MECHANICAL CHARACTERISTICS AND PARAMETRIC STUDY OF A KILOMETER-SCALE RAIL-CUM-ROAD CABLE-STAYED BRIDGE

To obtain the mechanical characteristics and influence of parameters of Hutong Yangtze River Bridge, the kilometer-scale rail-cum-road cable-stayed bridge with steel truss girder, a finite element model was used for static and dynamic structural analysis. Attention was mainly paid to the reasonable finished state of the bridge under the dead load, effects of live load with different length, natural frequency and effects of variation of overall design parameters.Under the reasonable finished dead state, the internal axial compressive force of the truss girder is larger near the pylon. The ratio of axial force in middle truss to side truss is about 1.1. According to the China railway code, effect of live load with infinite length is larger by about 10% compared to the case of finite length. Under different load combinations, the unfavorable region for strength and overall stability of upper chord is near the middle of the auxiliary span. And the position for lower chord is at the subsidiary pier and the pylon. Dynamic analysis shows that the first two mode shapes are symmetric lateral bending and longitudinal floating, with very close value of natural frequency. Furthermore, study shows the influence of several major parameters on structural rigidity and dynamic properties. These parameters can be summarized as the number of subsidiary pier, side-to-mid span ratio, girder height and width, and effective pylon height.