Shaking table tests on a spherical tank mock-up provided with seismic isolation and flexible piping connections

The Project INDEPTH (Development of INnovative DEvices for Seismic Protection of PeTrocHemical Facilities), supported by the European Commission, has the objective of developing and applying innovative seismic isolation and/or dissipation systems for critical structures at petrochemical facilities. In the framework of INDEPTH, integrated seismic protection systems have been conceived, developed and tested. They are aimed at protecting liquid-filled structures (product storage, spherical and LNG tanks), with new devices (fiber-reinforced isolators, buckling reinforced braces) specific for each application and new flexible piping couplings, to compensate the displacements resulting from the use of isolation systems. The research program has been focused on the selection of critical structures, the design and manufacturing of the devices, the numerical assessment and the experimental validation through shaking table tests [1-4]. A quantification of technical/economical/safety benefits with respect to the conventional state-of-theart measures presently adopted and potential application to retrofitting has been performed This paper describes the validation through shaking table tests of the effectiveness of the isolation systems on a spherical mock-up and the related piping system equipped with flexible joints. Different configurations of the mock-up have been tested, such as: fixed base, isolated base with High Damping Rubber Bearings, Fiber Reinforced Rubber Bearings and Lead Rubber Bearings. Furthermore, each configuration has been tested for three different level of filling to verify the sloshing behavior in the sphere and the effectiveness of the isolation systems at filling levels different from the design one (full sphere).