The Shear Lag Analysis Of The Deck To Combination Beam Of Cable-Stayed Bridge Under Compression-Bending Loads

Because of the advantages of having a lightweight, "board-belly" cross-sectional configuration has been widely used in civil and aerospace structural design. "Shear lag effect", which has different section stress performance of elementary beam bending theory, was considered as a unique mechanical structure phenomenonen and has been widely spread concern and attention in engineering. Nowadays, a large number of long span, lightweight, multi-span bridge structure (thin-walled boxes, T structures, rigid frames, composite beams, etc.), high-rise buildings have been spring up in our country, which have a more prominent of shear lag effect. The shear lag of the deck to combination beam of cable-stayed bridge under compression-bending loads was the object of study in this thesis. On one hand, the expression of shear lag factor, considered the effect of compression-bending loads, has been derived; On the other hand, the effective width and effective width coefficient of the multi-span cable-stayed bridge have been discussed systematically. Based on this, the shear lag effect of the multi-span cable-stayed bridge has been calculated and analyzed by using finite element method based on the engineering case. The effect of axial force on shear lag effect of bridge deck has been conducted a special analysis. Thesis work mainly includes the following components:(1) Considering the compression-bending loads interaction effect, the shear lag coefficient expression of multi-span structure has been derived, based on the energy variation method. And the methods for solving the shear lag coefficients of typical structures and components (double girder flange, cantilever beam) were analyzed and discussed;(2) The structure, structural characteristics, mechanical characteristics of multi-span cable-stayed bridge have been systematically elaborated and analyzed theoretically. And the research for performance characteristics of the deck shear lag effect has been carried out. Based on comparison and discussion of domestic and international design specifications, we proposed a method for solving the effective width of the deck to combination beam of cable-stayed bridge under compression-bending loads and the axial force transmission angle problem;(3) The spatial analysis model of the real bridge and the segmental analysis model of the bridge deck was established by using finite element method based on the engineering case. The shear lag effect of typical control cross section of the bridge deck under different conditions has been calculated and analyzed. Moreover the performance characteristics and distribution of the shear lag coefficient has been revealed; At the same time, the effect of axial force on shear lag effect of bridge deck has been conducted a special analysis, positive traits stress distribution and transmission angle of the deck have been get. The practical calculation method of deck effective width under axial force has been proposed, which can provide a useful reference for the structural calculation and design of the same type of bridge.