Skeletal Construction - Temporary Bus Shelter

BUILDING CONSTRUCTION II BLD 60703 OCTOBER 2018 REPORT

SKELETAL CONSTRUCTION TEMPORARY BUS SHELTER

AZEERAH MUBARAKH ALI 0328906

GAVIN TIO KANG HUI 0333373

NG ZIEN LOON 0328565

LOI CHI WUN 0328652

PRISCILLA HUONG YUNN 0332599

CONTENT 01

INTRODUCTION . . . . . . . . . . . . . 02

06

CONSTRUCTION DETAILS . . . . 20

02

DESIGN CONSIDERATIONS . . . 04

07

DESIGN ANALYSIS . . . . . . . . . . 29

03

DESIGN DEVELOPMENT . . . . . . 07

08

LOAD TEST . . . . . . . . . . . . . . . . 35

04

ORTHOGRAPHIC DRAWINGS . . 09

09

CONCLUSION . . . . . . . . . . . . . . 37

05

CONSTRUCTION PROCESS . . . . 14

10

REFERENCE . . . . . . . . . . . . . . . . 38

01 / INTRODUCTION 01.1

SKELETAL CONSTRUCTION

01.1 / SKELETAL CONSTRUCTION

Skeletal construction distributes lateral force to columns or walls through beams and transfers it vertically down to the foundation and then to the supporting soil beneath it.

In a group of 5 and in the scale of 1:5, we are to construct a temporary bus shelter which can accomodate 5-6 people with a maximum height of 600mm and a maximum base of 400mm x 800mm.

The bus shelter demonstrates an understanding of the issues of strength, stiffness and stability of structures including modes of structural system, forces, stress and strain and laws of static. It will be tested on its ability to take load applied in a specified duration.

2

02 / DESIGN CONSIDERATIONS 02.1 02.2 02.3

CLIMATE CONSIDERATIONS USER-FRIENDLY CONSIDERATIONS MATERIAL CONSIDERATIONS

02.1 / CLIMATE CONSIDERATIONS RESISTANCE TO WEATHER

“COOL� ROOF DESIGN

The openings and sliding panels reduces lateral wind forces, along with the ribbed metal roof directs water evenly.

The natural metallic finish of the roof, is made cool by painting a reflective coating on the metal roof. It can increase its solar reflectance and thermal emittance, allowing it to achieve cool roof status.

02.2 / USER-FRIENDLY CONSIDERATIONS COMFORTABILITY

VISIBILITY & SAFETY

The bus shelter is naturally ventilated for cooling. There is space for users to stand in order to accommodate more people in the bus shelter.

The use of polycarbonate allows the coach operator to see inside of bus shelter and vise-versa. It is also a crime prevention as the public and user are not secluded thus allowing complete visual and surveillance on the bus shelter.

MAINTENANCE The shelter can be maintained easily with use of timber joints as they can provide ease in removing and assembling parts for replacement.

4

02.3 / MATERIAL CONSIDERATIONS

CONCRETE FOUNDATION

METAL ROOF

Concrete properties have high compressive strength thus making it most suitable as the foundation.

Metal roofs can sustain wind gusts up to 140 miles per hour, will not corrode or crack, and may be impact-resistant.

Image 1 Concrete Foundation Image obtained from internet

Image 2 Timber Structures Image obtained from internet

Image 3 Metal Roof Image obtained from internet

TIMBER STRUCTURES

POLYCARBONATE

The custom-made structure is remarkably strong and durable although it is lightweight form of construction.

Polycarbonate is high-impact resistant, thus making it durable,, shatterproof, and energy efficient

Image 4 Polycarbonate Image obtained from internet 5

03 / DESIGN DEVELOPMENT 03.1

DESIGN DEVELOPMENT

03.1 / DESIGN DEVELOPMENT

1.

CUBOID

&

PRISM

Cuboid as the base provides better stability.

Prism with pitch on top weighs down the pressure to the bottom. Wide base strengthen the structure and able to accomodate more user.

4

SLIDING

PANEL

&

2.

WOOD SKELETAL FRAMING SYSTEM

Wood framing system (post, beam and joints) is used as the skeletal structure of the bus shelter.

