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Phase 2A used a two-story steel test building with a composite-slab second floor and a bare-steel roof deck. Added weight was applied only at the second floor. Conventional earthquake simulation was used with scaled ground motions from the 1994 Northridge Earthquake (Beverly Hills-14145 Mulhol.) at 50%, 100%, and 200% Design Earthquake (DE) levels, including sign-reversed motions. White-noise and impulse tests were used to identify dynamic properties. In this phase, the second-floor collectors experienced significant axial forces from diaphragm inertial loading, while the roof collectors were mainly subjected to flexural demands due to negligible roof mass. The Phase 2A specimen was a two-story steel building constructed by adding a second story onto the existing Phase 1 test building. It had a composite-slab second floor, a bare-steel roof deck, and perimeter collectors at both levels. Added mass was installed only at the second floor to generate diaphragm inertial forces during the earthquake-simulation tests. This configuration allowed evaluation of collector behavior when significant axial force developed primarily in the second-floor collectors, while the roof collectors experienced mainly flexural demand associated with story drift.
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Phase 3: Two-Story Building With Buckling-Restrained Braces, in Advancing Knowledge on the Performance of Seismic Collectors in Steel Building Structures: Shake Table Tests
Phase 3 incorporated Buckling-Restrained Braced Frames (BRBFs) into the two-story test building to evaluate collector behavior in the presence of a yielding seismic-force-resisting system. Conventional earthquake simulation was used with scaled ground motions from the 1994 Northridge Earthquake (Beverly Hills-14145 Mulhol.) at 50%, 100%, 150%, and 200% Design Earthquake (DE) levels, including sign-reversed motions. White-noise and impulse tests were used to identify and track dynamic properties. This phase enabled assessment of collector axial force, slab participation, and connection rotation under system-level interaction with brace yielding and load redistribution. For Phase 3, Buckling-Restrained Braced Frames (BRBFs) were added to the same two-story building used in Phases 2. The diaphragm, collector, and connection details remained the same. This specimen was used to evaluate collector behavior in a yielding structural system, including the interaction between diaphragm inertial forces, brace yielding, and load redistribution. Earthquake events consisted of acceleration time histories based on the 1994 Northridge Earthquake record (Beverly Hills-14145 Mulhol.), scaled to different Design Earthquake (DE) intensity levels. Motions were applied in both direct and sign-reversed directions. These events were used to evaluate collector forces, slab participation, inter-story drift, and connection behavior under increasing levels of seismic demand.
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- Award ID(s):
- 1662816
- PAR ID:
- 10661877
- Publisher / Repository:
- Designsafe-CI
- Date Published:
- Edition / Version:
- 1
- Subject(s) / Keyword(s):
- Collectors seismic collectors collector connections floor diaphragms composite slab steel buildings shake table testing floor acceleration simulation inertial force NHERI@UC San Diego Large High Performance Outdoor Shake Table (LHPOST)
- Format(s):
- Medium: X
- Institution:
- UCSD, University of Arizona
- Sponsoring Org:
- National Science Foundation
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Phase 2B used the same two-story configuration as 2A, but added weight at both the second floor and roof to increase diaphragm inertial forces. Testing again used scaled Northridge motions (Beverly Hills-14145 Mulhol.) at 50%, 100%, and 125% DE levels, including sign-reversed and repeat motions, with white-noise and impulse tests used to track system properties. In this phase, both the roof and second-floor collectors developed substantial axial forces in addition to flexural demands from story drift, allowing evaluation of collector-to-column connections under combined axial–flexural loading The Phase 2B specimen had the same structural configuration and collector detailing as Phase 2A, but added mass was installed at both the second floor and roof. This produced diaphragm inertial loading at both levels, leading to combined axial and flexural demands in the collectors and their connections. The Phase 2B specimen allowed direct comparison with Phase 2A to study the influence of mass distribution on collector forces.more » « less
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