Research On Punching Shear Performance Of Unbonded Prestressed Slab Column Structures

The experimental study,numerical simulation and theoretical analysis are the common research methods of design and computing because of the complicated stress of unbonded prestressed slab column joint.In this paper,a layered shell model is established by using Open SEES finite element platform,and the punching shear performance of unbonded prestressed slab column structure is simulated.Through a large number of numerical analysis,the simulation results are in good agreement with the test results.The rationality and reliability of the model are verified.A theoretical reference for the design of the unbonded prestressed plate column joints and specification revision is provided.1)In the early stage of the study,a grid beam model is established to calculate the unbonded prestressed slab column structure using fiber section.The plate is dispersed into a crisscross beam.Therefore,a simulation calculation and parameter analysis of nine prestressed beams are done using fiber section.The simulation results are in good agreement with the test results.It provides a reference for the later establishment of the grid beam model.2)The gird beam model is established with the fiber section,and the concrete is set repeatedly,which is not in accordance with the actual situation.Therefore,the modeling method of adding section is put forward,that is to say,the concrete strength of the longitudinal beam is reduced.Five externally prestressed beam specimens are modeled,and the externally prestressed tendons are modeled by this method.3)It is found that the fiber section simulation of unbonded prestressed slab column structure has limitations.The simulation and parameter analysis of five unbonded prestressed slab columns are carried out by using a layered shell model.The simulation results are in good agreement with the test results.On this basis,the stress increment analysis of prestressed tendons and deformation distribution analysis are carried out.The parameters such as the prestressed reinforcement ratio and the effective prestress are studied.