Building Structure - P1

Building Structure BLD 61003

STRUCTURAL DESIGN POST MORTEM SEM III Studio Project

VISITOR INTERPRETIVE CENTRE

Daren Lai Kam Fei

0332570

Esther Wong Jia En

0332188

Gavin Tio Kang Hui

0333373

Priscilla Huong Yunn

0332599

Wendy Lau Jia Yee

0333538

Yong Ping Ping

0332585

Table of Content

TABLE OF CONTENT Page 1.0

Introduction to Visitor Interpretive Centre

1

1.1

Design Concept

2

1.2

Spatial Qualities

3-6

1.3

Original Orthographic Drawings

1.4

1.3.1

Site Plan

7

1.3.2

Basement Floor Plan

8

1.3.3

Ground Floor Plan

9

1.3.4

First Floor Plan

10

1.3.5

Roof Plan

11

1.3.6

North Elevation

12

1.3.7

South Elevation

13

1.3.8

West Elevation

14

1.3.9

East Elevation

15

1.3.10 Section

16

1.3.11 Sectional Perspective

17

Existing Structural System 1.4.1

1.5 2.0

Materiality

18

Summary

19

Structural Analysis of Existing VIC

20

2.1

Foundation

21 - 25

2.2

Load Bearing Wall

26 - 31

2.3

Floor Slab

32 - 38

2.4

Staircase

39 - 41

2.5

Roof

42 - 45

Building Structure

i

Structural Design Post Mortem

Table of Content

TABLE OF CONTENT Page 3.0

4.0

Modified Drawing

46 - 47

3.1

Basement Floor Plan

48

3.2

Ground Floor Plan

49

3.3

First Floor Plan

50

3.4

Basement Floor Ceiling Plan

51

3.5

Ground Floor Ceiling Plan

52

3.6

First Floor Ceiling Plan

53

3.7

East Elevation

54

3.8

Section

55

3.9

Exploded Axonometric of Skeletal Structure

56

Proposed Modification

57 - 58

4.1

Post and Beam System

59 - 64

4.2

Reinforced Concrete Slab with Timber Decking

65 - 70

4.3

Light Weight Facade System

71 - 75

4.4

Foundation

76 - 79

4.5

Retaining Wall at Basement Floor

80 - 83

4.6

Staircase

84 - 87

4.7

Glass Bridge

88 - 91

4.8

Glass Curtain Wall

92 - 95

5.0

Conclusion

96 - 97

6.0

References

98 - 100

Building Structure

ii

Structural Design Post Mortem

Structural Analysis of Existing VIC

Introduction

1.0 INTRODUCTION TO VISITOR INTERPRETIVE CENTRE

Building Structure

Page 1

Structural Design Post Mortem

Structural Analysis of Existing VIC

Introduction

1.1 Design Concept As one ambles across the dirt roads that lace fields of vast greenery, it may be easy to overlook the layers of history and culture that make up the foundation of this alluring destination. After a series of events involving the claiming and reclaiming of land, undercontrolled by authorities. As years passed, forced to be out, choose to be back, the spirit of community and tradition that connected the people as one grew, gives rise to the characteristic beauty, Kampung Pulai. The VIC celebrates by reemerge the history delegate a locus of the spirit, place of belief, home for soul for Kampung Pulai.

Building Structure

Page 2

Structural Design Post Mortem

Structural Analysis of Existing VIC

Introduction

1.2 Spatial Qualities The tilted concrete wall creates a confined and restricted corridor symbolising the first approach of the locals with a huge curiosity wandering along the way until the spirit is found.

Ground Floor Plan

Slanted concrete load bearing wall

Vertical concrete load bearing wall acting as main support of the VIC

Figure 1.2.1 Interior Perspective 1 and 2

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Introduction

The journey then continues with a staircase which leads the users to go down into the underground glassbox surrounded with water which evokes a sense of being forced under control, having to go through the basement, helpless and choiceless.

Ground Floor Plan

Basement Floor Plan

Engaging with nature by embracing the soil ground as part of floor in the VIC

Ground floor RC flat slab

Figure 1.2.2 Interior Perspective 3 and 4

Building Structure

Page 4

Structural Design Post Mortem

Structural Analysis of Existing VIC

Introduction

Building advocate the concept home for soul, wall extended as roof form a shape of pyramidal to mimic a focus of spirit from the locals. Facade of the building was made from the raw concrete as a symbolisation of respect towards the history.

Ground Floor Plan

Load bearing wall allows clear span of open floor plan

Glass

curtain

wall

establishes

visual

connectivity

Timber staircase

Figure 1.2.3 Interior Perspective 5 and 6

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Introduction

Building advocate the concept home for soul, wall extended as roof form a shape of pyramidal to mimic a focus of spirit from the locals. Facade of the building was made from the raw concrete as a symbolisation of respect towards the history. Ample of light project from the void as the open skylights cast the lighting from the top of the building to the courtyard.

Roof Plan

First Floor Plan

Glass Bridge

Timber Slab

Skylight

Figure 1.2.4 Interior Perspective 7 and 8

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.1 Site Plan

Site Plan N

nts

Kampung Pulai, Gua Musang, Kelantan

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.2 Basement Floor Plan

A

A’

Basement Floor Plan N

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

Page 8

Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.3 Ground Floor Plan

A

A’

Ground Floor Plan N

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.4 First Floor Plan

A

A’

First Floor Plan N

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

Page 10

Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.5 Roof Plan

A

A’

Roof Floor Plan N

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.6 North Elevation

North Elevation

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

Page 12

Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.7 South Elevation

South Elevation

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

Page 13

Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.8 East Elevation

East Elevation

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

Page 14

Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.9 West Elevation

West Elevation

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

Page 15

Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.10 Section

Section A-A’

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.3.11 Sectional Perspective

Sectional Perspective

nts

The Visitor Interpretive Centre, Kampung Pulai

Building Structure

Page 17

Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.4 Existing Structural System The VIC guarantees its stability and structural performances by implementing load bearing wall and non load bearing wall. The four exterior concrete panels that tilted towards the centre line act as the load bearing walls, conducting its loads to the foundation from structure above. This VIC has a pyramidal outlook that envelops the entire structure.

Figure 1.4.1 Ground oor plan highlighting position of

Load bearing wall as the existing structural element

load bearing wall

in VIC functions to transfer load from roof, building structure dead load and live load on the first floor and ground floor to the foundation structure below.

