Reinforced concrete columns (precast, reinforced concrete, RC): installation, manufacturing, characteristics

Welcome to "All about Concrete," where we explore the intriguing realm of columns made of reinforced concrete. These structural components are essential to contemporary building because they give structures of all sizes stability and strength. We will examine the production, installation, and essential features of reinforced concrete (RC) columns in this post.

Columns made of reinforced concrete are vital parts of construction projects because of their strength and ability to support weight. To increase their strength, concrete is usually poured around a framework of steel reinforcement bars, or rebar. Because of their material composition, RC columns can effectively resist tension and compression forces as well as large loads.

The production of reinforced concrete columns necessitates exact execution and careful planning. First, structural specifications and architectural drawings are used by engineers to design the column. The next step is to prepare the concrete mixture, which consists of cement, aggregates, water, and additives, to the appropriate strength and workability.

When the concrete mixture is prepared, it is poured into a formwork that maintains the column’s shape. For in-situ casting, this formwork can be temporary; for precast columns, it can be permanent. Precast columns allow for controlled curing conditions and quality assurance because the concrete is poured into reusable molds off-site.

The rebar framework is carefully positioned within the formwork following the pouring of the concrete. To provide the best possible structural integrity, the steel reinforcement bars are positioned strategically in accordance with engineering specifications. With this reinforcement, the column is guaranteed to be strong and able to bear forces from both the sides and the top, keeping its shape over time.

It takes several crucial steps to install reinforced concrete columns correctly, ensuring structural integrity and alignment with the building framework. Cranes or other lifting machinery are used to move precast columns to the building site and raise them into place. In order to ensure a tight fit and alignment, on-site casting entails pouring concrete directly into structural supports or prepared foundation holes.

Once erected, columns made of reinforced concrete greatly increase a structure’s overall stability. They distribute loads to the foundation effectively and offer crucial support for beams, slabs, and other structural components. Because of its inherent qualities, which include its resilience to fire and adaptability to different environmental conditions, reinforced concrete is a highly preferred material in construction projects all over the world.

In conclusion, because of their strength, resilience, and adaptability, reinforced concrete columns—whether precast or cast on-site—are essential elements of contemporary construction. It is imperative for engineers, architects, and anyone involved in building design and construction to comprehend the manufacturing process, installation techniques, and essential characteristics of reinforced concrete columns.

Watch this space for more articles in the future as we delve deeper into concrete and all of its uses.

Purpose

Any reinforced concrete column’s primary function is to implement support for various building structures. Support beams, girders, purlins, arches, and balconies with columns. For added strength, metal rods are used to reinforce the heavy concrete used in their construction.

Columns are typically used to reinforce single- and multi-story residential and commercial buildings. Columns are relevant wherever it is necessary to transfer and distribute the load from floor structures and other elements in an even manner.

Columns take up the loads of the components above and transfer them to the ground when building frame-panel housing. In the construction of industrial complexes, columns are positioned all over the place to support floors, beams, and other structures.

Not only can columns made of reinforced concrete support heavy loads, but they also give the structure spatial rigidity.

Features of structures

Precast reinforced concrete columns are vertical elements with a small cross-section formed from a reinforced concrete mixture. Usually, they are employed to build a connected framework or frame.

• Head – takes the weight of the structure above.
• Rod – transfers the load from the head to the part below.
• Base – evenly distributes pressure and load along the foundation.

When neither of the two axes intersects the section, the rod can be classified as either of the two types. Pre-stressed reinforced concrete is used to create columns. There are two different forms of compression used: eccentrically compressed structures also absorb the bending moment, while centrally compressed structures only absorb the rod’s axial load.

Columns made of reinforced concrete are only used in compliance with technical requirements. Centrally compressed products are therefore limited to supporting roles and are installed in tunnels, residential buildings, and other locations where the supports are only subjected to vertical (axial) loads. Eccentrically compressed products are installed in areas (like workshops with overhead cranes) where the columns are also impacted by axial load.

Properties and characteristics

Every column made of reinforced concrete has to adhere to a set of rules and regulations. The number of storeys of the future building, its intended use, the local climate and weather, particular estimates of anticipated loads, etc. are all taken into consideration when choosing products for a given construction.

