Research On The Influence Of Ground Motion Characteristics To The Pounding Response Of Adjacent RC Frame Structures

The research of earthquake damage shows that the pounding of adjacent structures is one of the main reasons for the destruction and collapse of structural and non-structural components of buildings.Under the action of strong earthquake,the damage caused by the pounding of adjacent structures is mostly due to the influence of ground motion characteristics or the different dynamic characteristics of adjacent structures.In China,More than 85%of the large cities with a population of more than one million are located in seismic activity areas.Therefore,it is of practical significance to study the pounding of adjacent structures to ensure the safety of buildings and personal and property safety under ground motion in practical engineering.The research work and main conclusions of this paper are as follows:(1)The method of combining contact element model with finite element simulation is used to study.Based on the Hertz-Damp model,the dynamic equation of adjacent single-degree-of-freedom system considering pounding is derived.The influence of the distance between adjacent single-degree-of-freedom systems,the frequency and amplitude of external excitation(sine wave)on the pounding response of adjacent structures is studied by selecting the appropriate integral step size.The pounding response includes structural displacement pounding force and number of poundings.Studies have shown that the pounding of adjacent structures will have a significant impact on long-period structures.At the same external force frequency,as the system spacing or period becomes larger,the peak displacement of the adjacent single-degree-of-freedom system after pounding increases,the peak pounding force increases,and the number of poundings increases.When the period gap between adjacent single-degree-of-freedom systems is larger,the pounding response between the two is larger.When the adjacent system is at the same spacing or the same period ratio,the frequency of the external force is kept constant,and the larger the amplitude of the external force,the greater the pounding response;the amplitude of the external force is constat and the higher the frequency,the smaller the pounding response.(2)The definitions of near-field pulse-type,far-field pulse-type and near-field non-pulse-type ground motions are described.The finite element software ANSYS/LS-DYNA was used to establish the RC frame model of adjacent different story heights,and the influence of ground motion pulse,amplitude,fault distance and relative position of the structure on the pounding of adjacent frame structures was analyzed.The research shows that under the action of near-field pulse-type ground motion,the pounding response(inter-story displacement,velocity,acceleration)of adjacent frame structures is the largest,and the phenomenon of damage and collapse is most likely to occur.The adjacent frame structure will produce pounding force after pounding under the action of ground motion.The acceleration time history of the pounding layer of the structure appears pulse change,and the peak value of the interlayer displacement of the top layer increases significantly.(3)The spacing between adjacent frame structures is adjusted to simulate the change law of pounding response of adjacent frame structures under different seismic joints under the action of near-field pulse-type ground motion with the same acceleration peak.The results show that under the action of ground motion with different amplitudes,the peak velocity of long-period RC frame structure increases after pounding under the action of ground motion,and the pounding enlarges it.Keeping the structure spacing unchanged,the greater the amplitude of ground motion,the greater the inter-story displacement,velocity,acceleration and pounding force after the pounding of adjacent frame structures,and the more the number of poundings.Keeping the amplitude of ground motion unchanged,the larger the structural spacing,the smaller the inter-story displacement,velocity,acceleration and pounding force after the pounding of adjacent frame structures,the fewer the number of poundings,and the earlier the occurrence time of the maximum pounding force.At the same time,the distance between adjacent structures affects whether the pounding has an inhibitory effect on the structure or an amplification effect.