Building Structure and Components

7/28/2019 Building Structure and Components

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BUILDING STRUCTURE ANDCOMPONENTS-PART I

DR CHEAH CHEE BAN

SENIOR LECTURER OF BUILDING TECHNOLOGY

SCHOOL OF HOUSING BUILDING AND PLANNING


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BUILDING STRUCTURES-AN OVERVIEW

Building is a civil engineering infrastructure

which serves as a shelter for human to

execute various activities namely:

Residential

Commercial

Manufacturing


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Hence, the function of a

building structural system is to

sustain the self weight of the

building components and the

live load exerted on it byvarious human activities.

The load will be transferred by

various structural elements of

the building from all the floorsand roofto the foundation of

the building.


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The various structural

elements which are

responsible for distributionof

building loads are:

Slabs

Beams

Columns

Staircase Walls (Structural and Non-

structural)

Foundation system

(Shallow or deepfoundation)


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Eventually the

overall load of the

building will be

transferred to the

sub grade soil of

the proposed site

of the building bythe foundation

system of the

building structure.


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STRUCTURAL SLABS

Slab is a structural

component of a building

main frame which is

designed to sustain panel

load exerted from the

various floor uses.

Structural slabs are indirect contact with the

live load component of a

building.


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STRUCTURAL SLABS

Structural slabs are

usually designed as a

thin plated shell

member with limited

thickness


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STRUCTURAL SLABS

Panel loads are

then transferred

from slabs to

beams, columns or

walls in the form

oftrapezoidal,

triangular, uniformdistributed or

point load

depending on the


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STRUCTURAL SLABS

There are a number ofcommon types of slabs in

a building structure

namely:

1. Spanning slabs between

beams and walls

2. One-way pan joists

3. Two-way reinforced slabsupported directly by

column

4. Two-way flat slab

5. Waffle flat slabs

S S S


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SPANNING SLAB BETWEEN BEAMS AND

WALLS

Description:

Span continuously over

beams and wall supports

Thickness of slab varies

between 75mm-250mm.

Allowable span up to 7.4 m

between supports Widely used in the

construction of reinforced

concrete buildings in

Malaysia.



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WALLS

Advantages:

Simple formwork (timber or steel) for

fabrication of the slab.

Simple internal reinforcement

arrangement and design.

Well established design method

Allow for higher headroom of building

Disadvantages: High self-weight and inefficient load

transfer ability.

Intensive materials requirements

Not suitable for long span in excess of8 metres


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ONE WAY PAN JOISTS

Description:

Span continuously over

primary beams supports

Thickness of slab usually

fixed at 60mm

Presence of joists spanning

between primary beams.

Joist depth varies between150-510mm

Allowable span up to 12.3

m between supports


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ONE WAY PAN JOISTS

Advantages:

Simple internal reinforcement

arrangement and design.

Well established design method

Allow for longer span of slab

Disadvantages:

Intensive materials requirements

Not suitable for use when there islimited headroom available.


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TWO WAY FLAT PLATE

Description:

Two way reinforced concrete

slab which is supported

directly by column


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TWO WAY FLAT PLATE

Advantages:

Economical design with low formwork

and steel reinforcements requirements

Allow for higher headroom of a

building

Disadvantages:

Low load bearing capacity

Not suitable for use as heavy dutyfloor

High tendency ofpunching shear

failure upon over load.


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TWO WAY FLAT SLAB

Description:

Similar structural arrangement

as two way flat plate.

The presence ofdrop panel on

top of supporting columns is

the distinguishing feature of

flat slab from flat plate.

The drop panel enhances the

shear and bending moment

resisting capacity of the slab

at the column supports


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TWO WAY FLAT SLAB

Advantages:

Higher load bearing capacity as

compared to two way flat plate.

Economical design with low formwork

and steel reinforcements requirements

Allow for higher headroom of a

building

Disadvantages:

Not suitable for use as heavy duty

floor system.


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WAFFLE FLAT SLABS

Description:

Slab is supported by square

grid of closely spacedjoists

The waffle flat slabs are

formed by casting the slab

and joists integrally over

square dome forms

Thickness of slab is 50mm

and supported on grid of

joists with depth up to

400mm.


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WAFFLE FLAT SLABS

Advantages:

Exceptionally high load bearing

capactiy

Allow for very long span of floor up

to 14 metres between supports

Aesthetically appealing structural

form.

Disadvantages:

Material intensive and high cost for

fabrication.

Not suitable for building with

limited headroom

High self-weight and requires very

strong support.


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STRUCTURAL BEAMS

Structural beams are

horizontal members of a

building main frame which act

as the primary supports tostructural slabs.

It is also an intermediate

structural component of abuilding which transfer the

load from the slab to the

structural columns


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STRUCTURAL BEAMS

Under normal service condition,

structural beams are subjected to

combined bending ,shear stresses

and torsion.

Hence, structural beam is classified

as a moment-shear structural

members.

