Experimental Study On Seismic Behavior And Static Elasto-plastic Analysis Of Solid Steel Reinforced Concrete Middle Frame With Special-shaped Columns

Steel reinforced concrete (SRC) structure with special-shaped columns has muchevident superiority: on the one hand, it has the advantages of reinforced concretestructure with special-shaped columns, such as it can make better use of available space,improve the esthetic appearance of structure and give more free space for people toarrange; on the other hand, it overcomes the disadvantages of reinforced concretestructure with special-shaped columns, such as bearing capacity is insufficient andseismic performance is poor, so it is a promising structure system. Prior research hasfocused mainly on the members, the research on the soild SRC frame withspecial-shaped columns can not be found. In order to promote the research and theapplication of the SRC structure with special-shaped columns, the seismic performanceand static elasto-plastic behavior of the solid SRC middle frame with special-shapedcolumns were deep studied. The mainly work and conclusions are listed as follows:(1) Through the pseudo-static test of a two-bay and three-story middle frameconsisting of reinforced concrete beams and solid SRC special-shaped columns, thefailure process and pattern were obtained, and the mechanical behaviors such as theloading-displacement hysteretic loops, skeleton curves, ductility, the degradation lawsof stiffness and bearing capacity, the inter-story drift ratio, energy dissipation and thecumulative damage of the frame were analyzed. The results show that the solid SRCmiddle frame with special-shaped columns failed according to the beam hinge failuremechanisms, the hysteretic loops are plump, the average of the whole ductilitycoefficient is5.5, the elastic-plastic limit of story drift angle is between1/39and1/15,almost all of which are more than1/25, the equivalent damper coefficient is0.249. It can be concluded that the solid SRC middle frame with special-shaped columns hasexcellent seismic performance and can be used in the high seismic fortification areas.(2) Two different models of static elasto-plastic analysis were formed using twodifferent plastic-hinge models in the SAP2000, and through the comparison with theexperimental results, the results show that the analysis model built by the fiberplastic-hinges is more effectively to analyze the elasto-plastic behavior of the specialframe.(3) Parameters analysis were conducted to investigate the influences ofheight-thickness ratio of column limb, concrete strength, steel strength andbeam-column yield bending moment ratio on the static elasto-plastic behavior of thesolid SRC middle frame with special-shaped columns. Some laws were concluded asfollows: raising the height-thickness ratio of column limb or beam-column yieldbending moment ratio increases the horizontal bearing capacity of the frame obviously,while the increment of the horizontal bearing capacity caused by the raise of steelyielding strength or the concrete strength is smaller; with the increment of theheight-thickness ratio of column limb, the stiffness of the frame improves apparently,while raising the steel yielding strength, beam-column yield bending moment ratio orthe concrete strength only increases the stiffness at the intensifying stage after yielding;the ductility of the frame is almost unchanged when the height-thickness ratio ofcolumn limb, the steel yielding strength or the beam-column yield bending momentratio change, while with the increment of the concrete strength, the ductility decreases.