Cadd Mandar g

A project report on,

“Comparative study of simulation tools Staad V8, Etabs

2013, and Strap 2014 for seismic analysis of plan and

vertical geometrically irregular building using Indian

Standard Codes”

Prepared in partial fulfillment of

Study oriented project,

Course code: CE G611

Computer Aided Analysis and Design

Submitted by,

Mr. Mandar Ganbavale (2013H143013H)

Under guidance and supervision of

Dr. Chandu Parimi

Assistant Professor, Department of civil engineering.

Birla Institute of Technology and Science, Pilani.

Hyderabad Campus.

(2014- 2015)

ii

Comparative study of

simulation tools Staad V8,

Etabs 2013, and Strap 2014

for seismic analysis of plan

and vertical geometrically

irregular building using

Indian Standard Codes

iii

CERTIFICATE This is certified that the project entitled

“Comparative study of simulation tools Staad V8, Etabs

2013, and Strap 2014 for seismic analysis of plan and

vertical geometrically irregular building using Indian

Standard Codes”

Submitted by,

Mr. Mandar Ganbavale (2013H143013H)

In partial fulfillment of the requirements of course code CE G611 Study Oriented

project, BITS Pilani, Hyderabad campus for the academic year 2014-2015. It is the record of

their own work carried out under our supervision and guidance.

Dr. Chandu Parimi

(Assistant professor, Department of Civil Engineering)

Birla Institute of Technology and Science, Pilani. Hyderabad Campus.

2014-15.

iv

ACKNOWLEDGMENT

Firstly, I would like to thank the curriculum of BITS, Pilani for giving me this

opportunity in doing Study oriented project.

I sincerely appreciate Dr. Chandu Parimi for giving me opportunity to work on this

topic. I am grateful for his support and guidance that have helped me to expand our horizon of

thought and expression.

I am also thankful of my friends for their help in sharing the information about

various aspects of this project.

Mr. Mandar Ganbavale

(2013H143013H)

1

CHAPTER 1

INTRODUCTION

1. Objectives

The main purpose of this study oriented project is to detailed study the simulation tools

for seismic analysis and designing of structures.

Comparison of simulation tools STRAP, STAAD pro, ETABS and SAP 2000 for seismic

analysis of Plan and Vertical geometrically irregular multi-storey building.

2. Vertical and Plan irregular multistory buildings

According to IS 1893:2002 (Clause 7.1), there are mainly two types of irregularities,

Plan Irregularity

Vertical Irregularity

a. Plan irregularity –

Plan irregularity also of five types as follows:

i. Torsion Irregularity – To be considered when floor diaphragms are rigid in their

own plan in relation to the vertical structural elements that resist the lateral forces.

Torsional irregularity to be considered to exist when the maximum storey drift,

computed with design eccentricity, at one end of the structures transverse to an

axis is more than 1.2 times the average of the storey drifts at the two ends of the

structure.

ii. Re-entrant corners - Plan configurations of a structure and its lateral force

resisting system contain re-entrant corners, where both projections of the structure

beyond the re-entrant corner are greater than 15 percent of its plan dimension in

the given direction.

iii. Diaphragm Discontinuity - Diaphragms with abrupt discontinuities or variations

in stiffness, including those having cut-out or open areas greater than 50 percent

of the gross enclosed diaphragm area, or changes in effective diaphragm stiffness

of more than 50 percent from one storey to the next.

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iv. Out-of-plane offsets - Discontinuities in a lateral force resistance path, such as

out-of-plane offsets of vertical elements.

v. Non-parallel Systems - The vertical elements resisting the lateral force are not

parallel to or symmetric about the major orthogonal axes or the lateral force

resisting elements.

b. Vertical Irregularity –

Plan irregularity also of five types as follows:

i. Stiffness Irregularity -

1. Soft Storey - A soft storey is one in which the lateral stiffness is less than

70 percent of that in the storey above or less than 80 percent of the average

lateral stiffness of the three storeys above.

