Seismic evaluation, parameterization, and effect of light-frame steel studded gypsum partition walls
Davies, Ryan Douglas
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Contribution of nonstructural partition walls is often assumed negligible in the lateral response of common seismic force resisting systems. However, this assumption may become un-conservative as the sum effect of individual wall systems is considered. The first phase of the NEES Nonstructural Grand Challenge Project tested full scale light gauge steel studded gypsum partition walls using the University at Buffalo Nonstructural Component Simulator (UB-NCS). A description and experimental results for 22 different partition wall configurations is given. Included in the wall variations is material type, connections, testing protocols, wall dimensions, and boundary conditions. Innovative designs to reduce the seismic fragility of partition walls were also developed as part of the testing program. The experimental data is used to populate an extensive seismic fragility database for light gauge steel studded gypsum partition walls. Parameters for a tri-linear hysteretic model, aimed at reproducing the in-plane mechanical behavior of partition walls, are determined from the experimentally obtained force-displacement curves. Recommended parameters for in-plane walls are given for individual configurations and light gauge steel framed nonstructural partition walls. The calibrated partition wall models are combined with the structural model of an existing four story steel moment resisting frame medical facility to demonstrate the effect on dynamic properties. As the period of the structure reduces due to the increased stiffness from the partition wall systems, reductions in drift and absolute floor accelerations are observed. The assumption that these wall systems have negligible impact is disproven by the use of incremental dynamic analyses, performed according to the ATC-63 methodology. These analyses show that including the contribution of steel studded gypsum partition walls to the lateral force resisting system increases the building collapse safety margin by 43%.