number of cross-section

elements or, alternatively, a number of other parts (Figure 4, Figure 5). These parts can

be referenced to create a multiple series of structural elements within a single segment.

Parts can also be used to define composite action within a beam, consisting of two to

eight parts (Figure 6).




Only web

(cross-section A)

Only flange

(cross-section B)

Composite section

(cross-section C=A+ B)

Segment points

= Nodes

Figure 5 - Flange & web forming a composite cross-section




Modeler:

1 series of segment points

1 part

RmBridge:

1 series of structural nodes

1 series of structural elements

Modeler:


3 parts (A, B, C=A+B)

RmBridge:



Modeler:


2 parts (A, B)

RmBridge:



A

B

C=A+B

(composite)

Modeler:


12 parts (A-K)

RmBridge:



B

A

E

D

H

G

K

J

C=A+B F=D+E L=J+K I=G+H

B A

Figure 6 - Examples for parts forming various cross-sections




1.4.5 Variables

Certain geometric parameters may vary along an axis according to simple mathematical

rules (e.g. variations in cross-sections (Figure 7), distance of lanes from the main axis).

These rules, or functions, can be entered and referenced in the relevant input sequences.

H=f(station)

t=f(station)

Figure 7 - Cross-section shape & formulas

RM Bridge Main Input Window



2 Main Input Window

When the Modeler has been started, the main input window as shown in Figure 8 is

displayed. Axes, cross-sections, segments etc. may be defined with the respective

functions in the navigation tree, and the data are graphically presented in the graphics

window. The main window is also the input pad for axis definition in plan view.

Status-bar

Menu bar

Main toolbar

3D-view toolbar

3D-view orientation

Main 3D-View

Detailed

3D-View

Navigation

tree window

Figure 8 - Main input window

Program

version

Project

directory

Application

control




2.1 Program Version, Project Directory

The top-most line of the window is related to the super-ordinate RmBridge project and

shows the active project directory and the release number of used RmBridge program

version. The application control button at the top right allows for the program to be

minimized into a small icon (usually at the bottom of the window) or to maximize

the window. Only the -button is related to the Modeler session. It terminates the

Modeler input session and the program returns to the RmBridge analysis level.

However, no update of the analysis model is automatically performed when the Modeler

level is left.

In order to check the Modeler data, to create the respective geometry data of the

analysis model and to update the analysis model in the RmBridge database, the function

Remodel must be selected and started with the corresponding options (see chapter 8,

Creating the RmBridge Analysis Model).

2.2 General Toolbar

This toolbar provides access to some basic functions which can be called upon at any

point in an RmBridge session.

......... <show log-file> View history of program logs.

......... <explorer> Open the current project folder in windows-explorer.

......... <error> View warnings and errors of the recent calculation.

......... <calculator> Open windows calculator.

......... <text editor> Open and edit text files from the current project.

......... <Crt> Open and view plot files from the current project.

......... <freehand symbols> Show freehand symbols for view settings.

......... <RM-setup> Change GUI presentation parameters.

......... <print> Print plot files.

......... <help> View online help.




......... <manuals> View user guides online.

......... <Tdf> View tdf-report files.

2.3 Navigation Panel

In the navigation panel you can switch between three tabs:

<Navigation>: Selection of the different RmBridge functions or

sub-functions of the modeler respectively (axes, cross-sections, segments, ...). If

a super-ordinate RmBridge function is selected, the program leaves the Modeler

level without update of the analysis model and returns to the RmBridge level.

Within the Modeler the functions for defining and modifying axes, cross-section,

segments, etc. can be easily selected.

< >> >: Recent projects list. The previously used project directories are

listed. With double click it is easy to switch between different projects

(equivalent to File Open RmBridge Project.

<Disk:Size>: Allows for using Windows Explorer features within the project

directory.

2.4 Unit Control

In the configuration window shown on selecting Modeler Options Units the user

can change the units of the Modeler database for structural dimensions, cross-section

dimension, angles and temperatures. The data in the database are then presented in the

selected units in all input and output windows of the Modeler.

In general, all user-defined units shall be defined in the super-ordinate RmBridge level,

and to avoid defining deviating units in the Modeler. Different units in the analysis

model and the Modeler may cause severe problems, especially if variables as tables or

mathematical expressions are defined and used in the project.

2.5 Axis, Cross-Section and Segment List Windows

Every project may consist of an unlimited number of axes, segments or cross-sections.

Input actions always refer to the active object that is displayed in the corresponding

window. Clicking on the axis, cross-section or segment list icons at the top right of the

main window (Figure 8) leads to an input list, which contains all existing objects of the

selected type. Use the functions described in chapter 2.6 to modify the list or click on

the object in the list which needs to be activated for the ensuing input actions.




“Open list of axes”: Opens a list of the existing axes, which may be added, modified, or

deleted (see chapter 3 and 4).

“Open list of cross-sections”: Opens a list of existing cross-sections, which may be

added, modified, deleted, imported, or exported (see chapter 5). Global mesh

refinement can be selected here to refine all elements of one cross-section. The edges

of the elements are divided by the number of the input value. I.e. if you input ‘3’ for a

quadrangle you get 9 elements.

“Open list of segments”: Opens a list of the existing segments, which may be added,

modified, or deleted (see chapter 7).

2.6 Edit Functions

Several input sequences require selection lists to be edited. The icons in this vertical

toolbar at the left side of the window provide the functions for these actions. When the

corresponding input window is opened, the functions described below may be chosen.

A direct selection of these functions is also possible by hitting the right mouse button.

The selection of several lines of a list is done by either press the space key in the

corresponding lines or with “Ctrl + left mouse button”. The selected lines are

highlighted in red letters.

Opening the database in edit mode (modify function) is also possible by double clicking

on a line with the left mouse button.

“Insert before selected item”: Insert line before the selected object.

“Modify selected item”: Modify the selected object.

“Insert after selected item”: Insert line after the selected object. This function is only

available for lists which are not sorted automatically.

“Copy selected item”: Copy the selected object to the end of the list.

“Numbering”: Sort and re-number the list.

“Delete selected item”: Deletes the selected object.

2.7 Zoom functions

The scale and the position of the presentation on the screen can be manipulated by the

functions that can be reached by clicking the icons in this toolbar. All of these zoom

functions can also be activated by free hand symbols (see chapter 2.7.2).

In 3D view, the object can be rotated easily by holding the left mouse button and

moving the mouse.




2.7.1 Icons

“Full view”: Fit the entire project to the screen.

“Enlarge”, “Smaller”: Zoom into / out of the current plot.

“Shift left”, “Shift right”: Move the current plot left / right.

“Shift up”, “Shift down”: Move the current plot up / down.

“Redraw view”: Redraw the current screen.

2.7.2 Free-Hand Symbols

The RmBridge Modeler also recognizes a range of so-called free-hand symbols for

different screen manipulations. These functions are available in all graphic windows.

The symbols are drawn using the left mouse button while holding down the <Ctrl> -

button at the same time. The following symbols are available:




“Smaller”: Enlarge the view; picture becomes smaller (zoom out).

“Enlarge”: Scale down the view, picture becomes larger (zoom in).

“Full”: Fit the entire project to the screen.

“Redraw”: Redraw the current plot.

“Zoom”: The line represents the diagonal (to scale) of the required zoom rectangle.

“Up”, “Down”, “Left”, “Right”: Move the plot horizontally or vertically in the

direction of the drawn line.

“Previous”: Draw the previous screen.

“Hardcopy”: The actual screen is saved as bitmap (*.bmp) with the current screen

solution.

2.8 Modeling Functions

These icons provide access to the input and query functions for the definition of the

bridge axis, cross-sections and segments. These functions will be discussed in detail in

chapters 3 to 7.




