In-plane performance of nonstructural partition wall systems under cyclic load conditions

The objective of this research is to develop better understanding of the seismic behavior of nonstructural partition walls, and to improve their performance by utilizing a low cost damping system technique. The purpose of the proposed damping system is to minimize the repair costs in case of earthquake occurrence. This study describes an experimental program coupled with analytical investigation to modify the design and practice procedures of partition walls as specified by today's building code. The experimental program consists of testing nine full scale partition walls of 48.0 inch long and 96.0 inch high. The specimens were constructed using light gauge steel studs (18 gauge steel), the walls were sheathed on both sides with 5/8 inch gypsum boards (GB). Three design variables were used in the experimental work, these variables were; partition walls without damping systems, partitions with single damping device and partitions with double damping devices. In order to have a base for comparison, three specimens were tested with single-damping system (SDS), three specimens were tested with double-damping system (DDS) and three specimens were tested with no-damping system (NDS). The number of experimental specimens was chosen to allow for good assessment of the effectiveness of the systems used. The wall specimens were subjected to in-plane horizontal cyclic loading for drifts ranging from 0.25 inch to 2.75 inches (0.3% to 3% drifts of the wall height) in 0.25 inch increments. Test results included cyclic hysteresis and envelope curves of load-displacement relationships, the degree of damages and failure modes as defined by photographs taken during and after testing. Based on cyclic loading envelope curves; peak loads, capacity factors, dissipated energy and energy loss by damping systems and their corresponding drifts were determined. Further, comparison of the peak points envelopes for NDS, SDS and DDS damping specimens provided a vital understanding of the relative drift capacities of the walls. The ductility factor which measures the wall stability was also determined. Damages and failure modes were noted through visual inspection and photographs were taken during and after testing. The test results revealed that although damping does not significantly influence load capacity, it increased the failure drift for SDS and DDS by 33% and 67% respectively over NDS. Also, ductility factors increased about 38% for SDS and 68% for DDS over NDS, the cumulative dissipated energy increased 112% for SDS and 137% for DDS over NDS. The study showed that the energy loss was greater by about 33% for SDS and 106% for DDS in comparison to NDS. The research was extended to develop an empirical equation to predict the degree of damage in partitions with damping systems based on the numerical prediction of the energy loss. The proposed equation shows a good prediction of degree of damages when it is compared to the testing results performed in this project.