2# Beam-Producing Yard Achieves Outstanding Results

On October 18, 2017, the first box girder was successfully cast at the No. 2 Girder Fabrication Yard for the Hanghai Intercity Railway, constructed by China Railway Major Bridge Engineering Group.

The No. 2 Girder Yard for the Hanghai Intercity Railway, under China Railway Major Bridge Engineering Group, is located at DK29+000 in the center of the railway line. Covering a designed area of 160 mu, it is responsible for the fabrication and erection of 608 box girders for the Hanghai Intercity Railway. The box girder being concreted this time measures 35 meters in length, 10.6 meters in width, and 2 meters in height, requiring 233 cubic meters of C50 concrete, 57.8 tons of reinforcing steel, and 9.08 tons of prestressing steel strands, with a total girder weight of 649.4 tons.

To ensure the smooth concrete placement of the first box girder, the No. 2 Girder Yard Project Department of China Railway Major Bridge Engineering Group for the Hangzhou–Ningbo Intercity Railway undertook extensive preparatory work prior to construction. First, rigorous safety and technical briefings were conducted: the technical department compiled relevant data and code requirements for box-girder precasting into a comprehensive manual, distributed it to all project personnel, and organized centralized training sessions. Second, safety protection measures were strengthened: in response to potential risks to personnel and equipment safety as well as quality and safety during the pouring process, the project department assigned technical staff to remain on-site, providing continuous guidance and monitoring throughout the operation. The successful placement of this first precast box girder has laid a solid foundation for the full-scale commencement of subsequent box-girder precasting. (Contributed by Zhu Xiuwen)

----- Excerpted from the China Railway Engineering Construction Network

This intercity box girder has a deck width comparable to that of high-speed railway box girders, yet its overall height is only 2 meters, with a girder-end height of just 850 millimeters—making it the box girder with the smallest end opening currently in use nationwide. Previously, such end openings were typically constructed using wooden formwork or loose steel formwork, which are cumbersome to handle and result in slow construction progress. In this project, however, we have designed a fully automated, integral hydraulic internal form for the box girder. This innovative solution overcomes more than ten challenging issues, including limited cylinder stroke, interference between form-retraction operations and fresh concrete, the need for an integrated design of the mid-span gear blocks and formwork, and the large span involved. At the same time, the internal form is versatile enough to accommodate both straight and curved girders and ensures interchangeability across different girder fabrication yards. The resulting structure is lightweight, easy to operate, and delivers high construction efficiency.

This project features predominantly curved girder types for intercity bridges, with a wide range of curvature radii and complex variations in girder width and length. The formwork design emphasizes universality and interchangeability: the external formwork panel system adopts a retractable structure to accommodate multiple curvature radii for the girder flanges; the end-formwork is designed with a tension-bracing configuration that allows for rotation at various angles while ensuring no grout leakage during concrete placement.

The formwork structure is designed to be lightweight and refined, while simultaneously meeting the strength and stiffness requirements for girder casting and ensuring ease of operation. To facilitate smooth demolding, the formwork is divided into multiple sections at the change-of-section locations, with specially designed hinged lug plates. This box-girder design has been the subject of multiple patent applications, representing a technological breakthrough of unprecedented difficulty. Through concerted research and collaboration by the Dongfeng R&D team, the project has, for the first time in China, achieved fully automated hydraulic formwork closure for large box girders with the smallest end openings. This significant achievement has made an outstanding contribution to the successful placement of the first girder for the Maritime Intercity Railway project undertaken by the Bridge Bureau.