The Dynamic Performance And Seismic Study Of Single-Tower Self-Anchored Suspension Bridges With Spatial Cable

Self-anchored suspension bridge, a new type of special structure, is getting more and more favored in engineering field, because it has graceful appearance and good economic performance and is adaptable to topographical geological conditions. With the main cable directly anchored in the stiffening beam, the self-anchored suspension bridges have some differences with earth-anchored suspension bridges on dynamic characteristics. And the single tower spatial cable suspension bridge is quite different from the plane cable suspension bridge---because of the spatial characteristics of its main cables, the angle between the main cable and the axis of the bridge is variable, and its hangers incline on the lateral direction. Based on Dagu river channel bridge of Qindao bay bridge, a single tower cable suspension bridge with a span of 260m, this paper has studied its dynamic behavior and structural changes in various parameters on dynamic properties as well as its response under seismic action. The conclusion can provide some reference for similar bridges.A nonlinear finite element model about Dagu river channel bridge of Qindao bay bridge was established to analyze the dynamic characteristics of the bridge. The study shows that the mode of the bridge is rational and dense. The main cable anchored in the stiffening beam ends, so that the integral stiffness of the suspension bridge decreases and the natural period becomes longer. The bridge tower is single-pole tower. Its lateral stiffness is weak, so the transverse vibration of the tower appears earlier. There are five cable vibrations in the first ten modes, mainly due to low horizontal stiffness by smaller cable horizontal space.The dynamic characteristics structure parameter sensitivity of the bridge was studied. The main cable rigidity mainly affects first-order vertical bending and torsion of the suspension bridge, the vertical rigidity of the girder affects the first order vertical bending mode, cable vibration and stiffening torsional mode, the main impact of lateral rigidity of suspension bridge stiffening girder is lateral vibration mode, torsional rigidity mainly affects the first-order torsional mode of the suspension bridge; The longitudinal rigidity of the main tower affects the longitudinal floating mode of bridge; lateral rigidity of the main tower affects first-order transverse modes. The law obtained by research on the structural parameters influence on the dynamic characteristics of the self-anchored suspension bridge can provide scientific evidence for the dynamic optimization design of the connecting bridges.By self-anchored suspension bridge seismic theory, using response spectrum method and time history analysis method respectively, this paper analyzed the seismic performance of the single tower self-anchored suspension bridge to study the response of the bridge under seismic action. The results showed that the internal forces of the stiffening beam under the two combinations obtained by response spectrum are larger than those by time-history analysis method. The internal forces obtained by time-history analysis method between two different combinations are closer.