2. Extreme Soft Storey - A extreme soft storey is one in which the lateral

stiffness is less than 60 percent of that in the storey above or less than 70

percent of the average stiffness of the three storeys above. For example,

buildings on STILTS will fall under this category,

ii. Mass Irregularity - Mass irregularity shall be considered to exist where the

seismic weight of any storey is more than 200 percent of that of its adjacent

storeys. The irregularity need not be considered in case of roofs.

iii. Vertical Geometric Irregularity - Vertical geometric irregularity shall be

considered to exist where the horizontal dimension of the lateral force resisting

system in any storey is more than 150 percent of that in its adjacent storey.

iv. In-Plane Discontinuity in vertical elements resisting lateral force - An in-plane

offset of the lateral force resisting elements greater than the length of those

elements.

v. Discontinuity in capacity – Weak storey - A weak storey is one in which the storey

lateral strength is less than 80 percent of that in the storey above, the storey lateral

strength is the total strength of all seismic force resisting elements sharing the

storey shear in the considered direction.

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CHAPTER 3

COMPUTER TOOLS

1. STRAP –

STRAP is one of the most comprehensive and versatile structural analysis and design

software systems available on the market today. It's also the easiest to use, due to its superb graphic

user interface (GUI) and context-sensitive help system. It offers the engineer a powerful but

affordable tool for analysis and design of a wide range of skeletal and continuum structures such as

buildings, bridges, shells, towers and more.

STRAP uses graphical input for the generation of models and loads. Every drawing on the

screen can be printed, imported into other documents, or (through DXF) into drawings. Complete

analysis and design can be performed for any structure without ever referring to joint or beam

numbers. Load combinations can be created after analysis is performed. Combinations can be

changed instantly without solving the model again.

STRAP comes with design modules for designing reinforced concrete, post-tensioned

concrete and structural steel (hot-rolled and cold-formed). For the engineer interested in dynamic

effects, STRAP also includes modules for modal analysis, seismic response spectra calculations

according to many codes and time history response calculations.

The learning curve to start using STRAP is practically non-existent. The program's flow is

similar to the analysis and design process performed by hand. During the execution of every action

the prompt line at the bottom of the screen guides us through. Combine this with the context-sensitive

help.

2. STAAD Pro –

STAAD.Pro allows structural engineers to analyze and design virtually any type of

structure through its flexible modeling environment, advanced features and fluent data

collaboration. Flexible modeling is provided by a state-of-the-art graphical environment and the

design supports over 70 international codes and over 20 U.S. codes in 7 languages.

An array of advanced structural analysis and design features are included such as nuclear

certification for 10CFR Part 50, 10CFR 21, ASME NQA-1-2000, time history and push over

analysis and cable (linear and non-linear) analysis.

4

Efficiencies are gained through the ability to maintain and streamline current workflows

with fluent data collaboration. STAAD.Pro integrates with other Bentley products such as

STAAD.foundation and ProSteel and OpenSTAAD is provided for integration with third party

programs. Increased client base and therefore business growth can be realized in using

STAAD.Pro to serve a broad spectrum of structural design projects and a global market.

3. SAP 2000 –

From its 3D object based graphical modeling environment to the wide variety of analysis

and design options completely integrated across one powerful user interface, SAP2000 has

proven to be the most integrated, productive and practical general purpose structural program on

the market today. This intuitive interface allows you to create structural models rapidly and

intuitively without long learning curve delays. Now you can harness the power of SAP2000 for

all of your analysis and design tasks, including small day-to-day problems. Complex Models can

be generated and meshed with powerful built in templates. Integrated design code features can

automatically generate wind, wave, bridge, and seismic loads with comprehensive automatic

steel and concrete design code checks per US, Canadian and international design standards.

Advanced analytical techniques allow for step-by-step large deformation analysis, Eigen

and Ritz analyses based on stiffness of nonlinear cases, catenary cable analysis, material

nonlinear analysis with fiber hinges, multi-layered nonlinear shell element, buckling analysis,

progressive collapse analysis, energy methods for drift control, velocity-dependent dampers,

base isolators, support plasticity and nonlinear segmental construction analysis. Nonlinear

analyses can be static and/or time history, with options for FNA nonlinear time history dynamic

analysis and direct integration. From a simple small 2D static frame analysis to a large complex

3D nonlinear dynamic analysis, SAP2000 is the easiest, most productive solution for your

structural analysis and design needs.

4. ETABS 2013 -

The innovative and revolutionary new ETABS is the ultimate integrated software

package for the structural analysis and design of buildings. Incorporating 40 years of continuous

research and development, this latest ETABS offers unmatched 3D object based modeling and

visualization tools, blazingly fast linear and nonlinear analytical power, sophisticated and

comprehensive design capabilities for a wide-range of materials, and insightful graphic displays,

reports, and schematic drawings that allow users to quickly and easily decipher and understand

analysis and design results.

