The Mechanical Properties Of Concrete Laminated With Embedding Concrete Blocks Shear Connectors

This paper focused on reinforced concrete laminated slab with embedding concrete blocks shear connectors. This is a new kind of laminated slab with shear connector (LSSC for short). LSSC is made up of precast reinforced concrete base slab, precast concrete blocks shear connectors and cast-in-place reinforced concrete composite slab. Concrete blocks shear connectors are embedded in precast base slab and constitute a whole component, then cast concrete to the top or over the top of the shear connector to form a complete laminate slab. The precast concrete base slab and cast-in-place concrete composite slab are connected together by shear connectors and the shear connectors mainly bear the shear and tension between precast base slab and the cast-in-place slab so as to ensure the integrity of the slab.The mechanical properties of LSSC were mainly studied in this paper. In the research, there are two types of LSSC based on different boundary conditions, one is LSSC with four edges fixed boundary, the other one is LSSC with four edges on simply supports boundary. Both types of laminated slab were studied using the same research methods and the research contents can be summarized as the following aspects:(1) Based on nonlinear finite element software ABAQUS, the finite element models of LSSC were designed and analyzed. According to the load-deflection curves obtained by finite element simulation, the whole loading process of LSSC was analyzed in the paper. Through the analysis of the shear-load curves of concrete shear blocks, the whole loading process was obtained and the relationship between the shear and its location of shear connector was concluded.(2) Three main factors such as the shear area percentage, the friction coefficient and length-width ratio which influence the mechanical properties of LSSC were analyzed qualitatively. Five laminated slab models for each influencing factor were designed and by comparing the load-deflection curves, the influencing characteristics of three factors on mechanical properties of laminated slabs were analyzed respectively;(3) The corresponding relationship between each main factor (the area percentage of shear blocks, the friction coefficient and length-width ratio) and deflection when the tensile reinforcement was yielded was deduced quantitatively. The regression equation between them was obtained through mathematical regression method and the specific quantitative relationships between them were got. The midspan deflection formula of LSSC when tensile reinforcement was yielded was derived finally;(4) By changing the value of three factors and designing new models, the deflection formula was verified. According to the verification results, the applicability and accuracy of the regression equation was concluded, and the applicable conditions of midspan deflection formula of LSSC and the applicable scope of influencing factors when tensile reinforcement was yielded were given ultimately.