| Due to the advantages of high bearing capacity,good anti-seismic and fire-resistant performance,making full use of high-strength materials,saving formwork and convenient construction,steel tube confined concrete structure has a broad development prospect in various large structures such as high-rise and super-high-rise structures,sub-supporting structures of long-span spatial structures,heavy-duty structures and bridge structures.Numerous studies have been conducted on the steel tube confined concrete column and beam-column joints at present,,yet research on the seismic behavior of the structural system is relatively limited,leading to the insufficient design basis.To further improve the design approach of steel tube confined concrete,in this paper,the seismic behavior of circular Tubed Reinforced Concrete(TRC)and Tubed Steel Reinforced Concrete(TSRC)columns to steel beam frame is investigated,the main work and results are as follows:(1)Based on the existing research results of steel tube confined concrete,a stressstrain relationship model and a simplified loading and unloading rule for hysteretic behavior simulation of steel tube confined concrete were proposed.The solid and fiber element model of steel tube confined concrete column was established based on the ABAQUS and Open Sees platforms,of which the applicability and accuracy were verified by comparing with the existing test results.Based on the finite element analysis,the criterion for judging the plastic hinge and the limit shear span ratio of slender and short column were respectively proposed and suggested.(2)Hysteretic behaviors of two circular TRC column to steel beam frames and two circular TSRC column to steel beam frames with key parameters of column-beam strength ratio were tested.The load-displacement hysteretic curve,joint shear force-shear deformation relationship,displacement-frame material stress curve and failure mode of the specimen were obtained by the test.The bearing capacity and deformation capacity of frame,and the stress development of steel shape,steel bar and steel tube in the plastic hinge area of beam and column and of joint core area were analyzed.The test results indicated that the frame which met and broke the limiting value of "strong column and weak beam" showed typical beam hinge and column hinge failure mechanism respectively.Frames failed in different mechanisms showed quite different deformation mode and failure mechanism.Column hinge mechanism did not result in significant reduction of ductility and deformation capacity of the frame due to the good ductility and deformation capacity of the frame column.Even if the plastic hinge appeared in the frame column,the overall structure can still maintain good ductility.(3)The solid and fiber element model of the TRC/TSRC column-steel beam frames were built using ABAQUS and Open Sees platforms respectively,of which the accuracy was verified by comparing with the test results.Based on solid element model,stress development of beam and column,vertical deformation of the column,rotation of the joint core area and the influence of the floor slab were analyzed.Based on fiber element model,the parameters of axial load ratio,concrete strength,steel tube yield strength,diameter to thickness ratio,column length to diameter ratio,column to beam strength ratio and beam to column line stiffness ratio were analyzed,and the design suggestions of column to beam strength ratio were put forward.The effect of P-Δ on hysteretic behavior of frame and the seismic performance of frame with short column were analyzed using fiber element model.(4)Taking the TRC column-steel beam frame as a representative case,the seismic performance of the steel tube confined concrete frame structure system was studied.A total of five frame structure examples were designed to investigate the different seismic performance between steel tube confined concrete and concrete-filled steel tube frame structures,steel tube confined concrete frames with the same amount of steel in the column section but different reinforcement ratios,and steel tube confined concrete frames with different column to beam strength ratio.Using Open Sees software,fiber element models of each calculation examples were built,and pushover analysis,time history analysis,IDA analysis and seismic vulnerability analysis were carried out.The capability curve,yield mechanism,interlayer displacement and collapse resistance of different calculation examples were compared.Based on the results of frame test,finite element model analysis and static and dynamic elastic-plastic analysis of the structural system,suggestions for seismic design were put forward including the maximum applicable height,elastic and inelastic storey drift limit,the strength ratio of columns and beams,and the structural measures. |
PDF Full Text Request