Study On Interaction Of Superstructure-Pile Raft Foundation Of High-rise Building In Loess Area

The building structure consists of superstructure,foundation and soil,which have cooperative stress and deformation.The calculation method counts one by one for calculate simply.Without considering the coordination deformation of superstructure,foundation and subsoil,the calculation results are always in great error with the actual situation.The interaction is obvious especially in high-rise buildings.With the popularization of computer and the emergence of numerical simulation software,the study of interaction between the three can be achieved and be needed by more and more high-rise building construction now.Therefore,the study of interaction is becoming more and more important.With the increasing height of building,the pile raft foundation is more and more used in high-rise buildings.Pile raft foundation,whose bearing capacity is greatly improved,has the advantages of raft foundation and pile foundation at the same time.But the foundation form is complex and the research on the interaction is not enough.In addition,the study on the interaction of superstructure-foundation-soil of high-rise in the loess area buildings is further developed.In this paper,a high-rise shear wall structure in Xi'an is taken as an example:(1)Using the finite element software ABAQUS to establish the two models which consist of the joint action and non joint action,the article carries on the finite element analysis and comparison of two models under vertical load and horizontal load;(2)In terms of static analysis,the first consideration is the vertical load.Under the action of vertical load,the common action model is loaded step by step according to the loading method of the simulation.It is found that the stress of the superstructure is more obvious than that of the joint,especially the edge component is more obvious.The settlement and settlement difference of the raft and the stress in the raft are not smaller than those of the joint The maximum reaction force of the pile is the largest in the non-joint model,and the maximum pile top reaction force is the angle pile.In general,the pile top reaction force is less than the non-interaction model.It can be learned from the above that the design that does not take into account the common function is conservative on the basis of it and is unsafe for the superstructure.(3)In the dynamic analysis,the dynamic characteristics of the upper structure are considered when considering the joint action,and the vibration period and the corresponding modes of the structure are obtained.Compared with the model,the structural system becomes soft and the vibration period becomes longer;(4)Using the dynamic analysis of the natural vibration frequency and vibration mode,the seismic seismic response code is used to calculate the horizontal seismic force,and then applied to the structure in the form of static force.It is found that the lateral stress of the superstructure is larger than that of the non-co-acting model due to the existence of the foundation,and the average stress at the bottom of the upper structure is larger than that of the non-coacting model.The maximum stress is smaller than the non-interaction model;(5)To change the thickness of the raft,to study the influence of the variation of the raft thickness on the common action.Under the vertical load,with the increase of the raft thickness,the differential settlement of the raft can be greatly reduced.Under the horizontal load,Can significantly reduce the lateral movement of the superstructure.But the raft thickness increases,but also lead to the bending moment in the raft becomes larger,is not conducive to raft reinforcement.Therefore,the design should weigh the pros and cons to choose a reasonable raft thickness.