Seismic vulnerability of restrained and unrestrained block-type nonstructural components

In this paper, analytical techniques are used to determine the fragility of freestanding rigid equipment under seismic excitations and to further improve their seismic mitigation measures. These measures can be carried out using some types of restraints that reduce the displacements and accelerations considerably. The results show that fragility curves for restrained blocks are sensitive mainly to the dynamic coefficient of friction and to the ratio of the vertical component of the cable forces to the weight of the block and they have direct relation to the maximum magnitudes of the pseudo-velocity spectrum curves.