3D-Seismic Response Analysis of the Secondary Piping System in Building Under Bi-Directional Earthquake

The secondary piping systems running along the height of buildings are subjected to significant stresses and accelerations due to the earthquake. Extensive research on the seismic response of primary and secondary systems has been carried out in the past. State of the art review papers on the subjects summarizes those researches. Although the response of the secondary piping system running along with the height of the primary structure like the building has been studied before, the stresses and accelerations developed in the piping system developed due to the bi-directional earthquake are not widely studied. In this paper, a six storied building with a secondary system taken as a pipe running from 1st to 6th story on one side of the building is taken as an illustrative example. A 3-D model of the primary and secondary system is analyzed for bi-directional earthquakes. Considering the full interaction between the primary and secondary structures, the non- linear time history analysis is carried out in SAP 2000 to obtain different response quantities of interest for a PGA level 0.3g with the major to minor ground motion ratio taken as 1:2/3. Response quantities of interest include the maximum accelerations, maximum displacements, and maximum stresses developed at critical sections of the pipe. Also, the floor response spectra are obtained. Results of the numerical study indicate that significant accelerations and stresses are induced in the pipe for a PGA level of 0.3g; the absolute accelerations at the pipe supports vary significantly leading to the generation of large stresses in the pipe.