5

From the start of design conception through the production of schematic drawings,

ETABS integrates every aspect of the engineering design process. Creation of models has never

been easier - intuitive drawing commands allow for the rapid generation of floor and elevation

framing. CAD drawings can be converted directly into ETABS models or used as templates onto

which ETABS objects may be overlaid. The state-of-the-art SAPFire 64-bit solver allows

extremely large and complex models to be rapidly analyzed, and supports nonlinear modeling

techniques such as construction sequencing and time effects (e.g., creep and shrinkage). Design

of steel and concrete frames (with automated optimization), composite beams, composite

columns, steel joists, and concrete and masonry shear walls is included, as is the capacity check

for steel connections and base plates. Models may be realistically rendered, and all results can

be shown directly on the structure. Comprehensive and customizable reports are available for all

analysis and design output, and schematic construction drawings of framing plans, schedules,

details, and cross-sections may be generated for concrete and steel structures.

ETABS provides an unequaled suite of tools for structural engineers designing buildings,

whether they are working on one-story industrial structures or the tallest commercial high-rises.

Immensely capable, yet easy-to-use, has been the hallmark of ETABS since its introduction

decades ago, and this latest release continues that tradition by providing engineers with the

technologically-advanced, yet intuitive, software they require to be their most productive.

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CHAPTER 3

PARAMETERS USED (GEOMETRIC AND SEISMIC)

1. Materials properties

a. Steel -

i. Modulus of elasticity of steel, E = 200 GPa

ii. Poisson’s ratio, µ = 0.3

iii. Steel density = 77 kN/m3 (7.850 kg/m3)

iv. Yield strength of steel, Fy = 350 MPa

v. Ultimate yield strength of steel, Fu = 450 MPa

b. Concrete –

i. Characteristic strength of concrete, Fck = 25 Mpa

ii. Density of concrete, 𝜌 = 25 kN/m3

2. Building Parameters –

a. Beam and Columns - ISMB 450

b. Slab – 150 mm

c. Bay length – 6m (in each horizontal direction)

d. Storey height – (3.5m)

e. Supports – Fixed

3. Loading Conditions –

a. Dead Load = 4.75kN/m2 (Self weight 3.75kN/m2 + Floor finish 1kN/m2)

b. Live Load = 2kN/m2

Seismic weight –

c. Dead load = 1

d. Live Load = 0.25

Seismic parameters –

e. Code – IS 1893:2002 - Seismic analysis in X1 and X3 directions.

f. Method of combining mode shapes – Complete quadratic combination with damping

ratio 0.05

g. Zone – III (0.16)

h. Soil type – Medium II

i. Importance factor – 1.5

j. Reduction factor – 5

k. Time (Ta) – 0.7735 sec

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Fig. 1. Building 3D View

Fig. 2. Building Plan

8

Fig.3. Building Front Elevation

Fig.4. Building Side Elevation

9

CHAPTER 4

RESULTS

1. STAAD Pro

a. DISPLACEMENT:

10

b. BENDING

11

c. AXIAL FORCE

12

2. STRAP 2014 –

a. Bending Moments –

b. Shear Forces –

13

c. Displacement –

d. Modal results –

14

e. Mode Shapes –

f. Seismic Data –

15

3. ETABS –

a. Text File output -

ETABS v9.7.0 File:MODEL-1 Units:KN-m December 2, 2014 20:54 PAGE 1

A U T O S E I S M I C I N D I A N

Case: EQX

AUTO SEISMIC INPUT DATA

Direction: X

Typical Eccentricity = 5%

Eccentricity Overrides: No

Period Calculation: User Defined

User T = 0.7735

Top Story: 4

Bottom Story: BASE

R = 5

Z = 0.16

Soil Type = II

I = 1.5

AUTO SEISMIC CALCULATION FORMULAS

V = Z I Sa W / (2 R g)

Sa/g = 1 + 15T for 0.0 <= T <= 0.1

Sa/g = 2.5 for 0.1 <= T <= 0.55 (Soil Type II)

Sa/g = 1.36/T for 0.55 <= T <= 4.0 (Soil Type II)

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AUTO SEISMIC CALCULATION RESULTS