They do not serve as wall to segregate spaces into compartment, but to provide support for the superstructure. The entire building structure is not supported by any other structural component such as columns. The major disadvantage of load bearing

Figure 1.4.2 Section highlighting position of load bearing wall

walls is that if any of them collapse, it will definitely lead to structure failure.

Infill Materials

1.4.1 Materiality The main material used in the VIC is reinforced

Lattice Reinforcement

concrete. The large tilted concrete panels which work as wall as well as roof are regarded as an unfavourable way of constructing load bearing

Concrete

walls. It is because it imposes a heavy dead load to the first floor slab and the subsequent structural support below. Hence, it is uneconomical and infeasible.

Building Structure

Page 18

Figure 1.4.3 Construction detail of load bearing wall

Structural Design Post Mortem

Structural Analysis of Existing VIC

Original Drawings

1.5 Summary The VIC priorities aesthetics in design over consideration in conventional structural system. To conclude the existing structure in VIC, it does not have an organized structural system, and seems to be an structural design which is undeveloped and unplanned. The structural integrity could not support the building itself without breaking due to insufficient structural support provided.

Detailed structural issues and modifications will be further discussed.

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

2.0 STRUCTURAL ANALYSIS OF EXISTING VIC

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

2.1

Foundation

FOUNDATION 2.1.1

Overview

2.1.2

Rigidity

2.1.3

Strength

2.1.4

Feasibility

2.1.5

Stability

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Foundation

2.1.1 Overview Foundation is located below substructure (basement) of VIC to transmit the loads of superstructure into the supporting soil. Other than anchoring VIC to the ground, various types of foundation function differently respectively in order to distribute the non-uniform load from superstructure evenly to the subsoil. As for the VIC foundation, four pad footings are placed at four different corners below the basement.

Figure 2.1.1.1 Force transferring from superstructure above to pad footings below through load bearing walls

2.1.2 Rigidity All of the four pad footings are not connected with ground beam. Load bearing walls span between each footings by directly attached onto them. Pad footing acting as a structural component of its own rather than an assemblage of foundation component, causing insufficient lateral stability.

Figure 2.1.2.1 Disconnection between each pad footings

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Foundation

2.1.3 Strength The overall load on southwest of the VIC is heavier than that on northeast due to the presence of both ground floor and first floor at southwest, causing different pressure at both end of the VIC. The entire building might be inclined to southwest.

Figure 2.1.3.1 Improper alignment of foundation causing failing in supporting the building

Foundation is absent below ground floor slab. The ground floor slab sits on ground without any anchoring to the soil. The entire VIC structure rests on the four pad footings of 660mm x 600mm base each. The overly stressed pad footings might exceed the soil bearing capacity, leading to foundation settlement.

Figure 2.1.3.2 Absence of foundation below ground oor load bearing wall

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Foundation

2.1.4 Feasibility Soil condition is a crucial criteria in selecting the appropriate type of foundation. Load transfer from the VIC structure above spreads out within the footing approximately at an angle of 45째, then into the soil at a steeper angle of 60째 from the horizontal. Hence, the soil stratum right below the footing experiences the most pressure in relative to lower stratum due to the increasing area of contact earthward.

W - Footing Width

W

Critical zone compression

45째

for

60째 W

Figure 2.1.4.1 A distance equal to the footings width below the

Figure 2.1.4.2 Pressure exerted by unit area

footing, the unit soil pressure will drop by half. Going down the

in decreasing earthward

same distance again, the pressure will drop by two-thirds

Class of Materials

Load-Bearing Pressure (pounds per square foot)

Crystalline bedrock

12,000

Sedimentary rock

6,000

Sandy gravel or gravel

5,000

Sand, silty sand, clayey sand, silty gravel, and clayey gravel

3,000

Clay, sandy clay, silty clay, and clayey silt

2,000

Source: Table 401.4.1; CABO One- and Two- Family Dwelling Code; 1995.

The shallow soil has a relatively high load-bearing capacity, however, due to the presence of slope at northeast area whereby the soil is not compacted enough, pad footing is inadequate as foundation for the VIC since it is insusceptible to differential settlement.

Figure 2.1.4.3 Sandy gravel soil condition on Site

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Foundation

2.1.5 Stability Pad footing is used to transfer pointed load from columns of skeletal structure. Therefore, they are not suitable to transfer distributed load from the load bearing wall into the subsoil below, causing VIC being vulnerable to uplift forces and lateral forces such as wind force as well.

Figure 2.1.5.1 Distributed load from load bearing walls is supported by pad footings,

which

is

inadequate

Figure 2.1.5.2 Distributed load methodology

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

2.2

Wall

WALL 2.2.1

Load Bearing Wall 2.2.1.1 Overview 2.2.1.2 Strength 2.2.1.3 Stability and Rigidity 2.2.1.4 Economy

2.2.2

Glass Wall 2.2.2.1 Overview 2.2.2.2 Optimization 2.2.2.3 Economy

2.2.3

Retaining Wall 2.2.3.1 Overview 2.2.3.2 Strength

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Wall

2.2.1 Load Bearing Wall 2.2.1.1 Overview Load bearing walls are constructed to support all the dead load of the structure and live load. Four tilted precast concrete walls, forming the pyramidal shape of VIC and the vertical load bearing walls act as the active structural elements which bear and conduct weight from the roof and upper floor all the way to the foundation structure below.

Figure 2.2.1.1.1 Four tilted concrete planes which serve as load bearing wall to support the building structure

Figure 2.2.1.1.2 Position of load bearing walls in Ground Floor Plan

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Wall

2.2.1.2 Strength The four concrete walls act as the main load bearing wall for the VIC. Tilted concrete wall planes are subjected to horizontal loads like wind forces. A great amount of lateral load was also generated when the heavy concrete wall was placed in tilted which are susceptible to lateral deflection. Load bearing wall which is heavy in weight might not be able to support its dead weight when it was placed tilted.

Figure 2.2.1.2.1 Arrows lateral

wind

forces

indicate

that

exerts

pressure on building structure

Figure 2.2.1.2.2 Reaction force exerted along the edges of each concrete wall planes

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Wall

2.2.1.3 Stability and Rigidity The concrete load bearing walls do not establish all the way from foundation to the roof top to the whole structure. Disconnection of supporting structure between foundation and the top of building leads to instability within the whole structure.

Figure

2.2.1.3.1

Absence

of

secondary supporting structures other than load bearing walls

2.2.1.4 Economy The large area of the slanted concrete load bearing walls are costly as it demands more materials than in that of skeletal frame structure. The complicated construction method and the extensive labourers needed throughout the process are less cost-effective.

