Structural Design Post Mortem

School of Architecture, Building & Design (SABD) Bsc (Hons) in Architecture Building Structure (BLD61003)

ASSIGNMENT 1: STRUCTURAL DESIGN POST MORTEM for VISITOR INTERPRETIVE CENTER Kampung Pulai, Gua Musang

Group Members: Ng Zien Loon Chong Xian Jun Raemi bin Safri Yew Jey Yee Nicholas Wong Yew Khung Loi Chi Wun

0328565 0332605 0328385 0327708 0328559 0328652

Tutor: Mohamed Rizal Mohamed

STRUCTURAL DESIGN POST MORTEM for VISITOR INTERPRETIVE CENTER Kampung Pulai, Gua Musang

CONTENT

1.0 INTRODUCTION………………………………………………………………….. 1 2.0 VISITOR INTERPRETIVE CENTER……………………………………….. 2 2.1 INTRODUCTION………………………………………………………….. 3 2.2 DRAWINGS………………………………………………………………….. 4 3.0 DISCUSSION ON EXISTING STRUCTURAL SYSTEM…………...12 3.1 STRENGTH & STABILITY PROBLEM STATEMENT 1: STRUCTURAL SYSTEM…………………….. 13 PROBLEM STATEMENT 2: FOUNDATION…………………………………....18

3.2 FEASIBILITY PROBLEM STATEMENT 3: ROOF BEAM……………………………………...20 PROBLEM STATEMENT 4: ROOF STRUCTURAL ARRANGEMENT………………………………...22

3.3 INTEGRATION PROBLEM STATEMENT 5: ROOF DRAINAGE SYSTEM…………………………………………....23

3.4 ECONOMY PROBLEM STATEMENT 6: STRUCTURAL SYSTEM…………………….. 26 PROBLEM STATEMENT 7: WALL………………………………………………...28

4.0 MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTER……………………………………….. 30 4.1 PLANS………………………………………………………………………….. 31 4.2 ELEVATIONS……………………………………………………………….. 35 4.3 SECTIONS…………………………………………………………………... 37 5.0 CONCLUSION………………………………………………………………………. 39 6.0 REFERENCES……………………………………………………………………….. 40 40

CONTENT

1.0 INTRODUCTION

Structural design is part of the general design problems. In reality, it can be regarded as one of the most important design problems as it deals with life safety of the building occupants. An architecturally beautiful building without proper structural design would totally fail, to the extent it will cause fatality.

On the other hand, an unattractive building with sound structural system can ensure safety of building occupants.

One of the reasons students normally design irrational and uneconomical buildings is lack of basic understanding of structural theory, principles and structural behavior. As a result, the structural design is often left as an afterthought rather than incorporated into the design process. This assignment was designed to help students to better understand and appreciate structural design and hopefully to integrate this knowledge into their designs in the future.

INTRODUCTION

01

2.0 VISITOR INTERPRETIVE CENTRE 2.1 INTRODUCTION 2.2 DRAWINGS

02

VISITOR INTERPRETIVE CENTRE

2.1 INTRODUCTION Buildings are always seen in context with the physical site, however, the context that the villagers are living in is not just about the physical landscape, it’s about the spiritual desire they have, their practices and beliefs. They believe in paying reverence to their origin, they worship deities and pay respect to their forefathers without whom they will never had a beginning, hence, the ancestors are the origin of the beginning.

“It is only with the heart that one can see rightly; what is essential is invisible to the eye." - The Little Prince. Though essential, the unseen will be forgotten without a physical representation that can mark its presence.

The temple that was built for religious purposes preserved the practices and beliefs from the ancestor. Hence, a Visitor Interpretive Centre to commemorate the ancestor and their story is needed before it is forgotten.

People normally build houses for the inhabitation of human body, sometimes, we build for deities for religious purposes, but, how do we build for the departed spirit? If the building formwork is the outer body, then the casted concrete structure is the spirit within.

