The Analysis Of Pile-Soil-Structure Dynamical Interaction Based On Plastic Hinge Theory

Pile-soil-structure interaction is a focus topic in the field of Structure and Geotechnical Engineering. Mass of studies are based on rigid foundation when analysing structure seismic performance anciently. However, practical engineering indicates that soil-structure interaction has signified effect on the upper structure, even that the weaker the soil is, the more obvious interaction is. Nowdays, researchers use Finite Element Method(FEM) to solve the problem mostly. Although it caculates accurately, its operation hugeness is imaginabale, it cannot simulate structure's invalidation status sometimes. With the development of displacement/ performance-based antiseismic disign ideology, the static pushover analysis is becoming a popular tool. According to this method, structure seismic analysis can be simplified including elastic static property and dynamic result. Because analysis results are affected by lateral load patterns mainly, and it is an approximate method to assess structural antiseismic performance. A large amount of research indicate that, turning dynamic problem to static problem according to motive equation has great efficiency on the engineering design, so this thesis imports the pushover method in studying pile-soil-structure interaction. Based on the former research of lateral load patterns, patterns of uniform force distribution and triangular force distribution are used mainly.Based on the inelastic Pushover method, the response of pile-soil-structure interaction is researched. First of all, six-stories and thirty-stories reinforced concrete frames are analysed from the aspect of performance joint and distributing trend of plastic hinge. With the appearance of premier plastic hinge, the bending moment, axial force and torsional moment of first storey column, the storey displacement and inter-storey displacement can be obtained. Also, the factor affecting the interaction system of pile size, concrete grade of upper structure, spring density and soil scope are discussed.After these, refering to a test model, the steel frame's modal is obtained. Applying the former reason FEM model, the responses of two cases: rigid foundation system and considering interaction system are contrasted. With different soil scope, storey, soil characteristic, column size and pile length, different effects are received. Finally, some disciplinarians are gained.Through the above-mentioned analysis, we can receive the yeilding mechanism of the pile. Analysis shows that, from the aspect of displacement or performance-based seismic design, the pile-soil-structure interaction has effect on the upper system. In this thesis, we can conclude that, when the pile foundation satisfies bearing capacity and has small dimension, plastic hinge may appear on pile's top, so the top of the pile is weakness. All these results can help the subsequent test in a theory way.