| PEC column fabricated with thin-walled built-up section and reduced-section steel beam composite frame is a kind of composite structure system.At present,there are already some scholars have conducted series studies of PEC columns,PEC column-steel beam connections and related inter-storey substructure.However,the research results of seismic performance based on the whole structure is relatively scarce.Therefore,this paper selects a test specimen of one bay,two storey PEC column—reduced-section steel beam composite frame with end-plate connection to conduct quasi-static loading experimental study and finite element analysis to reveal its seismic performance.A 1: 2 scale test specimen was fabricated to carried out quasi-static loading test in structural laboratory.Based on experimental date,drawing hysteresis curve,skeleton curve and lateral resisting stiffness degenerated curve to analyses the seismic performance.Taking into account the stress behavior of the specimen during the test,the seismic performance of the specimen is analyzed from failure mode perspective.Experimental results show that the beam flange weakened section form obvious plastic deformation,the corresponding inter-story drift angles are 0.033 rad,0.026rad(forward loading)and 0.059 rad,0.032rad(reverse loading)respectively,which all surpassed the inter-story drift limit(1/50)at medium consideration earthquake level.Based on the simulation results,the seismic behavior of the specimens is analyzed from the aspects of hysteretic characteristics,lateral stiffness,structural damage process,inter-storey transfer mechanism and failure mode.The results show that the reduced-section of steel beam flange implement the plastic hinge region of connection region far away from the beam-column joint area;the plastic hinge formed at the end of the beam and the root of the PEC column translate the specimen structure into the plastic damage mechanism;the energy dissipation owes to the concrete crushing and the steel skeleton of PEC column root and the yielding of the reduced-section of the steel beam;the corresponding inter-story drift angles and connection rotation are 0.050rad、0.041 rad and 0.049 rad respectively which all outstripped the inter-storey drift limit(1/30)at rarely occurred earthquake level.There are differences between test and simulation curves as the negative allowrance of specimen dimension of processing,the misalignment of specimen assembly and data acquisition error,also the simplification and establishment of the finite element model are more ideal.The hysteretic curve of experimental and simulation are consistent with the trend.The curve is spindle shaped with good energy dissipation capacity.The failure process of specimen is basically consistent.The steel beam flange of upper level yield in the first instance and the yield of lower level steel beam flange and steel framework formed later.The failure mode of specimen is induced by the formation of plastic hinge at reduced cross-section of steel beam and the root of the bottom of PEC column.The location of the plastic hinges of the experimental specimen is consistent with the simulation specimen.Limited by loading condition of laboratory,the text specimen was loaded without vertical force.According to theoretical analysis,the structure can engender obvious lateral displacement under the lateral loading and the vertical force.An additional bending moment will be produced for the PEC column with vertical force,and the greater vertical force and horizontal displacement,the more obvious the P-Δ effect.The results show that the bearing capacity and the energy dissipation capacity of the model under axial force. |