The Visitor Interpretive Centre not only serves as a physical presence for the “departed spirits” but also feeds the human soul and human spirit, by creating an architecture that embodies spiritual senses of the site.

Figure 2.1.1. Street view of Visitor Interpretive Centre.

INTRODUCTION

03

VISITOR INTERPRETIVE CENTRE

2.2 DRAWINGS

ROOF PLAN 1:100

DRAWINGS

04

VISITOR INTERPRETIVE CENTRE

2.2 DRAWINGS B

A’

UP

SOUVENIR SHOP FFL 0.200

STORAGE UP

OFFICE

FFL 0.200

ATRIUM

FFL 0.200 M&E

RECEPTION

LOBBY / MARKET PLACE FFL 0.200

UP FFL 0.200

WATER GARDEN

STORAGE

FFL 0.200

B’

A FFL 0.200

DRAWINGS

GROUND FLOOR PLAN 1:100

05

VISITOR INTERPRETIVE CENTRE

2.2 DRAWINGS B

A’

UP DN

VIEWING DECK

UP

FFL 5.240

DRINKS KIOSK FFL 3.260

DN

OFFICE

FFL 3.260

VOID UP UP VOID

VOID

DN GALLERY FFL 3.260

VOID VIEWING DECK FFL 3.260

A

DRAWINGS

VOID B’

MEZANNINE FLOOR PLAN

1:100

06

VISITOR INTERPRETIVE CENTRE

2.2 DRAWINGS B

A’

UP

READING CORNER

UP

DN

FFL 7.040

UP ARCHIVE FFL 7.940

GALLERY

UP

FFL 6.140

UP

GALLERY

GALLERY

FFL 5.240

FFL 5.240

DN VOID

VOID

DN

METAL DECK ROOF METAL DECK ROOF

A

DRAWINGS

B’

FIRST FLOOR PLAN 1:100

07

VISITOR INTERPRETIVE CENTRE

2.2 DRAWINGS

NORTH ELEVATION 1:100

DRAWINGS

08

VISITOR INTERPRETIVE CENTRE

2.2 DRAWINGS

WEST ELEVATION 1:100

DRAWINGS

09

VISITOR INTERPRETIVE CENTRE

2.2 DRAWINGS

SECTION A-A’ 1:100

DRAWINGS

10

VISITOR INTERPRETIVE CENTRE

2.2 DRAWINGS

SECTION B-B’ 1:100

DRAWINGS

11

3.0 DISCUSSION ON EXISTING STRUCTURAL SYSTEM 3.1 3.2 3.3 3.4

STRENGTH & STABILITY FEASIBILITY INTEGRATION ECONOMY

12

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

3.1 STRENGTH & STABILITY One of the structural requirement for building structure is to have adequate strength and stability.

Strength is the capacity of the individual components, which together make up a structural system, to withstand the load that are applied to them.

Stability is the capability of a structural system to transmit loads safely to the ground.

PROBLEM STATEMENT 1: STRUCTURAL SYSTEM In the initial design, the structural system of the building was not well thought. The designer assumed all the concrete walls (200mm) to be load bearing and are able to support the whole building, without considering and analysing the distribution of load in the building. In addition, the wall consists of multiple openings and arcs which will reduce the strength of load bearing wall.

Figure 3.1.1. Section A showing load distribution of existing structure.

The random arrangement of semi-circular openings on the wall disrupts the flow of load transmission. The arches distribute the load to sides causing the loads to be concentrated at some points. Since the loads are not uniformly distributed along the wall, the uneven compression forces will be exerted on the wall. This will impose additional shear stress to the wall which might eventually lead to structural failure.

STRENGTH & STABILITY

13

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

Figure 3.1.2. Section B showing load distribution of existing structure.

The self weight of load bearing walls at first floor contributes a huge amount of dead load. North Gallery is supported by the walls below, but the South Gallery overhangs above the lobby.

