In the construction of steel structure engineering, the welding deformation directly affects the installation and function. Because of the additional bending moment and secondary stress produced during bearing, the service performance of steel structure engineering is indirectly affected, so the control of welding deformation is very important.

According to the causes and influencing of welding deformation, the following measures can be taken to control the deformation:

Reduce the cross-sectional weld area: on the premise that the weld is intact and free of excessive defects, the smaller groove size (angle and gap) shall be used as far as possible.

For steels with yield strength below 345mpa and poor hardenability, use small heat input, do not preheat as much as possible or reduce preheat and interpass temperature appropriately: give priority to welding methods with small heat input, such as CO2 gas shielded welding.Multi layer welding shall be adopted for thick plate welding instead of single layer welding as far as possible.

Under the condition that the design requirements are met, the intermittent welding method can be adopted for the welding of longitudinal stiffeners and transverse stiffeners

When both sides can be welded, the double-sided symmetrical groove shall be adopted, and the welding sequence symmetrical to the neutral axis of the member shall be adopted during multi-layer welding.

When the thickness of T-joint plate is large, the beveled corner butt weld shall be adopted.Controlling angular deformation after welding by anti deformation method before welding.

Control of post welding deformation by rigid fixture fixation.

The member reserved length method is used to compensate the longitudinal shrinkage deformation of the weld. For example, 0.5mm-0.7mm can be reserved for the longitudinal weld of H-shaped steel per meter length, and 0.5mm can be reserved for the length of the section steel corresponding to each pair of horizontal bars. The reserved perimeter method is used to compensate the longitudinal and transverse shrinkage deformation of the weld of cylindrical pipe members. If the plate thickness is greater than 10mm, 2.0mm perimeter is reserved for each longitudinal and circumferential weld.

For the distortion of long members, it mainly depends on improving the flatness of plates and the assembly accuracy of members to make the groove angle and gap accurate, and the arc direction or alignment accurate, so as to make the weld angle deformation consistent with the longitudinal deformation of flange and web along the length of members.

The number and size of welds shall be minimized in the design; The welds shall be arranged reasonably. In addition to avoiding dense welds, the position of welds shall be as close to the neutral axis of the member as possible, and the arrangement of welds shall be symmetrical to the neutral axis of the member.

Reasonable welding sequence shall be adopted during assembly welding of members with numerous welds or installation of steel structure works.

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