Research On Fundamental Behavior Of BFRP Form- Concrete Composite Deck Slab

Fiber-reinforced polymer (FRP) materials are considered to be a kind of ideal material to realize high performance and longevity due to their characteristics including light weight, high strength and fatigue-resistance, having the capability of enhancing and solving the durability issues induced by traditional materials. Nevertheless, because of low elasticity modulus and large deformation, the application of FRPs in deck structures is restricted. The combination of FRP profile and concrete can remedy that limitation, developing the advantage of corrosion resistance and high tensile strength of FRP and compressive property of concrete. However, the existing FRP profile-concrete composite deck slab shows the problems of excessive consumption of profile, low use ratio of section and insufficient property of composite connectors, based on which, to research and develop FRP-concrete deck slab system with high effective non-deformability and advantageous combination behavior, theoretical analysis and experimental studies were conducted in this paper as follows:(1) Design of BFRP form-concrete composite deck slab. Systematical researches and design were conducted for the geometrical section form of the form. On the basis of cross section stiffness maximization theory, the optimized geometrical morphology under a certain span was determined through finite numerical simulation analysis. In-depth and optimized studies were conducted in terms of section form, combination form and manufacturing technology, based on which, the concept of improving non-deformability through adopting identical FRP material was proposed. Furthermore, the design principle, manufacturing technology and process of self-balancing prestressed FRP form were elaborated.(2) Simulation test for concrete casting on BFRP form. With reference to relative specifications, simulation test for concrete casting on the optimized BFRP form and self-balancing BFRP form mentioned above were conducted. Monitoring and analysis for the variation of stiffness and stress during construction state were conducted. The feasibility of BFRP form as formwork during construction stage was validated and the stiffness improvement of the self-balancing form compared to the non-prestressed form was contrastively analyzed.(3) Static tests were conducted on seven composite deck slab with different parameters. The failure mode, ultimate bearing capacity, load-displacement curve, stress and strain in the form and stress in prestressing plate were studied systematically. The effects of corrugated tooth, hybrid junction by corrugated tooth and burnt-on sand, layout of reinforcing steel bars and shearing reinforcements and the properties of form (self-balancing form or non-prestressed form) on mechanical behaviors under normal service state and ultimate bearing state intensively were compared and analyzed.(4) Based on the analysis of the existing research results on FRP-concrete composite deck slab domestically and abroad, with reference to steel-concrete composite structure, the theoretical design formulas of bearing and shear capacity for BFRP form-concrete composite deck slab were deduced and established. Results obtained by the recommended formulas are preferably consistent with experimental results.