It is better to use U-beam steel for weighbridge. Why do you say so? Let’s have a look.
① Let’s first talk about the I-steel scale body, which takes the I-steel as the main beam, then connects with the diaphragm plate one by one, and then seals the plate at the bottom.
The U-shaped steel scale body is supported by U-shaped steel at the bottom according to the bridge principle. There are no sealing plates or formwork diaphragms.
In comparison, the weight of the I-steel scale of the same model is larger than that of the U-steel scale. The cost is higher than that of U-shaped steel scale. The I-steel scale body has a sealing plate to play the role of tension, while the U-steel does not.
Sanhe heavy industry weighbridge
② From the welding point of view, the U-steel scale is fully welded, while the I-steel scale is spot welded. Therefore, the industry believes that U-shaped steel is better than I-shaped steel.
At present, the manufacturers who produce weighbridge in the market mainly use U-shaped steel and I-beam. Among them, the U-shaped steel structure weighbridge has become the mainstream in the market. The U-shaped steel structure and U-shaped steel weighbridge are used by the weighbridge manufacturers in the United States, Germany, China and even the world.
③ I-beam belongs to the third generation weighing instrument product. I-beam says that there are two supporting beams at the bottom and the middle is empty, so the supporting performance is worse. Simply put, the ratio of steel structure is not very reasonable. The I-steel scale is made up of steel plates. But from the weight of the scale, the same tonnage I-beam is heavier than U-beam, which is the truth.
U-shaped steel is the fourth generation product of industrial weighing apparatus. Bending machine is the necessary equipment for U-shaped steel weighing apparatus. It costs more than 600000 yuan to buy this bending machine on the market, so the price of U-shaped steel scale is more expensive than I-beam The steel structure is reasonable, with good rigidity, strength and strong resistance to lateral force, so the scale body is anti winding and has a long service life. The bottom of U-shaped steel is designed with bridge structure.
1、 Structural form
The U-shaped beam structure is a reinforced prestressed concrete structure. Its overall design dimensions are as follows: the beam height is 1.8m, the width of the lower opening of the beam is 3.59M, 3.89M and 4.19m respectively, the width of the upper opening is 5.2m, 5.5m and 5.8m, and the thickness of the bottom plate is 0.26M. The web of the U-shaped beam is an asymmetric structure with an arc structure on one side and a straight-line folded oblique abdomen on the other side.
The beam span can be divided into four types: 22m, 24.5m, 25m and 30m;
It can be divided into standard equal width type and variable width type according to the line form.
Advantages of U-beam steel:
The prestressed concrete U-beam has a low building height, which is about 1/3 of the conventional simply supported box girder. Its web structure can effectively block the wheel rail noise, replace the guardrail on the bridge and part of the sound barrier, and prevent the vehicle from overturning after derailment. It is safer, and the overall building effect of the bridge is more slender. It is suitable for the urban rail transit viaduct bridge structure with high requirements for operation safety and landscape. It has a wide application prospect.
2、 Formwork works
According to the structural characteristics of U-beam, the project management department selects the full-automatic hydraulic sliding mode system.
The formwork system has many advantages, such as easy to move, fast installation and disassembly, good concrete structure forming effect and so on.
The bottom formwork of U-beam is in the form of steel structure, the framework is made of 14\i-steel with a spacing of 30cm, the panel is made of 10mm steel plate, and the connecting flanges on both sides of the bottom formwork are made of 12mm thick steel strip.
The internal and external formworks are hydraulically controlled and hinged to the support beam. The support beam is connected with the transfer support beam through screws, so that the internal and external side formworks, the support beam and the transfer support are connected as a whole.
The outer formwork is connected with the base plate by bolts, and the middle is provided with sealing rubber strips. The side formwork is supported on the ground by screw jacks and adjusting screws, and is provided with screw diagonal braces. The internal formwork is supported and contracted by the hydraulic cylinder, and adjusted to the specified size by the horizontal brace of the internal formwork.
- Bottom formwork installation
- Side formwork installation
Assembling outer formwork of U-beam
Install traveling support and main beam
Installation of inner formwork and hydraulic and traveling systems
Remove the internal formwork and polish the steel formwork panel
- End formwork installation
The end formwork adopts embedded structure, that is, it is embedded between the internal and external formwork, and the beam length is controlled by the position of the end formwork. According to the technical requirements of the drawing, the length of the beam end is different. Therefore, the shape and section of the end formwork are relatively complex. The whole end formwork is basically composed of 5 pieces. The shape and size of the end formworks on both sides are the same as that of the U beam web, i.e. large radius arc, which must be well matched with the internal and external formworks to effectively prevent slurry leakage during pouring and tamping. At the lower part of the end formwork, a large number of steel strands pass through, that is, all prestressed holes shall be accurately opened at the lower part of the end formwork.
- Formwork removal
The concrete strength of U-shaped beam during formwork removal shall meet the design requirements. When there are no specific requirements in the design, it shall reach more than 50% of the design strength. When the steam curing process is adopted for formwork removal, the temperature difference between the core and surface of the beam concrete, and between the surface and the environment shall not be greater than 15 ℃, and the edges and corners shall be complete. When the ambient temperature is lower than 0 ℃, the formwork can be removed only after the surface concrete is cooled to below 15 ℃; In the hot or windy dry season, the formwork removal process of removing the formwork section by section, covering while removing, watering while removing or spraying curing agent while removing shall be adopted.
The formwork shall not be removed in case of strong wind or sharp temperature change.
- Easy problems
① During the construction of beam making pedestal, the height deviation of strip beam foundation on both sides shall be strictly controlled to minimize the height of steel base plate during bottom formwork laying;
② During the trial assembly of formwork, the height deviation of adjacent formwork joints shall be strictly controlled to ensure the beam forming effect;
③ The hydraulic system of formwork shall be debugged in advance to strengthen the connection and fixation of soft and hard pipes;
④ The release agent shall be prepared with newly purchased materials, and waste materials shall not be used;