Figure 2.2.1.4.1 A precise and irreversible construction method is less economically eďŹƒcient

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Wall

2.2.2 Glass wall 2.2.2.1 Overview The transparent glass wall creates opening on the solid concrete wall, separating but connecting exterior with the users in the building structure. It is to preserve the natural view from site as an appreciation towards nature.

2.2.2.2 Optimization The huge span of glass at amphitheatre interrupts the structural integrity of the load bearing wall. Structural support for the large area of glasses is absent in order to create visual connectivity to the outdoor. Also, the glass panel has exceeded the regular maximum size of the locally-sourced glass material.

Figure 2.2.2.2.1 Huge span of glass without internal structural support exceeds the maximum size of glass installation.

2.2.2.3 Economy The existing glass material has a thickness of 200mm. The huge span of glass wall requires a thicker glass material which is more expensive than thinner glass to achieve a higher durability.

Figure 2.2.2.3.1 Location of glass wall in amphitheatre

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Wall

2.2.3 Retaining wall 2.2.3.1 Overview A rigid structure used to resist lateral force from the surrounding soil mass and to support the underground basement structure. The VIC has a ceiling height of 3100mm and retaining walls of 200mm thickness each along its four edges.

Figure 2.2.3.1.1 Retaining wall along the

Figure

2.2.3.1.2

Basement

retaining

basement perimeter

undergoing lateral forces from soil mass

wall

2.2.3.2 Strength The existing retaining walls are 200mm thick. The poor strength of retaining walls is insufficient to hold back the horizontal pressure from soil mass underground. The long span of retaining wall without installation of other secondary structural support has a high potential for lateral deflection due to the lateral pressures generated by soil mass and water pressure.

Figure 2.2.3.2.1 InsuďŹƒcient thickness of retaining

wall

may

undergo

lateral

deection due to horizontal pressure

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

2.3

Slab

SLAB 2.3.1

Overview

2.3.2

Timber Slab 2.3.2.1 Rigidity 2.3.2.2 Strength 2.3.2.3 Economy 2.3.2.4 Feasibility 2.3.2.5 Safety

2.3.3

Concrete Slab 2.3.3.1 Strength

2.3.4

Glass Bridge 2.3.4.1 Rigidity 2.3.4.2 Strength and Economy

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Slab

2.3.1 Overview It is a horizontal structural element that is supported by beam, column or ground. The spanning of slabs creates planes functioning as floors, ceilings and roof deck. The VIC consists of ground-bearing concrete slabs, two suspended timber slabs which are the mezzanine floor slab and first floor slab and a suspended glass slab functioning as corridors.

Figure

2.3.1.1

Section

highlighting position of oor slab

2.3.2 Timber Slab 2.3.2.1 Rigidity The suspended slabs of VIC sit directly onto the load-bearing walls

without

any

proper

connection. As a consequence, the load transferring to the foundation below will not be as effective and the significance of composite structure of timber and concrete could not be fully demonstrated.

Building Structure

Figure 2.3.2.1.1 Improper connection from slab to load bearing wall

Page 33

Structural Design Post Mortem

Structural Analysis of Existing VIC

Slab

2.3.2.2 Strength The slab designed is flat slab, so-called beamless slab. Load is transferred directly into the load-bearing walls. Due to the absence of intermediate support for the slab, it is less flexible for openings. The void of approximately 5.4 metres x 5.4 metres disrupts the structural integrity of the first floor timber slab.

Figure 2.3.2.2.1 Flat Slab example Figure 2.3.2.2.2 Huge void established interrupts the timber slab structural integrity

The tendency for slab deflection is high due to its large span. Strength of the timber slab solely dependant on the nature of timber since reinforcement steel bars cannot be integrated into timber. Therefore, precise structural calculation to suit the position of partition walls, glass curtain wall and sliding door is essential.

Figure 2.3.2.2.3 Timber Slab Deection

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Slab

2.3.2.3 Economy Flat slab is usually larger in thickness to increase its overall strength. The thickness of the flat timber slab is approximately 30 cm. A number of timber panels of 30 cm thick are needed to be assembled as a single composition. This requires a high cost for material. Regular maintenance is necessary for timber and this adds on to the cost down the road as well.

Figure 2.3.2.3.1 Fungus Attack

Figure 2.3.2.3.2 Termites Attack

The usage of thicker solid timber as material will add on to the overall weight of dead load. This will incur a higher cost for the amount of concrete and steel reinforcement needed for the foundation.

Figure 2.3.2.3.3 Heavy dead load of timber slab

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Slab

2.3.2.4 Feasibility Timber shrinks, swells, cracks, twists and bends over time and has a high sensitivity towards the climatic condition. Due to the tropical climate whereby our country constantly experiences hot and humid weather, the strength of pure timber slab will deteriorate after being in constant exposure to moisture.

Figure 2.3.2.4.1 Swelling

Figure 2.3.2.4.2 Cracking

The suspended one-way timber slabs are supported at the both end by the load bearing walls. The long spanning of timber slabs will affect its structural efficiency. Hence, they are not suitable to support unequal distribution of live load and unable to fully support the weight of its own.

Figure 2.3.2.4.3 Load bearing walls that give support to the one-way slab

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Slab

2.3.2.5 Safety The timber slabs behave as a unit component whereby a minor misperforming of a constituting segment of timber might lead to structural failure of the entire slab. This contributes to a high possibility leading to a serious incident when there is an occurrence of fire at any spot within the VIC due to the low fire resistivity of timber.

Figure 2.3.2.5.1 Burning test structure to examine the ďŹ re resistance on dierent types of timber

2.3.3 Concrete Slab 2.3.3.1 Strength The basement slab and ground slab are made up of solid concrete with direct contact to the soil beneath it.

However, there is no barrier that restricts ground moisture from entering the concrete which results in jeopardising the strength of concrete slab to support the subsequent loads from above.

Figure 2.3.3.1 Absence of concrete moisture barrier below the concrete slab

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Slab

2.3.4 Glass Bridge 2.3.4.1 Rigidity Glass bridge is used to provide an alternative pathway connecting landings of the staircase. Absence of proper connection to the first floor slab retards the load transferring mechanism as well.

