For reinforced concrete structures to be strong and long-lasting, reinforcement is essential. Adequate reinforcement guarantees that structural elements, such as beams and columns, can withstand the loads and stresses they are subjected to. All engineers and builders must be familiar with the fundamental procedures and methods for strengthening these structures.
Two of the most frequent elements that need reinforcement are columns and beams. Columns are essential to a building’s stability because they bear vertical loads. Conversely, beams manage horizontal loads and give vital support for roofs and floors. For each type of structure to function properly and safely, specific reinforcement techniques are required.
To reinforce columns and beams, a variety of strategies and tactics are used. The choice of reinforcement relies on various factors such as design specifications, load requirements, and environmental conditions. Conventional steel bars and contemporary composite materials are among the options available. We can learn more about how to improve the lifespan and performance of reinforced concrete structures by investigating these techniques.
Element | Methods and Techniques |
Columns | Use vertical and horizontal rebars, stirrups for confinement, ensure proper spacing, use tie bars to hold rebars in place, and maintain cover to protect against corrosion. |
Beams | Utilize longitudinal rebars for tensile strength, use stirrups for shear reinforcement, ensure proper anchorage of rebars, and maintain adequate cover to protect against environmental factors. |
In order to guarantee strength and durability, reinforcing reinforced concrete structures, such as columns and beams, requires a number of crucial procedures. This article examines these fundamental techniques, emphasizing how appropriate reinforcement maintains a building’s structural integrity, can sustain loads, and guards against failures and cracks. A clear explanation of fundamental reinforcement techniques will provide readers with a useful understanding of how to improve the longevity and performance of concrete structures.
- Why is reinforcement of structures required
- Works to strengthen reinforced concrete structures
- General information
- Indications for the use of work to strengthen floors
- Video on the topic
- Reinforcement of brick columns with a metal clamp made of an angle
- The best ways to fix a beam on a reinforced concrete column | Design of reinforced concrete structures
Why is reinforcement of structures required
The purpose of any reinforced concrete structure strengthening operation is to increase the structure’s capacity to support loads and increase its lifespan. A variety of products can be restored if they have been worn down over time or if external factors such as negative influences cause them to lose certain qualities.
- Increasing the load on the element due to strengthening or replacing structures located above (superstructure, reconstruction of premises).
- Modernization of process equipment and changes in process processes in a building that is being reconstructed.
- Acquired structural defects that have appeared as a result of improper operation of structures, spills or splashes of aggressive liquids.
- Operational wear and tear (when the bearing capacity is lost due to the impact of vibration/dynamic loads, the influence of an aggressive air environment and other factors).
- Accidental damage – when individual elements of the structure fail during dismantling, installation or transportation of process equipment.
Works to strengthen reinforced concrete structures
Concrete structure strengthening can be accomplished in a number of ways, some of which require the application of specific measures.
- Increasing the cross-section of certain components of structures – is implemented by concreting in layers with a reinforcing frame, by shotcreting, by injecting mortar into formwork.
- Strengthening of load-bearing parts by installing new elements – is achieved by correctly distributing pressure, reducing the impact on the part by installing additional elements.
- Increasing the technical characteristics of reinforced concrete products by installing external reinforcement frames – various anchors, channels, reinforcement, concrete layers, prestressed parts, steel sheets, etc. are installed..
- Release and accurately distribute the impact by transferring it to other parts of the structure – for this, new consoles are added, existing parts are modified, parts with a large mass are replaced with elements with a smaller mass.
- Installation of special soles, concrete piles, stops underground – usually using the method of drilling holes with diamond drills in the right places and then filling them with concrete mortar. This helps to increase the durability of underground elements.
General information
Any technique for reinforcing reinforced concrete structures entails significant and responsible construction operations, the execution of which calls for specific design expertise, computation knowledge, etc. Elements can be strengthened and rebuilt using a range of techniques.
When compared to traditional installation work, the processes involved in strengthening reinforced concrete structures are among the more complex ones. After all, the master does not have the chance to comprehend and observe the original position of the structure, there are no precise technical characteristics, etc., when restoring slabs or floors, foundations or trusses. This is particularly crucial to take into account in the case of older structures because of the dearth of knowledge regarding the placement of internal components, reinforcement, actual pressure distribution, etc.
Owing to the elevated degree of danger involved, these procedures are executed meticulously as per guidelines, adhering to numerous safety protocols and safety precautions. Particular installation circumstances are considered, such as restricted tool access, constrained space, and no ability to halt work.
With a clear definition of methods and technology planning, everything is done in accordance with a pre-prepared schedule to minimize risk and expedite work.
Qualified specialists from special government services are in charge of the work. In some cases, projects need approval before they can be properly carried out.
- Creation of unloading structures with a sequential change in the static work scheme.
- Building up sections in the format of clips, concrete blocks, shirts. Concrete blocks are made on 1 side, a shirt – on 3, a clip – on 4.
Production does not have to stop when creating unloading structures, which is often the most crucial aspect. Instead, the structure is strengthened directly during installation through collaborative work.
The second approach is pausing the work, partially unloading the structures in preparation for further loading, and incorporating various built-up element types. The technique is widely used, but it is labor-intensive, necessitates wet concreting procedures, and takes longer as the concrete gets stronger.
The following techniques are used to strengthen reinforced concrete structures by repairing the concrete’s protective layer: sealing individual chips and cavities and replacing or restoring the layer entirely or partially. The protective layer becomes thicker during a continuous replacement (minimum thickness is 3 centimeters for working reinforcement and 2 centimeters for non-working reinforcement and clamps).
