What is the difference between open and closed floor slabs?

　　Open floor bearing plates are important supporting products in steel structure buildings. They are made from galvanized sheets that are rolled and cold-bent, primarily used as formwork, but can also be selected for other purposes. Closed floor bearing plates have a shear groove added to the surface of the original floor bearing plate, allowing them to jointly bear loads through the wrapping effect of concrete, thereby increasing the strength of the floor. This not only allows the floor bearing plate and concrete to become a whole but also saves some tensile reinforcement.

　　1.Open floor bearing platesComparison of the shapes of open and closed floor bearing plates

　　The back of the closed floor bearing plate is flat, whileOpen floor bearing platesthe back of the open floor bearing plate is corrugated, making construction more complex. The first difference lies in the load-bearing strength of the plate itself after forming, and the second difference is in the closed floor bearing plate. After forming, the bottom of the plate is flat, facilitating secondary construction.Open floor bearing platesThe lower end of the open floor bearing plate also has an open concave-convex shape, which affects the appearance and complexity of construction.

　　There are various types of open floor bearing plates, which are frequently used in actual engineering construction. The core advantage of open floor bearing plates is their low price and high cost-effectiveness.

　　2. Comparison of the installation of open and closed floor bearing plates

　　1. When pouring concrete, the openings should be sealedOpen floor bearing platesto prevent slurry leakage from the bottom of the plate, while closed floor bearing plates should not be blocked due to the closed web;

　　2. Closed floor bearing plates completely reduce the amount of on-site rebar fabrication, decrease labor input, and accelerate construction speed;

　　3. Closed floor bearing plates should be processed in the factory according to the design floor drawings and have a numbered layout sequence. On-site construction does not require cutting and patching, making it convenient for steel structure companies to install on-site;

　　4. Since the bottom of the closed floor bearing plate is flat, the top surface of the steel beam's flange does not need to be coated with fireproof paint. However, there is a void that needs to be filled between the open floor bearing plate and the steel beam.

　　3. Fire resistance of open and closed floor bearing plates

　　During installation and use, open floor bearing plates are usually treated as formwork, and the exterior will be wrapped with reinforced concrete, requiring fireproof materials to be applied. However, it has been found that the fire resistance of closed floor bearing plates has been tested by a national inspection unit designated by the fire department. Moreover, there is no need to use fireproof materials, giving it a better comparative advantage.

　　4. Structural comparison of open and closed floor bearing plates

　　When constructing open floor bearing plates, sealing plates and baffles should be added. During the pouring and compacting of the floor concrete, slurry leakage is likely to occur, and the bottom of the plate should be tied with rebar, increasing the construction period. However, when constructing closed plates, only a baffle needs to be added, and no sealing plate is required. It is not easy to leak slurry on-site, saving time for tying rebar between the plate and the ground. Closed floor bearing plates are not easily deformed during installation, while open plates may reduce height and increase width during transportation and installation, requiring adjustments during construction; otherwise, the reduction in plate height may affect the cross-sectional properties, leading to construction accidents.

　　5. Economic comparison of open and closed floor bearing plates

　　The steel consumption of closed floor bearing plates is relatively higher than that of open floor bearing plates, thus the relative cost will be higher. Although there are many advantages, actual use needs to be purchased based on the project's specific situation, so the usage frequency of open floor bearing plates is also quite high.