With their adaptability to complex terrains and sleek linear aesthetics, curved steel box girder bridges are increasingly applied in projects such as urban interchange ramps and river-crossing bridges. However, due to the special mechanical properties caused by the curved structure and the high difficulty in geometric dimension control, their construction process must balance technical precision and procedural continuity. From the factory prefabrication of steel box girders to on-site installation, from structural connection to the completion of bridge deck systems, the scientific planning of each step directly affects the bridge's safety performance and construction efficiency. The following details the complete construction process of curved steel box girder bridges, providing clear operational guidance for engineering practice.

1. Segmentation and Fabrication of Steel Box Girders

The segmentation of steel box girder segments is determined based on bridge design, transportation conditions, and construction technology. Reasonable segmentation can reduce transportation difficulty and improve construction efficiency. Generally, factors such as curve radius and girder structure are considered to divide the girders into segments that are easy to manufacture and install. During the fabrication process, high-quality steel is selected, and strict control is imposed on dimensional accuracy. Advanced processing equipment and technologies are used to ensure that the geometric dimensions and flatness of each segment meet the design requirements. Welding parts are pre-treated to ensure welding quality. From raw material inspection to finished product acceptance, strict control is implemented in every link to lay a solid foundation for subsequent construction.

2. Transportation and Storage of Steel Box Girders

During the transportation of steel box girders, appropriate transportation tools (such as large flatbed trucks or barges) are selected based on the size and weight of the segments. The transportation route must be planned in advance to ensure smooth roads or waterways and avoid jolting and collision. Protective measures are taken to prevent damage to the segments. The storage site must be flat and solid, with dedicated storage supports installed, and the segments are stored in an orderly manner according to their serial numbers. Regular inspections are conducted during the storage period to prevent quality issues caused by moisture, deformation, etc. Different types of segments are stored separately for easy access. A reasonable transportation and storage method can effectively ensure the quality of steel box girders and the construction schedule.

3. Erection of Temporary Supports

Temporary supports are important load-bearing structures for steel box girder construction. Before erection, a detailed design is carried out based on the bridge structure and construction load. Appropriate materials (such as steel pipes and section steel) are selected to ensure the supports have sufficient strength, stiffness, and stability. In accordance with the design plan, precise measurement and positioning are conducted, and strict control is imposed on the verticality and spacing of the supports. Reliable connections (such as welding or bolted connections) are used for the support joints. After erection, a comprehensive inspection and acceptance are carried out; if necessary, preloading tests are conducted to eliminate inelastic deformation, providing a safe and stable support platform for steel box girder hoisting.

4. Hoisting and Positioning of Steel Box Girders

For the hoisting of steel box girders, appropriate lifting equipment (such as large tower cranes or floating cranes) is selected based on their weight, size, and on-site conditions. Before hoisting, the lifting equipment is fully inspected and debugged to ensure good performance. A reasonable hoisting sequence and method are determined—usually starting from one end to the other or from the middle to both ends. Reliable lifting points are set on the steel box girders, and protective measures are taken. During the hoisting process, close attention is paid to the operation of the lifting equipment and the posture of the steel box girders. Through precise measurement and control, the steel box girders are accurately positioned. After positioning, temporary fixation is carried out in a timely manner to prevent displacement.

5. Welding and Connection of Steel Box Girders

Welding is a key link in the connection of steel box girders. Before welding, the welding materials and equipment are inspected to ensure they meet the requirements. Appropriate welding processes (such as shielded metal arc welding and gas metal arc welding) are selected based on the steel material and welding position. Qualification verification is conducted for welders, requiring them to work with valid certificates. The welding process is operated in strict accordance with the welding procedure specification, with parameters such as welding current, voltage, and welding speed controlled. During welding, windproof and rainproof measures are taken. After welding, visual inspection and non-destructive testing are conducted to ensure the quality of the welds. For bolted connections, the bolt tightening torque is controlled to ensure connection reliability.

6. Construction of Bridge Deck System

The construction of the bridge deck system is carried out after the completion of the main structure of the steel box girders. First, the bridge deck pavement layer is laid, and appropriate pavement materials (such as asphalt concrete or cement concrete) are selected according to the design requirements. The flatness, thickness, and compactness of the pavement layer are controlled. Auxiliary facilities such as anti-collision guardrails and expansion joints are installed. The anti-collision guardrails must be installed firmly and straightly, with an aesthetic appearance. The installation temperature of expansion joints is strictly controlled to ensure good expansion performance. At the same time, the construction of the bridge deck drainage system is well done to ensure smooth drainage of the bridge deck, providing guarantee for the normal use of the bridge.

To Wrap up

In summary, the construction process of curved steel box girder bridges is a systematically interlinked project. From the precision control of segment fabrication to the coordinated cooperation of on-site installation, each process must adhere to specifications as the criterion and quality as the core to ultimately achieve the safety and stability of the bridge structure. If you are advancing a curved steel box girder bridge project or have questions about formwork customization and construction adaptation, please feel free to contact us—we will provide you with a free project adaptation plan evaluation. Subsequent articles will further elaborate on the key technologies for curved steel box girder bridge construction and the full-process quality control points (such as raw material testing, construction process monitoring, and finished product acceptance standards), helping engineering practitioners fully master the core construction capabilities of this type of bridge.