Analysis Of The PKG Prefabricated Bottom Plate In The Stress Stage And Study Of Considering The Effect Of Rib Opening On The Mid-span Displacement

In recent years,with the promotion of the country and the government,prefabricated buildings have gradually entered our field of vision,which has also brought a certain impact on the traditional construction industry.Projects that use prefabricated buildings must meet the requirements of the assembly rate before they can be approved.At present,components such as laminated floors,prefabricated stairs and prefabricated balconies are often used to increase the assembly rate of prefabricated buildings.Based on this background,Wu Fangbo and others proposed PK prestressed concrete precast floor,and the ribs reserved holes to increase the contact between the precast floor and cast-in-place concrete,so that the PK superimposed floor slabs are jointly stressed,but during the production process,PK precast The rib support of prestressed concrete precast floor is complicated.Therefore,based on the PK plate,the research group proposed the PKG prestressed concrete precast floor(that is,the ribs of the PK prestressed concrete precast floor were wrapped with cold-formed thin-walled C-shaped steel),and solved the rib support form.The problem has the advantages of one-time construction and maintenance,and improves the degree of industrialization.At present,the theoretical and experimental research on the bearing capacity of the PKG prefabricated floor and laminated floor is mainly carried out.The shear performance of the laminated surface is also analyzed.The results show that the artificial rough surface can meet the shear resistance of the laminated surface,making the PKG laminated Floor slabs work together and work together.The ribs of the prefabricated bottom plate of PKG are opened to increase the contact surface with the cast-in-place concrete to strengthen the integrity of the laminated floor.However,the PKG prefabricated floor rib opening in the construction stage will have an impact on the mid-span displacement,which will affect the overall performance of the work.Therefore,this article takes the PKG prefabricated bottom plate as the research object,first establishes the mechanical model under different stress stages and derives the corresponding expression;secondly,the numerical simulation method is compared with the test results to illustrate the feasibility of the numerical simulation method;then use This method analyzes the effect of rib opening size on mid-span displacement at different spans,and introduces the "stiffness functions x EI)(and x GA)(" to derive the functional expression of cross-sectionalmid-span displacement as a function of opening size;finally,consider floor assembly During the process,pedestrian loads affect the local stiffness of the PKG precast floor span.In the course of research,its main work is as follows:(1)The theoretical analysis of the PKG prefabricated bottom plate is carried out at the stress stage,and the applicability of the theoretical analysis is verified,so that the expression of cross-section design is proposed.(2)The variable load during the construction process is equivalent to a static load.ANSYS is used to establish the PKG precast floor model.The impact of the cross-sectional rib opening size on the mid-span displacement is analyzed at a span of 2700 mm-4200 mm.Finally Based on the analysis of structural performance,the size of the rib opening of the PKG prefabricated bottom plate under different spans is obtained.(3)Introduce the "stiffness function sum x EI)(and x GA)(" to consider the discontinuousness of the stiffness of the rib opening of the PKG prefabricated floor,derive the calculation expression of the effect of the rib opening on the mid-span displacement under bending and shear deformation,and carry out with the finite element value The comparison shows the applicability of this method.In order to facilitate engineering application,based on the results of finite element analysis,the "correction coefficient α" of the mid-span displacement of the cross-section under different spans is obtained by using the estimation method.(4)Based on the equivalent stiffness method,during the assembly process,SAP2000 is used to analyze the displacement response of the pedestrian load during the construction phase to the PKG precast floor span,and the local stiffness of the floor is checked.