When the steel structure is also damaged, we must immediately find and solve the problem, the main factors of steel structure damage are:

(1) The structural bearing capacity is insufficient due to load changes, overdue service, and changes in norms and regulations;

(2) the component due to various accidents caused by deformation, distortion, disability, depression, etc., resulting in the weakening of the component section, rod warping, connection cracking, etc.;

(3) Deformation, cracking and warping of components or connections under the action of temperature difference;

(4) Corrosion caused by the erosion of chemical substances and electrochemical corrosion resulting in the weakening of the cross-section of steel structure members;

(5) Others include mistakes in design, production and construction, and illegal use and operation during the service period.

There are three main technical measures for strengthening steel structures:

(1) Section reinforcement method: In the local or along the full length of the member with steel reinforcement, connected into the whole so that the common force;

(2) Change the calculation diagram: add additional supports, adjust the load distribution, reduce the internal force level, and force displacement of statically indeterminate structural supports to reduce the stress peak;

(3) Prestressed cable method: The use of high-strength cable to strengthen the weak links of the structure or improve the overall bearing capacity, stiffness and stability of the structure.