T Used = 0.7735 sec

C Used = 0.0422

W Used = 17424.11

V Used = 0.0422W = 735.26

Ft Used = 0.00

AUTO SEISMIC STORY FORCES

STORY FX FY FZ MX MY MZ

4 (Forces reported at X = 30.0000, Y = 9.0000, Z = 17.5000)

262.52 0.00 0.00 0.000 0.000 0.000


214.31 0.00 0.00 0.000 0.000 0.000


153.88 0.00 0.00 0.000 0.000 0.000


83.20 0.00 0.00 0.000 0.000 0.000

G (Forces reported at X = 21.5842, Y = 10.6392, Z = 3.5000)

21.35 0.00 0.00 0.000 0.000 0.000

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b. Bending Moment –

c. Shear Forces –

18

d. Storey Drift –

19

CHAPTER 5

COMPARISON

1. Base Shear comparison –

a. BM and SF comparison –

b. Base shear and Displacement comparison –

0

20

40

60

80

100

120

140

M A X B M - K N M M A X S F - K N

BM AND SF COMPARISON

STAAD Pro STRAP 2014 ETABS 2013

0

500

1000

1500

2000

2500

3000

BASE Shear - SRSS (kN) Displcament (mm)

BASE SHEAR AND DISPLACEMENT COMPARISON


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c. Seismic weight comparison –

d. Comparison table –

Results Staad Pro Strap 12.5 ETABS 2013

Base shear (SRSS) 634 kN 683 kN 735.26 kN

Seismic Weight 15048 kN 16200 kN 17424 kN

Scale factor 1.9845 1.9621 2.031385

Maximum Bending Moment 100.545 kNm 125.12 kNm 116.42 kNm

Maximum Shear Force 83.6792 kN 86.650 kN 88.74 kN

Maximum Displacement 820mm 867 mm 790 mm

13500

14000

14500

15000

15500

16000

16500

17000

17500

18000


Seismic weight

Seismic weight

21

CHAPTER 6

CONCLUSION

Actually the results of analysis should match with the classical analysis solutions, whatever the

type of analysis we do using whatever S/W package. The finer thing that we should note in all these

packages is that, there are parameters/properties such as boundary conditions, material properties etc.,

which are applied to the generated model by the software package by default at the initial stage. May

be the ambiguity we observed in results arise due to these default prams. And these by default properties/

parameters changes from one S/W package to other.

May be more inspection of these inputs may give better results! :) Sometimes closer or exact! :)

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CHAPTER 7

REFERENCES

[1] Giordano, M. Guadagnuolo and G. Faella “PUSHOVER ANALYSIS OF PLAN IRREGULAR

MASONRY BUILDINGS” The 14th World Conference on Earthquake Engineering October 12-

17, 2008, Beijing, China.

[2] Prof. K S Sable, Er. V A Ghodechor, Prof. S B Kandekar “Comparative Study of Seismic

Behavior of Multistory Flat Slab and Conventional Reinforced Concrete Framed Structures”

International Journal of Computer Technology and Electronics Engineering (IJCTEE) Volume

2, Issue 3, June 2012 17.

[3] Belejo, R. Bento & C. Bhatt “Comparison of different computer programs to predict the seismic

performance of SPEAR building by means of Pushover Analysis the SPEAR building by means

of Pushover Analysis” Instituto Superior Técnico, Lisbon, Portugal

[4] “DISPLACEMENT BASED DESIGN OF VERTICALLY IRREGULAR FRAME-WALL

STRUCTURES” – Rose school thesis work by SUHAIB SALAWDEH

[5] “Performance Based Seismic Design and Assessment of Irregular Steel Structures R. Peres, R.

Bento IST, Technical University of Lisbon, Portugal J. M. Castro Faculty of Engineering,

University of Porto, Portugal.

[6] “Seismic design of vertically irregular reinforced concrete structures” – Thesis work submitted

by Satrajit Das

[7] McCrum Lunch “Seismic Analysis of Braced Plan Irregular Structures Using Hybrid Testing

Daniel” lecture at the Department of Civil, Structural & Environmental Engineering, Trinity

College Dublin on 30th November 2011

[8] Shaikh Abdul Aijaj Abdul Rahman, Girish Deshmukh “Seismic Response of Vertically Irregular

RC Frame with Stiffness Irregularity at Fourth Floor” ISSN 2250-2459,ISO 9001:2008 Certified

Journal, Volume 3, Issue 8, August 2013

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