Seismic analysis and design of buildings equipped with Propped Rocking Wall systems
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Propped Rocking Wall (PRW) is an innovative technology which combines passive damping with unbonded post-tensioned rocking concrete walls. This system has been proposed to reduce economic losses associated with earthquakes by returning a building to a functional state following a design seismic event. The proposed seismic force-resisting system consists of a slender unbonded post-tensioned concrete wall which is "propped" near the top with multi-story diagonal steel braces equipped with passive supplemental damping devices. In this study, a closed-form solution was derived for the global hysteretic response of the PRW system and a parametric study was conducted to evaluate the effect of different structural parameters involved. A seismic Direct Displacement-Based Design (DDBD) procedure for buildings equipped with PRW systems was then developed. The proposed design procedure was first evaluated through a comparative study between the seismic performance of the introduced system as opposed to a similar system called Propped Shear Walls (PSW) from which the proposed system was originally inspired. The adequacy of the proposed DDBD procedure and further the performance of PRWs were then evaluated through a shake table testing program. Detailed modeling of the PRW test model was developed and validated with shake table test results. Numerical modeling of the PRW on the prototype scale was further adopted and used in a seismic vulnerability assessment study based on the Methodology presented in FEMA P695. Design verifications were then extended to taller buildings equipped with the proposed Propped Rocking Wall (PRW) system. For this purpose, the seismic response of an 8-story building was evaluated against the predetermined performance objectives set in the beginning of the design procedure. In addition, the sensitivity of the response parameters under consideration to three main design parameters was studied.