The section steel combination support is connected by high-strength bolts. During construction, attention should be paid to:

1High strength bolts shall not be used as temporary installation bolts. This can easily lead to incorrect alignment of the hole or forced alignment of the hole to make the connection platelaminating, screw thread damage, torque coefficient variation, uneven bolt shaft force, or internal stress of the connecting plate.

2Install high strength boltsDo not rub the surfaceCareless handling or inaction,willSo that there is a sandwich between the friction surfaces. If the friction surface is not properly protected.corrosionCan makeThe friction surface will be concave and uneven, reducing the connection strength. In this case, the friction surface must be retreated to ensure quality.

3,There shall be no gap between the connecting plates. Installing a high strength bolt, due to the defects of construction operation, such as using the reamer repair the hole, bolt not tighten around, make the iron into the friction surface, or joint of steel plate and steel buckling deformation, a burr hole, sundries are not completely eliminate between plate installation bolt, or improper construction order, from lateral to the order of the middle fastening bolt group, Often lead to friction surface most or local clearance, the bolt can not reach the specified pre-tightening shaft force, and greatly reduce the connection strength, force will make the connection slip.

4,If there are bolts of different specifications, do not replace the bolts, nuts, and washers at will. The nuts and washers of the high-strength bolts are tested and matched by the manufacturer to determine the torque coefficient. Mutual use will change the torque coefficient and not meet the required preload. When used, the buckle is loosened, which greatly reduces the preload and affects the connection quality.

5The tightening torque or shaft force of high strength bolts cannot be madeThe foot. In the installation process, due to the failure or error of the electric and manual wrench, the torque is insufficient; Or connecting plate notflat, apply the preload force without correction, so that part of the torque value is consumed to overcome the deformation; Or poor operation, although the wrench reading torque is achieved, but the actual preload is not achieved; Or part of boltmissingThe initial or final twist, so that the bolt group force is not uniform; Or finally screw the force value of the preload shaft that does not meet the design requirements, affecting the preload force and reducing the connection strength.

6,High strength bolts can not be cut by a final screw or not in the required order. This will make part of the axial force of the bolt consumed in the process of overcoming the deformation of the plate. When the surrounding bolts tighten, the axial force is distributed and reduced; In addition, in order to make the force of each bolt of the bolt group uniform, the initial and final screws should be tightened from the middle to the outside order. Take from both ends to the middle,willLead to the middle drum, so that part of the axial force consumed in overcoming deformation, so that the preload is insufficient, the friction coefficient is reduced, affecting the connection strength.

7,Can not appear the bolt is not satisfied with the buckle. This will make the nut prone to loosening under long-term or vibrational loads, reducing the preload and making the connection weak. This bolt must be replaced.

8,The friction surface between the connecting plate and the connecting surface shall not be polluted by oil or paint after treatment.

9,Angle brace and belly beamthelifting.

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