Analysis Of Interaction Between Transfinite Structure And Piled Raft Foundation

In the design of complex overrun structure,in addition to the gravity load,the seismic load and wind load should also be considered,which makes the stress of overrun superstructure and foundation structure more complex.The interaction of superstructure,foundation and foundation has been studied in theory for many years.However,in the actual design of overrun structure projects,most of them still adopt the traditional design method to calculate the superstructure and foundation separately without considering their interaction.However,in the actual project,the superstructure and foundation interact with each other.Simply calculating them separately will inevitably lead to the difference between the calculation results and the actual force,which may make some members in the traditional design scheme unsafe and some members too conservative,which is contrary to the original intention of the design.Taking an overrun structure project as an example,the finite element calculation is carried out by using the overall model of overrun structure.After setting the basic parameters according to the actual situation,the influence of superstructure stiffness,foundation structure and soil interaction between piles on the superstructure and foundation is studied by adjusting a single typical parameter in turn.The stress-strain characteristics of the model under earthquake action are analyzed,such as structural displacement,internal force of structural members,foundation displacement,foundation settlement and foundation reinforcement,and the characteristics of interaction between superstructure and piled raft foundation are studied,and the conclusions are as follows:(1)It is suggested that the stiffness of all superstructure should be considered in structural design.After increasing the stiffness of the superstructure,the stress of the foundation raft is more balanced,the phenomenon of stress concentration is reduced,the uneven settlement is improved,the amount of reinforcement of the foundation raft is saved,and the allocation of resources is optimized;(2)We must pay attention to the effect of foundation structure on superstructure.Considering the effect of the foundation on the superstructure,the displacement and uneven settlement of the foundation will cause the change of the additional stress,which will weaken the stiffness and integrity of the superstructure,resulting in the redistribution of the internal force of the walls and columns in the structural members,and the obvious increase of the bottom shear and bending moment,which may even make the structure in a dangerous state;In addition,it also shows the necessity of the application of piled raft(box)foundation in similar overrun structures;(3)The effect of soil between piles should be fully considered.Considering the interaction of soil between piles,the soil between piles will share part of the load and bending moment of the foundation raft,which enhances the integrity of the foundation.At the same time,the bottom shear force and bending moment of the superstructure members are also reduced,and the displacement and settlement of the foundation are much smaller than those without considering the soil between piles.(4)In the calculation process of pile raft foundation and superstructure of overrun structure,integral calculation analysis should be adopted.The results of the design can be used in the actual project,the superstructure may be unsafe and the foundation structure may be conservative;The interaction between superstructure and foundation is considered in the whole calculation analysis.Most of the results accord with the theoretical concept and the stress of the structure.