Experimental Study On Mechanism And Seismic Behavior Of Abnormal Reinforced Concrete Frame Interior Joint With Abrupt Beam Section

RC Beam-Column Joints is an integral part of the frame structure. joints play a role in transmission and distribution of internal forces in the structural, and keeping the structural integrity of an important role.the joint design in the current concrete code is mainly based on the general joints' experimental data, and the abnormal joint design is just based on the designer's experience, which is lack of perfect theoretical foundation. So, working on this kind of abnormal joints has theoretical values and practical useful values.The dissertation focuses on the research of the abnormal frame interior joints that occur in the reinforced concrete structure Based on pseudo-static test of four 1/3-scale model, and calculated shear strength of the joint by softened strut and tie model. Main conclusions are as following.1.Abnormal joint experiences first cracking, critical cracking, ultimate and damage states during experiment, Finding that the critical crack load was quite nearly with the ultimate load of abnormal joints. the reinforcing details of the test specimen, which were designed under the guideline of current codes, can not preserve the structural integrity and satisfy the strong joint demand.2.According to the experiment,analysising that geometry asymmetry, hysteresis loops, energy dissipation and ductility of the abnormal joints.3.Change of beam and column sections affects the joint seismic behavior distinctly, Making good construction measure, the abnormal joints have an important role in the performance. Increasing stirrup ratio is advantageous to performance of abnormal joints.4.This article is based softened strut-and-tie model on the mechanism of abnormal joints shear analysis. An through simplification and amendment of resisted bending arm, struts size and other parameters.take advantage of 8 abnormal joints were verified, The results showed that:the theoretical value calculated of softened strut-and-tie model is closer to experimental results.softened strut-and-tie model has a definite mechanical model, which can be more reasonably reflect the frame work joints on the resisted mechanism.