In the previous two articles, we have respectively sorted out the complete construction process of curved steel box girder bridges and conducted an in-depth analysis of the four key technologies: welding, hoisting, alignment control, and temporary support design and construction. However, whether it is the implementation of the process or the application of technology, "quality control" must ultimately be the core focus-only by integrating quality management throughout the entire construction cycle can we ensure that the structural safety, service performance, and durability of curved steel box girder bridges meet the standards. This article will focus on all construction stages, from raw materials to bridge deck system construction, and detail the quality control points for the construction of curved steel box girder bridges to safeguard project quality.

1. Quality Control of Raw Materials

The quality of raw materials for curved steel box girder bridges directly affects the structural strength, stability, and durability of the bridge. For steel materials, as the main supporting material of the bridge, their quality is of crucial importance. Before procureament, on-site inspections of suppliers should be conducted to understand their production processes and quality management systems. Upon delivery to the site, in addition to carefully comparing the quality certification documents with the design requirements, sampling for physical and chemical property testing is also required to ensure that indicators such as the yield strength, tensile strength, and elongation of the steel meet the standards. The quality of welding materials determines the reliability of the connection between various components of the steel box girder. Damp welding materials or those with mismatched models may cause defects such as blowholes and cracks in the welds, reducing the overall structural performance of the bridge. Therefore, the storage environment of welding materials must be strictly controlled, and their shelf life and appearance quality should be checked before use. For high-strength bolts, their quality is related to the tightness of the connection parts of the steel box girder and the force transmission effect. Sampling inspections of mechanical properties should be carried out by batch to ensure the uniformity of the torque coefficient and prevent potential structural safety hazards caused by bolt loosening. Only by strictly controlling the quality of raw materials from the source and preventing unqualified materials from entering the construction site can a solid foundation be laid for the high-quality construction of curved steel box girder bridges.

2. Quality Control of Steel Structure Fabrication

In the construction of curved steel box girder bridges, quality control of steel structure fabrication is an extremely critical link. First, in the steel plate cutting and blanking stage, high-precision cutting equipment should be used, and operations should be carried out strictly in accordance with the design dimensions to ensure the flatness and perpendicularity of the cutting surface and reduce dimensional deviations caused by cutting errors. The assembly process must be carried out on professional assembly jigs. Advanced positioning technology is used to accurately control the relative positions of various components. The gaps at each connection point are strictly controlled to meet the process requirements and avoid stress concentration caused by improper assembly. Welding, as the core process of steel structure fabrication, requires particularly strict quality control. Welders must possess corresponding qualifications and perform welding strictly in accordance with the qualified welding procedures. When multi-layer and multi-pass welding is adopted, the interpass temperature should be controlled, and welding slag should be cleaned in a timely manner. At the same time, real-time monitoring of the welding process should be strengthened, and non-destructive testing methods such as ultrasonic testing and radiographic testing should be used to conduct comprehensive inspections of the internal quality of the welds, ensuring that the welds are free from defects such as cracks and incomplete penetration. In addition, after the fabrication of the steel box girder segments is completed, a comprehensive dimensional review should be conducted to check whether their alignment, flatness, and other indicators meet the design requirements. Only by strictly controlling the quality in each fabrication link can high-quality steel structure components be provided for the subsequent bridge installation.

3. Quality Control of Steel Box Girder Installation

The installation quality of steel box girders is directly related to the overall performance and stability of curved steel box girder bridges. Before installation, a comprehensive inspection and acceptance of the temporary supports should be carried out to ensure that their foundations are firm, the structure is stable, and the bearing capacity meets the requirements. At the same time, the appearance quality and geometric dimensions of the steel box girder segments should be rechecked to ensure they conform to the design standards. During the installation process, accurate measurement and positioning are crucial. Advanced measuring instruments are used to monitor the position, elevation, and alignment of the steel box girders in real time, and adjustments are made in a timely manner based on the measurement data to ensure installation accuracy. During hoisting operations, the lifting speed and stability of the crane should be strictly controlled, and lifting points should be selected reasonably to prevent deformation or collision of the steel box girders during lifting and transportation. The splicing quality of adjacent steel box girder segments is the key. The splicing surfaces should be cleaned to ensure no debris, oil, or other contaminants. The splicing gap should be controlled to meet the design requirements. After the splicing is completed, welding and quality inspection of the welds should be carried out promptly, and the same high-standard testing methods as those used in the fabrication process should be adopted to ensure weld quality. After the installation is completed, a comprehensive inspection of the overall alignment of the steel box girders, the elevation of each control point, and the tightness of the connection parts should be conducted to ensure that the installation quality of the steel box girders fully meets the design and specification requirements, laying a solid foundation for subsequent construction and the safe use of the bridge.

4. Quality Control of Bridge Deck System Construction

The construction quality of the bridge deck system has an important impact on the service performance and durability of curved steel box girder bridges. In the construction of bridge deck pavement, first of all, the quality of the pavement materials should be guaranteed. The materials should be proportioned strictly in accordance with the design mix ratio, and the gradation of aggregates and various indicators of asphalt should be controlled. During the paving process, high-precision pavers should be used to ensure uniform pavement thickness. At the same time, the paving temperature and rolling process should be strictly controlled to ensure the flatness and compactness of the bridge deck, thereby providing good driving comfort. For the installation of guardrails, measurement and setting out work should be done in advance to ensure the accurate installation position of the guardrails. During the installation process, the perpendicularity and spacing of the guardrail columns should be controlled to ensure firm connection. The welded parts should be treated for rust prevention to ensure the overall stability and aesthetics of the guardrails and provide reliable protection for driving safety. The construction quality of the drainage system should also not be ignored. The slope of the drainage pipes should be ensured to meet the design requirements to prevent water accumulation. The pipe joints should be tight to avoid water leakage. The location of rainwater inlets should be reasonable to ensure smooth drainage, timely discharge of accumulated water on the bridge deck, reduce the erosion of rainwater on the bridge deck structure, and extend the service life of the bridge.

Conclusion

To sum up, from the source control of raw materials, to the precision management of steel structure fabrication, and then to the accurate control of steel box girder installation and the detailed optimization of bridge deck system construction, the quality control of curved steel box girder bridges is a systematic work that runs through the entire process and is interlinked. As a bridge formwork supplier deeply bound to quality control, we have always believed that high-quality formwork is the "pre-requisite guarantee" for quality control—whether it is the dimensional accuracy in the steel structure fabrication stage or the alignment adaptation in the installation stage, the formwork we customize can achieve high-precision forming and high-stability support, reduce construction errors, and lower the difficulty of quality management. If you need a customized formwork solution that adapts to your project's quality standards, please feel free to contact us.