| The slabs,as a horizontal structural member plays a crucial role in the overall performance and force transmission performance of the entire structure.The main types of prefabricated f slabs currently used are concrete laminated slabs,ribbed hollow slabs,etc.However,various practical problems will be encountered during the process of specific production and construction.For this,it is proposed to assemble an integral counter-ribbed floor slab.Assembled integral reverse rib slab is composed of prefabricated counter-ribbed slab and post-casting side girder,The whole slab has the advantages of high prefabrication rate,simple production and quick installation efficiency.This article mainly focuses on the assemble of integrated counter-ribbed slabs proposed by the task force.A load-bearing static test is performed on a prefabricated slab with four sides fixed on the ribs and a prefabricated slab on the ribs with one side added with reinforcing ribs.Emphasis is placed on the study of the mechanical performance of the integral,counter-rib floor and its connection with the surrounding area.Using ABAQUS finite element software to analyze the effect of grid thickness and rib beam height on the floor performance,the main conclusions are as follows:(1)Under the uniform load,cracks at the bottom of the two Reverse-rib slabs appear across the middle,parallel to the direction of the long side,both show a two-way stress state,but the number and spacing of cracks are significantly different.The gaps between the cracks on the floor slabs of the counter-ribbed prefabricated ribs are relatively sparse and the number of cracks at the bottom of the floor slabs is small and the reinforcements are added at the edges.(2)When the uniform load is added to the load standard combination,the deflection of the rib beam prefabricated panel with additional reinforcing ribs at the edges is 2.74mm,and the maximum crack width is 0.1mm;The deflection of the prefabricated counter-rib floor slab of the rib beam is 3.84mm,and the maximum crack width is 0.1mm,which is less than the deflection limit value of 17mm and the three-step crack width control limit 0.2mm in the current specification.(3)When the uniform load is added to the basic load combination,the midspan deflection of the rib beam prefabricated panel with additional reinforcing ribs at the edge is 3.61mm,and the maximum crack width is 0.15mm;the midspan deflection of the prefabricated ribbed girder floor is 4.53mm.The maximum crack width is 0.2mm,which does not meet the provisions of the current standard bearing capacity limit state deflection control limit 68mm and crack width control limit 1.5mm The experimental phenomenon and data analysis show that the connection structure with reinforced ribs at the edge does not significantly improve the bearing capacity of the whole slab,but it strengthens the connection between the prefabricated back rib floor and the periphery,and the edge floor is involved in the stress.(4)By numerically simulating and analyzing the expanded parameters of the assembled unitary counter-ribbed slabs,under the boundary conditions of simply supported and four-sided fixed branches,when the thickness of the lattice slabs of the ribbed beam is 50 mm to 70 mm,the assembly is increased with the increase of the height of the rib beam.The anti-crack performance,stiffness,and bearing capacity of the monolithic counter-rib floor are significantly improved.In view of the fact that there are no mature theories and design methods for this integral counter-rib around the world,this article does not consider the corresponding reinforcement structure in-depth,so we should further develop the in-depth improvement of the design theory and connection structure of the integrated monolithic counter-rib floor. |
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