Segmental beam

In recent years, with the continuous improvement of lifting equipment, cantilever construction method of beam bridge has been greatly developed. The cantilever construction method can be divided into cantilever casting method and cantilever assembling method according to the different manufacturing methods of the girder body. The cantilever assembling method is to divide the girder body along the axis of the factory or near the bridge site into appropriate length blocks for prefabrication, and then transport the girder body or flat car from the water or part of the completed bridge to the erection site, and use them. The movable crane is symmetrically and equally assembled on both sides of the pier column after lifting and prestressing is applied.

Short-line matching method (also known as movable base method) box girder prefabrication construction technology is a new Prefabrication Technology of cantilever assembly method. Because this technology has the advantages of fast prefabrication speed, good appearance quality, small prefabricated site, suitable for continuous or simply supported bridge structures, and no need to close traffic during installation. The formwork consists of fixed end die and bracket, lateral die and bracket, internal die and mobile bracket, bottom die and bottom die trolley, and hydraulic system. 1) The side die is fixed on the support system with spiral adjusting rod and rotating hinge, and the template can be adjusted by the spiral adjusting rod. 2) Each pedestal is equipped with two sets of bottom moulds and supporting platforms (used to match the beam section and the section to be poured), which are transposed to each other, and the trolley is used when moving out, and the gantry crane is used when moving in. The bottom die trolley is equipped with four hydraulic jacks, vertical and horizontal, which can be used to adjust the three-dimensional position of the bottom die and the matching beam section. 3) In order to adapt to the change of cavity size of each segment, the internal die is designed as a small composite template, which is assembled according to the prefabrication needs of each segment. The internal model system is fixed on the sliding beam, and the hydraulic system is used to expand vertically, open and close horizontally, and move in and out through a special trolley. The side formwork bracket must have enough stiffness and strength, and anchor firmly to prevent the lateral displacement and deformation of formwork in the process of concrete pouring: variable length, variable cross-section and curved beam prefabrication can be realized. Automation of template alignment: The accuracy of three-way alignment can reach <1 mm, and the template alignment can only take 1 hour.

Construction Technology of Prefabrication of Box Girder by Long Line Matching Method