Tension

Compression

Figure 3.1.3. Tensile and compressive forces acting on the floor of South Gallery

The floor of South Gallery is only supported at one end, hence the supported side of the floor can transfer the load down to ground while the overhanging side of the floor has to withstand the heavy load imposed by the walls above. The uneven load exerted on the floor creates tensile stress on top of the floor and compressive stress at the bottom of the floor. Combination of tension and compression forces will cause bending deformation. Hence, the floor is very likely to collapse.

STRENGTH & STABILITY

14

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

PROPOSED SOLUTION Skeletal structural system should be designed to support the whole building and distribute the load evenly. By doing this, the wall will be non-load bearing, hence openings and semi-arches can be located freely without affecting the strength and stability of building.

Figure 3.1.4. Overhanging semi-arches in existing design.

After changing the structural system of the building to skeletal system, columns and beams should be added to support the overhanging semi-arches.

Column

Beam

Figure 3.1.5. Modified Ground Floor Plan with columns and beams

STRENGTH & STABILITY

Column

Beam

Figure 3.1.6. Modified Mezzanine Floor Plan with columns and beams

15

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

Column

Beam

Figure 3.1.7. Modified First Floor Plan with columns and beams.

Figure 3.1.8. Modified section showing load distribution.

STRENGTH & STABILITY

16

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

Figure 3.1.8. Modified section showing load distribution.

STRENGTH & STABILITY

17

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

PROBLEM STATEMENT 2: FOUNDATION The existing design does not include a foundation system. Foundation helps securely withstand the loads through ground transmission without causing settlement or underground movement that might cause stability failure.

Load bearing walls in the existing design are not evenly distributed at site, and the north side of the building is 3 levels while the southern part is 2 level. Hence, the dead load of the structure is uneven which will lead to uneven settlement of the building.

Figure 3.1.9. Uneven settlement due to difference in weight of structure.

PROPOSED SOLUTION In order to be able to transfer the load of the building to the ground properly, a foundation system must be added to assist in load transfer especially with the problem of uneven distribution of dead load of the building. Due to the change to a concrete frame structure in the previous proposed solution (refer pg. 13) , it is best for the building to use a pad footing foundation. Pad foundation are optimum to support localised single-point loads, in this case, structural columns. The load from the column is transferred directly to the pad and is then spread by the pad to the layer of soil below it. Pad footing foundation is also economically better as compared to strip foundation, as it requires less amount of concrete used, thus it will save the cost of the materials as well as time to cure.

STRENGTH & STABILITY

18

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

Figure 3.1.10. Foundation layout plan.

Figure 3.1.11. Overall proposed skeletal structure.

STRENGTH & STABILITY

19

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

3.2 FEASIBILITY Feasibility is a broad term that discusses on the viability of a project in terms of in many aspects, ranging from technicality to social impact, economy to sustainability. However, in our report for building structure, we are focusing on the buildability of this project that can be discussed from two perspectives. Firstly, the availability of materials and products. Secondly, its availability to be handled by the production organization.

PROBLEM STATEMENT 3: ROOF BEAMS The initial design is feasible in terms of its availability of materials, as it is built out of mainly reinforced concrete. However, there are several flaws in the roof structure that result in the difficulties for structure to be to be constructed.

Figure 3.2.1. Roof plan showing the existing roof beams.

Redundant roof beams causing wastage of material and increased difficulties in building. Moreover, the use of excessive roof beams add too much weight upon the roof structure, causing difficulties for it to hold in place and support itself.

FEASIBILITY

20

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

PROPOSED SOLUTION The redundant roof beams have to be removed and the roof beams are integrated with the skeletal structure of the building to act as the main support for the roof structure.

Existing roof beams

Modified roof beams

Figure 3.2.2. Comparison between the simplified roof beams and the initial roof beams.

FEASIBILITY

21

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

PROBLEM STATEMENT 4: ROOF STRUCTURAL ARRANGEMENT

In general, there is a lack of attention to the design of roof structure.

Figure 3.2.3. Section cut showing the existing roof structure of the building.

