The measurement of steel structures usually includes the following steps:

1. Identification and classification of structural components: Based on construction drawings and design documents, identify various components in steel structures, such as beams, columns, frames, nodes, etc., and classify them according to their types and specifications.

2. Measurement of component dimensions: Measure the dimensions of each component, including length, width, height, etc. Measurement tools such as measuring tapes, measuring instruments, etc. can be used for measurement.

3. Calculation of the number of components: Based on the measured component dimensions, calculate the number of each component according to the component layout and requirements in the design documents. Usually, formulas or professional software are used for calculations, such as automated measurement software.

4. Calculation of component weight: Calculate the weight of each component based on its size and density. You can calculate by searching for the density table of steel or using professional software.

5. Calculation of Unit Quantity of Components: Summarize the quantity and weight of each component to calculate the unit quantity of each component, usually in tons or cubic meters.

6. Summary and verification: Summarize the quantity, size, weight, and unit engineering quantity of all components, and verify the calculation results to ensure accuracy.

It should be noted that the measurement method of steel structures may vary depending on different countries, regions, engineering projects, and design specifications, and the specific measurement method should be determined based on the local actual situation and regulatory requirements. When measuring steel structures, it is necessary to strictly follow the design documents and relevant specifications to ensure accurate and reliable measurement results.