What data should be used in the design of structural engineering specimens?

Steel structure engineering is a structure with steel as the main material, and it is one of the main types of building structures. Steel structure is one of the common structural forms in modern architectural engineering. China is the first country to manufacture load-bearing structures with iron. As early as the Qin Shihuang era (246-2 BC19 BC), iron was already used as a simple load-bearing structure, while western countries began to use metal load-bearing structures in the17th century. In the 3rd-6th century, the smart and industrious people of China built a suspension bridge with iron chains. The famous iron cable bridge of Dadu River in Luding, Sichuan, Yuanjiang Bridge in Yunnan and Panjiang Bridge in Guizhou are all models of early iron load-bearing structures in China.

1, structure

1. 1 The slenderness ratio of steel structure members can be detected and explained. The size of the component can be determined according to the provisions of section 6.4 of this chapter, and the slenderness ratio of the component should be calculated according to the actual size.

1.2 the connection of steel structure support system can be inspected according to the provisions of section 6.3 of this chapter; The dimensions of supporting system components can be determined according to the provisions in Section 6.4 of this chapter; It shall be verified or evaluated according to the design drawings or corresponding design specifications.

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

Step 2 paint

2. 1 The quality of protective coating for steel structure shall be inspected according to the current national product standards.

2.2 The derusting grade of steel surface can be determined by comparing the pictures in the current national standard "Rust Grade and Derusting Grade of Steel Surface before Painting" GB8923.

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

1 paint film thickness can be detected by paint film thickness gauge, and the number of sampled components should not be less than the minimum capacity of Class A samples in Table 3.3. 13 of this standard, nor should it be less than 3 pieces; Each piece is measured at five positions, and the value of each position is the average of the dry paint film thickness of three measuring points 50mm apart.

2 The coating thickness of thin fire retardant coatings can be detected by a coating thickness tester, and the measurement method should comply with the provisions of CECS24 Technical Specification for the Application of Fire Retardant Coatings for Steel Structures.

3. The thickness of thick fire retardant coating shall be measured with a measuring needle and a steel ruler, and the measuring method shall conform to the Technical Specification for the Application of Fire Retardant Coatings for Steel Structures (CECS24). The thickness value and deviation value of coating shall be evaluated according to Code for Acceptance of Construction Quality of Steel Structure Engineering (GB50205). 6.7.4 The appearance quality of paint can be inspected and evaluated according to different materials and the Code for Acceptance of Construction Quality of Steel Structure Engineering (GB50205).

3. Steel grid structure

3. The detection of1steel grid structure can be divided into bearing capacity of joints, weld, size and deviation, unevenness of members and deflection of steel grid structure.

3.2 The inspection of the bearing capacity of welded ball joints and bolted ball joints of steel space truss structures shall be carried out according to the requirements of JGJ78 Standard for Quality Inspection and Evaluation of Space Truss Engineering. For the existing grid structure with bolted ball joints, the joints can be taken out of the structure to test the ultimate bearing capacity of the joints. When the bolt ball joint is truncated, measures should be taken to ensure the structural safety.

3.3 Welds in steel grid structure can be detected by ultrasonic flaw detection, and the detection operation and evaluation should be carried out according to the requirements of Ultrasonic flaw detection and quality grading method for welded ball joint steel grid structure JG/T3034. 1 or Ultrasonic flaw detection and quality grading method for bolted ball joint steel grid structure JG/T3034.2. 3.4, and the appearance quality of welds in steel grid structure should be in accordance with the Code for Acceptance of Construction Quality of Steel Structures.

3.5 The deviation detection, detection methods and allowable values of solder balls, bolt balls, high-strength bolts and steel bars shall comply with the provisions of JGJ78 "Standard for Quality Inspection and Evaluation of Grid Structure Engineering".

3.6 The wall thickness of steel tube members of steel grid can be detected by ultrasonic thickness gauge, and the decorative layer should be removed before detection.

3.7 The straightness of the steel bar axis in the steel grating can be detected by the drawing method, and the straightness shall not exceed one thousandth of the length of the steel bar.

3.8 The deflection of steel grid structure can be detected by laser rangefinder or level gauge. The number of measuring points in each half span should not be less than 3, and there should be 1 measuring point in the span. The distance between the end measuring point and the end bracket should not be greater than1m..

4. Actual load test and dynamic test of structural performance

4. 1 For large-scale complex steel structure systems, on-site nondestructive real-load testing can be conducted to directly test the structural performance. The actual load inspection of structural performance can be carried out according to the provisions of Appendix H of this standard. The loading factor and judging principle can be determined according to the provisions in Appendix H.2, and can also be adjusted appropriately according to the specific situation.

4.2 When there is doubt about the bearing capacity of a structure or member, a prototype or full-scale model load test can be conducted. The test shall be entrusted to a professional organization with sufficient equipment capacity. Before the test, a detailed test plan should be made, including the test purpose, the selection or manufacture of test pieces, the arrangement of loading devices, measuring points and test instruments, the loading steps and the evaluation method of test results. The test plan can be made according to Appendix H and should be agreed by all parties concerned before the test.

4.3 For large and important new steel structure systems, actual structural dynamic tests should be carried out to determine the dynamic parameters such as natural vibration period of the structure. The structural dynamic test shall comply with the provisions in Appendix E of this standard.

4.4 Steel bar stress can be detected by resistance strain gage or other effective methods according to the actual situation.