Study On The Mechanics Performance Precast Prefabricated PC Continuous Beam

Fabricated structure is a form of structure in which the components are connected through a certain assembling means.All or part of these components such as beams,columns are processed in the factory and then transported to the construction site to complete the assembly.Steel structure,masonry structure and modern timber construction are all in the form of fabricated structure.The fabricated structure is employed in concrete structure because it can not only ensure the quality of concrete components,but also reduce environmental pollution,speed up the construction progress and achieve sustainable development.The reliability of the precast element joints has always been the key to ensure the whole performance of the precast concrete structure.In order to make the precast concrete to be more widely used,domestic and foreign scientific research institutions and scholars have carried out a lot of research,and the main research are concentrated on the joint connection.In this paper,two kinds of dry joint connections were proposed based on previous studies.The precast concrete beams were connected to be continuous beams by using the two kinds of joints,then the continuous prestressed precast concrete beams are formed by applying prestressing to the continuous beams.This paper studies from the following aspects:Five rectangular cross-section continuous concrete beams were designed and fabricated,including a cast-in-situ continuous concrete beam as a reference and four continuous precast concrete beams.The two kinds of dry joint connections were applied in the precast concrete beams.And two of the continuous beams were bonded prestressed precast concrete continuous beams.The test beams were loaded at every two points in each span,and the normal section bending tests under static load were completed,then the test data was obtained.The mechanical properties of the continuous precast concrete beams were analyzed based on the experimental data.The results showed that:The bearing capacities of precast concrete continuous beams in the form of welded connection were higher than that of bolt connection;The deflections of four continuous precast concrete beams were larger than that of the cast-in-situ continuous concrete beam,and the deformation of continuous concrete beam in the form of welded connection is basically the same as that of bolt connection;In the case of the same reinforcement,the joint connection method had no effect on the bending failure mode of the continuous precast prestressed concrete beam.And the bonded prestress strands could improve the mechanical performances of precast concrete continuous beams significantly.The finite element nonlinear analysis software ABAQUS was used to carry out the numerical calculation analysis of the five test beams.The results showed that the calculated values were in good agreement with the measured values;Then the analysis models of sixteen continuous precast prestressed concrete beams were developed using ABAQUS.The variables among these beams included integrated reinforcement rate,span-depth ratio,prestress degree and concrete strength.The simulation analysis results showed that the internal force redistribution were emerged significantly of each models;And the integrated reinforcement rate,prestress degree,concrete strength and span-depth ratio had different effect on plastic properties of continuous prestressed precast concrete beams,while the joint connections had little effect on the plastic properties of continuous prestressed precast concrete beams.Based on the experimental and finite element analysis results,the formula of moment redistribution coefficient of continuous prestressed precast concrete beam was presented.