“Open 3D-view”: Opens the window for a three-dimensional view of the defined

structure.

“Show ground plan”: Pops up the plan view window. (see chapter 3, Plan View

Geometry).

“Show elevation window”: Opens the input window for the definition of the axis in

vertical view (see chapter 4, Vertical View Geometry).

“Show cross-section window”: Opens the input window for the definition of cross-

sections (see chapter 5, Cross-Section Definition).

“Open segment points of current segment”: Opens the input window for section points

(see chapter 7, Segment Definition).

“Opens list of formulas and tables”: Opens the input window for arithmetic formulas

and tables (see chapter 6, Formulas).

2.9 Recalculation Functions

“Fast recalculation”: This button can be used to calculate all assigned FE-cross-sections

in the segment list.

“Recalculation with formula evaluation”: This button can be used to update FE-cross-

sections after a formula or table has been modified. In contrast to the button above, all

variable values are calculated by evaluating the formula and table expressions. This

type of calculation is more time consuming and is only necessary if a used formula or

table has been changed before.

2.10 File Functions

The functions in this toolbar manage the import and the export of data.

“Import from TCL file”: Data are read from an ASCII file created by ASCII export of

the Modeler database. The objects are transferred into the database. Note that only files

containing Modeler data can be read within the Modeler. These are TCL files created

from the Modeler level. TCL files describing the RmBridge analysis model cannot be

read, if the Modeler level is active.

“Export to TCL file”: The Modeler database is read and stored in an ASCII file in TCL

format for backup purposes (default name gp9.tcl). .

RM Bridge Plan View Geometry



3 Plan View Geometry

3.1 Introduction

First the axis has to be created in the axis list (see chapter 2.5).

“Show ground plan”: The geometry of an axis is defined by a series of axis elements.

In plan view these axis elements are straight lines, spiral curves, arcs, and cubic curves.

Spirals connect axis elements with different curvatures. The shape of the spiral is

defined by input parameters. An axis must be activated (see 2.5) before any axis

elements can be entered. Axis elements can be defined via input windows accessed

through the ‘Toolbar for horizontal axis definition’ (Figure 8). Axis elements are

always added at the end of the existing sequence. As soon as an axis element is fully

defined it is also plotted on the graphic screen. Once entered, the geometric properties

of axis elements can only be modified in the axis list, which can be reached by the

toggle button (“Switch to list view”). However, individual elements can be deleted

sequentially starting from the end of the sequence using the “delete last axis element”-

icon and new elements may be defined. This is done by choosing the icon “Delete last

axis element” (see chapter 3.2).

3.2 Toolbar for Horizontal Axis Construction

“Switch to list view”, “Switch to graph view”: Switch between the graph view with a

good overview of the axis and the list view where the axis parameters can be easily

modified.

“Append start point or straight line to axis”: Coordinates for a point (X, Y) can be

entered which defines the starting point of the axis. Every axis has to start with the

input of a point definition. A starting direction for this axis can also be entered by the

input of an angle.

“Append straight line to axis”: Defines a straight line along the axis. Only the length of

the straight can be entered as the direction is always given by the previous axis

elements. The line continues tangential to the endpoint of the last axis element.

“Append circle to axis”: The radius and length along an arc can be specified. A positive

radius signifies a left turning curve and a negative radius signifies a right turning curve

in relation to the axis direction. The line continues tangential to the existing part of the

axis.

“Append spiral to axis”: A spiral curve can be entered to smoothen the transition

between elements with different curvatures. This transition curve is defined by the

radius at the start and the end of the curve and the spiral parameter, which defines the

rate of change in curvature. The spiral continues tangential to the endpoint of the last

axis element.

RM Bridge Plan View Geometry



“Append cubic curve to axis”: A cubic element is connected to the previous axis

element. The input can be done either by radius with start and end radius or curvature

with start and end curvature. The curve continues tangentially to the endpoint of the

last axis element.

“Delete last axis element”: The undo icon deletes the last axis element in the active axis

after this action is confirmed one more time. This action can be repeated to delete

further axis segments.

3.3 3D Points

In addition to the axis definition the Modeler allows for defining and managing arbitrary

points in space. These points are named objects with the coordinates in space as

properties. They can be used in various situations as reference objects (e.g. as start point

of “Segments”).

The 3D point management also offers interfaces to other programs with a point database

(e.g. road planning software or geodesy programs). They allow taking over points from

point lists of other programs or storing such point lists for being used in other programs.

Note that the sequence of the coordinate values is X, Z, Y in the RmBridge coordinate

system, corresponding to the common sequence in geodesy applications, where X and Y

are the coordinate in ground plan and Z indicates the altitude.

RM Bridge Vertical View Geometry



4 Vertical View Geometry

4.1 Introduction

First the axis has to be created in the axis list (see chapter 2.5).

“Show elevation window”: The axis elements to describe the geometry of an axis in

elevated view available in the Modeler are straight lines, arcs and parabolas. These axis

elements can be entered in two ways: sequentially, or as a tangent polygon to be

rounded with parabolas in a further step. Horizontal co-ordinates and distances in these

input procedures are always measured along the axis (station). The station range of the

axis definition in elevated view may differ from that in plan view. A mouse-click on

the corresponding icon in the ‘Modeling functions’ toolbar (see chapter 2.8, Modeling

Functions and Figure 8) activates the input window for the axis in elevation as shown

in Figure 9.

Please note that an axis must be activated in the “Axis management window” and that

every axis must be defined in all three dimensions, i.e. in plan and elevated view.

Name of the active axis Close window

Graphic screen for

the axis in vertical

projection

Toolbar for vertical

axis construction

Status and prompt

Zoom functions

Figure 9 - Input window for axes in vertical view

RM Bridge Vertical View Geometry



4.2 Toolbar for Vertical Axis Construction

“Switch to list view”, “Switch to graph view”: Switch between the graph view with a

good overview of the axis and the list view where the corresponding values can be

easily modified.

“Append start point or straight line to axis”: Coordinates for a point (X, Y) can be

entered which defines the starting point of the axis. Every axis has to start with the

input of a point definition. A starting direction for this axis can also be entered by the

input of an angle.

“Append straight line by station”: A straight line of specified length can be entered.

The line continues tangential to the endpoint of the last axis element.

“Append straight line by station and height”: Defining the station or station increment

and the elevation at the end of the line specifies a straight line. The line continues

tangential to the endpoint of the last axis element.

“Append circle by station and radius”: Defines an arc. A radius and the length of the

arc can be entered. The arc continues tangential to the endpoint of the last axis element.

“Append circle by station and height”: The station or station increment in combination

with the elevation of the axis at the end define the geometry an arc element. The circle

continues tangential to the endpoint of the last axis element.

“Append parabola to axis”: A parabolic element is defined by the elevation at the end

and a station or station increment. The parabola continues tangential to the endpoint of

the last axis element.

“Delete last axis element”: The undo icon deletes the last axis element in the active

series after one more confirmation. This action can be repeated to delete further axis

segments.

“Parabola by rounding a tangent point”: Fits a parabola between two tangential straight

lines.

“Parabola by rounding a polygon of 3 lines”: Fits a parabola to a series of three straight

lines. The first and third straight line each serve as a tangent to the parabola and the

middle line is eliminated after clicking on this line.

RM Bridge Cross-Section Definition



5 Cross-Section Definition

5.1 Introduction

The geometry of cross-sections is defined by connecting intersection points of

construction lines (CL). Construction lines are entered using the tools in the CL-toolbar

at the top left hand side of the Cross-section input window (Figure 12). Each

construction line (CL) is constructed in relation to at least one other construction line or

to one of the two default construction lines ‘CL1’ and ‘CL2’, the two axes of the cross-

section. The intersection point of ‘CL1’ and ‘CL2’ marks the point where the axis

intersects the cross-section plane.