Firstly, there is no consideration in terms of the attachment of roof to the building. The roof panels are directly attached to roof beams without rafters and purlins as the result of the first problem statement, i.e. the excessive use of roof beams as support, leading to the negligence of proper attachment method.

Secondly, there are as many as 9 levels of roof, making it impractical and difficult to install drainage system.

PROPOSED SOLUTION Rafters and purlins are introduced and the number of levels of roof is reduced 6, greatly reducing the complexity of roof, allowing for a simpler drainage solution.

Figure 3.2.4. Section showing the updated design considering the roof structure.

FEASIBILITY

22

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

3.3 INTEGRATION Good structural design requires integration of the structure into the whole physical system of the building. Structural design has the potential to accommodate building services such ah lighting, ventilation, water supply, and so on.

PROBLEM STATEMENT 5: ROOF DRAINAGE SYSTEM The slanted roof of the existing building is not equipped with a proper drainage system. A roof drainage system is essential to effectively remove water and debris from the roof. It also helps to minimize groundwater accumulation around building foundation with the designated and proper flow of water. Proper roof drainage system also prevent water from backing up into the roof, hence reducing the risk of interior water damage.

Direction of Rain flow

Figure 3.3.1. Roof Plan showing existing design of roof

INTEGRATION

23

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

PROPOSED SOLUTION Roof drainage system should be installed to discharge rainwater systematically. Gutter is needed at the lower edge of the slanted roof to collect water for proper discharge. From the previous proposed solution (refer pg. 13), columns are added to the existing design to support the building. Hence, it can be utilized to integrate downpipe into the column to discharge water from the gutter.

Integration of downpipe into columns preserves the building aesthetic while decreasing the undesired visibility of exposed pipes on the elevations of the facade and interior spaces. Besides, the embed of utility pipes in concrete columns will not interfere with the reinforcement bars and column strength.

Direction of Rain flow Integrated Downpipe Gutter

Figure 3.3.2. Proposed roof drainage system with integrated downpipe.

Gutter The roof in the existing design consists of different angles of slope and edges due to the architectural design of different heights of walls and roof panels.

Therefore, to complement with the existing design of roof, multiple gutters are needed to be installed. In the previous proposed solution (refer pg. 22), leveling of roof is simplified which will ease the installation of gutter.

INTEGRATION

24

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

To complete the drainage system the gutters and pipes have to be fitted together with end cap, bracket hanger, leaf screen, downspout and splash block.

Gutter Screen End Cap

Elbows

Section

Inside Corner

Drop Cutlet Bracket Hanger

Hanger

Outside Corner

Downpipe

Splash Block

Figure 3.3.3. Example of typical gutter system

Figure 3.3.4. Exploded axonometric of roof drainage system components.

Downpipe A few considerations should be included when designing the downpipe: ●

● ●

●

Each downpipes should drain a maximum of 50 feet of gutter. Gutter expansion characteristics may further limit the distances, since water cannot flow past an expansion joint.

Avoid locations where water must flow around a corner to reach a downpipe.

The choice of construction material of column and downpipe should be durable such as reinforced concrete and polyvinyl chloride (pvc) to withstand and sustain the structural strength.

The size of downpipe should complement with the diameter of 350mm column of the building to have enough spacing from the centre.

Therefore, 68mm diameter pvc downpipe is suitable to be used.

68mm diameter PVC downpipe

350 x350mm concrete column

Figure 3.3.5. Size and materiality of column and downpipe.

INTEGRATION

Figure 3.3.6.

Example of rain water downpipe in between the reinforcement bar.

Figure 3.3.7.

Example column formwork for concrete casting.

Figure 3.3.8.

Example of casted concrete column and downpipe.

25

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

3.4 ECONOMY To construct a building, a lot of money is involved. Expensive structures do not often add value in the way expensive hardware or carpet may. What is usually desired in a building is simple adequacy, and the use of hard-working low-cost structure.

