Linear And Non-linear Analysis Of Composite Laminated Box Beams Under Pressing, Bending And Torsional Loads

Because of the speciality of lightweight, high strength, low consumption, good mechanical characteristics, corrosion resistant, fatigue resistant, absorbing shock, shaped convenience, facilitating construction, composite gets into people's graces in many industry departments, for example in the airplane, guided missile, underwater space, shipbuilding, automobile and building industries. In recent years, composite also show its strong predominance in traffic engineering and civil engineering.Thin-walled box beam structure gained widespread application in great span bridges and architectural engineering, which has become one kind of tendency using composite in the thin-walled box beam structure's construction and the reinforcement design. In the present case, composite box beam and composite-concrete compound thin-walled box beam structure's computational theory also occupies in the development. The predecessors already proposed many computational methods about composite thin-walled box beam structure, but shear lag and constrained torsion are hardly considered in these box beam's static and dynamics computational theories. Also hypothesis in these theories, lateral section stress is uniformly distributed along composite board thickness direction, which will produce big error in the strength calculation, the reason is that composite board is composed by certain layers and different angle will cause very big stress difference.On the basis of predecessor's theory and composite mechanics, the geometric non-linearity and many kinds of coupling effects are considered in this paper. First according to the fundamental assumption, corresponding displacement pattern is proposed and box beam's control differential equation is inferred according to the energy method, discovering that its structural style is too complex to directly solve its displacement. In order to solve this complex problem, the structural finite element method is used to resolve this question in this paper. And shape function is proposed. Through tedious computation, restraint torsional rigidity matrix and the equivalent pitch point load array are inferred about composite-laminated box beam. The equivalent pitch point load expressions under the different load situation, flange plate's single-layer normal stress and shear lag factors and web plate's single-layer normal stress are also listed. Corresponding computational procedure is compiled on the basis of the formulas.In order to confirm the validity of this paper's formulas, six examples are adduced about cantilever beam, simple beam and continuous beam. Through the linear and non-linear analysis of composite laminated box beams under pressing, bending and torsional loads, the validity of this paper is confirmed, because no matter the displacement value, stress value or shear lag factors, this paper's result and the finite element result tally well.Practices show that the study of this paper is significant in both theory and practical application.