The main factors of steel structure damage are: (1) insufficient bearing capacity of the structure caused by load changes, overdue service, and changes in specifications and procedures; (2) The component is deformed, distorted, disabled, dented, etc. due to various accidents, resulting in the weakening of the cross-section of the component, the warping of the members, and the cracking of the connection; (3) Deformation, cracking and warping of components or connections caused by temperature difference; (4) Corrosion due to the erosion of chemical substances and electrochemical corrosion lead to the weakening of the cross-section of steel structure components; 5) Others include errors in design, production, construction, and illegal use and operation during the service period.
There are three main reinforcement technical measures for steel structure: (1) cross-section reinforcement method: steel reinforcement is used locally or along the full length of the component, and it is connected into a whole to make it stress together; (2) Change the calculation diagram: add additional supports, adjust the load distribution, reduce the level of internal forces, force the displacement of the superstatically determined structure supports, and reduce the peak stress; (3) Prestressed cable method: use high-strength cable to strengthen the weak link of the structure or improve the overall bearing capacity, stiffness and stability of the structure.
20_ The difference between steel and Q235B and Q345B
