Dynamic Behaviour of Buildings Resting on Sloppy Ground

Abstract

The proper collection of seismic design forces for the
architecture needs the specification of the exacted intensity of ground shaking that the structure will undergo throughout their existence. In line to get anticipation of the end of life and destruction of buildings due to the ground shake, it is essential to know the components of the ground motion. The common significant dynamic components of ground motion are (PGA)peak ground acceleration, duration and frequency content. The essential standard method used by many seismic codes is to use PGA as a particular measure of ground motion intensity. Despite, as more earthquake studies obtained, it enhanced that the use of a single design spectral shape scaled by peak site acceleration is inadequate to cover over all sites. Many recorded earthquake ground motions have response spectra dramatically distinct from the standard design spectrum. The earthquakes have different predominating frequency contents inherently low, medium, and high.
The present study deals with the effect of the different dominating frequency contents of earthquakes on seismic behavior of R.C buildings resting on the sloppy ground.A linear time history analysis performed by using the relevant Finite Element Method (FEM) based software SAP2000 on sloppy ground buildings with three different ground motions of low, medium and high contents of the frequency with the same continuation and peak ground acceleration. The dynamic response of the R.C frame buildings due to the selected ground motions observed regarding storey displacement and base shear. It is found that low and intermediate frequency content ground motions had shown an essential impact on the seismic response of chosen R.C regular building frames and step-back building frames. Proceeding to the chosenR.C step back-setback building frames the medium and high-frequency content ground motions shown an essential impact on its seismic response. It is also observed that the end short columns in these buildings attract more-base shear compared to other columns. The base shear distribution among the columns is uneven this uneven distribution of base shear in columns leads to plastic hinge formation in the columns, which creates the profound impact in step-back and step-back–setback buildings.