Portal steel structure optimization design method and steps
August 02 03:06:34, 2025
The light gantry steel structure offers several advantages, such as low cost, lightweight, easy installation, and a short construction period. As a result, it has experienced rapid development in recent years and is widely used in industrial plants. However, during actual engineering design, the variable cross-section dimensions of the steel members—especially in gantry structures—require multiple trial calculations to determine. The lack of rich design experience among current engineers often leads to inefficiency in the design process. This can result inä¸åˆç† section selections, causing uneven stress distribution across the structure. Not only does this lead to poor economic performance, but it also compromises the overall safety of the structure. In some cases, individual members may even exceed the material's design strength, creating potential safety risks even after considering plastic deformation and stress redistribution.
The main optimization goal when designing a gantry steel structure is to minimize both the steel consumption and the overall cost while ensuring structural safety. This objective can be simplified by focusing on selecting economical and reasonable cross-sectional dimensions that meet the requirements of strength, stiffness, and stability, while keeping the cross-sectional area as small as possible.
The optimization method for gantry steel structures is similar to that used for grid structures. It typically employs the asymptotic full-stress method, where the cross-sectional dimensions of each member are adjusted through iterative calculations until they approach a full-stress state. This process continues until no further adjustments are needed, resulting in the minimal amount of steel being used and achieving the lowest possible cost.
Section size optimization involves choosing the most efficient cross-section that maximizes bending resistance while minimizing the section area. This ensures that the selected dimensions meet the strength and stability requirements under external loads, without using excessive material. Although the detailed optimization steps are not elaborated here, the process generally involves repeated iterations to achieve an optimal balance between performance and economy.
The step-by-step optimization analysis for a gantry steel structure includes the following: First, determine the initial cross-sectional dimensions of the structural members, either through software or designer input. Second, perform finite element analysis to evaluate the mechanical behavior of the structure under various loading conditions, including strength and stability checks. Third, re-optimize the cross-sectional dimensions using the full-stress method based on actual load effects and constraints. Steps two and three are repeated iteratively until the selected sections remain unchanged. Finally, check the deformation of beams and columns to ensure compliance with relevant standards. If deformation limits are not met, the section sizes are adjusted proportionally, and the optimization cycle is repeated until all components meet the required deformation criteria. Full-stress optimization typically requires multiple cycles, usually converging within 10 iterations. For stiffness-related deformation requirements, fewer iterations—typically 1 to 3—are often sufficient to achieve the desired results.