What are the reinforcement methods of steel structure?

A.The main methods of steel structure reinforcement are:

It can reduce the load, change the calculation figure, increase the cross-section and connection strength of the original structural member, and prevent crack propagation.

Other reinforcement methods may also be used when the mature experience is gained.

The steel structures that need to be strengthened are generally divided into partial reinforcement and comprehensive reinforcement according to the damage scope.

Local reinforcement is to reinforce a bar or joint with insufficient bearing capacity, including increasing the section of the bar, reducing the free length of the bar and strengthening the joint.

Local reinforcement is to reinforce a bar or joint with insufficient bearing capacity, including increasing the section of the bar, reducing the free length of the bar and strengthening the joint.

The overall reinforcement is to carry on the reinforcement to the whole structure, has not changed the structure static force calculation figure reinforcement method and changed the structure static force calculation figure reinforcement method two kinds.

Adding or strengthening the supporting system is also an effective method to reinforce the structural system.

The reinforcement method of increasing the original component section is the most material and labor cost method (but it is often feasible method); The most efficient and varied methods of calculating schematic diagrams are greatly reduced in cost.

B.Main factors of damage of steel structure and reinforcement measures

a.The main factors of steel structure damage are:

1.Insufficient bearing capacity of the structure is caused by load change, extended service, code and procedure change;

2.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.Temperature difference causes deformation, cracking and warping of components or connections;

4.Corrosion and electrochemical corrosion caused by the erosion of chemical substances weaken the section of steel structural members;

5.Others include mistakes in design, production and construction as well as illegal use and operation during the service period. This article is from Steel Structure Alliance.

b.There are three main reinforcement measures for steel structures:

1.Section reinforcement method: in the local or along the full length of the member with steel reinforcement, connected as a whole to make a common force;

2.Change the calculation diagram: add additional support, adjust the load distribution, reduce the level of internal force, the statically indeterminate structure support for forced displacement, reduce the peak stress;

3.Prestressed cable method: using high strength cable to reinforce the weak link of the structure or improve the overall bearing capacity, stiffness and stability of the structure.

c.Characteristics of traditional reinforcement methods for steel structures

Reinforcement of welded steel structure

When welding reinforcement, local rapid heating, and cooling process, welding area due to the constraints of the workpiece body around and can not freely expand and shrink, after cooling in the welding parts will produce welding stress and deformation, the high-temperature effect of the welding part of the organization and performance deterioration; And the welding seam is bound to have defects, will produce new cracks; There is residual stress in the welded structure, which combined with other effects may lead to cracking. Welding makes the structure form a continuous whole. Once the crack is unstable and expanded, it may be broken to the end and cause a major accident.

Steel bonding steel structure reinforcement

Structural adhesive is used to paste the steel plate to the part that needs strengthening, and the structural adhesive is used to bond the steel plate together to bear the force together, so as to improve the bearing capacity of the structure.

Paste reinforcement technology has obvious advantages :

(1) the specific strength and specific stiffness is high, the reinforcement basically does not increase the weight of the original structure and the size of the original component;

(2) The composite material has good fatigue resistance and corrosion resistance;

(3) Flexible composite materials have special advantages for arbitrarily closed structures and reinforced structural surfaces with complex shapes.

Good sealing, reduce the leakage and even corrosion hidden danger;

(4) it is simple and easy to operate, low cost, high efficiency, and can be constructed in small space, especially suitable for on-site repair;

(5) There is no open fire in the construction process, which is suitable for various special environments.

Disadvantages of adhesive reinforcement technology: in the experimental study of the shear capacity of the bonded steel of the flexural member, it is found that the glass phenomenon appears when the bonded steel plate is further loaded, resulting in the increase and decrease of the ultimate bearing capacity.

It is still necessary to study and give reasonable structural measures to ensure that the bonded steel reinforced steel plate does not peel off.

Bolted steel structure reinforcement

It is necessary to open holes near the damaged site, which weakens the section and makes it form a new stress concentration area, loosens the original bolt, and reduces the repair effect of the steel structure. The common bolt is easy to loosen under dynamic load, and the high strength bolt is easy to stress relaxation, which reduces the repair effect of the structure.

Above several high-rise steel structure reinforcement methods in addition to the above a few defects, there is a common defect: steel structure reinforcement selected material basic for steel, to reinforce the will bring too much weight to structure, and steel plate is not easy to cut into the shape of a reinforcement required, install transportation is difficult, after reinforcement completion, need antirust processing of steel, avoid steel rust unnecessary influence on structural adhesive, and maintenance workload is big, the cost is higher.

C.Technical advantages of prestressed steel structure reinforcement

a.The reinforcement work can be carried out under the condition of no unloading or stopping production.

b.Applying prestress can directly reduce the deformation and quickly eliminate the excess stress and internal force peak.

c.Compared with the non-prestressed method, the stress hysteresis can be eliminated, the high strength characteristics can be fully utilized, and the reinforcement efficiency can be improved.

d.Combined with reliable anchorage, the peeling stress of the bond interface can be reduced, the whole peeling can be avoided, and the reliability of reinforcement can be improved.

e.Reduce reinforcement cost and use cost.