Static And Dynamic Analysis Of Skew Slab Bridge

The constructions of highway network and urban interchange stimulate the development of skew bridge structures in China. Skew bridge span as little inclined shear deformation have some influence on its force, while the skew bridge which have a typical coupling effect of flexure-torsion is different from right bridge, coupled with the computing method of vehicle's impact factor recommended by Chinese"General code for design of highway bridges and culverts"was changed to use the fundamental frequency as a parameter, which made the calculation of impact factor into the problem of solving the fundamental frequency, so researches on the static and dynamic characteristics of skew slab are very important. Therefore, the following were studied in this paper:1.Based on the finite strip thought and displacement interpolation function of Bernoulli-Euler beam element, using the transformation relationship between skew coordinate and cartesisn coordinate system, a new kind of thin parallel slab element was established, element stiffness matrix and consistent mass matrix were derived. Using the thin parallel slab element, the calculating program was compiled. The thin skew slab under the distributed load and concentrated loads respectively, the deflection of the thin skew slab with the changing of skew angle was calculated. The vibrating frequencies of the thin skew slab bridge are calculated under different skew angles and under different span-width ratios respectively. The fundamental frequency for skew slabs can be used in the impact factor calculation of skew slab bridges.2.Based on the finite strip thought and displacement interpolation function of Timoshenko beam element, using the transformation relationship between skew coordinate and cartesisn coordinate system, a new kind of thick parallel slab element was established, element stiffness matrix and consistent mass matrix were derived. Using the thick parallel slab element, the calculating program was compiled. The thick skew slab under the distributed load and concentrated loads respectively, the deflection of the thick skew slab with the changing of skew angle was calculated. Boundary effects of simply supported thick skew slab were studied. The vibrating frequencies of the thick skew slab bridge are calculated under different skew angles and under different span-width ratios respectively. The fundamental frequency for skew slabs can be used in the impact factor calculation of skew slab bridges.3.Using ANSYS software, the vehicle-bridge coupling vibrating system was introduced to establish the analytical method. The vehicle-bridge vibrating properties were studied for one standard vehicle running along the edge and the mean line, two standard vehicles running abreast along the simply supported skew slab. The impacting factors calculated by different methods were compared to probe the dynamical property of simply supported skew slab. The impacting factors which the skew slab was meshed by plate element were compared with the impacting factors which the skew slab was meshed by beam element. The changing rules of impact factors with skew angle, vehicle velocity, and vehicle running manner were summarized.4.Using the parallel slab element which have established in the paper, three-span continuous skew slab bridge under the distributed load and concentrated loads respectively, the deflection of the skew slab bridge with the changing of skew angle was calculated. Boundary effects of three-span continuous skew slab bridge were studied. Using the vehicle-bridge coupling vibrating system, the vehicle-bridge vibrating properties were studied for one standard vehicle running along the mean line. The changing rules of impact factors with skew angle and vehicle velocity were summarized.