Qualitative Study On The Influence Of Typical Frame Structure On The Ground Motion Of Surrounding Soil Under The Vertical Incidence Of SV Wave And P Wave

When an earthquake occurs,the seismic wave is transmitted into the foundation through the soil,and then transmitted from the foundation to the structure,causing structural vibration.At this time,as a secondary source,the structure will cause the vibration of the soil and affect the vibration of the surrounding structures.In this paper,a three-dimensional efficient explicit implicit zoning algorithm is used to realize the simulation calculation of soil structure interaction.The soil is simulated and analyzed by the concentrated mass explicit finite element method combined with viscoelastic artificial boundary.The superstructure is modeled by ANSYS software and dispersed by finite element,and the structural response is analyzed by Newmark implicit integral format.According to the code,four soil models of different sites and three single frame structure models of different scales are established.The relationship between the influence of structure on ground motion and site category,structure scale,distance between soil and structure and relative position between soil and structure under the vertical action of SV wave and P wave is analyzed.At the same time,under the action of SV wave,the relationship between structural internal force and site type,the influence of interaction on frame structures with different heights and the influence of foundation buried depth on structural internal force are analyzed.The main conclusions are as follows:(1)Under the action of SV wave,the influence of frame structure on ground motion is significantly different under different site conditions.The influence range of class I site is the largest,and the influence attenuation of structure on ground motion is the slowest.As the soil becomes softer,the influence range of structure on ground motion decreases gradually,and the influence frequency band also narrows gradually and moves to low frequency.The softer the soil is,the faster the influence attenuation is.The influence of the structure on the ground motion decreases rapidly with the increase of the distance between the field point and the structure in a small range near the structure,but its influence range in the vertical direction is greater than that in the horizontal direction.At the same time,the influence frequency band in the vertical direction of the same field point is narrower than that in the horizontal direction.In the horizontal direction,the influence of frame structures with different sizes on ground motion is related to the site.Under the condition of class I site,the influence of structure on ground motion may be positively related to the size of structure in the horizontal direction.Under the conditions of class II and III sites,the influence of structure on ground motion is more complex,which is related to the frequency band of ground motion and the distance between soil and structure.Under the same frequency band,different distances may be positively or negatively correlated.Under the condition of class IV site,the frame structure has no significant effect on ground motion.At this time,the system mainly produces the response in the X direction,so the soil ground motion on the side of the structure is obviously affected by the existence of the structure.(2)Under the action of P wave,the influence of site type and distance between structure and soil on ground motion is similar to that under the action of SV wave.Under the condition of class I site,the influence range of structure is the largest,and the frequency bandwidth and frequency are high.As the soil becomes softer,under the conditions of class II and III sites,the influence range of the structure gradually decreases,and the influence frequency band gradually narrows and moves to low frequency.On the side of the structure,the influence range of the structure on the earthquake in the X direction is greater than that in the Z direction,while on the front side of the structure,the influence of the structure on the earthquake in the Z direction is greater than that in the X direction.Different from that under the action of SV wave,at this time,the impact of the three structures on the ground motion is closer,and the impact of the change of structure scale on the ground motion is significantly smaller,that is,under the action of P wave,the ground motion of the soil around the structure is not significantly affected by the change of structure scale.(3)Under the condition of class I site,the assumption of rigid foundation is close to the actual situation.After considering the interaction,the difference between the shear force between columns and the displacement angle between floors is small.With the softening of soil,the impact of interaction on the structure increases.It is obviously inconsistent with the actual situation to still use the assumption of rigid foundation.The higher the flexibility of the structure,the longer the natural vibration period is after considering the interaction,but the internal force of the structure is reduced by the interaction;The buried depth of the foundation is not the deeper the better.When the foundation is deeper and passes through the surface soft soil,the isolation effect of the soft soil will be lost,and the internal force of the structure will increase.Therefore,the buried depth of the foundation should be analyzed in detail according to the site conditions and structure.