3.

EXTENDED

ROOF

STRUCTURE

Roof is cantilevered at both sides with different pitch to create Saltbox Roof which is suitable for tropical climate.

LOUVERS 5.

Louvers filter direct sunlight while allowing sufficient natural light and ventilation to the shelter. Sliding panels with polycarbonate control internal ventilation, protect user from rain, and allow visual permeability at the same time.

REINFORCED CONCRETE FOUNDATION

Reinforced concrete foundation are added to anchor the bus shelter. Therefore, structure will be able to withstand higher load and have higher compressive strength.

7

04 / ORTHOGRAPHIC DRAWINGS 04.1 04.2 04.3

ROOF PLANS FLOOR PLANS ELEVATIONS

05 / CONSTRUCTION PROCESS 05.1 05.2 05.3

PRE-CONSTRUCTION FOUNDATION FLOOR

05.4 05.5 05.6

COLUMNS SLIDING PANEL SEATING

05.7 05.8 05.9

LOUVERS ROOF FINISHES

05.1 / PRE-CONSTRUCTION

1. Digital scaled model of bus shelter is made in SketchUp software

2. Dimensions are exported and listed to mark on the wood and customize different components of the shelter.

3. Woods needed for construction are prepared and cut according to the markings.

05.2 / FOUNDATION

4. Wooden blocks are connected to ground beam as the pad footing for the bus shelter.

5. The wooden foundation is being spray painted to represent reinforced concrete pad footing foundation.

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05.3 / FLOOR

6. Floor joist is attached to the bottom plate with 60mm spacing which represent 300mm in real scale.

7. Timber decking is screwed to the floor joist in perpendicular direction.

05.4 / COLUMNS

8. Half lap with tenon joint is used to connect bottom plate to the column.

15

05.5 / SLIDING PANEL

9. Frame for sliding panel is fit between columns and beam.

10. Polycarbonates are inserted into the sliding sash and fixed sash as glazing.

12. Support for the seating are attached to the column and the decking.

13. Seat decking is nailed to the support.

11. Sliding sash is fixed into the frame.

05.6 / SEATING

16

05.7 / LOUVERS

14. Timber planks are nailed to the columns with spacing to act as louvers.

05.8 / ROOF

15. Roof beam and top plate are attached to column using half lap joint.

16. King post are used to support the ridge board, a column is placed beneath the king post to transfer the load down to the foundation.

17. Rafters are laid accordingly using birdsmouth joint to create pitch for the roof.

17

05.8 / ROOF

18. Strut are connected to king post and rafter in include directory to prevent sagging of rafters.

19. Purlin are laid perpendicularly to the rafter for the attachment of metal decking.

20. Sand paper is used to smoothen the rough surfaces.

21. Varnish is painted and aerosol clear coat is sprayed over the shelter to enhance waterproofing feature of the shelter.

05.9 / FINISHES

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06 / CONSTRUCTION DETAILS 06.1 06.2 06.3

FOUNDATION TIMBER BASE FRAME TIMBER FLOOR DECKING

06.4 06.5 06.6

TIMBER COLUMNS TIMBER ROOF FRAME SLIDING PANEL & SEATING

06.1 / FOUNDATION Galvanised Screw

Galvanised U-bracket

Timber Base Frame

Concrete Ground Beam

Concrete Pad Footing

Figure 6.1.1. Connection and detail of timber base frame to concrete ground beam

CONCRETE PAD FOOTING The bus shelter consists of six concrete pad footings. They are used to support the ground beam. They take concentrated loads from a single point load such as the structural columns which are vertically above them and then spreads to the bearing strata of soil underneath. Since the bus shelter is made up of post and beam structure, pad footing is the most economic and ideal option for the skeletal structure.

: 250mm : 450mm : 450mm

Length Width

: 3800mm : 1800mm

Figure 6.1.4. Concrete Pad Footing

CONCRETE GROUND BEAM It is a rectangular structure that is connected to the pad footings through rebar. It is used to anchor each of the concrete pad footings below in their respective position as well as providing a stronger base structure for the timber floor frame .

