In stadium steel truss structure engineering, the design and removal of temporary support systems are crucial for ensuring construction safety, controlling structural deformation, and achieving efficient installation. The core of this process lies in providing stability to the steel truss during construction through scientific calculation and rational layout, and safely and orderly removing the supports after the structure is completed, avoiding damage to the main structure.
The design of temporary support systems must be based on structural stress analysis. During installation, the steel truss experiences complex internal force distribution due to its own weight, construction loads, and wind loads. The design requires the use of finite element analysis software to create a comprehensive model, simulating the stress state at each construction stage and clarifying the reaction forces and deformation requirements of the support points. Support locations are typically selected at the lower chord nodes or critical mid-span locations of the steel truss to effectively transfer loads and reduce structural deformation. For example, for large-span stadiums, support points may be spaced along the longitudinal direction of the truss, forming a stable support network to ensure the safety of the structure during segmented hoisting or high-altitude connection.
The type of support system must be selected in conjunction with the characteristics of the project. Common temporary supports include steel pipe scaffolding, lattice towers, and prestressed supports. Steel pipe scaffolding is suitable for low-height or regularly shaped structures, offering advantages such as flexible assembly and lower cost. Lattice towers are suitable for large-span or tall structures, their high strength and stability meeting complex stress requirements. Prestressed supports actively control structural deformation through tensioned cables or rods, making them suitable for projects with high precision requirements. The design must comprehensively consider the strength, stiffness, and stability of the supports to ensure they maintain a safety reserve even under the most unfavorable conditions.
The layout of the support system must adhere to the principles of coordination and economy. On the one hand, the support positions should correspond to the nodes or stress concentration areas of the steel truss to avoid overall structural deformation due to local instability. On the other hand, the number of supports should be minimized to reduce material consumption and construction costs. For example, by optimizing the support spacing, the amount of steel used in temporary structures can be reduced while meeting deformation control requirements. In addition, the support layout must consider construction space requirements to avoid conflicts with hoisting equipment, transportation channels, etc., ensuring a smooth construction process.
Preparatory work before dismantling is crucial for ensuring safety. After the steel truss is installed and reaches its design strength, a comprehensive inspection of the support system is necessary to confirm structural stability and the absence of abnormal deformation. A detailed unloading plan should be developed before dismantling, clearly defining the dismantling sequence, methods, and safety measures. A staged synchronous unloading method is typically used, gradually releasing the support load using jacks or sandboxes to avoid structural vibration or instability due to sudden load changes. During unloading, monitoring equipment such as total stations should be used to monitor key nodes in real time to ensure deformation remains within allowable limits.
The dismantling sequence design must follow the principle of "secondary before primary, symmetrical unloading." Generally, non-load-bearing or secondary supports are dismantled first, followed by primary supports. For horizontal support systems connected to vertical members, the connection between the horizontal supports and vertical members must be severed before dismantling the horizontal supports. During dismantling, it is crucial to maintain structural stress balance to prevent stress concentration in other areas due to localized unloading. For example, when dismantling multi-layered supports, the process should proceed layer by layer from top to bottom. After each layer is dismantled, the structural condition must be immediately checked, and dismantling of the next layer should only proceed after safety is confirmed.
Safety precautions during dismantling are paramount. The dismantling area must be cordoned off to prevent unauthorized personnel from entering. Workers at heights must wear safety belts, helmets, and other protective equipment, and be equipped with fall protection devices. Dismantling equipment, such as cranes and cutting machines, must be regularly inspected to ensure they are in good working order. For large or complex support components, a specific hoisting plan must be developed before dismantling, clearly defining the hoisting points, hoisting routes, and emergency measures to prevent accidents caused by component overturning or falling.
Post-dismantling cleanup and acceptance are the final stages of the project. After dismantling, the site must be cleaned up promptly, waste materials must be sorted, stacked, and transported away from the construction site, and the site must be kept clean. Simultaneously, a comprehensive inspection of the steel truss structure engineering is required to confirm there is no damage or deformation caused by support dismantling, ensuring the structure meets design requirements. Only after the acceptance inspection is passed can subsequent decoration or equipment installation work be carried out, laying the foundation for the overall handover and use of the stadium.
