STRUCTURAL ECONOMICS OF EARTHQUAKE RESISTANT DESIGN OF RC BUILDING

Abstract

The RC building, analyzed and designed to resist the conventional loads, i.e., gravity loads and imposed load possesses adequate strength and stiffness to resist the vertical loads. Such building will not suffer damage as long as the dead loads and imposed loads are equal to or less than the loads considered for the design. Such building does not have adequate strength and stiffness when it is subjected to additional lateral loads induced by the earthquake. During earthquake, the building, which is not designed to resist the earthquake loads, gets damaged. Our country experienced many earthquakes in the past, including Gujarat earthquake of January 26, 2001. To minimize the economic loss and loss of lives caused by earthquake, the building should be analyzed, designed and detailed such that the 'building does not collapse when subjected to the most severe ground motion. The simplest procedure for considering the earthquake effect is to compute design lateral loads which are considered along with the conventional loads. This procedure is valid when_ the building is of regular type, i.e., having symmetric plan and uniform distribution' of mass and stiffness along the height of the building. For a particular building, the magnitude of the lateral loads will depend on the zone in which the building is located and the type of soil on which the building is supported. The variation in the design lateral loads due to .seismic zone and the type of soil will affect the size of the structural members like beams, columns and foundations, which in turn will influence the structural cost of the building that has been calculated' by considering the cost of the materials which are structural steel and concrete. The other factors such as labour, non structural members, electrical and water fittings, etc., have not been considered.