5.3　Connection of High-strength Bolts

Ⅰ　Dominant Items

5.3.1　The connecting face of high-strength bolt shall meet the requirements in the design documents during fabrication of elements.The slip factor on friction surface of high-strength bolt shall be tested and re-inspected for each batch of steelwork during fabrication and installation.The friction surface that is processed on site shall be independently tested for slip factor and the result shall meet relevant requirements in current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures.

Check quantity:3 test pieces for each batch（2000tin divisional works is treated as one batch，a part of 2000t is also treated as one batch.When two or more treatment process are used，each process shall be independently tested）.

Check method:check the test report and re-inspection report for slip factor on friction surface.

Ⅱ　General Items

5.3.2　After the high-strength bolt pairs are fastened，2-3 threads shall be exposed on the bolt，it is allowable that 1 or 4 threads can be exposed on 10% of bolts，the threading direction of bolts shall be consistent except those due to structural cause.

Check quantity:5% random check for joints and at least 5 joints.5% random check for bolts on each joint and at least 2 bolts.

Check method:visual check.

5.3.3　The final fastening torque shall be checked 1h and within 48h after the high-strength hexagon bolt pairs are fastened，the result shall meet relevant requirements in current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures.

Check quantity:10% random check for joints and at least 5 joints.10% random check for bolts on each joint and at least 2 bolts.

Check method:as per current national standard of GB 50205 Code for Acceptance of Construction Quality of Steel Structures.

5.3.4　The end wobbler on bolt shall be removed after the torsional shear type high-strength bolt is finally fastened except those due to structural cause.The bolt pair whose wobbler is not removed shall be fastened with torque method or rotation angle method and marked，in addition，it shall be checked according to the final fastening torque check method in Appendix B of current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures.

Check quantity:5% random check for joints and at least 5 joints.5% random check for bolts on each joint and at least 2 bolts.

Check method:check the conditions of removed end wobble.The bolt whose wobble is not removed shall meet the requirements in current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures.

5.3.5　The connecting friction face of high-strength bolt shall maintain in a dry，tidy condition with no flashing，burr，welding spatter，crater，scale，oil stain and so on.The friction face shall not be painted unless otherwise specified in the design documents.

Check quantity:5% random check for friction faces and at least 4 points.

Check method:visual check.

5.3.6　The high-strength bolt shall thread into the bolt hole without restriction.The gas-cutting reamed hole shall not be used for high-strength bolt，the diameter of reamed hole shall not exceed 1.2 times of the bolt diameter.

Check quantity:full check for reamed bolt holes.

Check method:visual check and check with a caliper.