REBAR Rebar is made up of high tensile steel bars of 6mm diameter.

Steel bars from pad footings are extended into the concrete ground beam to reinforce the connection between them.

1325mm

Figure 6.1.2. Ratio of separation between each adjacent concrete pad footings is maintained at 1:1

Height Length Width

Figure 6.1.5. Concrete Ground Beam

Figure 6.1.6. Galvanised U-bracket

Figure 6.1.7. Galvanised Screw

Thickness Length Width

Head Diameter : 22mm Body Diameter : 12mm Body Length : 50mm

: 10mm : 150mm : 20mm

Figure 6.1.3. Connection of rebar from pad footing to concrete ground beam 20

06.2 / TIMBER BASE FRAME SKELETAL TIMBER BASE FRAME Four main timber beams and five floor joists are connected together forming the base frame of bus shelter. It serves as a primary supporting structure with the aid of columns to the other components of the bus shelter such as wall panels, roof structure, seats, etc. Weight of the seat and living load is transferred to the ground beams through the floor joists and eventually to the six concrete pad footings.

TIMBER FLOOR BEAM

TIMBER FLOOR JOIST

It acts as the main connection between columns and concrete frame and the horizontal support that holds the floor joists.

Five timber floor joists are arranged at 250mm interval. They are to distribute load evenly throughout the entire skeletal base frame system.

Height Width Length

Figure 6.2.1. Skeletal Base Structure Plan

: 150mm : 150mm : 3700mm & 1700mm

Figure 6.2.2. Timber Floor Beams

Height Length Width

: 150mm : 3400mm : 50mm

Figure 6.2.3. Timber Floor Joist

Galvanised Screw

Galvanised Joist Hanger

Thickness Length Width

Figure 6.2.4. Half Lap Joint to connect timber ground beams

Figure 6.2.5. U-Bracket to connect timber frame to concrete beam

Figure 6.2.6. Connection of timber floor joists are strengthen with galvanised joist hanger

: 10mm : 100mm : 75mm

Figure 6.2.7. Galvanised Joist Hanger

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06.3 / TIMBER FLOOR DECKING TIMBER FLOOR DECKING The timber planks are placed over the timber floor joists perpendicularly to ensure even distribution of forces exerted on it. Being the complement to the skeletal base frame, it provides additional strength to support the mobile living loads.

Galvanised Screw

Merbau Decking

TIMBER DECKING PLAN (Hide few decking to show structure below) 1.

2.

To label separation dimension To show materiality (zoom in then show merbau decking material)

Figure 6.3.1. Timber Decking Plan

Timber Base Frame

Concrete Ground Beam

Concrete Pad Footing

Twenty-one pieces of rectangular timber decking are arranged accordingly with a gap of 25mm in between. It is to enhance the bus shelter sustainability by taking into account the thermal expansion and contraction of each timber decking. They are attached to the base frame by screwing them at three points for each decking : both edges on the floor beams and on the middle floor joist and hence resulting in a firm attachment.

MERBAU WOOD Being the uppermost layer of the skeletal base structure, it would undergo significant abrasion compared to other layers.

Merbau wood is chosen as the material for timber decking. It is known for its low rate of expansion and shrinkage and hence being rated as first class for ground-use timber. Also, due to the fact that timber decking would be exposed to sunlight, merbau wood is able to retain its colour much longer than any other types of wood.

Length Width Thickness

: 1700 mm : 140 mm : 20 mm

Figure 6.3.2. Merbau Wood Decking

Figure 6.3.3. Components of The Skeletal Base Frame

Figure 6.3.4.

Living and dead loads are exerted on timber decking, which are then transfer to floor joists, ground beams and pad footing at last

22

06.4 / TIMBER COLUMNS TIMBER COLUMN Timber column is the vertical structure member of the bus shelter to transmit compressive load of the roof and lateral forces of ceiling beams and ground beams down to the foundation

Weight from ceiling structure itself

Forces exerted by wind from all direction

Figure 6.4.3. Timber Columns Height Width Length

: 150mm : 150mm : 1750mm & 2050mm

Figure 6.4.1. Load experienced by the roof structure is transferred to the pad footing through columns

TENON JOINT Columns are joined to the timber ground beams with tenon joint. A tenon joint is made by slotting a small protruding part of a timber into a fitting aperture without any aid of bolt or screw. Bolted or screwed joints would apply pressure over a small area which tends to weaken the structure.

