Structural safety problems often arise in the design life of buildings, either because of inadequate construction methods during the construction process or because of the short life of the building materials used, or because of sudden changes in the natural environment. Thus, detection, evaluation and reinforcement during the life of the building are particularly important, and there are differences in the methods of reinforcement used in different structural forms, which should be seen together。
Steel structural reinforcement method
The main ways to strengthen the steel structure are to reduce the load, change the structure calculation graphics, increase the cross-section and connection strength of the original structure components, and prevent cracking expansion. Other enhancements can be used when there is mature experience。
1. Structural change calculations
The reinforcement of the structure calculation figure is the reinforcement of the structure using measures such as changing the load distribution status, transmission routes, the nature of nodes and boundary conditions, adding additional poles and support, pre-responding forces and considering space teamwork。
The general reinforcement method for changing the structure calculation figure:
(1) structures can be strengthened by increasing the rigidity of structures or components: increasing support for the formation of spatial structures and measuring them by spatial structures; increasing structural loads and improving structural dynamics by adding support for increased structural rigidity or adjusting the self-invigoration frequency of structures; increasing structural stability by adding support or auxiliary rods to reduce the size of structures; focusing on strengthening the rigidity of a column in the stench structure so that it can absorb most of its levels in order to reduce the load of other columns; and strengthening the rigidity of structures by placing pull poles or moderately tight zips in structures such as towers。
(2) bended rods can be strengthened by modifying their cross-section internality: changing the distribution of loads, e. G., by converting a centralized load into multiple centralized loads; changing end-end support, e. G., by cutting the end of a condensation; adding an intermediate or connecting the end of a condensed structure into a continuous structure; adjusting the sub-branch of a continuous structure; transforming the structure into a pole-driven structure; and imposing pre-resistance。
(3) the frame may be strengthened by altering the inner strength of the pole: by adding a pole to the frame to the pole structure; and by adding a pre-resort pull。
2. Enhanced cross-section of components
When greater cross-section reinforced steel components are used, the selected cross-section form should facilitate the consolidation of technical requirements and take into account the condition of defects and damage。
3. Connected reinforcements and reinforcements
The choice of the method of steel structure connection, i. E. Welding, nailing, ordinary bolt and high-strength bolt connection, shall be determined on the basis of the cause, purpose, stress status, construction and construction conditions for which the structure needs to be strengthened, taking into account the original method of connection of the structure。
Welding, friction-type high-strength bolts, or, where warranted, welding and friction-type high-strength bolts, are generally suitable for strengthening steel structures. When welding is used, welding and connecting materials should be evaluated。
4. Fracture restoration and reinforcement
The structure shall be repaired if it is expansive or precipitous to cause fissure damage as a result of repeated load effects and inappropriate material selection, construction, manufacture and construction installation. Prior to the restoration, the causes of the cracks and the severity of their impact must be analysed, the structural improvement or reinforcement measures must be targeted and the building blocks that are not suitable for restoration should be dismantled and replaced。
Structure strengthening method
The reinforcement of the building structure is divided into two categories: direct reinforcement and indirect reinforcement, with the design being based on actual conditions and requirements for use。
1. Direct reinforcement methods for build-up structures
1 steel reinforced with concrete
The act is a form of compound cross-section reinforcement. The advantages are that the construction process is simple and adaptable, that the build-up is accompanied by a significant increase in carrying capacity and mature design and construction experience; that it applies to the reinforcement of columns and walls; and that its disadvantages are that the on-site construction has a long wet operation that has some impact on production and life, and that the reinforced buildings have a reduced net empty space。
2. Slurry reinforced by steel and cement
The act is a form of compound cross-section reinforcement. Its advantages are similar to those of reinforced steel-condensed concrete, but less so as to increase the carrying capacity; it applies to reinforced walls, and sometimes also to the closure of walls on both sides when reinforced by reinforced walls。
3. Add a pillar reinforcement
The act is one of the ways of strengthening the cross-section. The advantages are also similar to those of reinforced condensed concrete, but the carrying capacity is limited and less likely to meet seismic requirements, usually applied only in non-earthquake areas。
2. Indirect reinforcement methods applicable to construction structures
1 no glued steel outsourcing enhancements
The advantages of the act, which is a traditional reinforcement method, are that the construction is simple, the on-site work and the wet operations are less demanding and less resilient; that it applies to pillars that do not allow for greater cross-section dimensions of the original component, but that require a substantial increase in the cross-section carrying capacity; and that it has the disadvantage of being more expensive to strengthen and that it requires the use of steel-like protective measures。
2. Pre-resilience pole reinforcement
