Research On Performance Of Mechanical Connection Prestressed Concrete Solid Square Pile

With the rapid development of construction industrialization,assembled structure is getting more and more attention.Compared to ordinary precast square piles and prestressed high strength concrete piles,the application of mechanical connection prestressed concrete solid square pile in construction structure is also increasingly common,because of its convenient way of connecting and the production of a high degree of industrialization.However,domestic application in the area of seismic fortification stays limited due to the lack of relevant seismic study.Under the earthquake,pile to cast-in-place concrete pile-cap connection’ force is complex,and is easy to damage,so pile to cast-in-place concrete pile-cap connection is the key part while evaluating the seismic performance of mechanical connection prestressed concrete solid square pile.In this paper,the influence of axial compression ratio,cutting piles,and the reinforcement ratio to the seismic behavior and damage index of pile to cast-in-place concrete pile-cap connections are studied by testing specimens under a constant axial load and cyclically varying lateral load and is analyzed by the cumulated damage model based on the theory of energy dissipation and hysteretic behavior.The research process and results are as follows:(1)Considering the actual engineering situation,the influence of axial compression ratio and cutting piles to the destruction state of pile cast-in-place concrete pile-cap connections are studied by testing specimens under a constant axial load and cyclically varying lateral load.Then the bearing capacity,ductility,stiffness and energy dissipation effected by axial compression ratio and cutting piles are analyzed deeply.(2)In order to improve the seismic performance of pile to cast-in-place concrete pile-cap connections after arranging the rebar,pile-cap connections are studied by testing specimens under a constant axial load and cyclically varying lateral load,then the difference of the bearing capacity,ductility,stiffness and energy dissipation is analyzed deeply.(3)In order to study the pile-cap connections deeply,pile-cap connections are modelled under various axial compression loading using nonlinear finite element program ABAQUS.Comparison with the test data proves the validity of the monotonic simulation.Then further simulation on the influence of reinforcement ratio and effective prestressing force to the bearing capacity and plasticity are conducted based on the validity of monotonic simulation.(4)According to the measured hysteresis curve,the cumulated damage model based on the theory of energy dissipation and hysteretic behavior is employed to evaluate the damage index for the pile-cap connections under cyclic loading.Then the destruction state is studied deeply to provide the basis for engineering.