When the monolith’s properties are compromised, the reinforcement is coated in corrosion, or peeling of the protective layer is noticed, the protective layer is replaced. Subsequently, the previous layer is entirely eliminated, the reinforcement is free of rust, and a fresh layer of concrete is applied for protection.
In order to prevent further deformation of the structure in the event of significant damage to the surface concrete layer, reinforced concrete jackets are constructed. Use a trowel and manual plastering techniques to repair large damage. First, lay the material, then moisten it with water an hour later. Next, carefully sprinkle on the dry cement and smooth it with a trowel or metal/wood trowels.
The chipped areas should have a minimum depth of 1 centimeter throughout, with a gradual transition at a 90-degree angle from the chip to the entire protective layer. The depth of the chipped areas should not decrease towards the recess edge.
Shotcrete, which is applied under high pressure to form a strong and dense protective layer, is relevant if the amount of work is substantial. Single cracks wider than one millimeter are divided into a rectangle and calked with concrete when a monolith is ready for concreting. Use a reinforcing mesh with squares of 2.5–10 centimeters and a wire cross-section of 0.5–6 millimeters, fastening them to the main reinforcement where the chips are large and the reinforcement is visible.
Apply a layer of K-153 glue (epoxy-thiokol) to the concrete to improve the adhesion between the old and new. The adhesive is applied until the concrete is laid.
The most popular technique for strengthening structures is to create all-around clamps or extend one side of the structure to increase the cross-section. The bearing capacity of damaged or whole elements can be greatly increased by using such strengthening techniques.
In the event that a reinforced concrete structure’s cross-section is increased on one side, new reinforcement is welded (by electric welding, double flank seams) to the existing one using vertical and inclined clamps, short pieces, and bends.
The structure is strengthened in the following ways if there are local damages in the form of single or concentrated cracks with a minimum length: Local four-sided clamps are composed of metal clamps from prestressed vertical stirrups and reinforced concrete (reinforced with stirrups, bent/longitudinal reinforcement).
Longitudinal distribution angles, which should cover the entire damaged portion of the beam, are mounted beneath the stirrups when oblique or vertical cracks are noticed. Every stirrup has a shotcrete or concrete covering.
If the columns need to be strengthened, stirrups, spiral reinforcement, and longitudinal rods are used to reinforce the collars. The collar may be covered with shotcrete or concreted inside the formwork. For regular concrete, the wall must be at least 10 centimeters thick; for shotcrete, it must be 5 centimeters thick. It is preferable to chip away at the corners of the reinforced column.
The step of the stirrups is halved at the bottom and top of the column, along a length that matches the largest transverse diameter of the column. In the event that there are local defects, a reinforcing collar is constructed within the deformed zone’s bounds, ensuring a bypass of at least 50 centimeters in both directions.
- On the reinforcement side, chip off the protective layer at the welding points, clean the longitudinal reinforcement bars to half the diameter.
- Wash the concrete surface with a jet of water under pressure, if this is not possible, make notches with a chisel, brush, blow with air to remove dust, and then rinse with water.
- Apply plastic concrete to the wet surface (solution in a ratio of 1:2, in a layer 1-2 mm thick).
- Concret with new concrete.
Using metal brushes, sandblasting, or other techniques, all exposed reinforcing bars are meticulously cleaned to remove any rust, dirt, or scale. If the damage to the bars is severe, use a hammer or chisel to remove the damaged film, clean with a steel brush, and then weld new reinforcement. The bars are painted with a 1:2 cement mixture in a 2 mm layer prior to concreting.
The installation of the formwork allows it to be progressively raised to match the height of the reinforced beams and columns. When building formwork, make sure it has the appropriate holes and gaps, as well as special trays for concrete pouring and compaction. After that, give sprayed shotcrete or poured regular concrete the best maintenance possible.
Indications for the use of work to strengthen floors
In an emergency, actions are taken to enhance the properties of floors made of reinforced concrete. It is not possible to implement a set of measures for prevention or just that.
- The product has worn out and the strength indicators have decreased due to corrosion, deterioration of the properties of materials, due to external chemical influences.
- Change in the layout of the building – when the design of the load-bearing elements changes, as a result of which the pressure on the elements is redistributed.
- Increasing the number of floors in the building, which increases the pressure on the foundation, basement, ceilings, other elements, as a result of which deformations may appear.
- Soil movements that cause deformations of the foundation increase the load on the supports and walls, load-bearing elements of the structure.
- Deformation/wear of individual building elements due to military, man-made, natural impacts, accidents, etc..
- Reconstruction of the building or change in functions, due to which new methods of destruction appear (high temperatures, vibration and other impacts).
- Elimination of miscalculations that were made during the preparation of the project or the implementation of installation operations.
These are the primary issues, and reinforcing the ceiling might help solve them. After a careful analysis to determine the properties of the constituent parts, their ultimate strength, and the loads acting on them individually, the decision to reinforce the reinforced concrete structure is made.
Following the research, a project is developed based on the findings, which include the recommended reinforced elements, all technical data, and an indication of the costs associated with the various activities. It is usually impossible to do everything correctly without experience and knowledge, so professionals from design companies handle the calculations for strengthening floors.
For reinforced concrete structures to be stable and strong, reinforcement is necessary. The main load-bearing components in construction, columns and beams, need to be precisely constructed to ensure that they can withstand a variety of stresses.
Vertical reinforcement for columns aids in buckling prevention and compression resistance. These bars become more stable and effective when they are joined together with horizontal ties.
In contrast, beams require reinforcement in order to withstand shear and bending forces. Longitudinal and transverse bars that are positioned correctly can support weights and withstand cracking over time.
In general, safe and long-lasting building construction depends on knowing and using the proper reinforcing techniques for columns and beams. Reinforced concrete structures can have the desired longevity and performance with proper planning and implementation.