The act increases the carrying capacity of the pillars more significantly and strengthens their effectiveness reliably; applies to the reinforcement of the structure of the bodies that handle high stress and high variability; and has the disadvantage that they cannot be used for temperatures above 600°c。
3. Tectonic strengthening and repair of the structure
1 - add a ring to strengthen
When the beam set-up does not comply with the current design specifications, or when the bite is clearly defective at the intersection of the wall, or when the house is less holistic, the beam should be reinforced。
2. Reinforcement of beam pads
When the bricks under the beam are partially crushed or there is a local vertical crack under the beam, the beam cushion shall be reinforced。
3. Local dismantling of structures
When the house is partially broken but the cause of the break-up has not affected the weight and safety, the break-up wall may be partially removed and filled with bricks at the level of increased solubility。
4. Fractal repairs
Before crack repair is carried out, the cause of the crack shall be determined on the basis of factors such as the stress status of the building blocks and the characteristics of the crack, so as to allow for targeted crack repair or corresponding reinforcement measures。
Concrete structural reinforcement methods
Concrete structures are reinforced in the form of direct and indirect reinforcement, and are designed to select appropriate methods and associated technologies according to actual conditions and requirements of use。
General approach to direct reinforcement
Increased cross-section reinforcement
The addition of an active concrete layer in the areas where the condensed concrete elements are under pressure increases the effective height of the cross-section and expands the area of the cross-section, thereby increasing the resistance of the components to the straight cross-section, the ability to tilt the cross-section and the condensity of the cross-section, thereby strengthening it。
Within the condensed range, the positive cross-section carrying of concrete components increases with the size and intensity of the steel bars. An increase in the area of the main band can be an effective means of increasing the capacity of the positive section of the original component to withstand bend loads, given the low level of cross-section sprite. The addition of an existing concrete encirclement section to the x-rayed area will effectively increase the carrying capacity of the components and improve normal usage performance by working together with new and original components。
The construction process for greater cross-section reinforcement is simple, adaptable and has mature design and construction experience; and the concrete applied to beams, plates, columns, walls and general constructions is reinforced; however, the work on the site has been wet for a long time, with some impact on production and life, and the net empty of the reinforced buildings is reduced。
2. Replace concrete reinforcement
The advantages of the act are similar to those of a greater cross-section, and the reinforcement does not affect the net emptyness of the building, but there are also shortcomings in the length of the wet operation of the construction; it applies to the reinforcement of concrete bearings such as beams, poles, etc., which are of low or severely defective strength in the pressure zone。
3 with adhesive steel reinforced
Fortified steel is a packaged steel or steel plate to the outside of the reinforced components, and fortified steel reinforced steel condensed concrete beams should normally be contracted wetly, i. E., the binding of the steel with the reinforced components into a whole by means of epoxy resin slurries, and reinforced components, with a significant increase in the size of the laminated and pressured steel transects, resulting in a significant increase in cross-section load and transectivity。
The act, also known as wet-source steel reinforcement, is robust, simple to construct, and has a smaller on-site workload, but uses steel in large quantities and is not suitable for use at high temperatures above 600°c without protection; it applies to the use of concrete structures that do not allow a significant increase in the cross-section size of the original building, but require a substantial increase in its carrying capacity。
4. Sticky steel reinforcement
Solid solids are reinforced by external viscosed steel in convulsive blocks by pasting steel plates on the surface of parts of components with insufficient carrying capacity (the straight cross is being pulled, the positive cross is being pressured or is tilted) so as to increase the carrying capacity of reinforced components and make construction easier。
The act's quick construction, on-site no-wet operations or only a small number of wet operations, such as dusting, has little effect on production and life and, if reinforced, has no significant effect on the original structure's appearance and on the original net empty space, but the reinforcement is largely dependent on the adhesive process and operational level; it applies to subdued or reinforced components in a static environment。
5. Embedding fibres for plastic reinforcement
Embracing of external fibres is the placement of fibre-enhanced composites with glued materials in the zone where the reinforced components are to be used to work with the reinforced cross-section for the purpose of increasing the carrying capacity of the components. In addition to the similar advantages of pasting steel plates, there are also advantages of corruption resistance, damp resistance, little structural self-reliance, durability and low maintenance costs, but they require specialized fire protection and are applicable to a variety of resistant concrete structures and general structures。
6. Ribbon
The advantages and disadvantages of the act are similar to the enhanced cross-section approach; it applies to situations where concrete building blocks have insufficient tilt bearing capacity, or where horizontal binding on pressured components is required。
7, anchor anchoring method
The act applies to the retrofitting and reinforcement of the concrete bearing structures with a concrete strength of c20 ~c60; it does not apply to the above-mentioned structures and the lightweight structures, which have been severely weathered。
