Reinforcing methods of steel structure
reinforcing methods of steel structure
1
Modify steel structure and calculate graphic reinforcement method
The method of strengthening the structure by changing load distribution, force transmission way, node property and boundary condition, adding additional rod and support, applying prestress and considering space cooperative work are adopted. The general way to change the structure of a calculated graph is:
(1) increase support, form space structure, check according to spatial structure, add support, increase structural rigidity or adjust the natural frequency of structure, so as to improve the bearing capacity of structure and improve the dynamic characteristics of structure;
(2) adding support or auxiliary rod to reduce the slenderness ratio of the structure so as to improve its stability;
(3) in the bent structure strengthen a colonnade stiffness, which carry most of the horizontal forces, in order to reduce the load of other columns.
2
Additional fulcrum reinforcement method
When the beam and the plate are additionally provided with a fulcrum, the span is reduced, and the bearing capacity can be greatly improved, and the deflection of the beam and the plate can be reduced and limited. The utility model is suitable for strengthening the horizontal structure of beams, plates, trusses, grids, etc. in large span structures with unlimited headroom. Its advantage is simple and reliable, the drawback is that the use of space will be affected.
3
Bonded steel encased reinforcement
Steel reinforced concrete beam strengthened by wet method is the general outsourcing, using epoxy resin grouting method to steel and reinforced member bonded into a whole, after the reinforcement component, due to tension and compression steel cross sectional area increased greatly, so the normal section bearing capacity and stiffness are greatly improved.
4
Reinforcement by sticking fiber reinforced plastics
Paste fiber reinforced plastic reinforcement method not only has advantages of outsourcing bonded steel reinforcement method similar to the outside, is also resistant to corrosion, resistant to moisture, almost no increase in the weight of the structure, durable, low maintenance cost advantages, but need special fire protection processing, applicable to all kinds of mechanical properties of concrete structure component and the general construction.
After the completion of the reinforcement project, the small hammer is used to hammer and paste the steel plate to judge the bonding effect from the sound or to detect the paste density by the ultrasonic method.
If the anchorage area is less than 90% and the bonding area of the non anchorage area is less than 70%, then the paste is invalid and should be peeled and re pasted.
For major projects, in order to test the effect of strengthening to sampling for load test, generally only for load test using standard, load is removed to all and should be used to meet the design requirements, carry out the deformation and crack structure.
5
Prestressed reinforcement of steel structure technology
The bolt hole needs to be opened in the parent metal near the site of injury, weakened section, the formation of a new stress concentration zone; ordinary bolt under the dynamic loads of high-strength bolts loose, prone to stress relaxation phenomenon, reduce the effect of repairing structure. Sticking steel strengthening technology is to paste steel plate with special construction structure glue on the surface of steel structure, and stick it together with structural adhesive to work together to improve the bearing capacity of structure. The disadvantage is that the structural weight increases a lot, the steel plate is difficult to be made 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.
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