PROBLEM STATEMENT 6: STRUCTURAL SYSTEM The cost of in-situ concrete walls is very high, this is due to having to take consideration of the amount of labour required, the cost of the required formwork for the entire building, as well as amount of time required for the concrete to cast. Therefore, the total cost of the building would be extremely high compared to using other materials and systems.

PROPOSED SOLUTION Precast concrete frame structure should be used as the structural system as it would be a lot cheaper as compared to cast in-situ concrete. By using precast concrete column and beams with standard dimensions, there would be a lot of cost saving, as there would be no formwork required on site, lack of labour cost, as there only needs to be labour to set up the already made column and beams, as well as quick construction, due to getting it premade.

There is an additional cost for transportation however, comparing with the cost of casting in-situ, it is still the more economical choice.

Figure 3.4.1. Example of casting a cast in-situ wall.

ECONOMY

Figure 3.4.2. Precast concrete frame structure.

26

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

EXISTING

MODIFIED

Ground Floor

Ground Floor

Mezzanine Floor

Mezzanine Floor

First Floor

First Floor

Figure 3.4.3. Comparison of the use of existing and modified structural system.

ECONOMY

27

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

PROBLEM STATEMENT 7: WALL In the initial design, the building relied on in-situ concrete load bearing walls. However, with the change to a skeletal structure, there is an opportunity to change the infill of the wall as cast in-situ concrete is no longer needed. The high cost of the cast-in situ concrete due to labour, formwork and time makes it non economical.

PROPOSED SOLUTION As the load bearing component changes from wall to frame structure, it is more economical to use a brick infill in between the concrete column as opposed to cast-in situ concrete infill. Cast in-situ concrete walls would require large amounts of additional formwork for the walls, will take a lot of time to properly cure, as well as require additional steel and concrete as compared to using a brick infill. The aesthetics of a concrete wall could easily be made by using plaster on top of the brick wall. The use of a brick infill also allows for easy cheap and uncomplicated modification in the future.

Cast In-Situ Concrete Wall

Brick Wall Infill

Cubic meter of concrete requires 7.87 bags of cement, 0.15 brass of sand and 0.30 brass of aggregate

A cubic meter of brick work (1:6) in CM consumes about 2 bags of cement, 0.15 brass of sand and 500 bricks

Requires huge amounts of additional costly formwork before construction

Not much pre construction works

Requires proper curing - around 28 days

A lot faster to build - dependent on speed of labour

Generally requires more skill to cast

Generally easier to construct

Very difficult to alter as any alteration might drastically reduce its strength

It is easy to modify a brick wall than a concrete element

Figure 3.4.4. Table comparing the cost of cast in-situ concrete wall and brick wall infill.

ECONOMY

28

DISCUSSION ON EXISTING STRUCTURAL SYSTEM

However with the use of brick infill, some complicated wall designs in the building, in this case, the semi-arch wall, become too complex and too expensive to be done with brick infill. Therefore, some walls will require to be done with precast concrete.

Semi Arch Wall - Precast Concrete Brick Infill Wall

Figure 3.4.5. Section, showing complex shape of semi-arch wall and location of different wall types.

ECONOMY

29

4.0 MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE 4.1 PLANS 4.2 ELEVATIONS 4.3 SECTIONS

30

MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE cut

4.1 PLANS

ROOF PLAN 1:100

PLAN FOR ROOF PLAN

31

MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE

4.1 PLANS B

A’

UP SOUVENIR SHOP FFL 0.200

STORAGE UP

OFFICE

FFL 0.200

ATRIUM

FFL 0.200 M&E

RECEPTION

LOBBY / MARKET PLACE FFL 0.200

UP FFL 0.200

WATER GARDEN

STORAGE

FFL 0.200

B’

