Steel Structure The advantages of steel structures, such as their seismic resistance, wind resistance, durability, heat insulation, sound insulation, and comfort, are well-known. These advantages are due to the hard work of steel structure builders. After the completion of steel structure construction, the safety inspection of the steel structure project is crucial. Here's a detailed introduction to the key points of steel structure inspection, hoping it will be helpful:

 

1. Construction

1.1 The inspection and calculation of the slenderness ratio of steel structural members can be determined according to the provisions of Section 6.4 of this chapter. Member dimensions should be determined based on actual dimensions to calculate the slenderness ratio.

1.2 The connection of the steel structure support system can be inspected according to the provisions of Section 6.3 of this chapter; the dimensions of the support system components can be determined according to the provisions of Section 6.4 of this chapter; verification or evaluation should be performed according to the design drawings or relevant design specifications.

1.3 The width-to-thickness ratio of the steel structure component section can be determined by measuring the relevant dimensions of the component section according to the provisions of Section 6.4 of this chapter, and the calculation should be evaluated according to the design drawings and relevant specifications.

 

2. Painting

2.1 The quality of steel structure protective coatings should be inspected according to the provisions of the current national relevant product standards for coating quality.

2.2 The rust removal grade of the steel surface can be determined by comparing the pictures stipulated in the current national standard "Rust grade and rust removal grade of steel surface before painting" GB8923.

2.3 The coating thickness of different types of coatings should be tested by the following methods:

1 Paint film thickness can be tested with a paint film thickness gauge. The number of components inspected should not be less than the minimum capacity of Class A test samples in Table 3.3.13 of this standard, nor less than 3; 5 measurements per component, and the value of each measurement is the average of three dry paint film thicknesses measured at points 50mm apart.

2 For thin fire-retardant coatings, a coating thickness measuring instrument can be used for testing, and the measurement method should comply with the provisions of "Technical Regulations for the Application of Fire-retardant Coatings for Steel Structures" CECS24.

3 For thick fire-retardant coatings, a probe and steel ruler should be used for testing, and the measurement method should comply with the provisions of "Technical Regulations for the Application of Fire-retardant Coatings for Steel Structures" CECS24. The coating thickness and deviation values should be evaluated according to the provisions of "Code for Construction Quality Acceptance of Steel Structure Engineering" GB50205. 6.7.4 The appearance quality of the coating can be inspected and evaluated according to the provisions of "Code for Construction Quality Acceptance of Steel Structure Engineering" GB50205 according to different materials.

 

3. Steel Space Frame

3.1 The inspection of steel space frames can be divided into items such as the bearing capacity of nodes, welds, dimensions and deviations, straightness of members, and deflection of the space frame.

3.2 The bearing capacity test of welded ball nodes and bolted ball nodes of the steel space frame should be carried out according to the requirements of "Quality Inspection and Evaluation Standard for Space Frame Structure Engineering" JGJ78. For existing bolted ball node space frames, nodes can be removed from the structure for the ultimate bearing capacity test of the node. When intercepting the bolted ball node, measures should be taken to ensure structural safety.

3.3 Welds in steel space frames can be inspected using ultrasonic flaw detection. The detection operation and evaluation should be carried out according to the requirements of "Ultrasonic Flaw Detection and Quality Grading Method for Welds of Welded Ball Node Steel Space Frames" JG/T3034.1 or "Ultrasonic Flaw Detection and Quality Grading Method for Welds of Bolted Ball Node Steel Space Frames" JG/T3034.2.

3.4 The appearance quality of welds in steel space frames should be inspected according to the requirements of "Code for Construction Quality Acceptance of Steel Structure Engineering" GB50205.

3.5 The detection of welded balls, bolted balls, high-strength bolts, and member deviations, the detection methods and allowable deviations should be implemented according to the provisions of "Quality Inspection and Evaluation Standard for Space Frame Structure Engineering" JGJ78.

3.6 The wall thickness of steel pipe members in steel space frames can be tested using an ultrasonic thickness gauge. The surface layer should be removed before testing.

3.7 The straightness of the member axis in the steel space frame can be tested using the string method, and its straightness shall not exceed one-thousandth of the length of the member.

3.8 The deflection of the steel space frame can be tested using a laser rangefinder or a level. The number of measuring points in each half-span should not be less than 3, and there should be one measuring point in the mid-span, and the end measuring point should not be more than 1m from the end support.

 

4. Structural Performance On-site Load Test and Dynamic Test

4.1 For large and complex steel structure systems, in-situ non-destructive load tests can be carried out to directly test the structural performance. The on-site load test of structural performance can be carried out according to the provisions of Appendix H of this standard. The load factor and judgment criteria can be determined according to the provisions of Appendix H.2, or adjusted appropriately according to the specific situation.

4.2 If there is any doubt about the bearing capacity of the structure or component, prototype or full-scale model load tests can be carried out. The test should be entrusted to a specialized institution with sufficient equipment capabilities. Before the test, a detailed test plan should be developed, including the purpose of the test, the selection or preparation of the specimen, the loading device, the arrangement of measuring points and testing instruments, the loading steps, and the evaluation method of the test results. The test plan can be formulated according to Appendix H and should be agreed upon by all parties concerned before the test.

4.3 For large, important, and new types of steel structure systems, it is advisable to conduct actual structural dynamic tests to determine structural dynamic parameters such as the natural vibration period. Structural dynamic testing should comply with the provisions of Appendix E of this standard.

4.4 The stress of steel structure members can be tested by using resistance strain gauges or other effective methods according to the actual conditions.