How to strengthen the beam if the bearing capacity is insufficient, and how to strengthen the load b

It can be strengthened through the following aspects, limiting the use of loads and changing the use of beams and plates; Reinforcement design, pouring superimposed beams (laminated plates).

For columns, the peripheral cross-section is supplemented to reduce the axial compression ratio, and the use of steel bars to resist compression cannot be considered. Increase the size and thickness of the beam plate to increase the number of steel bars; Increase the number of beams and columns to share the bearing capacity, strengthen the concrete strength, and increase the bearing capacity; Find a design institute to redesign.

Bearing capacity: is a concept borrowed from the field of engineering geology, which originally refers to the strength of the foundation and the ability of the building to bear the weight, and has evolved into one of the most commonly used concepts to describe the degree of restriction on development. Ecology was the first to introduce this concept to this discipline.

Beam reinforcement is a common construction in reinforcement engineering. There are many solutions for insufficient bearing capacity reinforcement. At present, the most commonly used are pasting carbon fiber cloth and sticking steel.

If the bearing capacity is insufficient, how much is missing? A professional designer will calculate the data and then design the drawings whether to use carbon fiber or steel.

Generally speaking, if there is not much missing, it is best to paste carbon fiber, which is relatively low cost and convenient to build. The reinforcement ability of bonded steel is stronger than that of carbon fiber. A 3mm steel plate is equivalent to three layers of carbon fiber cloth.

Specific problems are analyzed in detail, and the following methods are commonly used:

1.externally bonded carbon fiber, steel plate and other materials;

2.Enlarge the cross-section;

3.Change the structural stress system.

How the load-bearing beam must be reinforced according to the prescribed procedures after it is broken.

1. First of all, temporary reinforcement measures should be taken: such as adding temporary support under the beam to ensure that the quality accident (problem) does not continue to develop and cause greater economic and other losses.

2. Entrust the original design unit or the design unit with corresponding qualifications to do the structural reinforcement design, and issue the design documents with the signature of the structural engineer and the design institute.

3. Entrust a unit with corresponding reinforcement construction qualifications to do reinforcement construction; Supervision conducts follow-up supervision.

4. After the completion of construction, organize acceptance, and all reinforcement materials should be archived after passing the acceptance.

Carbon fiber reinforced plastic (carbon fiber reinforced plastic) reinforcement repair concrete structure technology is a new type of reinforcement technology that has emerged in recent years, the technology is to apply carbon fiber this high-performance fiber to civil engineering, the use of tree finger materials to paste carbon fiber on the surface of the structure or component to form a composite material (CFRP), through its collaborative work with the structure or component, to achieve the purpose of reinforcing the structural component and improving the mechanical performance.

Carbon fiber material has the characteristics of high strength, high elastic modulus, light weight and good corrosion resistance, and its tensile strength is about ten times that of ordinary steel bars, and the elastic modulus is slightly higher than that of ordinary steel bars. There are two main types of carbon fiber materials used in the reinforcement and repair of concrete structures: carbon fiber materials and supporting resins.

Among them, the tensile strength of carbon fiber is ten times that of construction steel, and the elastic modulus is equivalent to that of steel, and the elastic modulus of some types (such as high elasticity) of carbon fiber is even more than twice that of steel, and the construction performance and durability are good, which is a good reinforcement and repair material; The supporting tree finger includes the underlying resin, leveling resin and bonding resin, the first two are used to improve the bonding quality of carbon fiber, and the latter function is to make carbon fiber and concrete can form a composite whole, and work together to improve the bending and shear bearing capacity of structural components, so as to achieve the purpose of reinforcing and reinforcing structural components.

The main mechanical index of carbon fiber cloth.

Tensile strength (mpa) elastic mold (mpa).

Elongation (%)

Technical Specification Indicator 3000

Design of matching resin binder material.

The supporting resin is formulated by the main agent and the curing agent, and is divided into winter type and summer type suitable for winter and summer use. The main agent and the curing agent are packaged separately, and when used on site, they should be mixed evenly according to the process requirements and in accordance with the specified ratio to form the required bottom resin, leveling resin and adhesive resin.

Bottom resin The role of bottom resin is to enhance the interface bond strength between surface concrete and leveling material or adhesive resin;

Leveling resin Leveling resin is to make the surface flatness meet the specified requirements, and has reliable bonding strength with the underlying resin and adhesive impregnating resin;

Adhesive resin Adhesive resin is the main adhesive material for pasting carbon fiber cloth, and its function is to make carbon fiber cloth and concrete fully bonded, so that they can bear the role of structure together.

The main mechanical properties of supporting resin binder materials:

Positive tensile bond strength (MPa).

Shear strength mpa).

Tensile strength (mpa).

Flexural Strength (MPa).

Bottom resin leveling resin.

Technical Specification Indicators.

and greater than times the tensile strength of concrete.

Adhesive resin technical specification indicators.

Same as the underlying resin.

Construction preparation 1), main materials: primer, adhesive, carbon fiber cloth.