Figure 2.3.4.1.1 Position of glass bridge being highlighted in First Floor Plan

2.3.4.2 Strength and Economy The bridge of a dimension of approximately 1 metre x 5 metres is suspended above the ground floor courtyard without any support, solely depends on the strength of glass. It is easy to break, hence is at risk of collapsing. In this case, thicker glass material is used to accommodate a higher stress threshold level by enhancing its durability through its thickness. Therefore, it is less cost-effective.

Figure 2.3.4.2.1 Absence of support under the glass bridge with a thickness of 200mm

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

2.4

Staircase

STAIRCASE 2.4.1

Overview

2.4.2

Rigidity and Stability

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Staircase

2.4 Staircase 2.4.1 Overview A structure that is provided with steps to communicate from one to another floor of the building. The opening or space occupied by staircase is known as stairway. The integral part between each floor in VIC mostly work as straight flight staircase.

Figure 2.4.1.1

Staircase

connecting basement and

Figure 2.4.1.2

Staircase connecting

ground floor and mezzanine floor

Figure 2.4.1.3 Staircase connecting first floor and ground floor

ground floor

Figure 2.4.1.4 Position of the most sizable staircase in amphitheatre highlighted in section

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Staircase

2.4.2 Stability and Rigidity The five meter wide timber staircase in amphitheatre does not have any stringer underneath which may cause lateral deformation of threads to occur easily. The absence of proper connection to any structural support induce staircase may not able to stand alone and most likely lead to a structure failure. The improper installation does not achieve the full load bearing capacity and largely reduced the stability of staircase.

Figure 2.4.2.1

Absence of structural

support underneath the staircase reduced stability of staircase structure

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

2.5

Roof

ROOF 2.5.1

Overview

2.5.2

Rigidity

2.5.3

Feasibility

2.5.4

Safety and strength

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Roof

2.5 Roof 2.5.1 Overview The VIC roof functions to shelter the space below and to provide protection from exposure to weather. It is extended to the ground slab in four different planes while intersecting along one line. All the four coplanar planes are titled and form a symmetrical pyramidal enveloping outer shell. An open skylight was introduced on the Southwest roof panel.

Opened skylight

Figure 2.5.1.1 Pyramidal assembly with an open skylight

2.5.2 Rigidity The tilted concrete panels does not have any proper connection to the load bearing walls for load transferring.

The absence of structural joint might lead to failing in holding the slanted roof structure in position.

Figure 2.5.2.1 Absence of structural joint to facilitate the load transferring from roof structure

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Roof

2.5.3 Feasibility Concrete roof as structure has a comparatively great physical weight which leads to many difficulties in building construction. The horizontal weight component of the tilted concrete roof panels might lead to overloading cracking when its compressive pressure exceed its flexural strength. Due to the hot and humid weather on site, concrete is subjected to concrete weathering.

Concrete Cracking

Concrete Weathering

Weight Horizontal Component Weight Vertical Component

Figure 2.5.3.1 Absence of structural spine at roof peak might lead to overloading cracking of the concrete panels

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

Roof

2.5.4 Safety and Strength An opening that functions as open skylight is introduced to one of the concrete panel roof structure. Void on roof structure is not positioned to achieve a perfectly balanced and symmetrical image which lead to imbalance loading. Two facing sides of the roof between the void have unequal areas of load distribution hence cracking may occur on the weaker side of the roof panel.

Figure 2.5.4.1 Unequal area of contact of the trapezium load bearing concrete panels

Figure 2.5.4.2 Void positioned asymmetrically structure disproportionate

on lead of

roof to load

distribution

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

3.0 MODIFIED DRAWINGS

Building Structure

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Structural Design Post Mortem

Structural Analysis of Existing VIC

3.0

Modified Drawings

MODIFIED DRAWINGS Page 47

3.1

Basement Floor Plan

3.2

Ground Floor Plan

3.3

First Floor Plan

3.4

Basement Floor Ceiling Plan

3.5

Ground Floor Ceiling Plan

3.6

First Floor Ceiling Plan

52

3.7

East Elevation

53

3.8

Section

54

3.9

Exploded Axonometric of Skeletal Structure

55

Building Structure

48 49 50 51

Page 47

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.0 PROPOSED MODIFICATION AND STRUCTURAL ANALYSIS

Building Structure

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.1

Post and Beam System

Post and Beam System 4.1.1

Overview

4.1.2

Proposed Modification

4.1.3

Structural Analysis 4.1.3.1 Economy 4.1.3.2 Optimization 4.1.3.3 Feasibility 4.1.3.4 Safety 4.1.3.5 Rigidity and Stability 4.1.3.6 Integration

Building Structure

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

Post and Beam System

4.1.1 Overview Post and Beam system is a skeletal framework that comprises of vertical structural posts and horizontal beams, jointed to form a structural frame into which walls are placed. As the frame is structural and carrying the roof load, number of interior walls are able to be reduced , making it suitable to create open floor plans. Post and beam construction is very flexible and can be used to create interesting and dramatic features and late modifications are able to be made at the construction phase.

4.1.2 Proposed Modifications I.

Replace shear wall system with post-and-beam

system,

then

identify the various points to place the columns and beams based

on

the

existing

wall

positions.

II.

Introduce additional columns and beams to enhance structural support. Column A1, B1 and C1 are

used

to

cantilevered

support ground

the floor

mezzanine. Column 2B, 2C, 3B and 3C are erected to support the void volume while column 4B and 5B are added to accomodate to the long span of the beam which requires more than 2 columns to support it.

Additional columns for extra support Columns replacing the original shear wall system Figure 4.1.2.1 Axonometric drawing showing post and beam system

Building Structure

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

III.

Post and Beam System

Beams are added in between every column to support and distribute the total load from the slabs. Beams are added to the raft foundation frame to support the whole building and allow a proper

load

distribution

pathway.

IV.

Additional beams area added to support the glass courtyard in the basement , having tall walls of glass erected, beams are used to secure them in place and prevent any shear movements.

V.

Beams are also added around the voids

on

the

first

floor.

Introducing a framed structure around the voids ,

the glass

bridge is not only stabilized but it also allows the load transfer from the first floor slabs to the columns

and

later

to

the

foundation.

VI.

Also , beams were added on top of the walls of the first floor. As there is no roof supporting structure, the beams added were to provide lateral support to the roof

from

tension

and

compression of the enclosing structure above .

Additional beams for extra support Beams replacing the original shear wall system

Building Structure

Figure 4.1.2.2 Position of beams from basement floor slab, Ground floor slab, 1st floor slab and above 1st floor walls.

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

VII.

Post and Beam System

Align the columns and beams according to a grid system to reduce mistakes done in structural planning.

