Experimental Research And Theoretical Analysis Of The Precast Concrete Warehouse Top Slab Of Bearing Behavior In Orthogonal Slab Laying Direction

The industrialization of China’s construction industry has developed to a new stage.As a new model of construction mode in the construction industry,prefabricated building is more in line with the requirements of national intelligent construction and construction industrialization on the premise of meeting the social development needs of national economy,construction environment and social benefits.The roof structure is symmetrical and suitable for prefabricated method.At present,the research on the warehouse roof structure of prefabricated storage buildings at home and abroad mainly focuses on the construction technology and plate and joint connection method of the warehouse roof structure.The prefabricated warehouse top structure is different from the traditional warehouse top structure,and the slab seam structure has a great influence on the structure performance.The existence of the plate joint makes defects in the integrity of the structure,resulting in the decrease of the stiffness of the plate joint position,by setting the plate joint connector can improve the overall performance of the structure,improve the stiffness of the structure,and delay the stiffness decline of the joint.Therefore,the efficient connection between the prefabricated RC warehouse top structure is the key link to ensure the effective performance of the structure.Based on this,according to the requirements of domestic and foreign building codes and national policies,the research group proposed a distributed mechanical connection technology,designed and conducted 7 prefabricated roof specimens and 4 static loading test under vertical load.Based on the test study,conducted refined finite element modeling analysis,and compared the differences,and proposed the stiffness calculation method of transverse plate are as follows:(1)The loading mechanism of the warehouse roof is studied through the vertical load manager loading test of the assembled warehouse roof sandwich board and the whole pouring warehouse roof sandwich board.Test results show that the distributed mechanical connector has behavior in orthogonal slab laying direction(OSLD);The initial bending stiffness of the initial loading is less than that of the comparison test under the same conditions,The stiffness decrease after the crack is less than the whole pouring comparison specimen;The crack at the end of the connector develops obliquely along the plate or toward the center of the plate seam;Under the same conditions,The greater the plate seam spacing,The slower the development of the seam cracks,And the smaller the crack density in the center position of the specimen;The rotation of each slab and the deformation of the slab joint are the main reasons for the deformation of the transverse slab;The bending stiffness of transverse plate of sandwich plate is affected by the number of joints,position and connections,The elastic deformation range of the prefabricated warehouse roof plate is greater than that of the whole pouring test piece.Appropriate to reduce the number of joints,increase the number of joints on a single joint or adjust the joints away from the span under the same conditions,can increase the elastic deformation section of the structure,improve the integrity of the structure.(2)Based on the principle of minimum section stiffness,broken line deformation theory and conjugate beam theory,the calculation method of prefabricated warehouse top slab transverse plate direction rigidity is proposed.Based on the bending deformation characteristics of the prefabricated warehouse top sandwich board,the deflection of the prefabricated warehouse roof board is calculated through three different theories.The minimum section stiffness method only considers the influence of the number of joint joints,The theoretical calculation results are more conservative,Can not reflect the actual deflection deformation of the prefabricated warehouse roof;The line deformation method considers the influence of the bending stiffness of the transverse plate,However,the theoretical analysis model does not consider the force deformation of the prefabricated plate,The error between the theoretical calculation value and the test results is relatively small,Good calculation accuracy;The calculation method of the conjugation method considers a variety of characteristic sections and prefabricated plates,Can better express the horizontal plate direction stiffness of the prefabricated warehouse roof plate,The average error of the theoretical calculated value and the experimental value is 10.5%,For a minimum error of 9%,The agreement degree was relatively good.(3)The finite element analysis model of prefabricated warehouse top sandwich plate and whole bin top sandwich plate is established and finite element analysis,which further reveals the loading performance of prefabricated warehouse top sandwich plate.According to the results of the finite element model of the assembled warehouse top sandwich slab,the stress of the top concrete,the bottom distribution reinforcement,the lower anchor bar of the connector and the deflection of the structure span are analyzed.In the simulation results,the average error of the specimen deflection and the test value is 14%,and the minimum error is 8%,which verifies the correctness of the finite element modeling method.Model concrete stress cloud map and the development and distribution of cracks,model hole plate and long anchor bar stress size and distribution and the development trend of the test strain,reveals the prefabricated warehouse top floor slab transverse force features,and according to the stiffness of the joint area.