• High resistance to external influences
• Compliance with the bearing characteristics specified in the documentation
• Ability to maintain original properties in a humid environment
• Stability to seismic negative impacts
• Resistance to subzero temperatures
• Long service life
• Rigidity and strength – the ability to withstand impact, deformation, mechanical loads

Any column made of reinforced concrete must have its load-bearing capacity as its primary feature. The building’s supports are positioned lower the higher the parameter. The highest load-bearing capacity precast reinforced concrete columns can be found in basements, lower levels of multi-story buildings, and single-story industrial facilities.

Columns with cantilever bulges at a level of three meters are used when building a structure with multiple floors. This indicates where the floor ends and is where the floors are put in place for the building of each new level.

Columns made of reinforced concrete are essential to the construction industry because they provide structures with strength and longevity. The installation, production method, and unique qualities of reinforced concrete columns are the main topics of discussion in this article. Every stage of the building process, from the painstaking manufacture of precast components to the on-site assembly of reinforced concrete columns, affects the buildings’ structural efficiency and integrity. Comprehending these procedures and attributes not only amplifies the pragmatic expertise of construction experts but also highlights the indispensable function of reinforced concrete columns in contemporary engineering and architecture.

Regulatory documentation

Every reinforced concrete column needs to adhere to all specifications and guidelines set forth by GOSTs and validated by pertinent documentation. Research and experiments are conducted, and the columns are examined through a variety of inspections before being brought into the market or construction site. As a result, everything needs to be thoroughly examined.

• GOST 25628 from 1990 – parameters of supporting columns for single-story buildings
• GOST 18979 from 1990 – specifies the characteristics of columns for multi-story buildings
• Series 04-1 – specifies the exact parameters for pouring the supports of a braced frame
• Series 1.823.1-2 – contains the technical characteristics of columns for agricultural buildings
• Series 1.423.1-3/88 – parameters of products used in the construction of single-story industrial buildings

What are they made of

Metal rods are put together into a mesh and then filled with concrete to create a reinforced concrete column. The GOST specifies the reinforcement coefficient and the rod diameter. Prefabricated/monolithic structures’ floors are maximally strengthened by the rods, which support the majority of the weight. Concrete is poured into the reinforcement using a specialized formwork; typically, cement grades M300–M600 are utilized for this purpose.

Rods or stronger reinforcing steel are used to reinforce columns. Products can be reinforced with cording, spiral reinforcement, clamp reinforcement, or no reinforcement at all, depending on the type of reinforcement used.

Types of products

Reinforced concrete columns can be square, rectangular, or round, depending on the kind of section. Production technology distinguishes between prefabricated supports (manufactured at the plant and delivered to the site ready-made) and monolithic columns, which are created directly at the construction site by pouring concrete into the formwork with a frame. Columns can be positioned as decorative elements on the facade, in the outer or middle row, or anywhere else depending on the building’s layout.

Columns can be butt and seamless on purpose. Buildings with a single story are constructed using joints-free supports. Butt columns from the lower, middle, and upper tiers are used to mount multiple columns on top of one another in multi-story structures.

The protruding consoles on the supports can have a height of 15 or 20 centimeters. They are made to support floor levels in between floors. Columns and non-console are present.

These days, columns made of reinforced concrete for two-story buildings are the most common. Their length is 8.4 meters, and they weigh approximately 3500 kg.

• K – for structures without bridge supports, overhead cranes and buildings equipped with overhead cranes
• KS – for structures in which there is a sagging lower chord
• KKP – building frames with bridge electric support cranes
• KD – for building frames equipped with electric support, overhead cranes, as well as structures without cranes
• KF – half-timbered columns (intended for half-timbering of wall fences of buildings)
• KK – used in the creation of building frames with bridge electric support cranes
• KDP – relevant for the frames of structures that are equipped with electric overhead bridge cranes
• KR – selected for frames of structures equipped with manual overhead travelling cranes
• KS – in structures where there is a sagging lower chord

Calculation features

It is vital to carefully carry out all calculations, identify the ideal load characteristics, and take into account the subtleties before choosing and installing columns. Therefore, for low-rise buildings (B30), columns filled with concrete with a strength of B15–B25 are used in production.

