This paper presents a five-step algorithm to determine the reasonable state of suspension bridges with spatial cables without theoretical derivation or original programming. The algorithm is extended from the common FEM analysis method with additional algebraic operation and flow control. The five-step algorithm is an efficient and convenient method for the general bridge designers in normal engineering practice and can be summarized as follows. In the first four steps, a main cable–only model is used considering the couple of the spatial main cable and inclined hangers. First, a set of ideal vertical components of the hanger forces is obtained by the rigid-supported continuous beam method. Second, the shape of the main cable in the midspan is calculated iteratively based on the designated sag. Third, the reasonable state of the main cable in the side span is determined by the force equilibrium of the IP point. Fourth, the anchor span is solved by the equilibrium of the splay saddle. Finally, a full-bridge model is activated and specially handled to complete the analysis. Next, a 1,588-m midspan suspension bridge with spatial cables is introduced as a case study. Several details and strategies are also presented. It is proved that the algorithm can avoid the theoretical derivation and simplify the programming on the premise of the necessary numerical precision.

Cable-stayed bridges have commonly been built for crossing large-span obstacles, such as rivers, valleys, and existing structures. Obtaining an optimum design for a cable-stayed bridge is challenging, due to the large number of design variables and design constraints that are typically nonlinear and usually conflict with each other. Therefore, it is a reasonable alternative to turn the large and complex optimization problem into two sub-problems, i.e., optimizing the internal force distribution by adjusting the cable prestressing forces, and optimizing the other sizing or geometrical parameters. However, conventional methods are lacking in efficiency when dealing with the problem of optimization of cable forces in the first sub-problem, under the circumstance that iteration between the two sub-problems is required. To address this, this paper presents a surrogate-model-assisted method to construct a cable forces predictor ahead of the structural optimization process, so that cable forces can be effectively predicted rather than optimized in each iterative round. Additionally, B-spline interpolation curve is adopted for variable condensation when sampling for the surrogate model. Finally, the structure optimization in the second sub-problem is performed by leveraging an optimization program based on particle swarm optimization method. The performance of the proposed framework is tested with a practical engineering application. Results show that the proposed method showcases good efficiency and accuracy. The theoretical raw material consumption of the towers and the cables is 32% lower than the original design.

Aiming at releasing the potential of BrIM model for improving the efficiency of bridge design and structural analysis, this paper analyzed the combined parametric method of BrIM models and built up structure properties for FEM, thereby established a three-class modeling frame and a new method of bridge analysis based on BrIM. To overcome the gap between BrIM and FEM in bridge structural analysis, the information of bridge structures and special analysis characteristics are set up to establish the reservoir of bridge structure analysis. The mesh controls of the bridge structural information is standardized and preset. The processing generates the corresponding switch file which file type is compatible with a variety of FEM analysis software tools. The seamless transition from BrIM to FEM greatly accelerated the design and analysis of bridges. The smooth parameter flow from the BrIM to FEM is also formed for quick information modification and mechanical analysis of bridge structures.

Bridges are typical structures that provide connections between destinations and therefore achieve transportation functionality

The suspension bridges in mountainous areas are commonly designed with asymmetrical overall layouts to match the terrain and construction under limited space. However, the effects and influences of the asymmetry parameters on the bridge performance have yet to be thoroughly investigated. To address this gap, based on a real-world suspension bridge with a main span length of 700 m, this paper first presents an improved shape-finding method that can fully consider the components of hanger forces in each construction step. In the iterative process, the shape of the cable is determined based on the equilibrium equations, and the hanger forces are calculated through the nonlinear finite element analysis. After deciding the bridge’s initial state, the asymmetry parameters’ effects are carefully investigated through finite element analysis under the static and seismic conditions. Results show that the side-to-span ratio of the main cable and the tower’s stiffness can affect the horizontally constrained stiffness, resulting in distinct bridge behavior. Moreover, reasonably designing the dampers between the tower and the girder can be beneficial in minimizing the longitudinal displacement and controlling the tower’s moment under the seismic situations.