Research And Analysis On Deflection Of Composite Beams With Corrugated Steel Webs

The composite beam bridge with corrugated steel webs is a new kind of composite bridge. The deformation features of the new structure are different from the concrete beams and the conventional steel-concrete composite beams. In this paper, the deflection calculation methods of the composite beam with corrugated steel webs are systematically analyzed and studied, considering the characteristics of its stiffness and the influence of shear deformation, slip effect and stress increment of the externally prestressed tendon. The main works are as follows:(1) Considering the influence of the shear deformation, the deflection differential equation of string of the composite beam bridge with corrugated steel webs is respectively established by static force method and energy variational method in this paper. Therefore, having the deflection differential equation of string, a calculation formula of mid-span deflection which is caused by shear deformation, and the short-term reduced rigidity of the simply supported composite beam bridge with corrugated steel webs under different loads,are provided. Compared with the space finite element model, it shows that the theoretical formula is accurate. According to the theoretical calculation and finite element analysis, it is concluded that the influence of height-span ratio on shear deformation is significant. And the critical value of height-span ratio of the simply supported composite beam bridge with corrugated steel webs is given in this paper for considering the influence of shear deformation or not.(2) The relative slip differential equation of the simply supported composite beam bridge with corrugated steel webs of embedded type and flange type that is widely used recently, according to the elementary beam theory, is established. Based on the equation, the calculation formula of mid-span additional deflection which is caused by the slip and the short-term reduced rigidity of the simply supported composite beam bridge with corrugated steel webs under different loads, are obtained. The space finite element model is established to verify the theoretical formula, and it is showed that the theoretical calculation value agrees with the finite element analysis value. And it indicates that the influence of slip on the deflection in the embedded type needn’t to be considered according to the theoretical calculation and the finite element analysis resuts, however, it is significant in the flange type.(3) A calculation formula for stress increment is established which considers the second-order effect of the composite beam with corrugated steel webs with externally prestressed tendon under elastic stage, based on the displacement coordination condition between externally prestressed tendon and the surrounding concrete. Compared the theoretical calculation values of stress increment with experimental values in other literature, the accuracy of the theoretical formula is verified as the both results are in good agreement. Combining second-order effect and stress increment of the externally prestressed tendon,a calculation formula of mid-span inverted camber due to the externally prestressed action is established. The analysis shows that the second-order effect of external tendons can be neglected under elastic stage.(4) A theoretical calculation formula of mid-span deflection and synthetical reduction of rigidity in a short-term, which considers the contribution of shear deformation and slip effect and stress increment of externally prestressed tendons to it, are obtained.