Study On Seismic Performance And Shaking Table Of Irregular Complex Connected Structures

Connected structures usually produce irregular vibration due to the interaction of multiple monomer structures,resulting in significant torsional effect.It is easy to slip at joints and produce huge internal force,even instantaneous collision,which leads to failure.In this paper,the elasticplastic development law of the structure and the collision effect between the connector and the main structure are studied under the background of the East Building Project of Xi’an Railway Station(Renovation and Extension).The dynamic response law of connected structure under earthquake is summarized,the weak area of structure is defined,and the basic characteristics of structure collision are studied,which can provide theoretical reference for similar projects.The main work and conclusions are as follows:The finite element model of the connected structure is established and its natural vibration characteristics are analyzed.The results show that the structure has obvious horizontal-torsional coupling effect.The dynamic elastic-plastic time history analysis under 8-degree multiple and rare earthquakes is carried out to extract the displacement and internal force response curves of the key components of each single structure.The results show that the deformation indexes such as inter-story displacement angle meet the requirements of the code,but the connecting body meets the requirements.The displacement response of the area near the support is large and the internal force of the member develops rapidly.The maximum bending moment of frame column is 3.96 times of that of elastic earthquake under rare earthquakes.The plastic development law of the structure under strong earthquakes is obtained,and the strengthening measures are put forward according to the mechanism and development state of plastic hinge.The prototype structure was simplified to a substructure model,and the 1:10 scale specimen was designed,and the shaking table test was carried out.The displacement and acceleration response laws of the model structure are analyzed,and the coordinated deformation relationship between the connector and the three monomers under rare earthquakes is expounded.The dynamic strain analysis of key components under different earthquakes is carried out,and the weak area and failure mechanism of the structure are determined.The test results show that the weak parts of the structure are mainly concentrated in the 2 or 3 stories of each region,and the cracks of the frame beams and columns are less developed under the fortification earthquake,which meets the fortification target of "repairable under moderate earthquakes";under the rare earthquake of 8 degrees,the cracks of the frame beams around the regions and near the joints intensify and take the lead in forming the plastic hinge mechanism.With the increase of the earthquake,the level of the end of the frame columns increases.The cracks deepen and widen gradually,the beams and columns rotate each other,and the structure enters the plastic state completely.However,the floor displacement and other deformation indicators meet the requirements of the seismic code and meet the seismic requirements of "large earthquakes do not collapse".It is suggested to increase the stiffness of the members around the small triangle area.The torsion effect of long-span truss is more significant than that of main structure.Under strong earthquake,the connection of bearing is the key point of design.In order to prevent the falling off of the embedded plate of bearing,it is suggested that the anchorage should be strengthened,and the rubber viscous damper element should be used to weaken the seismic response of truss.The ratio of the tensile stiffness to the span of the collision body is taken as the contact stiffness of the collision,and the peak displacement of the sliding support seat is taken as the initial clearance of the collision.The collision effect of the two structural forms is analyzed.By analyzing the internal force,displacement and plastic hinge mechanism of the connector and the key components,the collision characteristics of the two structures are compared,and the collision effect on the connector support is obtained.The influence of seat displacement and collision force is discussed.The influence of contact stiffness and initial clearance on collision effect is discussed.The results show that under strong earthquakes,the original structure is more likely to produce collision,which has a significant amplification effect on the internal force and displacement of the joints and frame beams and columns,and increases the plastic hinges of the joints and the damage degree of the members.The impact force and displacement of the structure increase with the increase of contact stiffness,while the change with the initial clearance is the opposite.It is suggested that the contact stiffness of the analysis of the impact effect of the connecting structure should be 5 × 106 kN/m greater than the axial stiffness of the main frame beam,and that the impact force at the support will disappear when the initial clearance is greater than 0.2 m.