Materials- Design & Construction

Full Session with Abstracts

339609-4 - In-Plane Behavior of Unbonded Post-Tensioned Masonry Wall

Friday, April 20
1:30 PM - 3:00 PM
Location: 201A

This presentation discusses an experimental study on four unbonded fully grouted post-tensioned masonry walls (PT-MWs). All walls had identical thickness/height/length of 190 mm/2000 mm/1400 mm and were constructed using concrete masonry units (CMUs) and mortar type N. Different horizontal spacing values of 400 mm, 600 mm, and 1200 mm were used between the post-tensioning bars in the walls. Only one wall had horizontal bonded reinforcement. Two different levels of post-tensioning force corresponding to an average post-tensioning compressive axial stress on the masonry of 1.35 MPa and 2.7 MPa were applied to the walls. Different initial post-tension stresses in the bars ranging from 0.32 to 0.63 of the yield stress of each bar were applied to the walls. The walls were subjected to incrementally increasing in-plane lateral displacement cyclic load applied to the top of each wall. The experimental results including damage pattern, force displacement response, residual drift ratio, masonry compressive strain, wall rotation, damping, stiffness, stiffness degradation and displacement ductility of the tested walls will be presented and discussed in detail. Furthermore, a database including 31 PT-MWs that have been tested by different researchers from New Zealand and U.S. was developed. The database was used to determine the seismic performance factors including ductility, response modification factor and displacement amplification factor for PT-MWs. Response modification factors of 4.27 to 7.76 and displacement amplification factor of 3.5 were obtained for post-tensioned fully grouted masonry walls. The ductility and response modification factor for ungrouted and partially grouted walls were much lower than those of fully grouted walls. This study also concluded that the axial stress ratio has a prominent effect on the ductility of PT-MWs. To provide a ductile response, it is recommended to limit the axial stress ratio to a value of 0.15.

Mohamed ElGawady

Mohamed A. ElGawady, Ph. D., is Benavides Associate Professor at Missouri University of Science and Technology (formerly University of Missouri-Rolla) with 20 years of experience in extreme loading and sustainability. Previously, ElGawady held positions at Washington State University, and University of Auckland. He served as a visiting Associate Professor at University of South Australia and Tokyo Institute of Technology. He also worked as a bridge engineer for three years. His research addresses the performance of existing structures under man-made and natural hazards.

ElGawady is a member of TMS 402/602 Main Committee and Secretary of its Prestressed Masonry Committee He is Chair ACI 441 Committee on Reinforced Concrete Columns, and co-chair of ACI 341 Committee on Seismic Behavior of Bridge Columns. He co-authored 60 referred papers published in tier one journals and 100 conference papers published in top national and international venues. He has been recognized by Missouri S&T through the inaugural Benavides Mid-career Endowment Award, and the Joseph H. Senne, Jr. Academy of Civil Engineers Faculty Achievement Award.

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339609-4 - In-Plane Behavior of Unbonded Post-Tensioned Masonry Wall



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