1 Select a pultruded profile with a reasonable cross-sectional shape

The FRP pultrusion process is particularly suitable for the manufacture of products having cross-sectional shapes such as I-shaped, angular, grooved, tubular, and round bars. These products are of slender construction and can be considered as rods or beams in use. The pultruded FRP grating is the product of the pultruded profile, which is optimized to be a new type of mesh structure. Therefore, the performance of the pultruded FRP grating mainly depends on the bending resistance of the pultruded profile. Bending strength and bending stiffness. The load-bearing strip in the grille is the main force-bearing member in actual use, and can be regarded as a simple-supported beam, which is subjected to bending force to produce a certain deflection.

It can be seen that in the same cross-sectional shape, the I-shape is better than the rectangle in terms of strength, the rectangle is better than the square, and the square is better than the circular shape. As a combination of several pultruded profiles, the grid should also consider various factors such as material properties, stiffness, and manufacturing processes. The I-shaped section is better than the rectangular section, but its forming process is difficult to control. Therefore, the reasonable shape and size of the section should be considered according to the specific technical requirements, bending strength, deflection conditions and ease of processing.

2 Reasonable configuration of reinforcement materials for pultruded profiles

As a pultruded profile of the load-bearing strip, the reinforcing material should be coated with a continuous layer of glass fiber in addition to the alkali-free roving. Taking the I-shaped profile as an example, there is a surface full felt package, and the two sides of the I-shaped profile are respectively covered with felt; and the hollow pipe is made of an inner and outer layer with a felt intermediate layer plus a roving or an intermediate layer wound with a loop yarn. Two methods of arranging the reinforcing material. These forms are very effective for improving the lateral strength of the pultruded profile and the overall bending resistance of the grid.

3 Choose the appropriate grid combination

Pultruded profiles with different cross-sections have slightly different combinations. Currently, wedge-type and casing-type are commonly used.

4 Determine reasonable grid assembly process parameters

(1) Requirements for punching process of load bearing façade

The center of the circular hole must be at the centroid of the cross section of the I-shaped profile or the rectangular profile. This can reduce the strength and stiffness loss of the load bearing member. The size of the circular hole should be moderate, and the excessively large circular aperture causes the strength of the bearing member to decrease; and the too small circular aperture is not conducive to the insertion of the intermediate coupling strip, which affects the assembly.

(2) Design of the spacing of the coupling strips and the void ratio of the grid

The spacing of the coupling strips determines the degree of density of the punching of the bearing surface and the performance of the entire grille. Generally, according to the actual use and theoretical calculation, it is best to choose 150mm or 30mm to ensure the performance of the grille. Requirements can save materials and reduce costs. The void ratio of the grid refers to the ratio of the void area of the surface of the grid plate to the surface area of the grid plate, which is related to the center distance between the load-bearing strips. In general, the smaller the center distance. The better the strength and stiffness of the grid, but it should be flexible according to the specific conditions of use. If it is used as a pedestrian path or platform, the distance between the two I-beams can be selected between 20-30mm. Through practical application, the effect is very good.