Also to ensure the original design intention is still remained, spaces are not changed or discarded but only adjusted in size to suit the post and beam alignments with the walls and structure .By aligning the post and beams with the walls, the contact points with the slabs above are aligned and thus, produces a more effective load distribution.

Figure 4.1.2.3 Modified basement plan with newly

Figure 4.1.2.4 Modified ground floor plan with

introduced gridlines and column arrangement.

newly

introduced

gridlines

and

column

arrangement.

Figure 4.1.2.5 Modified first floor plan with newly

Figure 4.1.2.6 Modified first floor plan indicating

introduced gridlines and column arrangement.

columns connected to beams above the first floor.

Building Structure

Page 61

Structural Design Post Mortem

Proposed Modification and Structural Analysis

VIII.

Post and Beam System

Extend the columns until the top to support the shell structure as well. Load from floor slabs and roof structure is now able to be transferred all the way to the foundation. Hence the compression of each columns are reduced which now allows the building to support more live load and dead load .

Figure two-way

4.1.2.7 oor

ModiďŹ ed slabs

with

beams

Building Structure

Page 62

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Post and Beam System

4.1.3 Structural Analysis

4.1.3.1 Economy By replacing the shear wall system to the post-and-beam system, it reduces the need for large amounts of reinforced concrete walls to support the structural load, now minimised to only the post and beams while the infill walls can be constructed with a more economical substitute.

The organised arrangement and alignment of columns will help to prevent any unnecessary mistakes during construction that may incur additional costs.

Issue solved

: High construction cost.

4.1.3.2 Optimization The shear wall system is changed to post and beam system, hence the role of walls have now changed from bearing structural load to acting as non-bearing infill walls, hence allowing the designer more freedom in designing the separation of spaces.

Issue solved

: Rigidity and over-enclosure of spaces.

4.1.3.3 Feasibility The narrow pathway and limited spaces on site causes difficulties in transporting and storing large building components such as shear wall to the site. However, post and beams can be directly cast on site using formworks which has greater convenience.

Issue solved

: Complications and restrictions in transporting large building components.

4.1.3.4 Safety By shifting the responsibility of load-bearing to the skeletal frame of the building instead of shear walls, it reduces the risk of structural failure and collapse of building if the walls are damaged especially during a fire.

Issue solved

Building Structure

: Danger of structural failure of building during ďŹ re.

Page 63

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Post and Beam System

4.1.3.5 Rigidity and Stability By increasing the number of columns and aligning the columns and beams to a proper grid pattern, the structural load of the building can be evenly distributed to the foundation.

Issue solved

: Uneven load distribution.

4.1.3.6 Integration As the walls are not the main load bearing structure, electrical services such as cables can be integrated how wires pass through column.

Issue solved

Building Structure

: Extra space allocated for service pipes.

Page 64

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.2

R.C. Slab with Timber Flooring

Reinforced Concrete Slab with Timber Decking 4.2.1

Proposed Modification

4.2.2

Structural Analysis 4.2.2.1 Economy 4.2.2.2 Strength 4.2.2.3 Safety and Stability

Building Structure

Page 65

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.2.1 I.

R.C. Slab with Timber Flooring

Proposed Modification Use two-way slab with beams instead of the initial flat slab system.

Figure

4.2.1.1

Modified

two-way floor slabs with beams

Figure 4.2.1.2 Flat slab (before modification)

Building Structure

Figure 4.2.1.3 Two-way slab with beams (after modification)

Page 66

Structural Design Post Mortem

Proposed Modification and Structural Analysis

II.

R.C. Slab with Timber Flooring

Justification of application of two-way slab : A.

Basement floor slab Ly/Lx = 13105/12600 =1.04 < 2 (Two-way slab) 12600

13105

B.

Figure 4.2.1.4 Position of beams of

Figure 4.2.1.5 Direction of forces through

basement floor slab

beams of basement floor slab.

Ground floor slab and first floor slab Ly/Lx = 17905/18015 = 0.99 < 2 (Two-way slab) 18015

17905

Building Structure

Figure 4.2.1.6 Position of beams of ground

Figure 4.2.1.7 Direction of forces through

floor slab

beams of ground floor slab

Page 67

Structural Design Post Mortem

Proposed Modification and Structural Analysis

R.C. Slab with Timber Flooring

18015

17905

III.

Figure 4.2.1.8 Position of beams of first

Figure 4.2.1.9 Direction of forces through

floor slab

beams of first floor slab

Installation of concrete vapour barrier at floor slabs that are susceptible to ground moisture, namely the ground floor slab and basement floor slab.

Figure 4.2.1.10 Concrete Vapour Barrier is layered before concrete slab construction

Building Structure

Page 68

Structural Design Post Mortem

Proposed Modification and Structural Analysis

IV.

R.C. Slab with Timber Flooring

Replace the timber structural material of first floor slab to reinforced concrete slab with timber flooring finish.

Figure 4.2.1.11 Modified first floor slab and indication of sectional call-out detail

Exterior

125

Interior

Floor slab

Solid timber flooring

Steel rebar 27

Wall Beam Timber battens Reinforced concrete floor slab

Column

Figure 4.2.1.12 Construction detail of modified R.C. slab with

Figure 4.2.1.13 Sectional call-out detail

timber flooring

showing connection between R.C floor slab to column and beam.

Building Structure

Page 69

Structural Design Post Mortem

Proposed Modification and Structural Analysis

R.C. Slab with Timber Flooring

4.2.2 Structural Analysis

4.2.2.1 Economy Timber is relatively more expensive than concrete, hence by changing to reinforced concrete floor slab, material costs are reduced while the timber floor finishing allows the initial earthy warm tone to be maintained.

Timber also requires extensive treatments and long term maintenance to prevent it from rotting, hence changing it to reinforced concrete is a more economical option.

Issue solved

: High material and maintenance cost of timber.

4.2.2.2 Strength Reinforced concrete has a larger load-bearing capacity, hence is more capable to handle the unequal distribution of live load on the first floor.

The concrete vapour barrier found in the ground floor slab and basement floor slab assists in guarding against ground moisture from penetrating the concrete structure, hence improving the overall strength of the building.

Issue solved

: InsuďŹ&#x192;cient load-bearing capacity and weakening of structure due to natural elements.

4.2.2.3 Safety and Stability The use of two-way slab with beams enables a more efficient distribution of load from the floor slabs to the foundation, hence it improves the overall safety and stability of the structure.

