Research On Reasonable Types Of High Strength Concrete Columns Confined By Butt-welded Closed Compound Stirrups And Honeycombed Steel Beam Composite Joints

This topic proposes a new RCS composite frame structure that is high strengthconcrete columns confined by butt-welded closed compound stirrups andhoneycombed steel beam combinational frame structure. Stress behavior of thebeam-column joints of the structure is not very clear, so it is necessary forexperimental study on the nodes.For the study the reasonable bolt layout and seismic performance of thesteel-concrete beam column joints connected by extended end-plate, this paper, afterlow frequency cyclic loading tests on71/2scale composite joints specimens of highstrength concrete columns confined by butt-welded closed compound stirrups andhoneycombed steel beam connected by extended end-plate with high-strengthbolts(Bolt arrangement、 diameter and number are different),the test phenomena andfailure mode are described,and according to the test results analysis the importantaspects of affect seismic behavior comprehensively. The aspects include the strainchanges,hysteretic curve，skeleton curve, stiffness degradation,displacement ductility,energy dissipation capacity etc，thus obtains the reasonable bolts arrangement forms.Based on the experimental study, restoring force models of different bolt layoutforms joints are proposed. The skeleton curves are set up based on a fiber sectionanalyses and a statistics regression analysis. By analyzing the characteristics of theP Δ hysteretic curve of the7joints, a series of hysteretic rules for different joints areproposed, which are already verified by comparing with the test.Results show that with the same arrangement of bolts, the greater the boltdiameter is, the higher its seismic and shear capability would be; Among differenttypes of arrangement for bolts, eight bolts arranged in three rows and three columnsof seismic shear bearing capacity is the highest form, eight bolts nodes arranged infour lines of two columns under seismic ductility and energy dissipation capacity isbest, but not much difference between the former, six bolts nodes arranged in threelines of two columns seismic performance is worst. so joints in which the bolts arelarger and arranged as close as possible to the beam flange are the more reasonable ones among steel-concrete composite joints of extended end-plate connection.