Study On Seismic Performance Of Multi-rise Concrete-filled Steel Tube Column-pinned Steel Beam-reinforced Concrete Core Tube Structure

Under the circumstance that search on structural systems suitable for industrial or semiindustrial construction is less,in this paper,the seismic performance of a new type of multi-rise CFST(concrete-filled steel tube)column-pinned steel beam-RC(reinforced concrete)core tube structure system,that is,a new type of structural system in which the joint of the steel beam with the CFST column and the RC core tube is hinged by full bolt connection,was studied.With the actual CFST frame column-core tube structure as the background,a 9-story 1/40 scaled model structure was constructed and carried out the shaking table tests.The damage characteristics,dynamic characteristics and seismic response of the structure were studied.The experimental results showed that the seismic damage mainly occurs on the concrete slab at the connection between the concrete slab and the CFST column,the concrete core tube and the steel beam.These damages include the connection damage and structural damage caused by deformation.The basic natural vibration periods increase with the increase of the seismic damage,the amplification factors decrease,and the lateral deformation and the inter-story drift significantly increase.The average maximum inter-story drift angle of the model structure exceeds 4.08 times of the no-collapse limit for the frame-core tube structure system,but multirise CFST column-pinned steel beam-RC core tube structure has no collapse.The torsion stiffness of the outer shelf is small,and the structural torsion response is dominated by the RC core tube.Compared with the super high-rise CFST column-pinned steel beam-RC core tube structure,the shear-weight ratio of the multi-rise structure significantly increases,but there is no seismic damage of the core wall due to excessive overturning moment.The correlation between the inter-story drift angle and seismic damage increases.By changing the aspect ratio and the core tube area ratio,the dynamic elastoplastic time history analysis was performed on the multi-rise CFST column-pinned steel beam-RC core tube structure,and the influence law of the seismic performance of the new multi-rise structure is studied.The basic natural vibration period,internal force,and deformation of the structure have obvious changes with different earthquake input strength,aspect ratio,and core tube area ratio.From the overall damage state,the structure of the example can achieve the fortification goal of “small earthquakes are not bad,medium earthquakes can be repaired,and large earthquakes do not fall down”.The new structure can tolerate greater rotation angle deformation due to the hinged characteristic of its joints,and the elastoplastic interlayer displacement angle limit of the new structure system can be appropriately relaxed.