Testing of Steel Structures - Steel Grid Structures

1. The inspection of steel grid structures can be divided into items such as the bearing capacity of nodes, welds, dimensions and deviations, 

unevenness of members, and deflection of steel grid structures.

2. The inspection of the bearing capacity of welded ball joints and bolted ball joints in steel grid structures should be carried out in accordance 

with the requirements of JGJ78 "Quality Inspection and Evaluation Standards for Grid Structures". 

For existing bolted ball node grids, nodes can be removed from the structure for ultimate bearing capacity testing. 

When intercepting bolted ball joints, measures should be taken to ensure structural safety.

3. The welding seams in the steel grid can be inspected using ultrasonic testing method. 

The inspection operation and evaluation should be carried out in accordance with the requirements of 

"Ultrasonic Testing and Quality Classification Method for Welded Ball Joint Steel Grid Welding Seams" JG/T3034.1 

or "Ultrasonic Testing and Quality Classification Method for Bolted Ball Joint Steel Grid Welding Seams" JG/T3034.2.

4. The appearance quality of welds in steel grid structures should be tested in accordance with the requirements of the 

"Code for Acceptance of Construction Quality of Steel Structures" GB50205.

5. The detection of deviations in welding balls, bolt balls, high-strength bolts, and members, as well as the detection methods and allowable deviation values, 

should be carried out in accordance with the provisions of the "Quality Inspection and Evaluation Standards for Grid Structure Engineering" JGJ78.

6. The wall thickness of steel truss steel pipe members can be measured using an ultrasonic thickness gauge, 

and the decorative layer should be removed before testing.

7. The unevenness of the axis of the members in the steel grid can be detected by the method of pulling wires, 

and its unevenness shall not exceed one thousandth of the length of the members.

8. The deflection of the steel truss can be detected using a laser rangefinder or a level. 

The number of measurement points within each half span should not be less than 3, and there should be 1 measurement point in the middle of the span. 

The distance between the end measurement points and the end support should not be greater than 1m.