Issue solved

Building Structure

: IneďŹ&#x192;cient load distribution.

Page 70

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.3

Lightweight Facade System

Lightweight Facade System 4.3.1

Proposed Modification

4.3.2

Structural Analysis 4.3.2.1 Economy 4.3.2.2 Safety and Feasibility 4.3.2.3 Rigidity and Stability

4.3.3

Building Structure

Case Study of Vodafone Headquarters

Page 71

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Lightweight Facade System

4.3.1 Proposed Modifications I.

Replace the initial idea of having a shear wall facade to a steel stud frame with infill concrete panel cladding as a lightweight facade system.

Figure

4.3.1.1

ModiďŹ ed

facade system of VIC

Fixing screws Call-out detail Lightweight concrete Steel reinforcement rods (8mm) Steel reinforcement rods (10mm) Precast concrete panel (20mm thick)

Light gauge steel frame Precast concrete panel

Figure 4.3.1.2 Anatomy of light gauge steel system with

Figure 4.3.1.3 Cross section of facade system

concrete

Building Structure

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

Lightweight Facade System

Fixing screws

Light gauge steel frame

Precast concrete panel outer side with smooth surface Precast concrete panel inner side with rough surface Figure 4.3.1.4 Sectional call-out detail of

Lightweight concrete (89mm

facade system.

thick)

II.

Fix the steel frame to concrete floor slab

III.

through bolt connection on steel plates.

Addition of a roof ridge board to connect the light gauge steel framework together.

Steel plate to have bolt connection to

Ridge

concrete raft foundation and steel

C-shaped inside a

frame.

track Fastened

member: section. with

Clip angle

screws through top

Precast concrete panel

and bottom flanges, as required.

Light gauge steel frame

Precast concrete panel

Steel plate Bolt connection Raft foundation

Figure 4.3.1.5 Light gauge steel frame to concrete raft

Figure 4.3.1.6 Light gauge steel frame to ridge board

foundation connection

connection

Building Structure

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

Lightweight Facade System

4.3.2 Structural Analysis

4.3.2.1 Economy Steel frame system requires lower cost and shorter construction schedule to assemble and construct, compared to constructing large areas of reinforced concrete shear walls, hence effectively cutting down on construction cost.

Issue solved

: High material and construction cost.

4.3.2.2 Safety and Feasibility Reinforced concrete shear walls are not suitable to be placed in a tilted position as its immense weight will impose overbearing load onto the structural system. The steel facade system with precast concrete panel cladding offers a much lightweight facade solution while still maintaining the intended exterior facade texture.

By implementing a lightweight facade system, the dead load imposed onto the structural system is reduced which lessens the risk of exceeding load-bearing capacity, hence is a safer and more feasible option.

Issue solved

: Danger to users due to inappropriate application of shear walls.

4.3.2.3 Rigidity and Stability By introducing a roof ridge and connecting the steel frame support to each floor slab, it allows the facade system to be integrated together with the main structural system as a single entity, hence making it more rigid and stable against external forces such as lateral wind forces or sudden ground movement.

Issue solved

Building Structure

: Instability of facade system.

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.3.3

Lightweight Facade System

Case Study

Vodafone Headquarters / Barbosa & GuimarĂŁes

Figure 4.3.3.1 Front view of the Vodafone

Figure 4.3.3.2 Back elevation of Vodafone

Headquarters, showing a lightweight concrete

headquarters

cladding system with glass openings

The Vodafone Headquarters provide an exemplary example for buildings using large areas of lightweight facade system with concrete cladding, and is able to create an interesting geometrical pattern on its facade.

The formalization of this concept is based on the material concrete, which through its plasticity, allows to create irregular and free-form shapes, working both as a structural solution and exterior appearance, creating a unique shape, a monolithic building, bringing cohesion and unity to the set. The technical complexity of the building leads to a periphery structural solution, a shell of concrete, like an egg, reducing internal support to the two stairwells and three central pillars, allowing great versatility in its interior space use.

In this case, it proves relevant for the facade design of the VIC where its exterior inclined facade planes can achieve the same concrete texture without having to rely on traditional solid concrete construction.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

Outside windows Grabs Metal structure Plasterboard Metal sheet IPE wood structure IPE slatted wood Thermic insulation Concrete wall Air gap White concrete panel

Figure 4.3.3.3 Section of part of the Vodafone Headquarters

Building Structure

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.4

Foundation

Foundation 4.4.1

Proposed Modification

4.4.2

Structural Analysis 4.4.2.1 Economy 4.4.2.2 Safety and Feasibility 4.4.2.3 Rigidity and Stability

Building Structure

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

Foundation

4.4.1 Proposed Modifications I.

Application of different types of foundation to suit the different element of building components that also have different requirement for load distribution.

II.

For the superstructure, use raft foundation to link the building structure together to reduce the risk of encountering differential settlement. The raft comprises a layer of reinforced concrete covering most parts of the building.

Figure 4.4.1.1 ModiďŹ ed section with

addition

of

raft

foundation for ground ďŹ&#x201A;oor and indication of sectional call-out detail.

Column Floor slab

Main

Secondary

beam

beam

Filling

between

raft and floor slab

Main beam

Secondary beam

Raft slab Figure 4.4.1.3 Callout of the raft foundation.

Figure 4.4.1.2 Plan view of the raft foundation

Building Structure

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Structural Design Post Mortem

Proposed Modification and Structural Analysis

III.

Foundation

Use strip foundation to support the basement retaining walls. Strip foundation consists of a continuous strip, provides continuous ground bearing under a linear structure.

IV.

Use reinforced concrete pad footings to support the newly added individual columns at the basement to ensure proper loads transfer to the ground .

Figure

4.4.1.4

section

ModiďŹ ed

showing

load

distribution pathway

R.C column Column reinforcement starter bar Footing reinforcement Figure 4.4.1.6 Construction detail of pad footing

Strip Foundation

Pad footing

Figure 4.4.1.5 ModiďŹ ed basement plan showing positions of

Figure 4.4.1.7 3D view of strip footing

strip foundation and pad footings.

Building Structure

Page 78

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Foundation

4.4.2 Structural Analysis

4.4.2.1 Safety The presence of slope on site might induce ground movement. Foundation is proposed to the ground floor to anchor the superstructure against the natural force and thus able to prevent the structures from falling apart and collapse.

Issue solved

: Absence of foundation for the ground floor slab

4.4.2.2 Stability and Rigidity Raft foundation is proposed for the ground floor slab so that it links the load distribution pathway of shell facade with the interior structure so the system becomes a single unit.

