Prestressed Steel - Concrete Composite Beam Deflection Analysis And Calculation Of Theoretical Research

External prestressed steel-concrete composite beams are a new kind of bridge structural type, which make good use of concrete, steel, external prestressing strand, take advantage of resistance to crushing and drawing, make up for their disadvantages. In the overseas, achivements about the structure in the field of construction and research are a great deal. Compared with prestressed rebar concrete beam, its stiffness is more little. Especially in the-big-span bridge, its deflection is a important control factor which influence its application.Based on conprehensive collction of existing research documents in and beyond the country, The performance of prestressed steel-concrete composite beams under monotonic loads, such as failure pattern, flexural capacity, prestressing loss of external tendons and deflection due to slip etc., are studied in detail. Studies shows that external prestressed steel-concrete composite beams have high flexural capacity and large displacement.Prestressed steel-concrete composite beams may be taken as a kind of composite structure composed of concrete slab and prestressed steel beams. Based on prestressed steel beams, considering effect of the method of construction to slip and stress increment, accoding to conception that procedure of calculation reflects the procedure of construction and change of structural internal force, making good use of the method of section conversion and making iteration reflect the coupling of slip and stress increment, bringing forth a method of iteration and modified stiffness to calculate the deflection of prestressed composite steel-concrete beams in normal servicing prase. the result testifies that the method is right and practical, when its result is compared with the result of a numerical approach with MEF (Finite Elements Method) used by the softwares Ansys(?).