Figure 6.4.4. Columns are placed directly above the pad footings to facilitate the transferring of forces downwards

Load from the columns is transferred to the pad footing below. The load is then spread out by pad footing into the ground. Line of action of the weight of the columns coincide with the centre of gravity of pad footings, which hence results in the absence of net moment along it.

Figure 6.4.5. Line of action of the weight of column

Figure 6.4.2. Tenon Joint 23

06.5 / TIMBER ROOF FRAME ROOF STRUCTURE

RAFTER

The roof structure of the bus shelter is designed to be light, practical and functional. It is a low slope roof which is tilted at two different angle entirely supported by five columns whereby two of them are longer than the other three.

Rafter is used to support the roof associated loads. It is the only slating structural component of the roof structure. Each of the rafters is extended from the ridge to the roof beam. By sitting on the roof beam, the rafter demonstrates an efficient mean of spreading the load exerted by roof structure down through the wall without creating pressure points where each rafter meets the wall

Metal Corrugated Roofing Sheet

Figure 6.5.2. Rafters

Dimension of the rafter is relatively smaller compared to the roof beam so that the overall roof structure is lighter in weight.

Thickness Width Length

: 100mm : 50mm : 1500mm & 1050mm

TOE-NAILING

Purlins

Toe-nailing method is used to fasten the joint whereby timber is fixed together by slanted application.

Ridge

Rafter

King Post Roof Strut

Figure 6.5.3. Birdsmouth Joint

Figure 6.5.4. Toe-Nailing Method

Roof Beam

Considering the bus shelter as a light skeletal timber construction,, rafters are connected to the roof beam with birdsmouth joint. Angles on both sides are carefully calculated with hypotenuse theorem and appropriate indentation is made on the rafter while maintaining its structural integrity.

Figure 6.5.1. Components of Roof Structure 24

06.5 / TIMBER ROOF FRAME ROOF BEAM

ROOF STRUT

KING POST

The roof beam provides lateral support to the columns and acts as the base for the roof structure. It holds all the five columns in their respective position

The roof strut is an integral part of load bearing for roof structure, designed to resist longitudinal compression.

Load from purlins and rafters are transferred to the ceiling beam at an angle of 45 degree.

The combination of rafter, purlin, king post, ceiling beam and strut forms a king post roof truss. King post receive load from the ridge at the end of the rafter which prevents the wall from spreading out due to thrust. It acts as a central vertical post for the roof structure, working in tension to support the roof beam below from a truss above.

Thickness Width Length

: 150mm : 50mm : 3700mm & 1700mm

Thickness Width Length

Figure 6.5.2. Roof Strut

Figure 6.5.1. Roof Beams

: 50mm : 50mm : 390mm & 725mm

Thickness Width Length

: 100mm : 100mm : 547mm

Figure 6.5.3. King Post

T-HALVING JOINT T-halving joint is chosen to connect the roof beam and column. Both opposing forces from adjacent beams which are angled at 90° are being eased off. Hence, there is no net moment about the column.

Ridge

Purlin

King Post

Strut 30°

45°

Column

Roof Beam

Figure 6.5.4. Net moment = 0

Figure 6.5.5. T-Halving Joint

Figure 6.5.6. Component of King Post Roof Truss 25

06.5 / TIMBER ROOF FRAME RIDGE

METAL CORRUGATED ROOFING SHEET

The ridge is the horizontal beam at the apex of the roof. It ensures high ends of all the rafters meet in a straight line and stay static. It is an add-on to the overall lateral stability.

The metal sheet spans between the purlins and is used as a diaphragm to transfer wind and seismic loads to the lateral structural frame below. Besides being noted for its longevity, it consists of high percentage of recycled material and 100% recyclable.

