SOME OF THE IMPORTANT CONSIDERATIONS RELATED TO EARTHQUAKE RESISTANT BUILDINGS/HOUSES

 

SOME OF THE IMPORTANT CONSIDERATIONS RELATED TO EARTHQUAKE RESISTANT BUILDINGS/HOUSES

(i) The behavior of a building during earthquakes depends critically on its overall shape, size and geometry, in addition to how the earthquake forces are carried to the ground. Hence, at the planning stage itself, architects and structural engineers must work together to ensure that the unfavorable features are avoided and a good building configuration is chosen.

(ii) A desire to create an aesthetic and functionally efficient structure drives architects to conceive wonderful and imaginative structures. Sometimes the shape of the building catches the eye of the visitor, sometimes the structural system appeals, and in other occasions both shape and structural system work together to make the structure a marvel. However, each of these choices of shapes and structure has significant bearing on the performance of the building during strong earthquakes.

(iii) The wide range of structural damages observed during past earthquakes across the world is very educative in identifying structural configurations that are desirable versus those which must be avoided.

 

(iv) In tall buildings with large height-to-base size ratio, the horizontal movement of the floorsduring ground shaking is large. In short but very long buildings, the damaging effectsduring earthquake shaking are many.

 

(v) Buildings with simple geometry in plan perform well during strong earthquakes. Buildingswith re-entrant corners, have sustained significant damage.

 

(vi) The bad effects of these interior corners in the plan of buildings can be avoided by making the buildings in two parts. For example, an L-shaped plan can be broken up into two rectangular plan shapes using a separation joint at the junction. Often, the plan is simple, but the columns/walls are not equally distributed in plan. Buildings with such features tend to twist during earthquake shaking.

 

(vii) The earthquake forces developed at different floor levels in a building need to be brought down along the height to the ground by the shortest path; any deviation or discontinuity in this load transfer path results in poor performance of the building

 

(viii) Buildings on slopy ground have unequal height columns along the slope, which causes ill effects like twisting and damage in shorter columns. Buildings with columns that hang or float on beams at an intermediate storey and do not go all the way to the foundation, have discontinuities in the load transfer path. Some buildings have reinforced concrete walls to carry the earthquake loads to the foundation. Buildings, in which these walls do not go all the way to the ground but stop at an upper level, are liable to get severely damaged during earthquakes. 

 

(ix) When two buildings are too close to each other, they may pound on each other during strong shaking. With increase in building height, this collision can be a greater problem. When 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 can be very dangerous.

 

(x) Looking ahead, of course, one will continue to make buildings interesting rather than monotonous. However, this need not be done at the cost of poor behavior and earthquake safety of buildings. Architectural features that are detrimental to earthquake response of Seismology buildings should be avoided. If not, they must be minimized. When irregular features are included in buildings, considerably higher level of engineering effort is required in the structural design and yet the building may not be as good as one with simple architectural features.