Experimental Study On Seismic Behavior Of RC Frame Exterior Joint Strengthened By Prestressed Closed Wire Rope Units

Due to the fact that the technique of traditional seismic strengthening for RC frame exterior joints exists many problems,this thesis use a new method for strengthening RC frame exterior joints by prestressed closed wire rope units.This technology’s main idea is using steel wire-ropes to loop around exterior joint reasonably then prestressing by the hollow jack and constrain the core area of the joint with anchorage.At the same time,it can make the wire rope-concrete mechanism working and making highly use of the wire ropes.Thus,enhancing the shear capacity and deformability of the joint core area.This technology could overcome the obstacles of frame beams.Meanwhile,the usage of prestressing technology can effectively decrease the hysteresis effect of wire ropes,which exists in the traditional technologies.In this thesis,the further research of improving the seismic behavior of the joints was carried out:Firstly,found the existing disadvantages of prestressed steel wire-strengthened RC frame exterior joints for deep summary,and optimizing the research results,set up prestressed wire rope units reinforced RC frame exterior joints designing method.Secondly,a test of six specimens which contains four strengthened joints and two contrasts was conducted,the results shows that:(1)using of prestressed closed wire rope units strengthening RC prestressed closed wire rope units specimen ultimate shear capacity and seismic performance can be increased.At the same time,with increasing of rope ratio,the seismic behaviour of these specimens was improved significantly.(2)Prestressed closed wire rope units can effectively delay the core concrete cracking.(3)Raising of the prestressing degree was propitious to confine the developing of cracks in earlier stage.(4)By tightening wire line hitches and pressure injection to pore channel can make sure anchoring,proving the feasibility of this reinforcement method,and providing the basis for the actual reinforcement engineering.Finally,numerical simulation under monotonic loading on the RC frame exterior joints was done by Abaqus,the FEM results showed reasonable agreement with theexperiment results,and the model can predict the behavior of the RC frame exterior joints precisely.On this basis,the influences of axial compression ratio and reinforcement ratio of beam to the skeleton curves of the RC frame exterior joints were studied by numerical calculation.