Experimental Study On Flexural Behavior Of Local Composite Continuous Hollow Slab

In this paper,a new type of assembled monolithic floor slab,named "local composite continuous hollow slab",is proposed.It consists of three parts: prefabricated variable cross-section hollow slab,ring beam and negative moment reinforcement of support,and partly post-poured concrete laminated layer.It forms a structure with hollow section and solid section to realize the stress state of continuous unidirectional slab.The slab has many advantages in ensuring the stiffness of prefabricated members,reducing the deadweight of floor slabs,reducing the overlapping cast-in-situ quantity,meeting the need of continuous force and strengthening the integrity of the connection between slabs and walls.It is a new product in the roof system of assembly building and has broad market application prospects.In this paper,the design of local composite continuous hollow slabs,bending performance test and industrialized production of prefabricated variable cross-section hollow slabs are studied.The following research work is mainly carried out:(1)On the basis of systematically analyzing and evaluating the performance requirements and technological requirements of the assembling monolithic floor in each stage,the product form,specification,modular engineering pavement,connection structure of construction nodes and pipeline laying of prefabricated hollow slab with variable cross-section are studied.The internal force calculation and analysis in construction stage and service stage are carried out,and the design of local composite continuous hollow slab is completed.(2)The bending performance test of two-span continuous slab was completed,and its mechanical properties such as stiffness,bearing capacity,deformation,crack development,negative moment reinforcement force transmission and internal force redistribution were studied.The whole process from loading to failure was simulated by Abaqus finite element software,and the simulation results were compared with the test results.The experimental and finite element analysis results show that the plate has good mechanical properties and can meet the performance requirements of each stage.(3)According to the characteristics of prefabricated variable cross-section hollow slab structure,specifications and production processes,combined with the production process and production conditions of one-step punching and extrusion of dry and hard concrete,two industrialized production schemes of "bottom steel mould method" and "cutting slotting method" are put forward,the design and manufacture of bottom steel mould are carried out,the length of cutting slot is calculated and determined,and the generation of the two schemes is formulated.Nine prefabricated hollow slabs with variable cross-section were produced,which verified the feasibility of mass industrial production,analyzed the economy and paved the way for its application in engineering.