A COMPARISON OF RULES FOR COMBINATION OF MODAL RESPONSES

Abstract

The importance of proper seismic analysis cannot be undermined for structures on the Indian Peninsula because of the presence of varying seismic zones. Alternatives to achieve the above end are available in numerous analytical techniques with varying degree of complexity and mathematical rigour. The most popular among the techniques for the determination of design parameters are the category of time history techniques and the techniques for the modal combination of responses or the Response spectrum techniques. The time history solutions involve the integration of the equations of motion either in the time or the frequency domains and form a deterministic basis for the evaluation of response parameters for a given time history.-On the other hand the combination of the modal, responses while lacking a formal mathematical and physical are able to provide some semblence to probable maxima with regard to the design vales to be adopted. This dissertation is aimed at examining the validity of the techniques of modal combination by using simulated time history solutions as a basis of comparison.