The dynamic characteristics of bridge structures are important in wind stability analysis, seismic design, fatigue assessment, health inspection, and maintenance of bridge structures; however, the mechanical and dynamic properties of different bridge types are different. A long-span cable-stayed bridge has the advantages of large flexibility, long natural vibration period, low natural frequency, dense spectrum, and denser modal than those of general structures. In this paper, the dynamic characteristics of a cable-stayed bridge with single pylon and single cable plane in the maximum cantilever stage and the complete bridge are analyzed. The single-tower cable-stayed bridge has some unique characteristics, such as lower cost, and a more beautiful appearance, but its torsional rigidity is lower, which increases the risk of wind damage and earthquake damage. Therefore, a finite element analysis of this bridge in the maximum cantilever state is carried out, and the influences of the main components’ rigidity, the inclination angles of the stayed cables, the supporting conditions, and the locations of the auxiliary piers are analyzed for the sustainability of this type of cable-stayed bridge. The analysis results show that a cable-stayed bridge with single pylon and single cable plane has more flexibility, and that the lateral rigidity and torsional rigidity are smaller. Structure rigidity, dip angles of the stayed cables, and positions of the auxiliary piers all have significant influences on the dynamic characteristics of cable-stayed bridges.

The dynamic characteristics are closely linked to the seismic stability and wind-resistant of the bridge. But different bridge types have different dynamic characteristics. In order to study the dynamic characteristics of a double-pylon cable-stayed bridge with a single-cable plane and steel truss girder whose main span is the longest in the world, the dynamic load test was done, and the finite element and the subspace iteration methods were used to analyze the vibration mode of the bridge. The influence of different structural parameters on the dynamic characteristics of the bridge was analyzed. The changed structural parameters are cable layout, stiffness of steel truss girder, stiffness of stayed cables, stiffness of pylons, the concentration of dead load, number and location of auxiliary piers, and structural system. The results show that the bending and torsion resistance of the double-pylon cable-stayed bridge with a single-cable plane and steel truss girder is weak. The torsional stiffness of the cable-stayed bridge with a double-cable plane is stronger than that of the cable-stayed bridge with a single-cable plane. The seismic stability and wind-resistant of the bridge can be improved by using light dead load, improving the stiffness of pylon and girder, and adding auxiliary piers scientifically. However, the change of cable stiffness has a complex influence on the dynamic characteristics of the bridge. The conclusion can offer references for the construction, maintenance, and design of the same type of bridges.

No abstract

The steel-concrete composite girder bridge with V-shaped piers is a new type of bridge structure. It has both the unique mechanical performance of a combined continuous girder and that of a V-shaped pier bridge. At present, studies on the mechanical properties of steel main girders combined with concrete deck slabs are mainly focused on the substructure for vertical piers, but piers and girders are not solidified. However, if the V-shaped piers are cemented to the main girder, the performance of the V-shaped piers will directly affect the performance of the total superstructure. The steel main girder and concrete deck slab of a steel-composite girder are considered to be different parts of the same section. The joint section is used to simulate the changes in section stiffness of each section during the different stages of construction. In this paper, the first steel-concrete composite girder bridge with V-shaped piers is studied in detail. The effects of different influencing factors on the structural forces are investigated using finite element analysis. The results show that the force performance of this bridge type is strongly influenced by the structure. These can provide guidance for the design and construction of this bridge type, which is of great significance.