Strip foundation is added to support the retaining basement wall to ensure the loads carried from the linear structures are transferred evenly to the ground.

Issue solved

: Insufficient lateral stability and overstressing of existing pad footings that might leads to foundation settlement.

4.4.2.3 Feasibility Strip foundation is a better alternative compared to the typically used pad footing for basement. Due to the long span of the retaining wall, pad footings are less practical as it will require a rather big amount of individual footings to support, as well as the large amount of formwork to construct it. Therefore, using strip foundation will be more practical and more convenient to construct.

Raft foundation serves to avoid differential settlement which otherwise would occur if pad or strip foundation is adopted.

Issued solved

: Insufficient lateral stability

4.4.2.4 Economy Raft foundation do not require excavation and is specifically designed for the building thus it can be more robust, quicker to build and often less expensive than traditional foundations.

Pad footing is the cheapest foundation type for individual columns.

Issue solved

Building Structure

: Cost inefficiency

Page 79

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.5

Retaining Wall

Retaining Wall at Basement Floor 4.5.1

Proposed Modification

4.5.2

Structural Analysis 4.5.2.1 Strength 4.5.2.2 Rigidity and Stability

Building Structure

Page 80

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Retaining Wall

4.5.1 Proposed Modification I.

Counterforts are attached to the inner face of the wall along the edge with the 3 stories building at an interval of 1200mm. The soil mass under the adjacent building is more compacted than the opposite side across the VIC whereby there are only trees and a 5 metres high public toilet. Hence, more lateral pressure will be exerted along that edge and extra supports will be needed.

VIC

Loose

Compacted

soil

soil

Figure 4.5.1.1 Site context of the VIC. Figure 4.5.1.2 ModiďŹ ed basement plan indicating position of counterforts.

Counterforts

Counterfort at spaced intervals

Lateral pressure from soil mass

Figure 4.5.1.3

Application of counterfort to resist

Figure 4.5.1.4 3D view of counterforts

lateral pressure from soil mass.

Building Structure

Page 81

Structural Design Post Mortem

Proposed Modification and Structural Analysis

II.

Retaining Wall

Increase the thickness of the basement retaining wall until 400mm.

Figure 4.5.1.5 ModiďŹ ed section

indicating

thicken

the

basement

retaining wall

Building Structure

Page 82

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Retaining Wall at Basement Floor

4.5.2 Structural Analysis

4.5.2.1 Strength Increase in wall thickness increases its load bearing capacity and thus increases the overall strength.

Issue solved

: Poor strength in resisting lateral pressure due to insuďŹ&#x192;cient wall thickness

4.5.2.1 Rigidity and Stability Counterfort ties the wall and the base slab together. It is used to resist lateral force and reduce the shear and bending moment.

Issue solved

: Long spanning of wall without structural support which might causes lateral deďŹ&#x201A;ection.

Building Structure

Page 83

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.6

Staircase

Staircase 4.6.1

Proposed Modification

4.6.2

Structural Analysis 4.6.2.1 Economy 4.6.2.2 Safety 4.6.2.3 Rigidity and Stability

Building Structure

Page 84

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.6.1 I.

Staircase

PROPOSED MODIFICATION Introducing three stringers underneath the 5m amphitheater staircase, two on the side and one in the middle .

II. III.

Imposing double stringer on the side of the two 2.6m wide amphitheater staircase.

Concrete stringers with timber decking for thread and riser are proposed.

Figure 4.6.1.1 Staircase is

located

at

the

amphitheater

Figure 4.6.1.2 After adding stringers to the staircase

Building Structure

Page 85

Structural Design Post Mortem

Proposed Modification and Structural Analysis

IV.

Staircase

Stringers is the most complicated part of the stair, if even one notch is just a little bit off it can cause the steps to creak and be unstable. To solve this issue, the stringer proposed are connected to the concrete ground floor slab and top landing by angle brackets and tension control bolts.Tension control bolt is a heavy duty bolt that is usually used in steel frame construction.

Stringer

Angle Bracket

Tension Control Bolts

Figure

4.6.1.3

Stringer

connection to ground ďŹ&#x201A;oor slab

Tension Control Bolts

Stringer

Figure

4.6.1.4

Stringer

connection to top landing Angle Bracket

Building Structure

Page 86

slab

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Staircase

4.6.2 Structural Analysis

4.6.2.1 Economy Instead of using timber stringers, concrete stringers with timber decking is proposed. The cost for long term maintenance and cost for timber is will be conserved. Thus, the original design intention is also remained .

Issue solved

: High maintenance and material cost

4.6.2.2 Safety By imposing double stringer on the normal staircase , it creates a boundary to prevent people from tripping as the two flanking staircases and the amphitheater staircase are not aligned and of different sizes.

After modification for stringer, the support is sufficient to allow live load to add together with dead load , creating a safe environment for users to sit and maneuver on the amphitheater.

Issue solved

: Lack of skilled workers and high cost of transportation

4.6.2.3 Rigidity and Stability After imposing of stringers, the live load of above the staircase is able to be evenly distributed to the foundation and first floor slab. Thus, deformation of the threads can be prevented.

Issue solved

Building Structure

: Plausibility of structure failure

Page 87

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.7

Staircase

Glass Bridge 4.7.1

Proposed Modification

4.7.2

Structural Analysis 4.7.2.1 Economy 4.7.2.2 Safety 4.7.2.3 Stability

Building Structure

Page 88

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.7.1 I. II.

Glass Bridge

PROPOSED MODIFICATION Introducing I-beam to support the glass bridge Aligning the I-beam to the primary beam from the void

III.

I-beam is bolted with aligned bracket into the primary concrete beam .

IV.

Replacing the single huge glass panel with several pieces of smaller panels.

V.

Framing the pieces of glass panels with aluminium members.

Figure 4.7.1.1

Addition of I-beam

below the glass bridge

Figure 4.7.1.2 Glass bridge slab is divided to several panels of smaller glass planes

Building Structure

Page 89

Structural Design Post Mortem

Proposed Modification and Structural Analysis

VI.

Glass Bridge

The main issue of the glass slab bridge is that it sits between voids without any support underneath as can see from ( Figure 2.3.2.2.2 ). Thus , prone to deflection due to the huge span of glass that depends solely on the strength of the glass to distribute load . By introducing I-beam , the bending and shear loads of the glass slabs will be carried. The load now can be transferred to the surrounding ground slab as the i-beam is connected to the primary beam of the building instead of being channeled by itself.

