Basic planning considerations.pptx

8/13/2019 Basic planning considerations.pptx

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Basic planning considerations for tallbuilding design include the followingparameters (Ali and Armstrong, 1995):

planning module; lease span; ceiling height; floor -to-floor height;

depth of structural floor system; elevator system; core planning; parking


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Francisco Mujica (1977, p.25) states that The modern skyscraper is abuildingof great height constructed on a steel skeleton and provided with high

speed electric elevators


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1- Frame (rigid frame) systems;2- Braced frame and shear walled framesystems;3- Outrigger - belt truss systems;4- Framed tube systems;5- Braced (exterior braced) systems;6- Bundled tube systems.


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Rigid frame systems are not efficient for buildings

taller than 30 stories, because lateral deflection dueto the bending of columns causes the drift to be toolarge (Taranath, 1998)

On the other hand, introduction of steel bracing orshear walls, which interact with the frame, increasesthe total rigidity of the building and the resultingsystem is named as braced frame , or shear walledframe system .

While braced frame system is utilized in steelconstruction, shear walled frame system is utilized inboth reinforced concrete and composite construction.

These systems are stiffer when compared to the rigidframe system, and can be used for buildings up to 50stories


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Shear walled framesystems

Braced frame systems

(c )Diagonal less

available space

(a)X the least

Availablespace

(b)K-openings

possible

(d)Knee larger

openings

Representative shear walled frameTypical floor plan of core structure

with structure


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Braced frame systems are utilized in steel construction

This system is a highly efficient and economical system forresisting horizontal loading, and attempts to improve theeffectiveness of a rigid frame by almost eliminating the bending ofcolumns and girders, by the help of additional bracings.

It behaves structurally like a vertical truss, and comprises of theusual columns and girdersEssentially carrying the gravity loads, and diagonal bracingcomponents so that the total set of members forms a verticalcantilever truss to resist the horizontal loading.

Historically, bracing has been utilized to stabilize the buildinglaterally in many of the worlds tallest structures, including;


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ChryslerBuilding, NewYork, U.S.A. (24)

Empire StateBuilding, NewYork, U.S.A. (30)


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S h e a r w a l le d frame systems are utilized; reinforced concrete composite construction

Sh ea r wa l l s , first used in 1940, may be described asvertical cantilevered (konsol kiri) beams;

resist lateral wind seismic loads acting on a building transmitted to them by the floor diaphragms

S h e a r w a l l s are generally parts of elevator service cores frames ;

to create a stiffer and stronger structure.


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These elements can have various shapes such as circular, curvilinear, oval, box-like triangular rectilinear.

Reinforced concrete's ability to dampen vibration , to provide mass to a building;

makes it a good choice ofmaterial


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For composite tall buildings, the selection of structuralmaterials coming first in the construction is oftendetermined by the choice of construction technique .

In one version concrete core is cast first followed by the erection of the steel surroundingEven though the structural steel framing may proceed slowlywhen compared to traditional steel building

The entire construction period can be decreased owing to the rapidinstallation of elevators mechanical electrical systems of the core

While the construction outsidethe core proceeds

at the sametime


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In another version; steel erection columns are utilized within composite shear walls;

to serve as erection columnsto steel erection proceedsas in a conventional steel building

After the steel erection has reached a certain level, concreting ofcore starts using conventional forming techniques

Basic planning considerations.pptx

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