Seismic performance of small span-to-depth ratio coupling beam with strengthened reinforcement
LIU Bin;ZHANG Jingshu;ZHOU Jialai;Key Laboratory of Mechanics on Disaster and Environment in Western China of the Ministry of Education, Lanzhou University;School of Civil Engineering and Mechanics, Lanzhou University;
Coupling beam with strengthened reinforcement is reinforced by HRB400 or higher strength bar, densified and strengthened crude side bar, and strengthened stirrup. The side bar and the stirrup can form two or more layers high-strength steel grid to bear shear and improve the seismic behavior, and the construction is more convenient, which is applicable for small span-to-depth ratio coupling beam. Based on the existing experimental work on the seismic behavior of the conventional coupling beam with a small span-depth ratio, the nonlinear finite element method was used to study the seismic behavior of the coupling beams with a span-to-depth ratio of 1.25 and various reinforcement details. It is indicated that the coupling beam with strengthened reinforcement has a higher bearing capacity, because there are two peaks on its skeleton curve. Its decline rate of load is approximately 39.42% of that of the conventional coupling beam, while its peak load is 1.37 times. The coupling beam with strengthened reinforcement has a good deformation capability, because the peak displacement is 3 times as large as that of the coupling beam with the concentrated diagonal reinforcement, crossing diagonal reinforcement or diagonal brace reinforcement. It is recommended that the calculation method for the deep beam should be used to calculate shear strength of the coupling beam with strengthened reinforcement.