VII.

Expansion joint covers were required at one end of the glass bridge to accommodate building movement due to settlement, expansion and contraction.This supports the weight of the panel and copes with the expansion by absorbing the compression.

Floor Slab

Expansion Joint Aluminium frame

Glass Panel

I-beam

Angle Bracket

Bolt Nut , Anchor Bolt Primary Beam

Supporting

Figure 4.7.1.3 Connection between concrete slab and primary beam, primary beam and I-beam , I-beam and glass panel.

Building Structure

Page 90

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Glass Bridge

4.7.2 Structural Analysis

4.7.2.1 Economy Introduction of I-beam as a support system for the glass bridge allows the use of glass panels with normal thickness.This not only is enable to save on construction cost needed to connect a big span of thick glass but as well save on transportation cost as moving several panels of glass is more convenient than a thick huge piece of glass.

Connection of several glass slab together instead of using a single huge glass slab will also save on labour cost. As a lot of manpower is need to carry such a huge slab in comparison with the flexibility of the connection of several glass slabs.

Having aluminium frames will provide a quicker and easier installation, which saves both time and money. As they are light , thus easily transported and maneuvered.

Issue solved

: Lack of skilled workers and high cost of transportation and construction.

4.7.2.2 Safety By reducing the possibilities of imposing too much load on the bridge, it directly reduces the chances of the glass slab cracking or collapsing, creating a safer environment for user to pass.

Issue solved

: Dangers of structure failure.

4.7.2.3 Stability The I-beam creates support for the glass bridge as it connects to the primary beams of the structure . This allows the live load to be evenly distributed.

Using aluminum reduces the weight of the completed assembly at the same time maintaining the strength and load bearing capabilities required.

Issue solved

Building Structure

: Withstanding external loads like compressive, tensile and moment.

Page 91

Structural Design Post Mortem

Proposed Modification and Structural Analysis

4.8

Glass Curtain Wall

Glass Curtain Wall 4.8.1

Proposed Modification

4.8.2

Structural Analysis 4.8.2.1 Economy 4.8.2.2 Safety 4.8.2.3 Rigidity and Stability 4.8.2.4 Feasibility

Building Structure

Page 92

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Glass Curtain Wall

4.8.1 PROPOSED MODIFICATION I. II. III.

Reducing the height of curtain glass wall.

Replacing one huge span of glass to smaller size glass panels.

Imposing unit and mullion connections in between the glass panels .

Figure 4.8.1.1 Glass curtain wall located at the West Elevation of the building.

Figure 4.8.1.2

Glass curtain

wall located at the North Elevation,

where

the

amphitheater is.

Building Structure

Page 93

Structural Design Post Mortem

Proposed Modification and Structural Analysis

IV.

Glass Curtain Wall

Transom or horizontal rails are horizontal members on the curtain wall panel. The mullions or vertical rails are anchored to the edge slab or beam. They are mainly involved in supporting the dead weight of the curtain.

Supporting lateral load

Beam

Supporting vertical load

Glass Panels

Mullions Transoms

Figure 4.8.1.3 Components of a unit and mullion curtain wall system

Mullions

Spacer

Structural silicone Glass Panel Backer Rod

Figure 4.8.1.4 Callout detail of a mullion connection to glass panel

Building Structure

Page 94

Structural Design Post Mortem

Proposed Modification and Structural Analysis

Glass Curtain Wall

4.8.2 Structural Analysis

4.8.2.1 Economy Connection of several glass slab together instead of using a single huge glass slab will save on labour cost needed to carry and skilled workers needed to construct the structure.

Large unit may also increase transportation costs from the factory to the site and erection costs of placing the units on the building.

Issue solved

: High transportation, construction and labour cost.

4.8.2.2 Safety Forces on the curtain walls are transmitted to the building frame by the mullions, this restrain the lateral buckling which would occur on a single wide span glass panel. This reduces the possibilities of the glass panel to crack and take the tensile stresses if cracking do occur..

Issue solved

: Possibility of cracking of glass curtain wall and collapsing.

4.8.2.3 Rigidity and Stability Introducing the unit mullion system as the connection for the curtain wall will provide rigid support to the glazing while dividing the adjacent glass units. Differential movement between curtain wall units is accommodated at the vertical and horizontal unit joints.

Issue solved

: Deformation of structure.

4.8.2.4 Feasibility Unit mullion system also requires less space on site for layout thus providing an advantage for the building site which has space limitations.

Issue solved

Building Structure

: Lack of space on site for storage.

Page 95

Structural Design Post Mortem

Conclusion

5.0 CONCLUSION

Building Structure

Page 96

Structural Design Post Mortem

Conclusion

5.0 Conclusion The amendment on the structure of Visitor Interpretive Centre based on the in-depth structural analysis has improved the overall buildability of the building. The main purpose of the modifications were to improve on the stability and rigidity of the of the structural support system while simultaneously enhancing on the safety and economy of the project by reducing the cost of construction and optimizing the full utilization of the structural members. Thus, proposing appropriate and relevant modifications while preserving the original design intention and aesthetics to the fullest extend.

The proposed modifications are summarised as following : 1.

Post and beam system in replacement of the load bearing structural wall system.

2.

Introducing a grid system complementary to post and beam system by realigning the walls and spaces within accordingly.

3.

Two-way slab in replacement of the flat slab system.

4.

Instead of having the entire suspended slab as solid timber structure, reinforced concrete slab with timber decking is proposed.

5.

Thick load bearing concrete enveloping panels are being modified into a lightweight facade.

6.

A composition of three different types of foundation is being applied.

7.

Accustom the properties of retaining wall to the site condition.

8.

Complying the staircase structure with the regulation and building requirement.

9.

Adjust the glass panel size to an adequate dimension for the use as floor slab and curtain wall.

Building Structure

Page 97

Structural Design Post Mortem

References

6.0 REFERENCES

Building Structure

Page 98

Structural Design Post Mortem

References

6.0 References Book 1.

BS 8110: Part 1: 1985. British Standard: Structural Use Of Concrete. Part 1. Code Of Practice For Design And Construction. British Standards Institution (BSI)

2.

C. K. Wang.1993. Intermediate Structural Analysis. New York: Mcgraw Hill Book Company.

3.

D.F Mccarthy. 2002. Essentials Of Soil Mechanics & Foundations: Basic Geotechnics, 6th Edition. New Jersey: Prentice-Hall, Inc.

4.

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