When you think of a total precast building system you think of a well-rehearsed orchestra. Each instrument plays a particular role and no one can substitute for another. The brass section is the fundamental, load-bearing and essential structure, which is considered as precast columns. If they are not in place, the whole show wouldn’t work.
Today, total precast building systems have become a mainstream approach for delivery of structures ranging from residential towers, to industrial warehouses, in the UAE construction market. In those systems, precast columns do more than just support; they are integral to the system. This guide covers all of this — and how and why it all begins with the column design.
What is a Total Precast Building System through Columns?
It’s helpful first to have an understanding of what is meant by a total precast system, before examining the role of the column itself.
Precast concrete Columns can be the main structure of a building, which acts as the roof, floor, and lateral load transfer system. If both structural and architectural precast elements are designed as an integrated, coordinated system, it is called a Total Precast System (TPS).
With a total precast building, the entire structure and the facade are made up of concrete prefabricated pieces that interrelate and connect seamlessly from the start, functioning as a single entity. Every element, from foundations to facades, is designed together for perfect harmony rather than pieced together from various systems and systems that are hoped to work well together.
Total precast buildings consist of a number of precast elements such as footings, beams, slabs, columns, walls, facades etc. Partial precast construction is a mix of precast elements and cast in place concrete members which are called hybrid construction.
Leading manufacturers such as Gulf Precast, Hard Precast Building Systems (HPBS), Abu Dhabi Precast and Dubai Precast all provide end to end total precast building systems in UAE. The column is one of the first components that is placed in the ground — and one of the most important to coordinate properly throughout the entire system.
The Second Most Critical Role is Primary Structural Role – Gravity Load Transfer
The primary function of the precast column in a total precast system is to transmit the gravity loads (weight of each floor, each beam, each wall and each occupant above) safely down through the system to the foundation.
A vertical member of structural support that transfers loads from beams, girders and slabs to the foundation. They can use particular features or fittings, as per the necessity of the project.
Precast columns are made in a controlled environment out of the way of the job site to provide vertical load-carrying capability. They maintain both stability and proper performance of the building by conveying the loading on the slab and beam through the slab and into the foundation. The elements are engineered for both axial and lateral loads and pre-engineered connections ensure speedy on-site erection.
This load transfer takes place in a staged sequence in a total precast system. Hollow core slabs or double tee slabs are used as floor slabs, which are linked with precast beams. The beams support on corbelled precast columns. The columns support and transfer the weight of all the floors above them to the foundations below. All components in the chain rely on correct positioning, sizing and connection of the columns.
The Skeleton Frame: What the Precast Concrete Columns Do to Create the Structural Grid
Precast columns are not always used individually. They describe the overall structural framework of the building; the spacing of the bays, the floor-to-floor heights, and the structural frame’s relationship to the architectural layout of the building.
Precast beams, rafters or trusses are supported across the bays by columns which may be single or multi-storey in height in a skeletal frame system. It enables the use of large columns, spaces between, little or no visual disruption in open spaces and the use of a variety of cladding elements for the facade.
This ability of an open plan is one of the most valuable commercial properties of the total precast system in UAE market. The developer of a commercial office tower, logistics warehouse or multi-storey car park requires clear and unobstructed floor space. The precast skeletal frame (columns at the structural grid intersections and nothing more) provides just that.
A full precast system building can typically be constructed within 10 – 14 days per floor according to the building area and logistics capacity. The frame system may be designed to resist lateral loads with core or shear walls used to provide additional lateral load resistance as required.
That’s a rate of 10 to 14 days per floor, not a theoretical rate. It has been proven by UAE manufacturers in actual projects. The speed is made possible by the use of and columns — factory-cast columns that are delivered on-site ready to stand and will have no curing time, and no formwork to strip.
The Column is a Place to Connect the System to Itself as a Connection Hub
Now this is something truly interesting in structural engineering with precast columns. With total precast building systems, the column is more than a vertical load carrier. It is the main connection point where beams, slabs, walls, the staircase components and foundation components meet and share forces among each other.
For precast concrete structural columns, the connections and supports are key elements in providing the stability and continuity of membranes. Depending on structural requirements, the column is connected to the foundation by grouted pocket systems, anchor bolt base plates or grouted sleeve connections.
Each level of the column supports the beam through cast-in corbeling or steel insert plates. The hollow core slabs or double tee units now support the beams which in turn create the floor diaphragm. All of the loading is done through the column.
The most important part of the prefabricated systems are the connections between the components in the precast system. The joint should resist any external loading forces including own weight, live loading and seismic forces. The joining of precast columns and beams should be made quickly, efficiently and structurally sound.
It is this connection role that makes precast column design a crucial engineering concern from the outset of any project in the UAE. If the corbel is not detailed adequately, the grouted sleeve is not designed properly or the cast-in plate is not aligned, it causes problems that cascade throughout the system. To ensure connection detailing is an integral part of the design, rather than an afterthought on site, the better precast manufacturers do this.
The Lateral Stability System Comprises Precast Concrete Columns That Work in Conjunction with Shear Walls
One of the most prevalent misunderstandings about total precast systems is that columns are exclusively used to resist lateral loads such as wind pressure, building sway and in some areas, seismic loads. They don’t work in isolation in well-designed systems.
