NEHRP Clearinghouse
- Title
- Cyclic Bond Tests and Plastic Hinge Away from Column. Proceedings of the National Meeting of the Universities Council for Earthquake Engineering Research (4th) Held at University of British Columbia, Vancouver, British Columbia, Canada on June 28-29, 1976.
- File
- PB289422.pdf
- Author(s)
- Popov, E. P.; Bertero, V. V.; Galunic, B.; Lantaff, G.; Viwathanatepa, S.
- Source
- National Science Foundation, Washington, DC. Applied Science and Research Applications., June 29, 1976, 6 p.
- Abstract
- Earlier tests on half-scale beam-column subassemblages representing the third floor of a typical 20-story ductile moment-resisting frame have clearly demonstrated the possibility of a severe cyclic bond degradation at the interior joints. The design of these subassemblages was based on the conventional approach of the strong column and weak girder. In that series of experiments, the beam reinforcement was continuous, consisting of four No. 6 bars at the top and three No. 5 bars on the bottom of the beam. In these experiments the plastic hinges were formed in the beams at the faces of the column, corresponding to the locations of maximum moment. After repeated displacements into the inelastic range, the cracks in the beams at the column faces became very large and the bars extending through the column began to lose their bond. Eventually, at large ductility ratios the bars slipped completely through the column causing a large drop in stiffness and eventual failure. The experimental work reported in this paper addresses this problem of bar slippage in the column. Two different techniques for solving this problem were studied. Cyclic bond tests, the first technique, were directed toward a study of the anchorage characteristics of bars of sizes frequently encountered in practice. The novel feature of these experiments was an arrangement where a bar was being simultaneously pulled from one side and pushed from the other. This condition corresponds to the one observed in the columns in the earlier tests. The other technique was to design the beam so that the plastic hinge forms away from the face of the column thereby increasing the anchorage length.
- Keywords
- Seismic design; Earthquake resistant structures; Reinforced concrete; Framed structures; Columns (Supports); Construction joints; Buildings; Earthquake engineering; Cyclic loads; Concrete construction; Dynamic structural analysis