Compute the column’s cross-sectional area immediately. This parameter, which is determined using the following formula, aids in maintaining compression uniformity:

Once the area indicator has been established, you can compute the remaining parameters while accounting for the installation features, operating conditions, and other indicators that may have an impact on the column’s cross-section. Due to their complexity, the computations are typically carried out using specialized tools. It is necessary to consider the strength of the support and the likelihood that it will be connected to the building’s base and floor slabs. When using this parameter, the computed cross-section for reinforcing reinforced concrete beams is increased.

Installation of columns

For low-rise buildings, reinforced concrete columns are typically installed in a single piece; however, lengthy products are shipped in sections to the construction site for additional assembly. They are typically installed in a glass foundation or a column base.

Most often, columns are mounted on a glass base, pre-filling it with concrete. The width of the concrete layer can be different and depends on the project and the length of the support. Before starting the installation of reinforced concrete columns, marking is performed, marking the places on the base where it is planned to install the columns. If the products are mounted under the beams, then careful marking of the beam axes is performed from the side of the crossbars. Special clamps are mounted on very long columns.

Utilizing "on the weight" technology, they are installed by sending a crane into the base glass in accordance with the markings, after the supports are secured with frame fasteners. Next, the submerged column’s verticality is examined, it is lowered, and concrete is poured into the cavity, fastened with metal wedges or reinforced concrete.

It is forbidden to work on the supports in any way while the concrete is hardening in the cavities (and even more so, to lower subsequent elements of the structure).

Similar techniques are used to secure the supports in unique sub-columns; in this instance, the connection is welded. One of the support’s edges is welded while it’s still suspended. The entire installation is then completed using custom braces. After a thorough inspection, the intersection of the column and sub-column is welded, and the exterior is covered with concrete mortar.

Typically, square supports are mounted independently. However, the supports may be expanded and crane-mounted if they have crossbars. As previously mentioned, the lower columns are mounted in sub-columns or on a glass base according to their height. After that, they are examined and secured. After that, the columns are fixed to the lower supports’ ends (or beams).

• According to the marks with a thorough check of the position with a plumb line, connection using welding (column supports are used)
• On the ends of the supports with previously fixed conductors with checking along the breakdown axes
• Assembly on the ends of the lower columns with temporary fastening and mandatory checking by a group conductor

Modern construction relies heavily on reinforced concrete columns because of their strength, adaptability, and durability. These columns, whether precast or cast in place, are crucial structural components that sustain infrastructure and buildings all over the world.

Precast reinforced concrete columns are produced in controlled environments off-site, guaranteeing excellent quality and uniformity. This technique reduces construction time and costs by enabling effective production and quick on-site installation. Precast columns are delivered, set in place with the help of cranes, and are immediately prepared to support heavy loads.

Conversely, reinforced concrete columns that are cast-in-place undergo direct pouring and molding at the construction site. This approach allows for flexibility in design and can handle intricate architectural specifications. Before pouring concrete, construction teams carefully shape and reinforce the columns to make sure they adhere to strict structural and aesthetic requirements.

There are similarities between precast and cast-in-place reinforced concrete columns. To improve their ability to support loads and withstand cracking under pressure, they are reinforced with steel bars or mesh. The majority of the column structure is composed of concrete, a composite material that is renowned for its strength and durability and for its ability to withstand compression forces.

The performance and sustainability of columns made of reinforced concrete are still being enhanced by recent developments in concrete technology. Cutting-edge reinforcement materials and high-performance concrete mixes are examples of innovations that improve structural integrity while having a smaller negative environmental impact. These advancements guarantee that reinforced concrete will always be a mainstay of building projects, satisfying the requirements of the infrastructural difficulties of the modern era.

In summary, precast or cast-in-place reinforced concrete columns are an example of how engineering precision and real-world application can coexist. Their manufacturing and installation procedures emphasize dependability and efficiency, which are essential for guaranteeing the security and durability of infrastructure and buildings. The versatility, durability, and strength of reinforced concrete make it an essential material for use in a wide range of architectural and engineering contexts, even as construction techniques change.

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