Dowden, Clayton, Li, Berman, Bruneau, Lowes and Tsai 2016
The authors evaluated two SC-SPSW systems (FR and NZ), identical except for their posttensioned beam to column connections. Excitations designed to mimic three different seismic hazard levels were applied to the specimens pseudodynamically.
System Concept
The SC-SPSW systems were designed to require no repair after an earthquake with 50% probability of exceedance in 50 years (50/50), repair of only web plated and recentering after a 10% in 50 year earthquake (10/50) with a target drift ratio of 2% and collapse prevention after a 2% in 50 year earthquake (2/50) with a target drift limit of 4%. Because these objectives were proposed prior to system design, each part of the SC-SPSW system was developed explicitly to meet these conditions.
Experimental Study, Results, and Discussion
Both specimens were subjected to a loading protocol consisting of pseudodynamic (PSD) and quasi-static cyclic testing. Test sequence proceeded as follows: an elastic PSD free vibration test starting at a roof displacement of approximately 0.13%, an elastic cyclic test of two cycles at 0.15% roof drift, PSD tests representing seismic hazard levels of 50, 10 and 2% probability of exceedance in 50 years, and inelastic cyclic tests. For the FR connection, the inelastic test consisted of two cycles of loading at 4.5% drift while the NZ connection was tested with two cycles of loading that increased in drift values starting at 2.5% and increasing by increments of 0.5% until a maximum of 4.5% drift that was repeated an additional three cycles. Between tests, no repairs were made to either specimen which may have influenced results, because in an actual building, repairs would likely be made between earthquakes. For the 50/50 ground motion (GM), the specimens remained essentially elastic with minor web plate yielding. For both specimens, peak roof drift was no more than 0.5%. Specimen FR had a larger stiffness due to the decompression moment effects of the closed beam-to-column PT connection that is not present in Specimen NZ. For the 10/50 GM, both specimens experienced some web plate tearing which is attributed to the development of large tensile strains at the corners of the infill web plate due to localized stress concentrations and out-of-plane buckling along the free-edge of the infill plate corner cut-outs. However, this web tearing had little effect on specimen strength. There was minimal localized yielding on the boundary frame of both specimens. For the 2/50 GM, further web tearing was observed, however a majority of the web plate remained attached to the boundary frame. Cumulative localized yielding of the boundary frame was insignificant. Overall data shows that both specimens achieved all performance objectives for each hazard level.
Reference
Dowden, D. M., Clayton, P. M., Li, C.-H., Berman, J. W., Bruneau, M., Lowes, L. N., and Tsai, K.-C. (2016). “Full-Scale Pseudodynamic Testing of Self-Centering Steel Plate Shear Walls.” Journal of Structural Engineering, 142(1).