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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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Predetermined Collector Force and Rotation Histories Tests on AFW, in Advancing Knowledge on the Performance of Seismic Collectors in Steel Building Structures
Predetermined Collector Force Histories Tests on AFW were conducted to understand the performance of All Flange Weld (AFW) collector connection under different levels of seismic hazards. A test collector with AFW collector connection, was designed, fabricated, and tested under predetermined seismic collector force and inter-story drift histories, without composite slab and gravity loading. The AFW collector connection demands were obtained from nonlinear time-history analyses of archetype steel buildings. Based on these analyses, representative collector force and story drift demands were selected for the test specimen. Snippets of the loading histories corresponding to different seismic hazard levels were extracted, and each loading history was subdivided as necessary based on force and rotation increments. The selected snippet histories of drift and collector force were applied consecutively. For each loading step, the reaction column was first rotated to the target drift using reaction actuators, followed by application of the corresponding collector force through the loading actuators. This procedure was repeated sequentially until completion of the selected snippet. These tests provide insight into the performance of the AFW collector connection under seismic load demands associated with different earthquake hazard levels.
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- Award ID(s):
- 1662816
- PAR ID:
- 10661913
- Publisher / Repository:
- Designsafe-CI
- Date Published:
- Edition / Version:
- 1
- Subject(s) / Keyword(s):
- Seismic Collector Collector force demand connection rotation demand all flange weld (AFW) large scale predetermined time histories
- Format(s):
- Medium: X
- Institution:
- Lehigh University/ University of Arizona
- Sponsoring Org:
- National Science Foundation
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