topic 2 stability of structure

8/14/2019 Topic 2 Stability of Structure

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Presented by:

~ Nor Jauriah bt Othman

~ Fairuz Nadia bt Salim

DESIGN, INNOVATION AND

INVENTIONS


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Example the shapes of objects that

are stable

Trusses

Beam bridges can span

a greater distance with

a thicker beam. But

there is a limit, becausetoo thick a beam will

sag into the river. An

alternate solution is to

build a beam oftriangles, a "truss,"

which is much lighter

than a beam of similar

thickness. A truss is

extremely strong and


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The Arch The arch is used in

tunnels, bridges andmany other structures

because is can bear agreat deal of weight(load). The arch formtransforms the verticalpressure of thestructure above intolateral(sideways) pressure.The Romans used the

arch in many of theirbuildin s.


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The Flying Buttress

The force is

transferred to the

buttress which helps

support the building

so it will be able to

support the roof

without collapsing


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Burj Dubai Dubai,

United Arab Emirates

Taipei 101 Taipei,

Taiwan


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Serpentine GalleryPavilion 2006


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Factorsaffecting the

stability of astructure

Height- The lower the structure, the more

stable the object is

- P is more stable because it isshorter

Base area- The larger the base area, the

more stable the objects is

- L is more stable because it haslarger base area.


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Importance of stability Racing cars are built

low. They have widetyres. The tyres are setwide apart to give thecar a large base area

Some furnitures aremade stable by havingbroad legs that are set

wide apart

Some appliances aredesingned with a largeand heavy base


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Factors that affect the strength of a

structure

The types of materialsused to build it

1) Steel wires - bundledtogether to make

suspension bridge cablesare one material strong intension

2) Stone - strong incompression.

- Ex: The Egyptianpyramids, which are madeof stone blocks, someweighing over a tonne.

The blocks on the bottomsupport the weight of the

How the structuredare placed

- A structure whichcracks, breaks orcollapses easily is notstrong

- A strong bridge is notonly able to stand itsown weight, but also be

able to stand strongwind and vibrations


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A Structure that

withstand demanding

conditions of the

Earth


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WHY EARTHQUAKE?

Most of the damage we associate with

earthquakes involves human-built structures:

people trapped by collapsed buildings or cut off

from vital water or energy supplies

It might seem obvious to say that earthquakes do

most of their damage by shaking the ground.

When the ground beneath a building shakes, it

makes the building sway as the energy of a

quakes wavesmoves through it.

Do you think that a skyscraper would be more

dangerous than a smaller office building?:
http://www.exploratorium.edu/faultline/basics/waves.htmlhttp://www.exploratorium.edu/faultline/basics/waves.html


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The taller a structure, the more flexible

it is. The more flexible it is, the less

energy is required to keep it from

toppling or collapsing when the earth's

shaking makes it sway.

Because shorter buildings are stiffer

than taller ones, a three-story

apartment house is considered more

vulnerable to earthquake damage than

a 30-story skyscraper.


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Example

The TransAmerica pyramid inSan Francisco is famous forits architecture: a wide base

that narrows as it goes upincreases the buildingsstability.

A network of diagonal

trusses at its base supportsthe building against bothhorizontal and verticalforces.


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INTRODUCTION

The Transamerica Pyramid is San

Francisco's tallest building.

The Pyramid has 49 stories and a

212 foot spire. The height from

the apex to the ground is 845

feet. The base width is 175 feet.

The pyramid is flanked by a set of

structures that look like wings.


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The Uniqueness of the Building

The unique structuralfeature of this taperedbuilding is the truss

system above the firstfloor.

The photos are courtesyof the EarthquakeEngineering ResearchCenter, University ofCalifornia, Berkeley.


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The Truss System

The truss system supports

both vertical and horizontal

loading.

The building is carefullyengineered to take large

horizontal base shear forces.

The overhead X-bracing

resists torsional movement of

the building about its vertical

axis.


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Roller coaster--one of

the scariest structures

around. But scary as

they are, coasters arebasically just bridges

with incredibly steep

hills. Coasters'

triangular trusses makethem extremely strong

structures.


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REFERENCE

Building that withstand earthquake

http://www.exploratorium.edu/faultline/damag

e/building.html

The TransAmerica

http://www.vibrationdata.com/earthquakes/Pyr

amid.htm
http://www.exploratorium.edu/faultline/damage/building.htmlhttp://www.exploratorium.edu/faultline/damage/building.htmlhttp://www.vibrationdata.com/earthquakes/Pyramid.htmhttp://www.vibrationdata.com/earthquakes/Pyramid.htmhttp://www.vibrationdata.com/earthquakes/Pyramid.htmhttp://www.vibrationdata.com/earthquakes/Pyramid.htmhttp://www.exploratorium.edu/faultline/damage/building.htmlhttp://www.exploratorium.edu/faultline/damage/building.html

topic 2 stability of structure

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