Finite Element Analysis Of Assembled Concrete Frame Joints With High Strength Bottom Bars Anchored By Unsaturated Grouting

In recent years,with the continuous development of the construction industry,the application of prefabricated concrete structure has been vigorously advocated and supported by the industry;for the prefabricated components connected by sleeve grouting,the grouting degree is an important factor affecting the bearing capacity of joints;in addition,the application of high-strength reinforcement in China is gradually increasing,the research on the use of high-strength reinforcement in prefabricated concrete structure It will have practical significance.In this paper,the three-dimensional finite element model of prefabricated reinforced concrete frame beam column joints with htrb600 high-strength reinforcement anchored into the joint core area is established by using CAD and ABAQUS software.By changing the grouting rate,axial compression ratio and concrete strength grade of the sleeve in the upper precast column,the failure modes of the specimens are analyzed according to the cloud chart output by the software,and the nodes with different grouting rates are obtained The mechanical properties of precast precast reinforced concrete beam column joints with high strength bottom bars anchored in different grouting rates are summarized by comparing with the specimens with integral precast.The following conclusions are drawn through the research in this paper(1)Except for the model-4 specimen with 60% grouting rate,the failure mode of other specimens is bending failure of beam root,which meets the seismic design requirements of "strong joint,weak component".The failure of model-4 starts at the junction of the cast-in-place joint core area and the lower precast column.The peeq of the reinforcement skeleton in the core area of the joint is the largest,reaching 0.5233,and the concrete in the core area of the joint is most seriously damaged;(2)Under the same grouting rate,the greater the axial compression ratio is,the greater the stress of the precast concrete column section is,and the greater the damage range of concrete in the core area of cast-in-place joint is.The results show that when the axial compression ratio increases by 0.1,the maximum concrete stress value of precast column increases by about 20%,and the damage range increases by about 1 / 3;when the axial compression ratio increases by 0.2,the maximum concrete stress value of precast column increases by about 50%.(3)Under the same grouting rate,the higher the concrete strength grade,the greater the concrete compression damage value.Among them,the compressive damage value of C30 concrete is 0.9678,the compressive damage value of C40 concrete is 0.9725,and the compressive damage value of C50 concrete is 0.9772,which is close to complete damage,but the damaged area also increases with the increase of concrete strength grade and decrease.