What are the reinforcement methods for steel structures-2
3. the prestressed steel structure reinforcement technology
3.1 The traditional steel structure reinforcement problems:
When the welding is strengthened, the high temperature will cause the organization and performance of the welded parts to deteriorate. Moreover, the weld must be defective and new cracks will be generated. The residual stress exists in the welded structure, which may lead to cracking. Welding so that the structure to form a continuous whole, once the instability of the crack expansion, it is possible to break in the end, causing a major accident.
The use of bolted connections in the vicinity of the damaged parts of the base material on the hole, weakened the cross-section, the formation of a new stress concentration area; ordinary bolts in the dynamic load under the loose, high-strength bolts prone to stress relaxation phenomenon, reducing the structure of the repair effect The Bonded steel reinforcement technology is in the steel surface with a special structure of the adhesive structure of the steel plate, relying on structural adhesive to make the whole work together to improve the structural capacity. The common drawback of these reinforcement methods is to increase the weight of the structure, the steel plate is not easy to produce into a variety of complex shapes, transportation and installation is not convenient, and the steel plate is easy to rust, affecting the bond strength, high maintenance costs.
3.2 paste the characteristics of reinforced steel structure:
Paste the reinforcement of the steel structure is the use of adhesive will be affixed to the surface of the steel structure damage, so that part of the load through the adhesive layer to the upper, reducing the structural damage site stress. Paste reinforcement technology has obvious advantages:
(1) the specific strength and specific rigidity, after reinforcement does not increase the original structure of the original weight and the size of the original components;
(2) composite material has good anti-fatigue properties and corrosion resistance;
(3) Flexible composites have a particular advantage for any of the closed structures and the surface of the reinforced structures that are complex in shape. Good sealing, reducing the risk of leakage or even corrosion;
(4) simple, low cost, high efficiency, in a small space can also be construction, especially for on-site repair;
(5) no fire in the construction process, suitable for a variety of special circumstances.
3.3 Advantages of prestressed reinforcement:
(1) reinforcement work can be carried out without unloading, non-stop conditions;
(2) the application of prestress can directly reduce the deformation, the rapid elimination of stress and internal force beyond the peak;
(3) Compared with the non-prestressing mode, the stress hysteresis can be eliminated, and the high-strength characteristics can be fully utilized to improve the reinforcement efficiency.
(4) combined with reliable anchoring, can reduce the adhesive interface of the peel stress, to avoid the overall peeling, improve the reliability of reinforcement;
(5) reduce the cost of reinforcement and the use of cost.