Response Reduction of Secondary Piping Systems in Base-Isolated Buildings

The secondary piping systems running along the height of buildings are subjected to significant stresses and accelerations due to the earthquake. Extensive study has been carried out in the past on the seismic response of primary and secondary systems. The effectiveness of the base isolation in minimizing the responses of the secondary piping system for a bidirectional earthquake is evaluated by comparing the responses between the secondary piping system attached to base-isolated and fixed base buildings. Response reduction in the stresses and accelerations developed in the piping system due to the bidirectional earthquake is not widely studied. In this paper, two 3D models of a six-storied building are taken for the study; one is fixed base and the other is base isolated. For the isolation, lead rubber isolators are used. Both buildings connected a secondary piping system, which conveys fluid running along with the height on one side of the building. Both buildings are studied under bidirectional earthquake ground motions with 1:3/4 ground motion ratios. Full interaction between the primary and secondary system is considered. In SAP 2000 the non-linear time history analysis is carried out to evaluate different response quantities of interest at various levels of the PGA. The results of the numerical analysis suggest that the use of a base isolation system in the building gives significant protection to the secondary system. It reduces the peak stresses of the secondary system at critical sections by about 60–70%.