Installation Process of Box Girder Formwork

With the rapid development of modern economy, the development of science and technology in construction engineering is becoming more and more important. Many high-tech designs are applied to it, especially box girder technology, which solves many problems in bridge design and provides a strong guarantee for the implementation and development of urban construction. This paper discusses the design and construction of internal and external formwork for box girder.

In recent years, box girder formwork has been widely used in the field of engineering construction. The box girder template is integrally formed at one time, and the template adopts all-steel structure, which has good overall entry and exit and hydraulic folding effect. However, there are two kinds of templates for the structure on the market at present. One is that the main beam is divided into two layers of trusses, and the top shaft cylinder is located in the middle. This kind of main girder structure is damaged because the main girder is divided into two layers, and the main girder is often deformed; one is that the main girder is a steel box type. Since the jacking oil cylinders are installed on both sides of the main beam, the jacking oil cylinders on both sides of the main beam cannot be lifted synchronously, and the oil cylinders on the other sides relieve pressure in one direction, and the formwork is easy to overturn. The side mold is designed with a manual structure without tie rods and consists of an outer mold, an outer mold truss and a truss support.

The radian of the beam bottom plate is completed by the side form. One-to-one configuration with basement membrane, simple and reliable connection. The side formwork panel adopts 8mm steel plate, and the back of the panel is supported by channel steel to connect the truss. The vertical height between the outer mold and the bottom film can be adjusted by a manual jack at the bottom of the outer mold truss. The wing mold and the outer mold truss of the outer mold are supported by adjusting screws to adjust the straightness and line type of the mold. In order to facilitate the construction, the outer side of the wing formwork is widened by 1m, and the upper part of the side formwork can be installed with rails as ground rails for maintenance of box cars, working platform cars and slurry lifting trowels. At the same time, it can also be used to arrange the walkway and railing of the vibration bridge. Escalators are set at both ends for construction personnel to go up and down. The steps are 29cm high and 25cm wide, with two at each end. The length of the side form without the escalator is 32.6 meters, and the total width is 14 meters. Two attached vibrator hanging plates are arranged within 1.2m of the lower part of the side die.

The outer mold truss is composed of two main trusses composed of section steel, which are connected horizontally. The role of the external mold truss is to ensure the stability of the entire external mold shape as a skeleton. Manual jacks are set at each node at the lower part of the outer mold truss to adjust the installation height and demoulding of the outer mold. The side formwork is designed with 5 4m standard sections, and 2 4m section prefabricated 24m box girders can be removed.

Box girder formwork, also known as steel plate box girder, is a common structural form of long-span bridges. Generally used for long-span bridges. It looks like a box, so it is called a steel box girder. Steel plate box girder is a kind of structure commonly used in engineering. In order to study the effect of diaphragm spacing on the deformation of simply supported steel box girders under concentrated load, the deformation effect and rigid torsion effect of simply supported steel box girders with different numbers of diaphragms under concentrated load are compared, and the curve of the maximum deformation effect with the number of diaphragms is obtained. The concentrated load is applied to the top of the box girder web, and the load decomposition method is used to calculate according to the four working conditions of deformation, rigid torsion, symmetrical bending and eccentric load.