Each cross-section is partitioned into cross-section elements. A cross-section element is

a two-dimensional three or four-sided area enclosed by parts of CL's. All relevant cross-

sectional properties are computed from this cross-section element mesh, the direction of

input has no influence on the result. Adjacent cross-section elements must share corner

nodes to ensure correct connectivity in the cross-section element mesh (Figure 10), even

across part boundaries.

The sides of the cross-section elements must not intersect.

1 1 1

2

2

2

wrong

1

2

2

2 correct

1 1 1 1

Figure 10 - Connectivity of cross-section elements over part-boundaries

Cross-section elements with different properties can be grouped into cross-section parts.

Figure 12 shows the connection between CL’s, cross-section elements and parts.

Certain “reference points” within the cross-section such as reinforcement-points, stress

check points, connection points, temperature points or geometry points can be

identified. These points may consist of single points or be integrated in polygons.

A solid graphic cursor signifies that an input function is active. Use the <Escape> -

button to terminate an input sequence and to switch the cursor back to a dashed line

type. Please note that a cross-section must be activated in the “Cross-section

management window”. The logic connection between cross-section geometry and

segment-points is made at a later point (chapter 7, Segment Definition).




CL1

CL2

Construction

lines

Cross-section

elements Parts

Figure 11 - Construction lines – cross-section elements – parts

The icons at the top left of the cross-section window are pop out icons, which can be

accessed by hitting the right mouse button and choose from the list (Figure 12).

There are several possibilities of automatic element mesh refinement:

Global mesh refinement: All elements are subdivided automatically (see chapter 2.5).

Local mesh refinement: Elements containing a reference point are refined (see

chapter 5.9).

Individual mesh refinement: An individual refinement of any element can be defined

(see chapter 5.7).




Cross-section

lock

CL-toolbar

Dimension line

Zoom functions

Status and prompt line

Delete

construction

lines

Create element Stiffeners

Create link

Reference points

Elongation or shortening

of construction lines

Part list Variable list Layers

Reference

sets list

Figure 12 - Cross-section input window

5.2 Construction Line (CL) Toolbar

CL’s are always defined in relation to one or more existing CL’s. These dependencies

are stored and can be viewed at a later stage. In order to create a new CL, an existing

CL must be activated and the dependencies entered (e.g. parallel, at an angle…). An

existing CL stays active until an input function is quit (<Esc>) and the cursor line type

has switched back to dash. Information about active CL’s can be requested via the

“Modify” -button in the “Edit toolbar” (chapter 2.6). Prompts in the “Status and prompt

lines” ask for the necessary information for these geometric operations. Numeric input

(e.g. distances) is specified in the “variable list”. That may be a constant value or a

variable, which may be defined in the input field at the bottom right of the window.

“Parallel translation”: Generates a CL at a certain distance parallel to an existing CL.

The distance is measured perpendicular to the reference CL (Figure 13a). Follow the

prompts and enter the distance through the “formula and parameter list”.




“Parallel translation along an axis”: Generates a CL at a certain distance parallel to an

existing CL. The distance is measured parallel to one of the axes (‘CL1’ or ‘CL2’)

(Figure 13b). Follow the prompts and enter the distance through the “formula and

parameter list”.

“Parallel translation along a point”: Generates a CL at a certain distance parallel to an

existing CL. The distance is measured perpendicular to the reference CL starting at a

specified point (Figure 13c). Follow the prompts and enter the distance through the

“formula and parameter list”.

“2 Intersection points”: Click on two existing intersection points of CL’s to specify a

new CL. Use the trim-functions or to crop the CL or to activate the whole CL.

“Absolute angle”: Click on an existing intersection point of two CL’s and generate a

new CL with an absolute angle (angle from the horizontal axis anticlockwise) given by

the “formula and parameter list” (Figure 13d). Use the trim-functions or to

activate the whole CL or to crop the CL.

“Angle relative to a base line”: Click on an existing intersection point of two CL’s,

specify one of the two reference CL’s as a reference line to generate a new CL at an

angle to the reference line given by the “formula and parameter list” (Figure 13e). Use

the trim-functions or to activate the whole CL or to crop the CL.

“Intersection polygon”: This function supports the definition of polygons which serve

the same purpose as construction lines. The polygon is defined by a series of CL-

intersection points and an optional parallel distance given by the “formula and

parameter list”.

“Parallel translation of a polygon”: A polygon parallel to an existing polygon at an

orthogonal distance given by the “formula and parameter list” can be created by this

function.

“Trim polygon”: An intersecting CL can trim a polygon.

“Delete unused construction lines”: Deletes all polygons and CL’s, which are not

referenced by cross-section elements, parts or reference points.

“Elongation or shortening at begin”: Trims the positive side of the active CL at x/y = 0.

Use this function again to un-do the trim function. This function also changes the

default for new CL’s, note the status line.

“Elongation or shortening at end”: Trims the negative side of the active CL at x/y = 0.

Use this function again to un-do the trim function. This function also changes the

default for new CL’s, note the status line.

“Change side”: Switches a parallel or an angle to the other side of the reference CL. A

CL must be activated for this function.

“Change object color”: The color of the constructions lines may be changed directly by

pressing the icon.




Reference CL

Distance

(variable field)

New CL

(a)

Reference CL

Distance

parallel to axis

(variable field)

New CL

(b)

Reference CL

Distance

(variable field)

New CL

(c)

Reference point

(intersection point

of two CLs)

Absolute angle

(variable field)

New CL (d)

Reference point

(intersection point

of two CLs)

Relative angle

(variable field) New CL (e)

Reference point

(intersection point

of two CLs)

Reference CL

Figure 13 - CL definition




5.3 Variables and Cross-Section Input

During the definition of construction lines (CL’s) for the cross-section input, certain

values have to be specified to define the exact position of CL’s in relation to others (e.g.

angles, orthogonal distances). These values are entered through the “Variable list” (see

Figure 12). If the user types a numeric value directly into the input field, then this value

will be taken as constant for every station along the axis. Alternatively the little arrow

next to the input field can be clicked. This leads to the actual “Variable list”. This list is

manipulated by the usual edit functions (see chapter 2.6, Edit Functions). Each

parameter is assigned to an alphanumeric name, a default value for representation

during the axis-independent cross-section definition and a dimension-type). At a

different point during the input session, a station-dependent function can be defined (see

chapter 6, Formulas). The cross-section parameter can be related to this function (see

chapter 7) and all elements that are related to the variable CL can be computed in their

true, station dependent shape.

5.4 Part, Formula and Point Lists

When cross-section elements are generated they are assigned to the part number which

is specified in the “Part list window” (see Figure 12).This list contains the numbers,

reference points and composite definitions. The part number is plotted in the middle of

each cross-section element. A valid part number must be specified when elements are

created. If a new part is created a part reference point for this part must be defined.

Some functions require the input of numeric or parametric data. These values can be

directly entered in the “Variable list window”. In some instances this value is not

constant for all cross-sections in a segment. Alphanumeric parameters can be specified

for these situations and can be activated by clicking on the arrow next to the selection

window (Details see chapter 6, Formulas).

Reference points can be specified for stress checks, reinforcement specification and

temperature definitions or to be used as connection or geometry points. These points are

grouped together logically and a group name must be specified through the “Reference

points list” before such points are defined.

5.5 Layers

All the different drawing elements can be defined on different layers to obtain clearly

arranged cross-sections. Up to ten layers are possible.