Thickness Width Length

Galvanised Screw

Ridge Cover

: 100mm : 197mm : 3700mm

Figure 6.5.1. Ridge

PURLIN Purlin acts as the secondary structural support to the roof structure. Being supported by the rafters below, purlins allow the bus shelter to span wider in the direction parallel to them.

Thickness Width Length

Figure 6.5.2. Purlin

: 50mm : 50mm : 4000mm

Thickness Length Width

: 2mm : 4000mm : 1570mm &1180mm

Figure 6.5.4. Connection of corrugated metal roofing sheet to timber roof frame

Figure 6.5.3. Metal Corrugated Roofing Sheet

NOTCH JOINT Notch joint is used to connect purlins to the rafters. Equal amount of material is removed from both to create identical groove. The resulting thickness of the joint is same as that of the thicker component, the rafter. As such, both components are prevented from moving without materially weakening them.

Figure 6.5.5. Notch Joint connecting purlins to rafters

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06.6 / SLIDING PANEL & SEATING SLIDING TIMBER PANEL

POLYCARBONATE

SEATING

Timber stud wall system is incorporated into the design of the sliding panel. Stud wall is non load-bearing and is used to hold the sliding panel and polycarbonate .

Polycarbonate is a lightweight thermoplastic material that is lightweight and durable. It shades the users from Ultraviolet Radiation (UV) and also allows visual permeability from the interior.

Timber decking of the seating is arranged with a gap in between to provide adequate ventilation below .

Galvanised Screw

Sliding Panel

Thickness Width Length

: 5mm : 300mm : 1550mm

Timber Plank

Support

Figure 6.6.1. Sliding Timber Panel

Figure 6.6.3. Polycarbonate

Figure 6.6.5. Seating Polycarbonate Head

Jamb

SLiding Sash

Fixed Sash Sill

Figure 6.6.2. Components of Sliding Panel

Due to Malaysia tropical climate of frequent rainfall and exposure to sunlight, silicon sealant is chosen as the adhesive to connect polycarbonate to the timber frame. It has strong binding properties and is highly resistant to weathering.

Figure 6.6.4. Sliding Panel Section

Thickness Width Length

: 20mm : 100mm : 3400mm

Silicon

Figure 6.6.6. Seating Timber Plank 27

07 / DESIGN ANALYSIS 07.1 07.2

NON-STRUCTURAL ANALYSIS STRUCTURAL ANALYSIS

07.1 / NON-STRUCTURAL ANALYSIS

RAIN

SUNLIGHT

Bus shelter designed to provide protection from rainfall. Application of saltbox roof allows efficient flow of rainwater from both sides of slope. Roof panel is tilted 45° on the back side and 20° on the front, a higher degree to emphasize the entrance of the bus stop . Sliding door also provides extra protection to users from rain splashes from the sides of bus shelter.

Roof of bus shelter is built of metal very strong and resilient corrugated metal which can withstand extreme temperatures. Metal reflects radiant heat from the sun, minimizing midday heat gain.

Polycarbonate on sliding door is able to reduce heat build up during hot days as well as having uv protection properties, this increasing thermal comfort of the bus shelter.

VENTILATION

HUMIDITY

Natural ventilation is allowed through the permeable wall of louvres on the back elevation of the bus shelter .Sliding door also provides extra ventilation when opened .Air flow is maximized, creating a highly ventilated space, thus providing maximum thermal comfort towards the users.

Varnish coating was applied to all timber parts of the structure. Its water resistance property allows the timber to retain from splitting and cracking due to the humidity of the climate. The maximum air ventilation also reduces humidity level, thus enhancing the comfort of the users.

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07.2 / STRUCTURAL ANALYSIS FLOOR SYSTEM : ONE-WAY SYSTEM Load is distributed throughout the bus shelter, it is supported by beams and columns in one direction. Uniform distribution of concentrated load is directed upon each pad footing.

Formula :

3700 1700

>

2

Figure 7.2.1. Plan of view of load distribution

Figure 7.2.2. Axonometric of the direction of load distribution

30

07.2 / STRUCTURAL ANALYSIS STATIC LOAD/ DEAD LOAD Dead load refers to the weight of the permanent structural elements of the bus shelter. Force acting upon the structure is constant. It is transferred from the roof to the vertical columns , to the floor slab and to the foundation.

