For a large weighing instrument, as long as the total weight of a vehicle does not exceed the instrument's maximum weighing capacity, it should be allowed to be weighed. Therefore, when designing a large weighing instrument, the parameters of the vehicle being weighed are usually determined first. Then, based on the maximum value of the vehicle's parameters, the structural dimensions of the weighing instrument's load-bearing structure are calculated using the principles of mechanics of materials. With the development of the transportation industry, there is an increasing demand for large-tonnage vehicles, especially those with large single-bearing load capacities. Therefore, during the design phase, a vehicle model with a larger concentrated load capacity should be selected for verification, and the material specifications and structural type of the load-bearing structure should be chosen accordingly. Below, we take two vehicles with the same load capacity as examples: a five-axle semi-trailer and a three-axle dump truck. The main load of the five-axle semi-trailer is borne by the four axles in the middle and rear, while the main load of the dump truck is borne by the two rear axles. Thus, for vehicles with the same load capacity, the axle load of the semi-trailer is significantly lower than that of the dump truck.

If the force exerted on the load-bearing structure by the dump truck is a concentrated load, the force exerted by the semi-trailer on the load-bearing structure is a locally concentrated load.

When using standard weights with the same load according to the verification procedure to verify the weighing instrument, the weights are evenly distributed on the load-bearing structure, resulting in a uniformly distributed load on the load-bearing structure. From the above, it is clear that our weighing instrument design is based on the parameters of the vehicle being weighed, not on the load applied during verification. Of the three loading methods, the dump truck loading method has the greatest impact on the load-bearing structure because it applies the vast majority of the 100t load to the two rear axles as a dynamic load. The uniformly distributed weight loading method has the least impact on the load-bearing structure. It not only applies a static load but also distributes the weights evenly across the entire area of the load-bearing structure.

II. Design Concept The U.S. Federal Highway Administration more commonly describes this type of bridge design as considering umbrella loads, as shown in Figure 4. It assumes that the bridge is designed for the most severe operating conditions, sufficient to withstand umbrella loads, and the overload effects of vehicles passing through using this bridge design. The design goal of large weighing instrument load-bearing structures must meet usage and verification requirements. The US Manual 44 uses concentrated load (CLC) for testing truck scales, axle load meters, and combined truck/livestock scales to ensure safety and metrological performance when weighing special vehicles. my country uses weight trolleys to test rail scales, also to ensure the load-bearing structure can meet stiffness requirements and guarantee metrological performance under unconventional conditions.

2. From the above calculations, it is clear that the deformation of the load-bearing structure after adding 25% load weight in the railway vehicle calculation formula is 0.1 cm, and the deformation caused by the weighing trolley is 0.098 cm. Therefore, if the rail scale is tested according to the weight trolley requirements, it is equivalent to loading the load-bearing structure with a load of 125% Max. However, with the emergence of heavy-haul vehicles such as C70 and C80 on railways, should the weight of the weight trolley also be increased? 3. To ensure consistency between calibration results and actual usage conditions, similar to the off-center load test method for railway scales, it is recommended that all vehicle scales undergo off-center load testing using the rolling load method. This is because only in this way can manufacturers be forced to consider the issue of concentrated loads during product design.