The quality and performance testing of steel structure connections can be divided into the testing of welding connections, welding nail connections, bolt connections, high-strength bolt connections, and other items. The quality of primary and secondary welds that require full penetration in design, as well as strong butt welding and splicing welds of steel that are not required in design, can be tested using ultrasonic testing method. The testing should comply with the following regulations: 1) The quality of steel structure engineering should be tested in accordance with the provisions of the "Code for Acceptance of Construction Quality of Steel Structure Engineering"; 2) Sampling ultrasonic testing can be adopted for the performance of existing steel structures; 3) The classification of weld defects should be determined according to the "Classification of Manual Ultrasonic Testing and Testing Results for Steel Welds". 1. When inspecting the appearance of welding seams in steel structure engineering, the method of sampling and inspecting the appearance quality of welding seams can be adopted for existing steel structures, or the method of sampling and inspecting according to the scope specified by the commissioning party can be adopted. The external dimensions and appearance defect detection methods and evaluation standards of welds should be determined in accordance with the "Code for Acceptance of Construction Quality of Steel Structures". 2. The mechanical properties of welded joints are inspected by taking test specimens, but measures should be taken to ensure safety. The inspection of the mechanical properties of welded joints is divided into items such as tension, surface bending, and back bending, and each inspection item can take two samples each. The sampling and inspection methods for welded joints should be determined in accordance with the "Sampling Methods for Mechanical Property Testing of Welded Joints", "Tensile Testing Methods for Welded Joints", and "Bending and Flattening Testing Methods for Welded Joints". The strength of welded joints should not be lower than the minimum guaranteed value of the base material strength. 3. The quality inspection of steel structure engineering can be carried out by selecting a certain number of welding nails for bending inspection after welding. The inspection method and evaluation standards include hammering the welding nail head to bend it to 30 °, and the weld seam and heat affected zone can be judged as qualified if there are no visible cracks. 4. Bolt inspection 1) The material properties and torque coefficient of high-strength large hexagonal bolt connection pairs, inspection methods and rules should be determined in accordance with the "Technical Conditions for High Strength Large Hexagonal Head Bolts, Large Hexagonal Nuts, and Washers for Steel Structures", "Code for Acceptance of Construction Quality of Steel Structures", and "Code for Design, Construction, and Acceptance of High Strength Bolt Connections in Steel Structures". Conduct high-strength bolt connection quality inspection, and sample the bolts to obtain exposed threads. The exposed threads should be 2-3 threads. 10% of bolt threads are allowed to be exposed with 1 or 4 threads. Author: Fang Shi Housing Testing and Appraisal Institution https://www.bilibili.com/read/cv16455490/ Source: Bilibili