SHEAR WALL AND FRAME SYSTEMS

In general the structural system used for medium-rise or high-rise buildings is a choice, in one form or another, between loadbearing wall systems, also known as shear wall systems, and frame systems. Frame and shear wall systems may be combined in the same building. A loadbearing wall is one used to carry gravity load but is known as a shear wall if it also transfers horizontal forces to ground.

Whatever structural system is used, it must be able to carry the vertical loads caused by gravity forces, and the horizontal loads caused by wind and earthquake forces. Earthquakes may cause additional vertical forces to act on the structure but damage is most likely to occur as a result of the horizontal forces on the building due to earthquakes. The horizontal forces are extremely important in the design of high rise buildings.

High rise buildings are those for which the scale effect of an increase in height has a significant influence on the structural design. In general this scale effect is connected with buildings above about twenty storeys in height for which the ratio of height to least horizontal dimension is greater than five. As buildings increase in height, more efficient ways of providing lateral stiffness are necessary to control horizontal movement and these can have a significant influence on the form.

Medium rise buildings may be said to include buildings which are lower than high-rise buildings but still more than about five storeys in height.

Vocabulary:

efficient [I'fISqnt] a. – эффективный

medium-rise building ['mJdIqm raIz 'bIldIN] – здание средней этажности

scale effect ['skeIl I"fekt] – влияние масштаба

whatever [wPt'evq] pron. – какой бы ни

Answer the following questions:

1. What is the structural system used for medium-rise or high-rise buildings?

2. What is the difference between a loadbearing wall and a shear wall?

3. What must a structural system be able to do?

4. Why are the horizontal forces important in the design of high rise buildings?

5. When do more efficient ways of providing lateral stiffness become necessary?

6. What buildings are said to be medium-rise ones?

Plans of buildings stabilised by shear walls, left, and by frames, right.

Plans of buildings with frames and shear walls

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