The layers window can be opened by clicking on the arrow beside “Layers” at the

bottom left of the window. The active layer may be chosen (only one at a time

possible). An unlimited amount of visible ones can be displayed at once.




5.6 Cross-Section Lock

Once a cross-section is assigned to a structural element (see chapter 8 Creating the R)

the cross-section is “locked”. It cannot be modified unless it is “unlocked” by clicking

this icon. This prevents accidental changes to data that may already be used for analysis

in RmBridge.

5.7 Element Definition

This group of functions supports the definition of cross-section elements. These three-

or four-sided cross-section elements are the basis for a cross-sectional finite elements

(FE) analysis that determines the structural cross-section properties. Every cross-section

element must be assigned to a part number, which needs to be entered in the “Part list

window”.

5.7.1 Icons

“Linear 4-point element”: Generates a linear cross-section element. Click on three

intersection points of CL’s to define the first three points of a cross-section element. By

clicking on the first intersection point once again a three-node element will be created

(Figure 14b). Click on a fourth intersection point of two CL’s to define the fourth node

of a four-node cross-section element (Figure 14a). By clicking on the right mouse

button or the <Esc> -button the input is terminated.

“Linear 8-point element”: Generates a cross-section element, which allows for curved

edges. These elements need the definition of three or four corner points and one point

for each curved side. To create a three-sided cross-section element (Figure 14d) six

intersection points have to be clicked. Click on the first intersection point once again

the three-sided cross-section element is defined. Continue with the definition of point

number seven and eight for a four-node element (Figure 14c).

Copy functions see chapter 5.7.3.

“Rounding an element edge”: This function turns a linear cross-section element side

into a quadrangular cross-section element side. A rounding radius can be specified that

determines the curvature of the side. A positive radius signifies outward bulging of the

cross-section element (Figure 14e) and a negative radius signifies inward bulging

(Figure 14f).

“Assign element to active part”: Re-assigns a cross-section element to the active part

number.

“Shear lag property”: Toggles the shear state of a cross-section element. Cross-section

elements can be switched to a state where they only carry shear loads (no bending!) and

back to a state where they carry both, shear and bending. This function controls the

definition of effective widths (shear lag).




“Assign shear factors”: Shear factors for Qy, Qz, and Mx may be entered.

“Create stiffener at element edge”: This function allows creating bracings at existing

cross-section elements easily. Follow the prompts and modify the dimensions of the

bracing in the opened input window “New element Stiffener” (Figure 15). Note: It is

not yet possible to combine stiffener with local or individual mesh refinement.

linear Mixed – linear &

curved sides

(a)

(b)

(c)

(d)

(e)

(f) -R

+R

curved parabolic

Figure 14 - Cross-section elements.

Thickness 2

Depth

Width

Angle 1 Angle 2

Thickness 1 Thickness 3

Figure 15 - Bracing elements




5.7.2 Individual Mesh Refinement

When selecting an element and hitting the “Modify”-button, an individual mesh

refinement can be chosen by selecting a refinement type of the list (Figure 16).

Figure 16 - Individual mesh refinement

If other border elements exist where edges are parted, the neighboring elements are also

refined automatically, corresponding to the prior refined element (see chapter 5.9.2,

Local Mesh Refinement).

5.7.3 Copying Elements

There are four different possibilities to copy elements within a cross-section. The copied

elements depend geometrically on their source elements. If the geometry of the source

element is changed, the geometry of the dependent elements changes as well.

Construction lines and reference points are not copied.

“Copy elements to active part”: With this function one or more elements of a part can be

copied to an active part. The current part (to which the new element should be copied to) has

to be activated in the input field for parts. The position of the copied element relative to its

active part position is the same as the relative position of the source element to its part

position. Elements get copied to the active part by clicking the source elements. Follow the

prompts in the command line.

1

1 1

1

2

Source element Copied element

1

Part position 1 2

Part position 2

Figure 17 - Copying of elements to an active part


M o d e l e r U s e r G u i d e 5 - 1 0


“Copy elements by mirroring”: With this function one or more elements can be mirrored

relative to a specified axis. The mirror axis is a chosen construction line.

1 1

1

1

Source element 1 Copied element 1

1

1

Mir

ror

axis

Source element 2 Copied element 2

1

1

Figure 18 - Copying of element by mirroring

Note that after copying, rotating and mirroring elements, the position of the axis

(intersection point of construction line 1 and 2) has the desired position in your defined

overall cross-section.




“Copy elements by rotation”: With this function elements may be copied and rotated about a

defined angle (). This angle has to be input in the “Variable field” as constant or as variable.

Choose the centre-point (intersection point at two construction lines). By clicking on a source

element it will be copied and rotated about the specified angle. This procedure may be repeated

infinitely.

1 1

1

Source element

Copied element

Figure 19 - Copying elements by rotation

“Copy elements by translation”: With this function elements can copied and moved along a

chosen base line. The required distance in the base line direction has to be input in the

“Variable field”. This can be a constant or a variable, which has been defined before.

5.8 Link Segments

5.8.1 Principles

They were created especially to construct truss girders, though this instrument can be

handy in many other cases e.g. cross beams, diaphragms, braces, or to create cables of

suspension bridges.

First nodes are being defined in 3D space along the axis (see Figure 20). The first two

dimensions for the nodes are defined as a cross-section. The third dimension is added by

using segments.

Any of the nodes can be connected by link segments. A link segment may only lead

from one node to another node.




Figure 20: Truss girder definition with link segments.

It is necessary to define at least two cross-sections: one for the geometrical definition of

the cross-section of e.g. truss girders, and the second to define the cross-section of the

link segment beam. It is possible to define different cross-sections at begin and end of

every “Link segment”.

The cross-sections of the link segments are easily defined as any other girder.

5.8.2 Link Segment Cross-Section

To define the location of the link segments in 3D space you have got to define nodes.

The first two dimensions are added in the cross-section window. This is done by adding

“parts”. Open the parts window by clicking on the arrow beside “Part:” at the bottom of

the cross-section window. Then hit the “insert” icon. Select “Cable” or “Node”,

depending on what you want to create. For truss girders you have to choose “Node”. If

you choose “Cable” the link segments that you create is only able to support tensions.

After that you have got to define which nodes the link segments are connecting.

“Create link”: This is done by choosing this icon at the top of the cross-section screen.

After clicking on two nodes, an input window pops up (You can also double-click on

the same node for link segments along the axis!).

Here you have to input

a name (which you need later in the segment list),

2D location between the created nodes (“Parts”-you have to take care of the order of

your input),

the position of the beams of the link segments (You can change the starting and

ending location by clicking on the button <Change> - the position of the link

segments and the position of the beams can be different!),

and the segment point steps (you can imagine it as the third dimension).

For every location in space you have to create an own link segment.




Note: The position of the link segment can be different to the position of the

beam itself.

Further definition for link segments see chapter 7.8, Link Segment.

5.9 Reference Points

The functions in this toolbar facilitate the definition of points within a cross-section.

These points can be used as:

“Reinforcement points” specify the position of conventional reinforcement bars

within the cross-section.

“Stress-check points” provide stress results, which can be requested at a later stage

and can be used for various design checks (e.g. fibre stress check).

“Temperature points” definition for temperature loading definition.

“Connection Points” specify the actual points of contact between segments

(Figure 3).

“Geometry points” for the positioning of internal cables.

Points are grouped together logically. Group names must be assigned in the “Reference

points list”.

5.9.1 Icons

“Reference point at an intersection point”: Intersection points of CL’s can be identified

as reference points in this function.