Figure 7.2.3. Right elevation view of static load distribution

IMPOSED LOAD/ LIVE LOAD Live load is the load carried by the secondary structural elements which will be transferred the primary structural elements.This includes non-permanent and temporary loads such as humans, animals and rain .

Figure 7.2.4. Right elevation view of live load distribution

31

07.2 / STRUCTURAL ANALYSIS WIND LOAD

PERMEABLE

Wind load refers to the force of the wind that acts on the bus shelter. The permeable wall of louvres (gaps between louvres) is designed to allow wind to pass through in and out of the structure.This allows the resistance to the strong wind and lateral forces to be increased, decreasing the chances of shear load

Figure 7.2.5. Right elevation view of wind load

WALL

The opening between the louvres of the wall encourages wind flow through the bus shelter. This allows the prevention of wind load trapped inside the bus shelter , in addition to promoting ventilation.

Figure 7.2.6. Back elevation view of wind flow through permeable walls

32

07.2 / STRUCTURAL ANALYSIS SKELETAL FRAME CONSTRUCTION The main construction elements in timber skeleton frame construction consist of vertical supports such as columns and horizontal beams. This supporting structure has developed from timber frame construction methods.

HORIZONTAL STRUCTURES

VERTICAL STRUCTURES

RIDGE

ROOF BEAM

KING POST ROOF BEAM

STRUT

COLUMN

FLOOR BEAM COLUMN

FLOOR BEAM

Figure 7.2.7. Isometric view of horizontal structures

Figure 7.2.8. Isometric view of vertical structures

33

08 / LOAD TEST 08.1

LOAD TEST

08.1 / LOAD TEST

ROOF

BENCH

FLOOR DECKING

2 books were placed on top of the roof to test the live loads acting upon the roof such as rain.

2 books were placed on bench to test the live loads imposed by the users that sit on the bench.

3 books were placed on the timber floor decking to test the live loads imposed on the timber decking such as weight of users .

Total Load: 6 kg

Total

Total

Test Result :Successfully withstand the load

Test Result : Successfully withstand the load

Load

:

6kg

Load

:

9kg

Test Result : Successfully withstand the load

35

09 / CONCLUSION 09.1

CONCLUSION

09.1 / CONCLUSION

Through this project, we were able to gain a better understanding of the means to design a bus shelter structure while implying construction knowledge that we have learnt in class. Our bus shelter was designed with the combinations of cuboid and prism form to promote stability of the structure.

Several considerations were taken to ensure the durability, buildability of structure as well as the safety and comfort of the users. Designs were adapted to suit the climatic factors of our country. Also, since the structures of our bus shelter are built of timber, we have learnt the importance of joints to ensure the efficiency of our bus shelter in terms of stability and strength.

37

10 / REFERENCES 1.

APTA Transit Infrastructure. (2010). Bus Stop Design and Placement. APTA Standards Development Program, 14.

2.

Bielefeld, B., Kummer, N., Hanses, K., Steiger, L., Hanses, K., & Achilles, A. (2015). Basics building construction. Basel: Birkhäuser.

3.

Chudley, R., & Greeno, R. (2006). Advanced construction technology (4a. ed.). Harlow: Pearson Educación.

4.

Chudley, R. (1977). Construction technology. London: Longman.

5.

Chudley, R., Greeno, R., Hurst, M., & Topliss, S. (2012). Advanced construction technology. Oxford: Pearson.

6.

Energy Saver. (n.d.). Cool Roofs. Retrieved from Energy.gov: https://www.energy.gov/energysaver/energy-efficient-home-design/cool-roofs

7.

FIDLER, H. (2008). Advanced building construction: A manual for students. BiblioBazaar.

8.

Kumudamani, K., & Kuppuram, G. (1990). Building construction. Delhi: Sundeep Prakashan.

9.

McKay, W. B., & McKay, J. K. (1975). Building construction. London: Longman.

10.

Steiger, L. (2007). Timber construction. Basel: Birkhäuser.