With that the bending moment,shear force and torsion are the

three major parameters considered

in the analysis and design of

structural beams.


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STRUCTURAL BEAMS

There are a few types of

structural beams which are

commonly used in building

construction. They are:

Reinforced concrete beams

Structural steel beams

Pre-stressed concrete beams


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REINFORCED CONCRETE BEAMS

Overview

RC beams which are commonly used in the

Malaysian construction industry is a composite

structural member.

It is fabricated using the combination of structural

concrete and steel reinforcement bars

For common application, reinforced concretebeams has a rectangular cross section.


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Load and stress mitigation mechanism

The load transferred from the slabs to the beams

are in the form ofpoint load or uniform load

The gravity load transferred from the slab onto a

structural beam will be converted into bendingmoment, shear forces and torsion which act

directly on the beam member.


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The compressive stress induced bybending moment within the cross

section of a reinforced concrete

beam is resisted by the concrete

matrix of the beam. The tension stress induced by

bending moment within the cross

section of a reinforced concrete

beam is resisted by the steel barsembedded in the concrete matrix.

Meanwhile, the shear stress and

torsion stress component in the

structural member is resisted by

both steel and concrete matrix.


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Analysis and design consideration

There are two basic design of a reinforced

concrete beam namely:

Simply supported beam

Continuously spanning beam

The bending moments and shear forces of a beam

is determined by modeling a beam as a bending

structural member.


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(Contd)

The design of a reinforced concrete

beam involves the calculation to

determine:

The cross section of concreterequired

The number and size of steel

reinforcements bar required

to sustain the gravity load

transferred to a beam

The design of reinforced concrete

beam is usually performed using the

British Standards BS 8110-Part 1 and

Eurocode 2-EN 1990


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STRUCTURAL STEEL BEAMS

Overview

Structural steel beams is commonly used in the

construction oflong spanning structures such as

factory or storage building

It is also commonly used in countries with activeseismic activities due to its high ductility

performance


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Overview

Structural steel beams is fabricated using hot

rolled structural steel section

For common application, structural steel beam

has standard I-cross section or H cross section.


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are in the form ofuniformly distributed load


structural beam will be converted into bendingmoment, shear forces and torsion which act

directly on the beam member.


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Any compression stress and tension stress

induced by the bending moment on steel beam

will be resisted by both flange and web of the

steel beam Meanwhile, the shear stress and torsion stress

component in the structural steel member is

resisted mainly by web of the beam


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Structural steel beam are usually designed as a

single span simply supported structural member.

The bending moments and shear forces of a beam


structural member.


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Analysis and design

consideration (Contd)

The design of a structural steel beam

involves the calculation to determinethe size of steel cross section and

joint required to sustain the gravity

load transferred to a beam

The design of structural steel beam isusually performed using the British

Standards BS 5950-2000


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PRESTRESSED CONCRETE BEAM

Overview

Pre-stressed concrete beam is commonly used in

the construction ofvery long spanning structures

(span >20 metres) such as factory, storage buildingor bridges.

Besides, it has an extremely high bending load

bearing capacity.

S SS CONC A


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Overview

Pre-stressed concrete beams is fabricated using

the combination of high tension yield cable (Grade

>1200MPa) and high strength concrete matrix(Grade >70MPa).

Tensioning force is induced within the cable

placed in the beam member using a high capacity

hydraulic jack.



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are in the form ofuniformly distributed load


prestressed concrete beam will be converted intobending moment, shear forces and torsion which

act directly on the beam member.



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Load and stress

mitigation mechanism The tension stress induced by

the bending moment on pre-

stressed concrete beam will

be transformed intocompression stress by the

high tension force cable

embedded in the concrete

matrix

Meanwhile, the shear stress

and torsion stress component

in the structural steel

member is resisted mainly by

steel reinforcements providedin the beam.



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Prestressed concrete beam are usually designed

as a single span simply supported structural

member. The bending moments and shear forces of a beam


structural member.



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There are two forms of prestressed concrete

namely:

Pre-tensioning beam member

Post-tensioning beam member



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Analysis and design

consideration

Pre-tensioning:

Tensioning force of the

cable is induced beforethe placement of

concrete.

Post-tensioning:

Tensioning force of thecable is induced after

the placement and

hardening of concrete.



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Analysis and design

consideration (Contd)

The design of a prestressed

concrete beam involves thecalculation to determine

the size of concrete cross section,

number ofhigh tension cable and

the tensioning force of cable

required to sustain the gravity

load transferred to a beam



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Analysis and design consideration (Contd)

The tensioning force induced in the steel is usually

in the range of 50-500 tonnes.

The design of reinforced concrete beam is usuallyperformed using the British Standards BS 8110-

Part 2.



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CYBERJAYA FLYOVER COLLAPSED:WHAT

ACTUALLY HAPPENED?



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SPECULATIONS.....


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Presented by

DR CHEAH CHEE BAN | SENIOR LECTURER, SCHOOL OFHOUSING BUILDING AND PLANNING

Building Structure and Components

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