“Reference point relative to an elements node”: Allows the definition of reference

points in relation to cross-section element nodes. The two offset distances to the node

in X and Y direction (DX, DX) and the types must be specified.

“Reference point relative to element edges”: Two orthogonal distances from two

element edges (DX, DX) give the position of reference points generated by this

function.

“Reference point relative to the center of gravity or the assigned part”: The selected

reference point is always located in the center of gravity of every cross-section along

the axis, even if the cross-section is varying. The center of gravity in X or Y direction

may be selected.

“Reference point with absolute coordinates”: Points can be entered with their co-

ordinates and their types.

5.9.2 Local Mesh Refinement

The local refinement can be used for stress check points. While inserting of modifying

stress check points the “Activate local refinement” may be selected. The element where




this point is situated is automatically refined. The refinement depends on where the

stress check point is located in the element – see Figure 21.

If the point is in the centre (point 1) the element is refined like the left element in

Figure 21.

If the point is near to the edge in the centre (point 2) the element is parted like in the

centre.

If it is near to a corner (point 3) the refined mesh looks like in the picture on the

right.

1

2

1

3 2

3

Figure 21 - Local mesh refinement.

If other border elements exist where edges are parted, the neighbouring elements are

refined automatically, corresponding to the prior refined element. In Figure 21 these are

the points 2 and 3. The refinement looks as in the Figure 22.

Figure 22. Mesh refinement – bordering elements.




5.10 Dimension Line

“Length dimensioning”: This tool allows a simple definition of dimension lines within

a cross-section. An existing CL as a reference line for the dimension line and two

points between which the distance has to be measured have to be selected. The

dimension is drawn over the first selected dimension line.

“Angle dimensioning”: With this simple angle dimensioning tool it is possible to

measure an angle between two CL’s. The dimension value is drawn along a defined

CL.

5.11 Import and Management of Cross-Sections

“Import cross-section from catalogue”: This button, offered in the “cross management

window” (Figure 23), opens a catalogue with already existing cross-sections (Figure

24). Different types of cross-sections can be selected. The name of the new cross-

section - given by the user - cannot be equal to an existing cross-section name. With the

<Apply> -button the currently chosen cross-section will be copied into the current

project.

Opens the cross-section

catalogue (Import of a

cross section into the

current project) Writes selected cross-

section to the cross-

section catalogue

Import of DXF files

(AutoCAD)

Figure 23 - Cross-section management window

It is recommended to save your own catalogue into a ASCII-file after modifying

it, but don’t use the name gpcata_e.dat (English version) in the

program directory, because this file will be overwritten by an

update or a de-installation of GP. The access to ASCII-

interface of catalogue is possible in the cross-section

management window.




Groups of

different cross-

section types

Pre-view of a

selected cross-

section

Cross-sections

in the selected

group

Applys the

selected cross-

section

Figure 24- Import – cross-section window

When opening ”Catalogue” ”Work on catalogue” the cross-section catalogue can be

managed (see Figure 25). The list on the top left of the opened window shows all

existing cross-section groups. With the “Edit functions” at the top left, new groups can

be created and existing groups can be modified or deleted.

The list at the bottom of the window contains all cross-sections belonging to the

selected group. With the “Edit functions” at the bottom left, these cross-sections can be

copied, modified or deleted.

“Import from TCL file”: Clicking on this button the windows open file dialog for

selecting a ‘catalogue-file’ opens. A pre-defined cross-section catalogue is stored in the

current program directory. The selected file is opened in the ASCII import mode. By

clicking the left mouse-button while pressing the <Ctrl> -button a cross-section can be

marked. With <Apply> the selected cross-section will be copied to the current project.

“Export to TCL file”: This function saves the whole cross-section catalogue into a

named TCL file.




Pre-view of a

selected cross

section

Edit functions

(Insert/modify/

Delete)

ASCII-„Import-button“

resp. „Export-button“

Cross sections

in the selected

group

Groups of

different cross

section types

Figure 25 - Cross-section catalogue-management window




“Export cross-section to catalogue”: This function offers the possibility to insert a user

defined cross-section from the Modeler to the cross-section catalogue. This application

is offered in the cross-section input window (Figure 26). A cross-section, to be added

to the catalogue, can be assigned either to an existing group or to a new one. In the

input field “description” cross-section specific details can be input. With <Apply> the

cross-section is added to the selected group. In the window at the top right the pre-view

of the selected cross-section is shown (Figure 26).

“Import cross-section from AutoCAD file”: DXF/DWG formats can be imported to a

defined insertion position to the RmBridge Modeler.

View of the

created cross-

section

Description of

the created

cross-section

Shows the

existing cross-

sections of the

selected group

Applys a new

cross section

Different

groups of

existing cross-

section types

Figure 26 - Insert cross-section window

RM Bridge Formulas



6 Formulas

6.1 Introduction

Certain geometric parameters may vary along an axis in accordance with certain

(mathematical) rules (e.g. variations in the flange depth, distance between two main

girders). These rules, or functions, must be taken into account at three different stages

during the input in the Modeler (Figure 27). Firstly, the variable parts of a cross-section

must be identified as such (see chapter 5.3, Variables and Cross-Section Input).

Secondly, the actual rules must be entered. This is the purpose of the functions

explained in this chapter. And thirdly, the cross-section parameter must be related to

the appropriate mathematical expression, so that the exact position of the variable parts

can be computed as functions of the station along a segment.

constant

constant

constant

fh(s)

Stations – s

fh(s)

s=a s=b

fh(s=a)

fh(s=b)

constant

constant

Figure 27 - Variable flange depth

6.2 Expressions and Tables

The respective variation rules can be entered in two different ways – mathematical

expressions or tables. For the definition of both the following pre-defined functions are

available:

RM Bridge Formulas



Station values “sg” (global station), “sl” (local station), “sp” (segment

point number).

Constants “pi” and “e”.

Basic trigonometric functions “cos()”, “sin()”, “tan()”, “acos()”, “asin()”,

“atan()”. Please note that all angles are given in radians!

Basic exponential and logarithmic functions “sqr()”, “ln()”, “log()”,

“exp()” with (exp(2.5) = e2.5

).

Logic functions “abs()”, “min()”, “max”, “hright()”, “hleft()”, “dirac()”,

“diract()”.

abs(a) gives the absolute value of the argument.

min(a,b) gives the smaller value of two arguments.

max(a,b) gives the greater value of two arguments.

hright(a,b) =1 if a>b, else =0

hleft(a,b) =1 if a<b, else =0

dirac(a,b,eps) =1 if b-eps<a<b+eps, else =0 (Figure 28a).

diract(a,b,eps1, eps2) = triangular interpolation (Figure 28b).

(a) 1

0

dirac() eps

a b

(b) 1

0

diract() eps1

a b

eps2

Figure 28 - Logical functions dirac() and diract()

Mathematical expressions can be entered alphanumerically (e.g. x^2/sg+cos(sg-50)). An

internal interpreter converts the expression into station-dependent geometric properties.

In many instances it is more practical to enter the station-dependent information for

certain known points and to interpolate between these points. For these cases, so-called

tables can be generated. Two values need to be entered for each discrete point – the

station (Var A) and the value of the function at this station (Var B). A number of

different interpolation functions are available in the Modeler (constant (Figure 29a),

linear (Figure 29b) and three different parabolic functions (Figure 29c-e)).

Both, mathematical expressions and tables, can reference other functions – both built in

or user-defined at a different point in the formula window. The <i> -button brings up a

graphic representation of the active table. For expression names only use characters a-z,

A-Z in the first position and in addition 0-9 and the symbol ‘_’ thereafter. Do not use

predefined function names.

Note: It is not allowed to use identical names for tables or functions as for

existing names of already defined variables.

