Study On The Basic Properties Of PVA Fiber Reinforced Concrete And Its Application In Seismic Joints

Joint is an important part of the frame structure,which plays the role of connecting the beam and column,transferring the internal force and coordinating the deformation.The investigation shows that the damage of frame structure is more concentrated in the frame node and the failure that due to joint lose efficacy is generally difficult to repair.To meet the "strong column and weak beam" principle,the section size is often too large or more stirrups,which brings great trouble to the construction,at the same time,it is difficult to control the cracks.PVA(polyvinyl alcohol)fiber,as a kind of external fiber in seismic resistance,has attracted more and more attention in recent years.By using the fracture mechanics and micromechanics theory,PVA fiber reinforced concrete obtained more than 3% tensile strain in the case of fiber volume accounted for 2%.It has a good toughness,good nonlinear deformation and remarkable crack control ability,which can change the brittle failure mode into ductile failure.Therefore,the research and application of PVA fiber reinforced concrete will provide a new solution for the cracking of concrete structures.Based on the Natural Science Foundation Project and PVA fiber concrete joint test,the research contents of this paper are as follows:1.In this paper,24 PVA fiber standard specimens were made for the Basic performance test,and using the test process and results described the cracking process of fiber reinforced concrete.Then compared the performance curve with that of ordinary concrete.2.8 different PVA fiber reinforced concrete frame joint specimens and 1 ordinary specimens were tested under low cyclic loading.The main parameters are the stirrup ratio and axial compression ratio.To study the feasibility of PVA fiber replacing the core stirrups.3.Simulate the low cyclic loading test of PVA fiber reinforced frame joints using finite element software OpenSeeS,conside the mechanical properties and failure mechanism of such joints and calculate the ductility coefficient,stiffness degradation and viscous damping coefficient.4.Simplify the shear model of PVA fiber reinforced frame joints,and establish the strut and tie model in core area.Analyze the formula of shear bearing capacity by comparing the experimental and simulated values.5.Based on the test,using the finite element software OpenSees to simulate the seismic performance of PVA fiber reinforced frame joints under low cyclic loading in different bending moment coefficients and further ensure the optimum ratio of column to beam moment for the requirements of "strong column and weak beam".