A FFL 0.200

PLAN FOR GROUND FLOOR

GROUND FLOOR PLAN 1:100

32

MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE

4.1 PLANS B UP A’

DN VIEWING DECK

UP

FFL 5.240

DRINKS KIOSK FFL 3.260

DN

OFFICE

FFL 3.260

VOID UP UP VOID

VOID

DN GALLERY FFL 3.260

A

PLAN FOR MAZZANINE FLOOR

VOID VIEWING DECK FFL 3.260

VOID

B’

MEZANNINE FLOOR PLAN 1:100

33

MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE

4.1 PLANS B A’

UP

READING CORNER FFL 7.040

UP

DN

UP

GALLERY

ARCHIVE FFL 7.940

UP

FFL 6.140

UP

GALLERY

GALLERY

FFL 5.240

FFL 5.240

DN VOID VOID

VOID

VOID

VOID

DN VOID

METAL DECK ROOF

METAL DECK ROOF B’

A

PLAN FOR FIRST FLOOR

FIRST FLOOR PLAN 1:100

34

MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE

4.2 ELEVATIONS

NORTH ELEVATION 1:100

ELEVATIONS

35

MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE

4.2 ELEVATIONS

WEST ELEVATION 1:100

ELEVATIONS

36

MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE

4.3 SECTIONS

SECTION A-A’ 1:100

SECTIONS

37

MODIFIED DRAWINGS OF VISITOR INTERPRETIVE CENTRE

4.3 SECTIONS

SECTION B-B’ 1:100

SECTIONS

38

5.0 CONCLUSION

In conclusion, there are several structural issues that we have identified from this building, i.e. strength and stability, feasibility, integration and economy.

One of the major flaws in the initial design is on its structural strength and stability. In the case study, the structural system used was load bearing wall. Nonetheless, it is coupled with the extensive use of large openings that break the even distribution of load, causing loads to be concentrated on certain points and deem load-bearing wall unsuitable.

Feasibility, integration and economy are also aspects of our study in this project. In terms of feasibility, the study focuses on the and practicality of design. For example, the buildability of roof structure was discussed. A good structural design requires integration of the structure into the whole physical system of the building. In this case, the study is also directed to the integration of drainage system. Last but not least, economy considerations were discussed in terms of the choice of structural system and building materials.

The modifications of the building are to improve the structural integrity of the building based on the understandings on issues mentioned above. A precast concrete frame structure system is introduced to counter the issue of strength and stability, resulting in opportunities that follow.

Firstly, the use of brick wall infill that saves time and cost. Secondly, integration of drainage system with the frame structure. The feasibility of building is improved by fixing the roof structures.

CONCLUSION

39

6.0 REFERENCES Concrete Frame Structures - Understanding Building Construction Retrieved from http://www.understandconstruction.com/concrete-frame-structures.html Binding Concrete Layter Reinforcement of Pad footing - Akin Tee (2019) Retrieved from https://www.academia.edu/37760172/Blinding_concrete_layer_Reinforceme nt_of_pad_footing The Use of Precast Concrete Systems in the Construction - H.N Nurjaman Retrieved from http://www.iitk.ac.in/nicee/wcee/article/14_05-06-0028.PDF Gutter and Downspouts - Copper Development Asociation Inc. (2019) Retrieved from https://www.copper.org/applications/architecture/arch_dhb/arch-details/gut ters_downspouts/ Rainwater System - Brett Martin (2008) Retrieved from http://www.brettmartin.com/~/media/Files/Plumbing-and-Drainage/Rainwat er/Rainwater-Product-Guide.pdf Embedments in Concrete - Madeh Izat Hamakareem (2019) Retrieved from https://theconstructor.org/concrete/embedments-reinforced-concrete/21700 / Roof Drainage System Design - Chris Drake (2018) Retrieved from https://bigreddog.com/roof-drainage-system-design/ Building Construction Illustrated - Francis D.k Ching (2014) Building Construction Illustrated. New Jersey : John Wiley & Sons Inc. Design of External Walls Retrieved from https://www.bca.gov.sg/Professionals/Iquas/gpgs/WEWall/WEWChpt2.pdf

REFERENCES

40