I'll take a look at what the two upstairs have to say

The key depends on where your frame beam is, if you don't pay much attention, it's still the second one, the first one says that the cost is too high, carbon fiber composites are generally used to repair the theme beam, and the one used to reinforce is expensive, as long as the original beam does not have cracks. It is not necessary to use those for the sagging case.

There are three ways to reinforce, one is to increase the cross-section, the second is to reduce the beam span, and the third is to weld the angle steel skeleton around the frame beam.

Frame beam (kl) refers to a beam connected to a frame column (kz) at both ends, or a beam connected to a shear wall at both ends but with a span-to-height ratio of not less than 5. Now in structural design, there is another point of view for frame beams, that is, beams that need to participate in seismic resistance. Pure frame structures are becoming less and less common with the rise of high-rise buildings, and the frame beams in shear wall structures are mainly beams that participate in seismic resistance.

Well, that's pretty much it

Featured Q&A: How to strengthen a load-bearing beam after cracking.

1. Increase the cross-section of the beam. That is, pouring an extra layer of concrete on either side of the beam and implanting some reinforcement to increase the load capacity of the whole beam. This method has a wide range of applications, and the construction is simple, which affects the clearance of the house; The effect is also affected by many factors, such as material properties, construction techniques, joint construction, and so on.

2. Paste the steel plate on the surface of the beam. The original number of steel bars of the beam is increased, so that its stiffness and compressive and shear resistance are improved. In this case, the choice of binder is important, and a special structural adhesive is required.

It is required to have good elasticity, aging resistance and strong adhesion.

3. Paste a carbon fiber cloth on the bottom of the beam.

The effect is the same as that of the steel plate, that is, let the two work together, so as to improve the overall load-bearing. Before pasting, the area should be cleaned up, that is, the weak surface layer should be removed, the inner layer should be sanded, and the adhesion of the fiber cloth and the beam should be increased.

4. Increase the support point of the beam. This reduces the span and allows the load to be dispersed, thus enhancing the overall load-bearing of the beam. This method is more suitable for the reinforcement of beams with large structural spans that are not too limited in space, and the method is simple and reliable, but it has a slight impact on the use of space.

5. There is also prestressing.

to reinforce the method. That is, the external bracing and pulling steel is applied to it, so that the prestress acts on it, thereby changing the force.

According to what you said, the span of the frame beam is 1 14 to 1 8 of the distance between the nodes of the two columns, so that the beam height is appropriate. However, the structural drawing is 650mm, which is the reinforcement calculated according to 650mm, so if you reduce the beam height, the safety of the beam will be reduced, and the calculation of bearing capacity and the calculation of the limit may not meet the requirements. Even if the beam is constantly unsafe, it is easy to produce cracks and disturbances, which affect the use.

Brick walls do not carry loads in the frame. The best way is to explain the situation to the designer and let him calculate it again according to the reduced beam height value, I think it should not be over, otherwise the designer will not increase the beam size and waste materials. Keep in mind that the construction must be done according to the drawings in the future, and discuss with the designer if you want to change it.

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What are the reinforcement methods for load-bearing beams?

1. According to the length of the dismantled wall and the accumulation of various loads borne by the upper part of the wall, the cross-sectional size of the beam is determined, and then the reinforcement is calculated.

2. On both sides of the wall that needs to be removed, set up steel pipe support columns, add beams, and add backing plates to support the floor slab on the wall to maintain its original stability, and add steel wedges to support it. The cross-section and spacing of the top columns are determined by load calculation. The fulcrum is located in the long range of 100 mm from the end of the plate (the top layer of a single or multiple layers).

For multi-layer or bottom-layer beams, the position of the pouring hole is generally less than 2 meters, and the pouring hole can be on the upper side.

3. Under the condition of ensuring the firmness and stability of the column, the wall is dismantled. At the same time, the lower wall of the beam should be removed according to the cross-sectional size of the beam and the supporting length, and the debris should be removed. In order to prevent the concrete of the original joint of the slab from falling, the steel support can be increased according to the spacing not more than one meter, and within the beam concrete pouring range, after the formwork is supported, the beam concrete is poured sequentially from one end or both ends along the upper edge of the floor slab, and after the concrete is mixed, the standing time should not exceed the length of the early solidification time of the concrete.

The spacing is about 1 meter, and the concrete hole with a diameter of about 150 mm is opened.

4. The bottom mold of the beam can be dispensed with, and the bottom mold can be separated from the masonry with an isolation layer, followed by the reinforcement of the beam, and finally the side mold, and the template must be firm to meet the design size construction and safety needs of the beam section.

5. Concrete is poured into the beam from the pouring hole on the floor slab, starting from one end of the beam first, and when pouring into the second hole, the first hole is subject to the slurry. Until the concrete of the entire beam is filled with filling.

6. When the concrete strength reaches 100% of the standard value of the design strength grade, the formwork will be removed.

The simplest and most practical way to reinforce columns.