How architectural features affect buildings during earthquakes?
Answers
The earthquake forces developed at different floor levels in a building need to be brought down along the height to the ground.
Any deviation or discontinuity in this load transfer path results in poor performance of the building.
Figure 3a shows buildings with vertical setbacks, which cause a sudden jump in earthquake forces at the level of discontinuity.
Figure 3b shows buildings that have fewer columns or walls in a particular storey or with unusually tall storey tend to damage or collapse.
The buildings with an open ground storey intended for parking collapsed or were severely damaged in Gujarat during the 2001 Bhuj earthquake. Figure 3c shows buildings on sloppy ground have unequal height columns along the slope. It causes ill effects like twisting and damage in shorter columns.
Figure 3d shows buildings with columns that hang or float on beams at an intermediate storey and do not go all the way to the foundation. It creates discontinuities in the load transfer path.
Figure 3e shows buildings, in which reinforced concrete walls do not go all the way to the ground but stop at an upper level. These walls are liable to get severely damaged during earthquakes.
Courtesy - IIT Kharagpur
Adjacency of building
When the two buildings are too close to each other, it may pound on each other during strong shaking. With increase in building height, this collision can be a greater problem.
When the two building heights do not match, the roof of the shorter building may pound at the mid-height of the column of the taller one. This is very dangerous. (See Figure 4)