| Slab-column structure is widely used in large space multistory factory,warehouse and public building. It has characteristics of space clear concise,flexible layout, reducing the floor height etc. But there are also some defectsof slab-column that brittle punching failure easily occurs in the slab-columnnode. As a result, the slab-column nodes need to be repaired andstrengthened for various reasons in engineering practice. A new methodusing CFRP reinforcement the slab column connections is put forwardthrough the domestic and foreign researches about slab-column nodepunching failure and strengthening. The1/4scale models with and withoutCFRP reinforcement have been made during the test, with the help of whichmodel test research and nonlinear finite element analysis have been done byselecting a grid in the middle of actual slab-column structure.(1) The1/4scale model of slab-column structure tests have been doneboth before and after the models were reinforced. And further analysis ofpunching failure mechanism of slab column node has been made afterwards.The test results show that in the event of slab column structure of punchingfailure, often accompanied by slab flexural crack. The punching cracksoccur in the pillar corner and then develop to the column edge. The CFRPreinforced slab-column node program is able to improve the punching shearcapacity, compared with slab column structure without reinforcement, thepunching shear capacity has been improved27%.(2)The contrast of the load deflection curve of both former and latterexperiment leads to a result that shows before cracking punching node, twocurves almost coincide, which means CFRP reinforcement doesn’t improvethe stiffness of the building before it cracked, and the punching crack load ofCFRP reinforced slab column structure is lightly higher than that of slabcolumn structure without reinforcement, this shows CFRP reinforcementplays a certain role in improving the punching cracking load of slab-columnconnections. After cracking punching node, the stiffness of slab columnstructure with CFRP reinforcement is higher than the stiffness of thosewithout it, and the effect of CFRP increases from this moment. When thepunching failure is happening, the ductility of CFRP reinforced slab column structure increases58%, compared with slab column structure withoutreinforcement.(3)By making nonlinear analysis of test model with the help of ANSYSfinite element software, a result that shows finite element calculation andexperimental values are in good agreement has been found. By comparingthe finite element analysis with the experimental results, we found thatsolid65should be selected for concrete unit and smeared crack model andW-W five parameter failure criterion be used during the process, andbeam188for steel unit, taking the effect of the longitudinal reinforcement inthe destruction of anti-punching into consideration, and shell41unit forCFRP. We also found that punching performance of slab-column structureboth with and without CFRP reinforcement can be well simulated by usingSeparate finite element model.(4) Punching capacity calculation formula which is suitable for CFRPreinforced slab-column connections was proposed and punching shearcapacities of Slab-column node both before and after reinforcementcalculated by combining results of model test research and nonlinear finiteelement analysis. At last, the theoretical calculations and experimentalresults, finite element results were compared to verify the feasibility of theformula. |
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