RM Bridge Formulas



(a)

a

b

(b)

a

b

(c)

a

b (d)

a

b

(e)

a

b

constant linear

parabolic 0 parabolic 1

parabolic 2

Figure 29 - Interpolation functions for tables

6.3 Formula Input Window

Formulas consist of a name for subsequent identification, a mathematical expression, its

actual value, its type and an additional description.

RM Bridge Formulas



Mathematical

expressions and

table lists

Table

values Point edit

functions

Table

display

Table Load/Save

functions

Figure 30 - Formula input window.

The “Edit functions” described in chapter 2.6 (icons at the left side of the window) serve

as tools to work on the “Mathematical expressions and tables list”. The “Point edit

functions” provide access to the “Table points” of the active table. An active table can

be displayed on a separate graphic window by clicking on the <i> –button (Figure 30).

With the tools at the bottom of the window, one or several tables may be saved or

existing tables can be loaded. So, modifying and editing tables is easily done in the text

editor.

The actual or all defined tables can be saved to a simple ASCII format by clicking the

button <Save> respectively <Save all tables> . The ASCII files can be edited,

modified and extended. <Load> reads the changed file and updates the listing. Different

input types can be selected. <Load all tables> loads all saved tables and overwrites

the existing ones. This is a very powerful and easy to handle input facility for tables.

RM Bridge Segment Definition



7 Segment Definition

7.1 Introduction

Segment information is built from data generated by the functions described in

previous chapters. The geometry of segments in longitudinal direction depends on the

reference line (or axis for master segments) and in orthogonal directions on the shape

of the cross-section. All geometry definitions may be given in terms of formulas.

Segment points govern the degree of structural discretization within segments. The

structural system for RmBridge, which will be generated from the Modeler data, will

have a structural node at each segment point and structural elements between the

respective consecutive nodes.

Please note that a segment and an axis must be activated in the “Segment management

window” and the “Axis management window”.

Segment

point list

Active segment

point details -

before

Active

segment

point details -

after

Select active

segment

point details

Figure 31 - Segment definition input window




The following segment types are available in the RmBridge Modeler:

Main Girder

Pier

Cable

Free Pier

Cross Member




7.2 Further Functions in the “Segment Management Window”

“Toggle segment point/element view”: Switch between segment point and element

view. In segment point view the start and the end points of segments are shown

(=connection between segments), whereas in element view only the elements

(segments) can be changed.

“Move segment points”: To move segment points, mark one line in the segment list and

hit the “Move segment points” button. All the following segments to the end will be

selected. As “Station difference” enter a value for the displacement of the segments.

This displacement must not exceed the previous segment.

“Fast recalculation”: This button produces updated data if cross-sections have been

modified after they having been assigned to segment points previously. All cross-

section inputs have to be marked by an „OK“ in the segment point list.

“Recalculation with formula evaluation”: In contrast to the button “Recalculate”, all

variable values are calculated by evaluating the formula expressions.

“Show coordinates”: Shows the co-ordinates of the existing segment points.

“Show graph”: The existing FE cross-sections of the active segment can be displayed

by using this button (including formula evaluation).

<Connection> “Connection”: Defines connections between segments or

between a segment and a rigid support point (see chapter 7.2.1,

Connections).

<New “sg”-table>

“New “sg”-table”: This function is used to define tables with

the functions “sg”, “sl” and “sp” (station dependent functions),

which will be assigned to the segment points. The function “sg”

returns the global station at the segment point. The function “sl”

returns the local station at the segment point. Local means that

the station at the 1st segment point is 0.0 and the station of all

following points are related to the first one. The function “sp”

returns the number of the segment point.

<Points by Ref.-Segment>

“Points by reference segment”: Segment points related to points

of a reference segment can be defined. To each reference point,

a point in the current segment will be searched, where their

distance line is positioned normal to the axis of the current

segment. Optionally, two different tables may be built and

stored in files that consists of the distances between the points

and the angles between the cross-sections at the points,

respectively.

“Segment point details”: Switch between variable view

(variable definition) and parts view (material, numbering and

group definition).




7.2.1 Connections between two nodes

The connection input window (Figure 32) opens on clicking the <Connection> button.

Four possibilities are offered:

“New rigid” connection between two segments (e.g. topologic connection of two

segments to an overall structure) input by two parts or segment points,

“New Spring-0” for a connection to the ground from a node of any segment

point (spring constants are defined by clicking on <Constants>),

“New Spring” for a general connection between two segment points and

“New Abutment” as a fast abutment definition.

Description of the

defined connections

Create new

connections

Schema of the

connections

Figure 32 - Connection at segment points.

New Rigid Connection

When clicking on this button, a window for detailed input data opens to define a new

rigid connection between two segment points (Figure 33). The parts of the cross-

sections in the existing segments have to be numbered. The respective connection points

must have been defined before in the cross-section definition.

A beam can have only one rigid connection each at the start as well as at the

end.




First segment point

Connection-part of

the segment-point

2nd

connection-point

(segment, part)

Figure 33 - Rigid connection between two segment points

New Spring-0

With this function a spring element between an existing connection point (reference

point) of a cross-section and the “earth” (node 0) can be defined. Springs of this type

can be connected to a structural node of any segment point. The element number, the

spring constants and the direction of the spring have to be specified using the button

<Constants> in the input window shown in Figure 34.

Select a segment-

point for the

connection

Select a

defined

connection-

point

Selection if nodes

should be defined

by parts or by free

node number

Define the

constants of

the springs

Figure 34 - Spring to node 0 (rigid base)

New Spring

This function opens a window where springs between two connection points in the

cross-section can be defined. At least one node of a spring element has to be connected

to a structural node. The other node can be situated at a connection point anywhere




within the cross-section. The element number, the spring constants and the direction of

the spring have to be specified using the button <Constants> in this input window.

Select the segment-

points of the 2-node-

spring

Select the

connection-

points

Select a segment

for the spring

connection

Define the

constants

Figure 35 - Spring between two nodes

New Abutment

The RmBridge Modeler provides the possibility of a quick and easy abutment definition

(standard abutment with 2 bearings).

Figure 36 - Abutment definition for a hollow box bridge

In most cases the Modeler automatically recognises the corresponding connection

points depending on the position of the segment. It is just necessary to enter the element

numbers of the springs, modify the spring constants, if necessary, and enter the node




number where the spring-0 should be connected to. For conventional input see chapter

0.0.0.

7.2.2 Modelling Supports with Spring Elements

Supports with a discrete stiffness can be defined by using spring elements. The local

orientation of these springs in comparison to the global coordinate system of RmBridge

is shown in Figure 37. The Modeler automatically creates the local coordinate system of

these spring elements, taking into account the plan angle α2 of the superstructure

elements the spring is connected to. The local axis xL of the springs is always oriented

in the global YG direction, i.e. the elevation angle α1 will be set to 90°. The plan angle

α2 will always be zero. The angle β will be created as the angle between the global X-

axis and the tangent to the horizontal projection of the respective superstructure axis.

XG XG

2=0°

1=90°

=90° I

xL yL

zL

ZG

YG

K

YG

ZG

=0°

xL

yL zL

I

K

2=0°

1=90°

Figure 37 - Orientation of spring elements, for the final RM “Left Hand System”

Figure 37 shows the generated axis system for superstructure axes in global x (β = 0)

and z (β=90°) directions. To achieve a consistent logical model of the support spring,

the axis, the cross-sections of girder elements, the segment numbering and assignment,

and the part numbering and assignment must have been defined before.

Note that any angle β directly defined by the user will be added to the default

angle derived from the superstructure axis direction, i.e. angles entered by the

user represent the angle between the superstructure axis direction and the main

principal inertia plane of the pier or bearing modeled by the spring.

