Study On Mechanics Behaviors Of Prestressed Steel High Strength Concrete Composite Beams

Along with applying the pre-stressed force in concrete and steel structures, it is being used in the composite beams of steel and concrete. Putting the pre-stressed force in the steel of composite beams can expand elastic of materials, raise load-bearing capacity and steady of structure, save the materials, reduce the cost, increase the fatigue strength and reduce deformation of structural members. Putting the pre-stressed force in the concrete slab of composite beams on bearing negative moment can make the investment properties of steel and concrete, defer the crack appearing in concrete slab, prevent the expand of the crack, add the rigidity of the composite beams, reduce the scope of stress and strengthen the service life of the composite beams. Recently, many civil engineering scholars pay attention to the research of the pre-stressed force composite beams performance, it has been studied more about the pre-stressed force composite beams of steel and concrete, but it is scarce about the pre-stressed force composite beams of steel and high strength concrete. In this item, the pre-stressed force composite beams of steel and high strength concrete are researched from test research, theory and numerical analysis.On the basis of test research of steel-HS concrete composite beams, the working mechanisms and the breaking patterns are studied on putting the pre-stressed force in steel below wing on bearing positive moment and putting the pre-stressed force in the concrete slab or steel upper wing of composite beams on bearing negative moment. The deformation、slip、 increment of pre-stressed steel bar and changeable strain of concrete and steel beams etc. of pre-stressed composite beams are analyzed.The stress state of pre-stressed composite beams is analyzed in detail on every working stage. The calculating formulas of composite beams elastic and plastic ultimate anti-bending capacity on bearing positive moment and negative moment are established. Using elastic theory establishes the calculating formulas of the relative slip of the interface and the deformation subjected to slip effect of the pre-stressed force composite beams. The calculating formulas of internal increment of pre-stressed steel bar of simple composite beams and continuous composite beams on bearing positive moment are established. The constructed method of vertically tensioned pre-stressed on composite beams is put forward. The calculating formula of controlling stress is established. To analyze internal force use deformed relation on every working stage. The constructed method of FRP strengthening steel-concrete pre-stressed composite beams is introduced and to every working stage puts up analysis of internal force. The calculating formulas of elastic and plastic carrying capacity are established.Using synthetic method explores nonlinear full-range analytic program of pre-stressed composite beams and FRP cloth pre-stressed composite beams. The working performance of composite beams is further defined on different working stage. By calculating analyzes the ductility of pre-stressed composite beams and FRP cloth pre-stressed composite beams.