Study On The Seismic Behavior Of Steel Frame Joints With Steel-Concrete Composite Beams

A large number of earthquake disasters occurred these years show that thedestruction of steel-concrete composite beams mostly occurred in the beam-columnjoints. Therefore， studying the seismic behavior of the joints is an important part ofthe seismic performance of the steel frame structures with steel-concrete compositebeams. This article is funded by the National Natural Science Foundation (50978074)，mainly studying the seismic performance of steel frame joints with steel-concretecomposite beams， and the main work is as follows:seismic performance of the31/2carrying capacity scale steel frame joints withsteel-concrete composite beams were experimented， mainly studying the effects thejoint location (two middle joints， one side joint)， the combined effect (changingconcrete slab effective width) have on the seismic performance of specimens. Thefailure mode of the joints， influencing factors， stress distribution， the hysteresiscurves， the energy dissipation capacity， displacement ductility， strengthdegradation and stiffness degradation properties have also been studied. Studies showthat:(1) bolt-welded steel frame joints with steel-concrete composite beams should bestrengthened on the middle joints for preventing the steel beam flange buckling， andanchorage of longitudinal reinforcement located on the column flange plate of sidejoints should also be strengthened.(2) bolt-welded steel frame joints with steel-concrete composite beams do nothave significant strength and stiffness degradation， and normalized stiffness is mainlylocated in the range of0.85to1.0.(3) increasing the width in the range of the effective width of concrete slab， canimprove the seismic performance of steel frame joints with steel-concrete compositebeams. Therefore， the reasonable effective width of the concrete slab should beselected in practical engineering design.(4) the joint displacement ductility factors of bolt-welded steel frame joints withsteel-concrete composite beams are located in the range of3to5， while thedisplacement ductility factor of pure steel frame joints is about1.5. Therefore， thesteel frame joints with steel-concrete composite beams have better ductility，approximately2to3.5times of the pure steel frame joints.Finite element models were created using general-purpose finite element softwareABAQUS to test the three specimens， monotonic loading of elastic-plastic analysisand cyclic loading elastic-plastic analysis were implemented， and finite element analysis and experimental results were compared. That joint finite element analysisresults under monotonic loading and cyclic loading test results are in good agreement，and can be used as a supplement for test data; steel frame joints with steel-concretecomposite beams taking the combined effect of the concrete slab into considerationhave better seismic performance than pure steel frame joints not taking the combinedeffect into consideration.