Simple Supports connected to a Structural Node

Using the <Connection> -button in the „Segment input-window“ allows for creating a

support by selecting „New Spring-0“. This spring element connects the node “0” (rigid

base) with the defined connection point (“CP0”) of the cross-section at the specified




segment point. By using the <Constants> -button the stiffness of the spring element

can be modified. It must be carefully checked if any rotational stiffness term (CMY,

CMY, CMZ) must be entered in order to avoid torsion freedom of the connected

superstructure.

Be careful when defining the stiffness because of the local co-ordinate system

(Xlocal, Ylocal, Zlocal) differing from the global system (see 7.2.2).

The structural length of spring elements is zero per definition with a length of zero. An

appropriate eccentric connection from the connection point “CP0” to the structural node

is generated automatically in the Modeler.

Structural node 101

“CP0”

CP0“ Spring “0”

Spring-element 1101

Co-ordinate -system

structure (global)

Co-ordinate -system

spring (local)

AXIS

1

Yglobal

Zglobal

Xglobal

Xlocal

Zlocal Ylocal

CMX

CMY

CMZ

Figure 38 - Simple support and connection to the structural node

Definition of a simply supported Pier

First, a new segment (slave segment) and a cross-section for the pier have to be defined.

In the “Segment list window” (Figure 8) the name of the segment and the type of the

segment “Pier” have to be entered. The default for the direction of the cross-section of

the pier is exactly horizontal. By entering an angle a rotation of the pier about the

vertical axis can be defined. With the input of the reference-segment and one connection

point, the position of the pier is exactly defined in relation to the main girder. In the

“Segment point list” (Figure 31) the height of the pier and the segment points, which

govern the degree of structural discretization within the segment can be entered (the

height 0.00 m should be defined at the top of the pier).

The master-segment and the slave-segment have to be connected. This function is

offered in the “Segment input-window” of the “pier segment”. By using the button

<Connection> a “New spring” between the two segments can be created. The input

terms are the two segments (seg1, seg2) to be connected, the corresponding segment

points and the parts of the cross-sections as well as the number of the element (1105).




Also the position of the element and the connection points belonging to them (“CP0”,

“CP1”) are requested in this input window (Figure 39).

The connection from the pier to the “earth” will be defined as a support spring (“New

spring-0”) (see chapter 0.0.0).

Co-ordinate -system

structure (global)

Co-ordinate -system

spring (local)

Length of zero

Spring-element 1105

node 1105

node 101

Support-spring 1100

“CP0“

+0,00

(spring – “0”)

seg1 (master-segment)

seg2 (slave-segment)

“CP1“

Yglobal

Zglobal

Xglobal

Xlocal

Zlocal Ylocal

CMX

CMY

CMZ

Figure 39 - Pier support definition

Multiple Bearing/Spring Support Definition

A predefined input window of the following definition is described in chapter 0.0.0.

First, the required connection points (called in the following “CP0”, “CP1” and “CP2”)

have to be defined in the “cross-section window” (see chapter 5.9). The connection to

the “earth” will be created with a “New spring-0” over the <Connection> -button in the

“Segment input-window”. After the input of the segment points, the element number,

the connection point and the “Free node number”, (1100) the spring can be generated

(The connection to “Node 0” will be created automatically.). The input of “free node

number” is necessary because otherwise the connection from “CP0” would be created

directly to the structural node (101) (see chapter 0.0.0).

By clicking on the <Constants> -button the corresponding stiffness of the spring

(KN/m) as well as a deviation from the direction of the local co-ordinate system can be

entered and modified.

The connection to the structural node (101) will be defined eccentrically with two

spring elements created as “New springs”. In the input window the segments, the

segment points, the start node (1100), the element number (1101, 1102) as well as their

element position (“CP1”, “CP2”) have to be entered (see Figure 40).

The structural interpretation of this input sequence is an eccentric connection between

node 1100 and node 101. The stiffness of the two piers will be regulated by the spring

constants of the spring elements situated in “CP1” and “CP2”.




spring 101

“CP0”

(spring 1100)

“CP2” “CP1”

Co-ordinate -system

structure (global)

Co-ordinate -system

spring (local)

AXIS 1

(spring-element 1101)

Spring-element 1100

Yglobal

Zglobal

Xglobal

Xlocal

Zlocal Ylocal

CMX

CMY

CMZ

Node “0”

(spring-element 1102)

Figure 40 - Multiple spring supports

7.2.3 Cross members

Cross members are needed for the simulation of transverse structural behaviour of

roadway slabs (double T-beams, multiple box-sections….). Two examples are shown in

Figure 41 - Examples for cross-member definitions.

Part 1

Cross-member element Cross-member elements

Part 2 Part 1 Part 2 Part 3 Part 4

Figure 41 - Examples for cross-member definitions

For a reasonable cross-member definition a minimum of two parts must be

defined to be connected by cross-members.

Where cross members need to be positioned between two main girders, connection

points have to be defined in the respective cross-sections (see chapter 5.9).

New cross members are constructed like any segment by inserting a new segment and

define as segment type “Cross member”. First, all parameters of one cross member

segment is defined and after that it may be copied (see chapter 7.3).

The geometry of a cross member is defined by its connection points and the associated

parts of the cross-section (Figure 41 - Examples for cross-member definitions).




Details about the material as well as the cross-section of the cross member can be

defined in the pop-up window after pressing <Additional Parameters> .

Assignment of cross-sections to the cross-members

7.2.3..1 Generating tables for b1 and b2

Already defined tables can be assigned to the width of the reference cross-section. If the

main-girder elements have different element lengths, with this feature the cross-sections

for the cross-members can be created with the corresponding width (the width of the

cross members varies with the element length of the main-girder).

This requires that the reference cross-section be created with the variable

dimensions b1 and b2 (see Figure 42).

7.2.3..2 Use of the function _hdp (half distance between two segment points)

The width of cross-sections (b1, b2) depends on the adjacent element lengths before and

after segment points of the main-girder (b1=L1/2, b2=L2/2) (see also chapter 0.0.0).

Instead of assigning tables with the corresponding width of the cross section, there is

also the possibility to assign the function _hdp(-1) and _hdp(1). When using these

functions, the program automatically calculates the width of the cross-sections from the

adjacent half girder element length for generating the appropriate cross-sections. The

expression _hdp(-1) delivers the half element length “before the segment point” and

_hdp(1) the adjacent half element length “after the segment point”. This expression can

be combined also with formulas and other expressions.

Note, that for arranging the cross-sections at the correct position, the

eccentricity check boxes (Y, Z) have to be clicked in the input field of the cross-

member definition.

Figure 42 - Variable defined reference cross section

Comments on eccentricities in Y and Z-direction

The following example shows a general view of a double T-beam. The plotted cuboids

represent a cross-member element, which is connected at two defined connection points

between two series of longitudinal girders.




Figure 43 - General view of a double T-beam

Cross-section arrangement in longitudinal direction (plan view):

Figure 44 - Plan view of cross members cross-sections

Li Element length

bi Half element length (bi=Li/2)




Created Cross-section of the Cross-member:

Figure 45 - Cross-section of the cross-member

Note that in the Modeler GUI cross-sections are generally presented as views

against the axis direction. In order to define the eccentric position of cross-

member elements properly, they must usually be oriented from the right main

girder to the left main girder, e.g. from axis 2 axis 1 as shown in Figure 43 -

General view of a double T-beam).

Position of the cross-section of the cross-member without consideration of the

eccentricities:

Figure 46 - Cross-section without eccentricities

This means that the drawn cross-section (see Figure 45) will be input at the specified

connection points in the middle of the upper edge of the cross-section with b1=b2

=(L1+L2)/2.

