Investigation On Performance Of Low Damage Precast Prestressed Concrete Frame Joints

Precast prestressed concrete frame structure combines the advantages of precast frame structure and prestressed structure,which is with characteristics of high construction efficiency,energy saving and environmental protection,overall performance and good seismic performance.At present,the research on this kind of structure is shallow and the demonstration project is less.Therefore,with the support of building industrialization supporting development research projects of Beijing Construction Engineering Group,this paper makes a comparative analysis on the test and numerical simulation of the foot frame joints and draws the important conclusion,which can provide reference for the study of the whole assembled frame structure and the demonstration project design and construction.The contents of this paper are as follows.Firstly,the design and construction of the test node are carried out.On the basis of the existing research,the paper sums up the working mechanism and the node structure of the joint connection,probes into the new type of precast nodes.This project makes reference to the PRESSS Design Handbook introduced from New Zealand for designing the prefabricated joints under the premise of incomplete domestic relevant specifications.A number of construction difficulties have been solved in the construction process,such as assembling,grouting and prestress tensioning.The experimental study of 4 feet(3 prefabricated nodes and one cast-in-place node)was carried out,the theoretical design bearing capacity is equivalent between the cast-in-place node PCJ1 and the precast node PCJ2.The only variable of the three precast nodes is the area of common reinforced.Through comparing and analyzing the RCJ1 and PCJ2,I find that the seismic performance of prefabricated joints is better than that of cast-in-place nodes,which has the advantages of small residual deformation,strong self-centering capacity,small damage range and easy to be repaired.From the comparison and analysis of three prefabricated nodes shows that,with the increase of the diameter of steel bar,the bearing capacity,the oneself distortion,the energy dissipation capacity and the prestress increment gradually become larger,but the ductility performance decreases gradually.The comprehensive analysis shows that the range of the reasonable self reduction ratio of prefabricated joints is around 1.58.On the basis of experimental research,this paper uses finite element software of Msc.marc to compare and analyse the seismic performance of precast joints,such as failure mode,deformation properties,bearing capacity and prestress increment.Finally,I carry out parametric analysis for tension control stress.The simulation results show that with the increase of tension control stress,the load capacity of the joints can be improved correspondingly.Finally,on the basis of node test and numerical simulation,Based on the,this paper use SAP2000 finite element software to make a pushover nonlinear analysis of the cast-in-place concrete frame structure and the precast prestressed concrete frame structure,and obtains thebase shear force-top displacement curves of precast structure.This project compares and analyzes the seismic performance of the structure under the frequent earthquake and rare earthquake of 7 degree and 8 degree,and get the performance points of different fortification intensity and different seismic levels,which is in the target performance range.It is proved that the structure meets the seismic performance requirements.In the study of structural failure mechanism,I conclude that the two kinds of structure is beam-hinge mechanism.