Abstract
This paper describes the testing and behavior of a 40% scale coupled core wall structure with fully unbonded post-tensioned coupling beams and unbonded flexural (vertical) mild steel reinforcing bars below the wall pier toes. The specimen with C-shaped piers included the bottom three stories, a large portion of the tributary floor slabs, and the foundation of an eight-story prototype structure, and was tested under quasi-static reversed-cyclic lateral loads combined with tributary gravity loads. The elimination of mild steel reinforcement across the beam-to-wall interfaces was a significant simplification for construction. Ultimate failure of the structure was caused by low-cycle fatigue fracture (preceded by buckling) of the extreme flexural mild steel bars crossing the wall-to-foundation interfaces. This failure mode was significantly delayed (resulting in greater ductility capacity) because of the deliberate unbonding of the flexural bars crossing into the foundation below the wall pier toes. The coupling beams provided adequate and stable coupling to the structure throughout the test. The energy dissipation in the system was significantly above the minimum level prescribed by ACI ITG-5.1, demonstrating the adequacy of the design.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1381-1392 |
| Number of pages | 12 |
| Journal | ACI Structural Journal |
| Volume | 113 |
| Issue number | 6 |
| DOIs | |
| State | Published - Nov 1 2016 |
| Externally published | Yes |
Bibliographical note
Funding Information:This project was funded by the National Science Foundation (NSF) under Grant No. CMMI 1041598 as a part of the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR). This award was a part of the National Earthquake Hazards Reduction Program (NEHRP). Support of the NSF Program Director Dr. J. Pauschke is gratefully acknowledged. At Lehigh University, laboratory staff members C. Bowman, P. Bryan, D. Fritchman, T. Maurullo, G. Novak, and E. Tomlinson, faculty member S. Pakzad, and graduate students G. Shahidi and K. Kazemibidokhti contributed to the construction, instrumentation, and testing of the specimens. D. Fields, A. Haaland, and J. Mouras of Magnusson Klemencic Associates contributed to the design and detailing of the structure. The help of K. Bondy, consulting structural engineer, is also acknowledged. The concrete was donated by Essroc Italcementi Group, PT anchors were donated by Hayes Industries, Ltd., PT strand was donated by Sumiden Wire Products Corporation, and formwork was donated by A.H. Harris and Sons, Inc. Additional material donations were from Dayton Superior Corporation and Casilio Concrete. The findings, recommendations, and conclusions are of the authors and do not necessarily represent the views of those listed.
Publisher Copyright:
Copyright © 2016, American Concrete Institute. All rights reserved.
Keywords
- Coupled shear walls
- Coupling beams
- Digital image correlation
- Earthquake-resistant structures
- Post-tensioning
- Reinforced concrete
- Seismic analysis
- Structural design
- Testing