Position of the cross-section of the cross-member with consideration of the Z-

eccentricity:

Figure 47 - Cross-section considering the Z-eccentricity




The cross-section of the cross-member will be inserted according to the defined

geometry in z-direction and in y-direction at the upper edge of the cross-section.

Position of the cross-section considering both eccentricities (Y, Z):

In this case the cross-section will be inserted according to the defined cross-section (see

above Figure 45) at the specified connection point.

7.3 Copying Segments or Sequences

The RmBridge Modeler offers the possibility to copy complete segments in a simple

way (e.g. pier segments, longitudinal girders, etc) and to insert them at a desired

position. It is also possible to copy segment parts within a segment, allowing for an

efficient definition of the complete segment.

7.3.1 Copying Complete Segments

In the “Segment input window” this function offers the possibility to copy complete

segments and to insert them at a desired position. At first, the segment to be copied has

to be marked. By clicking on the “Copy” function in the “Edit-toolbar” the segment will

be duplicated. The opened input window “Copy Segment” allows for specifying the

position of the copied part exactly.

All definitions in this segment will be copied. The segment may be introduced by

the user individually. Afterwards, the user can modify the attributes.

7.3.2 Copying Sequences of a Segment

With this function specified, sections (sequences) of a segment can be copied. The

advantage of this feature is that recurrent identical sections can be copied and must not

to be recreated.

The section of the segment to be copied can be marked by clicking the first and the last

line of the desired section with the left mouse button and the pressed key <Ctrl>

simultaneously. The marked lines change to highlighted red.

Afterwards click on the “Copy” function in the “Edit-toolbar” and the information

window, which is shown in the lower picture (Figure 48.) is displayed. There you can

check if the chosen section of the segment is the desired one and after clicking <OK> the

sequence of the segment is copied subsequent after the cursor position (dotted line).

All definitions in the copied section, used cross-sections, attachment pier segments and

support definitions are taken along.




Figure 48 - Copying sequences of a segment

The numbering of copied elements and spring elements has to be assigned

afterwards by editing subsequently. This guarantees that the user can create the

numbering in accordance with his personal ideas.




7.4 Existing FE-Cross-Sections at the Segment Points

All segment points of the active segment are shown in this list. It can be manipulated

with the general edit functions described in chapter 2.6. New points can be added and

existing points modified or deleted. For each segment point several pieces of

information need to be entered:

The cross-sections immediately to the left and immediately to the right of the section

point

Parameter “DCROSS” (transversal shift of the cross-section at the section point)

Parameter “DVERT” (vertical shift of the cross-section at the section point)

Parameter “DA” (rotation angle about the segment reference line)

Parameter “DB” (rotation angle about the horizontal cross-section axis)

This segment point specific information can be edited in the input window shown in

Figure 49 for one or more segment points.

Figure 49 - “Modify segment point” input window

7.5 Active Segment Point Details

If variables have been used during the definition of a cross-section, then these variable

parameters have to be coupled with formulas to enable the station-dependent

computation of cross-section geometries. These specifications are made for each side

(left and right) for each segment point.

The assignment of tables to the respective segment-points takes place in the “variable-

list” after the “segment-input window” has been opened (the radio-button “variables

must be activated). By double-clicking a line of the variable lists or by pressing the




symbol “Modify” on the left side of the variable lists, the input window for the

assignment of expressions opens. By clicking on the desired line and pressing the key

<Ctrl> simultaneously (the marked line is highlighted with red color) a new “value” or

“table” can be assigned in the input field “expression” directly or selectively by clicking

on the arrow-button. To copy variables from begin to the end of the segment or vice

versa (left table to the right), select the desired lines of the table and copy the desired

expressions from the one table to the other by hitting the <All> or the < > key.

Note that if you change tables or formulas, you have to reassign these tables or

formulas to the specified variables.

7.6 Stay cable input

It is very easy to build up the whole model of a stayed cable bridge using the RmBridge

Modeler. In addition to the already discussed topics for modeling the main girder and

piers, the user has to define the stay cables. For each stay cable an additional segment

using the segment type “Cable” has to be created. Connection points at the

corresponding cross sections where the cables shall be connected have to be predefined.

The cable creating steps are the same as with cross members, described in chapter 7.2.3.

7.7 Segment Type „Free Pier“

The segment type “Pier” needs an absolute connection to a segment type “Main Girder”.

Which means: no “pier segment” if there is no “Main girder segment”.

Since it might be reasonable to generate a pier on its own without going through a main

girder segment definition, the “Free Pier” can be defined as well.

The segment type “Free Pier” needs no connection to an existing segment but the

definition of free points in the point management window (name, x-,y-,z-coordinates) to

define the geometrical definition. These free points have to be selected when defining

the new segment using the type “Free Pier”.

7.8 Link Segments

To prepare the cross-sections for the link segment definition see chapter 5.8, Link

Segments.

You have to add one segment in the segment list to define the main girder (which is

shown in the segment list window as <Base Segment>).

Open the segment point list of the girder and part it in so many segments, that you can

define all the nodes of the main (truss) girder (you have to adjust that definition with the

link segment definition in the cross-section window).

To define the link segments corresponding to the main girder, press <Link Segments>

“Create Link Segment” at the top of the segment list window.




In the popup window you input

the link segment name defined in the cross-section window,

the points and positions where this link segment shall be created,

the activation or deactivation of the link segment (when deactivated, link segments

will not be calculated),

the position of the link segments - at the begin or at the end of the segment,

the cross-sections of the link segment beams,

the link segment cross-section plane (normal to cross-section, vertical and horizontal

in elevation),

and you can insert hinges.

Note: It’s very useful to control the connections of the link segments with the

‘3D view’ window while creating them.

After that, you choose ‘ Parts’ and hit the ‘Edit’ icon on the left side of the segment

list window.

Here you apply a group, a material and a numbering of the link segment beams (They

are named ‘B’ plus the chosen number).

RM Bridge Creating the RmBridge Analysis Model



8 Creating the RmBridge Analysis Model

This is the final step in a Modeler session. Geometric data generated in the Modeler is

exported into the RmBridge database in accordance with some basic rules. This is done

in the <Remodel> input pad as shown in Figure 50.

Figure 50 - Data export to RmBridge

Das <Remodel> pad contains three principal options:

1. Recalculation

2. Check Numbering

3. Create Model

If the option Recalculation is selected, the geometric data describing the structure in the

Modeler are evaluated in order to be suitable detailed to describe the analysis model.

This detailed data can then be directly transferred to the RmBridge analysis database.

These concerns in principle the evaluation of all tables and mathematical formulas, and

the assignment of the respective numerical values to the individual segment points and

elements (see also 2.9).

The option Check numbering brings about a proof check whether the numbering of the

individual segment points and elements is complete and consistent, and whether a

meaningful mathematical model for the structural analysis can be created. If the option

Create Model is selected, the proof check of the numbering is in any case performed.

RM Bridge Creating the RmBridge Analysis Model



If the option Create Model is selected, the data of the analysis model are created and

stored in the RmBridge analysis database. Additional options govern, whether the

existing RmBridge analysis database shall be initialized before inserting the Modeler

data, or whether the new data only replace those data of the analysis database, which

have been defined in the Modeler database.

Other additional options can be set in the <Options> menu. They allow for the data of

different object categories (cross-sections, segments, etc) to be excluded or included in

the transfer process.

This <Options> menu also governs the storage of backup files for saving the current

status of the Modeler database. These backup files are TCL files in ASCII format.

Different export possibilities are available.

Rmbridgee Modguide

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