Experiment on seismic behavior of RC beamcolumn jointsafter fire and strengthened with CFRP(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2018年06期
- Page:
- 49-59
- Research Field:
- 桥梁与隧道工程
- Publishing date:
Info
- Title:
- Experiment on seismic behavior of RC beamcolumn jointsafter fire and strengthened with CFRP
- Author(s):
- XU Yuye; GAO Wei; LUO Yi; HU Jie
- (College of Civil Engineering, Huaqiao University, Xiamen 361021, Fujian, China)
- Keywords:
- structure engineering; seismic performance; pseudo static test; beamcolumn joint; after fire; CFRP reinforcement
- PACS:
- -
- DOI:
- -
- Abstract:
- This paper presents an experimental study of the seismic behavior of reinforced concrete (RC) beam column joints after fire and strengthening with foldline CFRP sheets. Pseudostatic loading was applied to RC beam column joints with orthogonal beams and floor flanges. Experimental tests were conducted on three specimens: one with no fire, one subjected to fire, and one subjected to both fire and strengthening with CFRP sheets. The ISO 834 standard temperature rise curve was used for the fire test, and the part beneath the floor of the joint was subjected to fire. The axial compression ratio of the column was maintained at 0.25. The effects of high temperature (due to the fire) and CFRP strengthening on the failure mode, hysteretic curve, skeleton curve, load bearing capacity, ductility, stiffness, and hysteretic energy of the joints were investigated. The results show that shear failure occurred in the core area of each joint. The maximum bearing capacities of the joint without fire and the joint subjected to fire are achieved at the displacement angles of 3/100 and 4/100, respectively. The corresponding maximum widths of the inclined cracks are 2.0 and 1.9 mm, respectively, in the core area of the joints under the displacement angles. The stirrups in the core area of the joint which is not subjected to fire, and that of the joint after fire and with CFRP reinforcement are founded to have yielded. The seismic performance of the joint is significantly reduced after a fire lasting 90 min. Specifically, the cracking load, yield load, ultimate load, and ductility coefficient of the joint are reduced by 41.3%, 18.5%, 15.8%, and 14.8%, respectively. Furthermore, strengthening the joint that is subjected to fire with CFRP sheets provided only limited improvements in the seismic performance of the joint, and this strengthening could not restore the bearing capacity to the same level as that of the specimen that is not subjected to fire. The cracking load, yield load, and ultimate load of the joint subjected to both fire and strengthening with CFRP are, respectively, 16.5%, 4.0%, and 3.4% higher than those of the joint that is subjected to fire but not strengthened. These parameters are 31.6%, 15.2%, and 12.9% lower than those of the joint that is subjected to fire, respectively. The study concluded that further investigation is needed on the seismic strengthening scheme and design method for RC beam column joints subjected to fire. 3 tabs, 14 figs, 25 refs.
Last Update: 2018-12-18