Introduction 1

Design Concept 1

Massing 3

Design Development 4

Material Analysis 8

Construction Progress 12

Design Considerations 14

Loads and Forces 15

Joints 19

References 23

The purpose of this project is to create an understanding ofskeletal structural components and how it reacts underloading. Convincing understanding on how skeletalconstruction functions are to be demonstrated. A 1:5 scalemodel of a bus shelter that can accommodate 5-6 people isto be built based on structural considerations and twoforms.

Sustainable design and tropical climate with hot and humidweather were taken account. Thus, bamboo is selected asthe main material for the structure of our bus shelter.Bamboo is easily renewed and inexpensive. Together withits thatched roof design, it responds to its tropical contextand reflects our local culture.

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2

The overall massing of our design is based on twobasic forms, a triangular prism above a cuboid with abase scaled 2:1. This design lowers the overall centerof gravity as the form below has more mass than theform above, making it stable.

This design is highly conventional and functional,suiting its purpose as a bus shelter that isconstructed to accommodate 5-6 people.

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The initial design is composed of multiple triangularshapes, making it relatively complex. However, userrequirements were not taken much consideration andavailable user space is not sufficient if according to scale.

The following design simplifies its shape and structure,maximizing space available for passengers waiting for thebus. In spite of that, the pitched roof structure is notsteady enough due to lack of load bearing qualities.

4

This design makes the seating part of its structure. Still, thisdesign is disadvantageous due to lack of appropriatebracings.

Next, the design is changed by converting the walls thatwere initially merely screens to load-bearing structures.Vertical columns are repeated to distribute the load fromthe roof to the ground. Even so, the pitched roof is not wellsupported and wobbly.

5

The eventual design utilizes bracings to keep the structure in tact, making thestructure more resistant to external forces by distributing loads to the ground.Joists were added to strengthen the roof. The structure is made out of bamboowhile the pitched roof is covered with nipa palm leaves with a canvas beneath,suiting its tropical context. Its structure is simple yet efficient. Amendmentswere made as the construction of the 1:5 model proceeds.

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Prototypes

Prototype 1:

The actual material, bamboo isimplemented. It displays the overallmain frame of the design and serve asan experimentation on a final 1:5 scale.It is flimsy, indicating the fact thatmore varieties of joints are to beexplored

Prototype 2:

PVC pipes were used. All memberswere connected with the bolt and nutsystem. It is highly sturdy and strongyet lacks qualities and characteristicsdisplayed by bamboo.

Prototype 3:

Cardboard tubes were used. Comparedto PVC pipes, it is more similar tobamboo in terms of texture and origin,making it a more accurate depiction ofbamboo. A combination of bolts, nutsand ropes are applied for its joints,making it comprehensive.

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Bamboo (thicker ones represented by cardboard tubes)

Advantages:Light, Easy to transport, Natural surface doesnot require any coating

Disadvantages: Flammable

Cotton Canvas

Advantages: Waterproof, Strong, High tensile capacity,Provide shade

Disadvantages: Shrinks after long periods of usage

Nipa Palm (Nypa fruticans) Thatched Roof

Advantages: Waterproof, Available locally, Lightweight, Sustainable and recyclable

Disadvantages: Labour intensive, Flammable

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Gypsum Plaster

Advantages: Light, Durable, Low thermal conductivity, Good fire resistance, Mouldable, Water resistant

Disadvantages: Slightly soluble in water

Concrete (represented with cement)

Advantages: High durability, Low maintenance cost, Least likely to corrode, Non-combustible, Withstand high temperatures

Disadvantages: Less ductile, Low strength-to-weight ratio

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Bolts and Nuts

Made of stainless steel, it does notrust in outdoor conditions, serving asthe main connector and joint for thebamboo structure

Fiber Strand Braided Rope (represented with cotton rope)

Having high strength and abrasionresistance, this rope is used to tiesome of the bamboos in place

Polypropylene Rope (represented with cotton string)

Impermeable to water, it is strongenough to hold the canvas and doesnot absorb rain

10

Cardboard tubes (used to represent bamboo)

Thatched roof made out of nipapalm leaves

Cut bamboo (used for roof structure members)

The usage of bamboo makes thestructure light while the attap roofmade out of nipa palm leavesfulfils its tropical requirements.

These materials are economicaland cheap as they are easilyavailable locally here in Malaysia.

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Main frame constructed by joining tubes in right angles

Inverted V bracing and seats added

2 central columns connected to thebeams and ridge screwed in place

Diagonal bracings attached to rafters

Canvas sewed onto the rafters followed by having the thatched roof tied to the ridge

Entire structure placed onto pad footings with cavities that are designed to fit the columns

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Procedure:

1. Drill holes

2. Saw extra tubes

3. Tie up tubes in right angles

4. Screw in bolts and nuts

5. Sew canvas

6. Tie up thatched roof

7. Cut off extra leaves

8. Set cement in formwork to create pad footings

13

The ends of the bamboo tubes are filled withgypsum plaster, preventing rainfall from enteringthe bamboo and alter the weight of the overallstructure.

