The High Pier Second-order Effect Of A Single Particle System Under Vertical Earthquake

Firstly, the research status of vertical seismic action and the secondary effect on high bridge pier(single-mass system) under seismic action are briefly introduced in this paper. , It is indicated that the dynamic response under vertical seismic action is not fully understood. Then the kinetic equation is established considering secondary effect additional horizontal force, analysis secondary effect versus the dynamic responses of the vertical seismic action, also its effect on secondary effect and the influencing factors by theoretical derivation and numerical simulation.Specific content and the main conclusions are as follows:â‘ the high bridge pier is simplified to single-mass system, investigate second-order effect versus the dynamic responses of the vertical seismic action. First, with lateral circumstance, vertical seismic independent action, analyze effect on structural dynamic response using the simplified model, and then analyse the effect under the simultaneous action of horizontal and vertical seismic in actual earthquakes.On the basis of the contrast analysis result, draw the main conclusion.For the same vertical seismic waves, the dynamic responses cindering vertical seismic action are basically the same with or without lateral displacement; which indicates that secondary effect have no effect on vertical dynamic response of single-mass-string system.â‘¡To investigate the effect of vertical seismic on secondary effect, analyze vertical seismic effect on top Coolum lateral using simplified model and the actual seismic respectively, and make a further study in influence factors of structural horizontal lateral.On the basis of the contrast analysis result, draw the main conclusion:1) In the simplified analysis mode, according to the variety of axial force caused by the vertical seismic, its effect on secondary effect can be equivalent to a horizontal dynamic motivation. Because of the spectrum characteristics of equivalent horizontal motivation and vertical seismic waves are basically the same, while the farmer's period is shorter, so the secondary effect caused by vertical seismic action is far less than static secondary effect in general case. That is the vertical seismic effect on structural lateral is extremely small.2) Under the simultaneous action of horizontal and vertical seismic, the secondary effect caused by the vertical seismic can be equivalent to effect on the horizontal stiffness, there are non-synchronization between horizontal and vertical structural dynamic response,so the influence of vertical seismic versus horizontal stiffness is variable.