General approach to indirect reinforcement
1. Pre-resilience reinforcement
(1) persistence of pre-resilient horizontal pull
The reinforced concrete at the pre-repulsive level is condensed and, as a result of the combined effect of pre-force and additional external loads, the pull generates an axle pull inside the pole, which is transmitted to the building through the anchor of the pole in a nuanced manner (when the pole is closely bound to the bottom of the beam, the pole is bent together with the component, at a time when a part of the pressure is passed directly to the bottom of the component), which produces a eccentric pressure in the component, which overcomes the bends generated by some of the outer loads and reduces the effect of the outer load, thereby increasing the anti-convulsive capacity of the component. At the same time, the pressure of pulling poles to components has led to reduced, controlled, and tilted cross-section resistant to shear loads。
Because of the horizontal lifting of poles, the cross-section stress feature of the original component has changed from bending to eccentric pressure, and therefore the carrying capacity of the reinforced component depends primarily on the carrying capacity of the original component under the convulsion state。
(2) reinforcement of poles under pre-resilience
A reinforced concrete component is fixed by a pre-resilient pull pole, which forms a composite ultra-silent structure consisting of a reinforced component and a down-resilient pole, which, acting in conjunction with the outer load and pre-resilient force, produces an axial force in the lifting pole and is transmitted to the reinforced component by means of a combination of points with the component (low-strength and pole-end anchor points), offsetting part of the load, changing the internal force characteristics of the original component and thus enhancing the carrying capacity of the component。
The act reduces the stress level of the reinforced components, not only to make the reinforcement work better, but also to increase the overall carrying capacity of the structure considerably, but the reinforcement has some effect on the original structure's appearance; it applies to the reinforcement of mass or heavy structures and the reinforcement of concrete components in high-resilient, high-resilient conditions, but, in the absence of protection, cannot be used for temperatures above 600 °c or for condensed and condensed structures。
2. Increase support reinforcement
The objective of the additional sub-point reinforcement is to reduce the computational boundaries of the bent building blocks to reduce the impact of the load on the reinforced building blocks and to increase the level of the structural load. The act is simple and reliable, but it is susceptible to undermining the original description and use of buildings and may reduce the use of space; it applies to the consolidation of concrete structures permitted under specific conditions。
3. Other enhancements
Auxiliary structural strengthening is the partial or total sharing of the load of the reinforced beams with alternative support components such as steel, steel slabs or condensed concrete beams。
With the addition of armpits in the vicinity, the effective level of cross-sections in the vicinity has increased, resulting in increased cross-section resistance and shear resistance。
3. Technologies for use in conjunction with concrete structural enhancement
1. Transfer of technology
A generic description of technologies such as the removal of pillars (or walls), beams and beams and beams; an integrated technology consisting of technology such as the reinforcement of the relevant structures, the elevation and repositioning of the upper structure and the removal of obsolete components; a retrofitting that applies to existing buildings; and the advantages of a short construction time, low cost and low impact on life and production compared to traditional practices, but higher technical requirements, which require skilled workers to do so to ensure safety。
2. Tighting
A simpler and effective connection and anchoring technique for concrete structures; it can be implanted in ordinary steel bars or bolt anchors; it has been widely applied to the retrofitting of existing buildings, such as the remediation of broken steel bars or the deviation of steel bars from the design position in the construction work, the reinforcement of components by an increased cross-section, the extension of the upper structure, the length of beams, poles, floors and the embracing of the upper structures。
3. Combination technology
Depending on the cause, nature and size of the concrete cracks, different cover-up methods are used to repair them, allowing for the restoration of the reduced use function and durability of the structures as a result of the cracks; they apply to the treatment of the various types of cracks in existing buildings, but, in addition to repairing, corresponding reinforcements are required. Internal amendments。
The internal process of repairing is the use of a pressure pump to put glue material pressure into concrete cracks, which is rigid and which restores the wholeness of the original structure through its adhesiveness. The method applies to the larger width of the cracks, which affect the integrity and safety of the structure and its durability, or to the repair of the cracks required, for example, to protect against water seepage。
4. Technologies for carbonized concrete restoration
This refers to techniques that contain the corrosive erosion of steel by carbonization by restoring or increasing resistance to the alkaline (passivation) of concrete。
5. Concrete surface treatment technology
This refers to specific techniques for cleaning concrete surface stains, oil trails, residues and other attachments, such as chemical methods, mechanical methods, sand spray methods, vacuum fumes and water pumping methods。
6. Concrete surface sealing technology
Technology for waterproofing, tideproofing and fracking of concrete using flexible sealant filling, polymer slurries, coatings, etc。
7. Other technologies
E. G. Structure, building transfer technology, restructuring self-invulsive frequency technology, etc。
