Study On Mechanical Behavior Of Composite Beam With Concrete Filled Steel Tube And FRP Slab

Fiber reinforced polymer has many advantages such as resistance to corrosion and fatigue, high strength-to-weight ratio, electromagnetic neutrality, relative ease of applications and ease of industrialized construction. Used as a single building material, however, FRP has some disadvantages such as high cost in the first time, low rigidity, brittle failure and easy of local buckling. For the sake of making full use of FRP, the most effective structural style is the composites structure with FRP and the tradition materials as concrete and steel. As a result of used by the tradition materials, not only the good compressive strength of concrete and the excellent ductility of steel are developed, but also the brittle characteristic of FRP is improved and the flexural bearing capacity is increased. As present, the study on composites structure with FRP-concrete and steel is not enough overseas, and a vacancy in China. Based on this, the mechanical behavior of a new composites structural style, namely, composites beam with concrete filled steel tube and FRP slab is studied in this thesis.In this paper, the mechanical properties of the composites beam are studied by the methods of theory analysis and numerical evaluation. Meanwhile the theoretical calculating system is also established systematically, which is suitable for the composites beam. The works of this thesis are as follows:According to the different position of natural axis, the stress changes of the freely-supported and continuous composites beam in each loading stage are analyzed in detail. The calculating formulas of elasticity flexural bearing capacity and plastic collapse flexural bearing capacity of composites beam are established. Due to the slippage differential equation between concrete filled steel tube and FRP slab deduced, the slippage calculating formulas along the beam length are established under symmetrical load, uniform load and concentrated load. The parameters effects on slip are discussed. Using the energy method and variational approach, the calculating formula of axial force and deformation along the beam length is presented. The nonlinear analysis program of the composites beam is developed and the curve of the bending moment-curvature and load-deformation are gained. The influencing factors are discussed by the example in the thesis.