Hybrid Testing of a Full-Scale Three-Story Soft-Story Woodframe Building


Hybrid testing was conducted on a full-scale three-story soft-story woodframe building in the SEESL at the University at Buffalo. For the hybrid test building, the numerical substructure was composed of the bottom soft-story, and the physical substructure consisted of the two upper stories. Slow pseudo-dynamic testing was carried out on five different retrofits following performance based design criteria, the FEMA P-807 guidelines, and a single retrofit which was designed based on engineering calculations (similar to what might be done in a typical engineering office). These retrofits were tested to varying levels of seismic intensity. A single performance-based seismic retrofit was tested with real-time hybrid testing investigating the torsional response. The test program concluded with real-time hybrid testing of an overly-retrofitted model to collapse. The results to the hybrid tests are presented in the final report. This project impacts the research community by providing the first hybrid simulation in which the physical substructure was two-thirds of the entire structure, specifically two full building stories, while the numerical substructure was a single full building story. Major project outcomes included: PBSD Retrofits: Validation of new performance-based seismic retrofits (PBSR). PBSR provide a great option for building owners/stakeholders who want excellent performance above building code minimums. The SMA retrofit tested here met all performance objectives, however modification could be conducted to achieve a more linear distribution of the seismic demand vertically on the building stories. Soft-Story-Only Retrofits: Verification of soft-story-only retrofits following the FEMA P-807 guidelines to meet performance objectives and prevent collapse was achieved. Additionally, a soft-story-only retrofit designed based on engineering calculations (similar to what might be done in a typical engineering office) using a distributed knee brace (DKB) was investigated and its performance verified to provide adequate resistance when subjected to large displacement demands. Investigation and determination on the effects of these soft-story-only retrofits on damage to the upper stories was achieved. Some of the higher intensity ground motions shifted damage to the second (un-retrofitted) story, but drift peaks were maintained within the design expectations. Collapse Testing: The collapse shift into the upper stories was quantified when the first story was over-strengthened. It required an approximately 125%-150% MCE ground motion to collapse the upper stories. The collapse mechanism of a woodframe building, and the collapse capacity of the un-retrofitted structurally-deficient upper stories composed of archaic building materials was investigated and determined.

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Texas Advanced Computing Center





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