Within the limited given size, the long benchmaximizes the number of people able to sitwhile waiting for the bus. The roof providesshade, making the user experience comfortable.Moreover, the absence of a wall in front allowseasy access in and out of the bus shelter. Thewalls were not covered to allow betterventilation and view.

Also, the pitched roof inspired from vernaculardesign suits its tropical site context andrequirements.

14

The entire structure is symmetrical and has equalcomponents on both sides, equally distributingloads to the ground. This ensures that there is nostress accumulated on specific points on thestructure.

In the trusses, the joints are of pin type andconsist of tensile and compression axial forcemembers.

The frame resists vertical forces such as rain andgravity as well as lateral forces including windand earthquakes. Loads are interconnected intriangular and rectangular formats, resulting inthe structure’s sturdiness.

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Asides from being structurally stable, the busshelter must be able to withstand weather.This explains its pitched roof thataccommodates rainwater drainage. Thus,preventing ponding and extra weight fromaccumulating on top of the structure.

Two central columns of the bus sheltertransfer loads directly to the ground,making the process of transmittingloads highly efficient yet notinterrupting its functionality.

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Diagonal bracing technique was applied onthe roof to resist different forces, namelyexternal forces such as wind blowing on agable end, lateral forces and overturningforces. These bracings also prevent thethatch roof and canvas from sinking in atthe centre.

Torsion and bending is reduced by applying threeinverted V bracings on three sides of the bus shelter,making this structure functional, rigid and safe forusers. These bracings direct load to the six footings.

Inverted V bracings are used at a lower heightcompared to diagonal bracings. This lowers thestructure’s centre of gravity as inverted V bracingscarry more weight. A heavy material, concrete isused at its base to serve this purpose as well.

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Thatched roof and canvas

Diagonalbracing

Inverted V bracing

Pad footing

Beam

Column

Rafter

Ridge

A system of beams, columnsand bracings create a strongstructure that distributes theweight of the roof to six padfootings on the ground.

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Bolt and nut joints secure twobamboos of different angles togethertightly through holes drilled intothem. 36 bolt and nut joints are usedin this design. This type of joint canbe assembled and removed withcorrect equipment such as pliers andscrewdriver, making it strong enoughalbeit adding up to the temporaryquality of the bus shelter.

Bolt and Nut

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6 concrete pad footings , 4 with rectangular cavities and 2 with circularcavities, are specially designed to slot the columns and bracings that aretransmit load from above.

These heavy footings support and elevate the whole structure of thebus shelter, making them key members of the whole design.

Slotting Technique

20

Square Lashing

This rope tying techniquefastens two poles together andis able to fix the position ofintersection between somecolumns and beams inperpendicular degrees.

A clove hitch is made on the vertical stick near the intersectionpoint of two sticks followed by weaving the rope under andover the crossed sticks alternately.

After finished weaving the lashing , therope is wrapped between the poles andpulled tightly. It is then ended withanother clove hitch.

21

Ladder Lashing

This technique is applied toattach the thatched roof to theridge of the roof. A series ofknots were tied from one end toanother, zigzagging through thebeam that keeps the leaves intact.

Both series of knots on the twothatched roofs attached to theridge are mirrored to oneanother. A canvas, a diagonalbracing and two rafters preventthe nipa palm leaves fromdropping into the bus shelter.

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23

E-Rigging.com (n.d.). 3-Strand Twisted Manila Rope. Retrieved 9 May 2016 from http://www.e-rigging.com/rope

Geffre, J. (2001, August 20) The Six Boy Scout Knots. Retrieved May 9 2016 from

http://www.t53.info/uploads/Knots_and_Lashings_Primer.pdf

Hong Kong Scouts Organization. (n.d.) Knots. Retrieved 9 May 2016 from

http://www2.hkedcity.net/sch_files/a/mkm/mkm-boyscout/public_html/new_page_3.2.3.1.htm

Lokesh, M. (2012, August 2). Civil Engineering: Difference Between Frame and Truss. Retrieved 9 May 2016 from

http://www.geekinterview.com/talk/20452-difference-between-frame-truss-civil-engineering.html

Menards Shop Department (2016, September 5). Polypropylene Rope. Retrieved 9 May 2016 from

http://www.menards.com/main/tools-hardware/material-handling/ropes-rope-handling/3-8-x-50-hollow-braid-

polypropylene-rope/p-1444439543028.htm