The economy of precast should be obvious when considering both gravity load-bearing and lateral load resistance in an entire precast concrete building system. Precast shear walls provide a structural core on which lateral loads are passed through floor diaphragms. The shear walls connect to each other both horizontally and vertically and at corners so that they provide a structural tube, which cantilevers from the foundation. All lateral loads are transmitted to a moment resisting frame with rigid connections between beams and columns, where necessary.
In UAE building design, the optimum total precast building system consists of shear walls around lift shafts and stair cores. Within a structural system, the lateral loads (wind and seismic) are transferred through the floors and roofs as well as gravity loads. These components also provide bracing to vertical elements and protect them against abnormal loading.
The precast columns take the gravity loads. Shear wall cores are used to resist lateral loads. Distribute lateral forces over the floor plate to cores is the function of the floor diaphragm. The outcome is a system in which each part performs its most appropriate function — and no part is required to perform in a counter instinctive way.
This is What UAE Total Precast Systems: Real Project Evidence Has to Say About Precast Concrete Columns
The UAE’s top precast production companies are large enough to make total precast building systems true reality for any type of project.
Gulf Precast’s engineers can design a cast in situ solution and turn it into a precast solution to create value engineering savings. The company has knowledge of the structural design of total building systems, redesigning from conventional to precast systems, the manufacturing of precast and prestressed concrete components, and the erection and turnkey delivery of precast/prestressed concrete projects.
The Total Precast Solutions provided by HPBS range from design and value engineering to manufacturing, logistics and installation of precast concrete products. The Dubai Investment Park facility produces some 700 cubic metres of precast elements in a day and has a fleet of 106 trailers and trucks on site delivering precast elements to the site throughout the UAE.
These are not precast column manufacturers. They not only join columns, beams, hollow core slabs, walls, staircases and foundations together as a coordinated structural system, but do so with a single team, handling design coordination, manufacturing sequencing and erection. The column is the base of the whole system and also the point of stability around which the whole system is designed and offered.
The Ability of the Column to be Designed Allows for Architectural Freedom
It is often thought that precast construction is a “one size fits all” approach — that if a building is made of standardised factory components, it has to be a standardised building shape. In fact, the opposite is frequently the case for a precast system of which the columns are a component.
Precast concrete is a versatile material that can create nearly any form — curved and radial sections, adaptability in connection points and load paths. High strength, prestressed concrete structural members provide high strength and provide smaller sections, longer spans or both when compared to other structural systems.
The smaller section of the column frees the flexibility of the architectural floor plan. Incorporating the longer spans between the columns allows for fewer columns, creating space for retail space, parking, or open office plan areas. In lobbies, entrance canopies and podium structures, circular or L-shaped columns meet the architectural requirements without impacting the structural system’s performance.
The best building systems are not necessarily ones that have a lot of things bolted on. These are the ones that are solved, that the structure, envelope, performance and finish are solved as one engineered piece and only sent to site. This is the Total precast frames approach — performance and freedom of the building design with fewer elements, quicker and more lasting service life.
Build Up the Benefits of Designing a System Centered on Precast Concrete Columns
One of the most commercial motivating factors for a UAE developer to adopt total precast systems is the issue of speed. The direct and measurable contribution of the precast column to that speed is what’s being discussed here.
By eliminating multiple trades on site and having multiple precast elements being installed in a coordinated way to create an insulated, robust superstructure, a total precast system can see up to 25% increase in construction time.
On-site, columns are delivered ready prepped for corbelling, with connections pre-detailed, and reinforcement projections in place. The crane is used to lift the column and to set it on the foundation connection that has been created, and erection can be done at once. No formwork assembly, no rebar fixing, no pour and wait. The sequence of the next column of picks is the same.
It is very important to detail precast columns. It helps to position lifts correctly, minimising risk and enhancing efficiency when handling and transporting. Easier coordination of beams, slabs and footings will also continue as construction works proceed due to the smooth detailing.
The UAE job involved a 20-storey residential tower that had the same floor plates repeated over hundreds of column lifts and on this project, that consistency of detailing is multiplied by programme savings, that a cast-in-place job can never beat.
What This Means to the UAE Developers and Contractors for Precast Concrete Columns
The function of precast columns in total precast building system is not only a theoretical study. It has real commercial ramifications for all stakeholders.
It allows developers to finish the programme quickly, control costs and have buildings that can be transformed into commercial or residential open plan space, without columns blocking usable floor space.
For structural engineers, it is designing up-front, rather than bolting on at the end, connections, column-shear wall interaction.
For contractors, it means arranging crane picks, deliveries and temporary propping to align with the precast erection logic as it is not necessarily aligned with a traditional cast in place pour schedule.
For procurement teams, it translates to getting it from a DM-certified UAE precast manufacturer that supplies columns, part of a total precast system that is fully coordinated with beams, slabs and the walls that interact with them — not as separate products that are not connected to the rest of the system.
Gulf Precast has a vast experience in structural design for the entire building system, converting a conventional building to a precast system and delivering the entire project from design through to last element installed on site.
Final Thoughts on Precast Concrete Columns
The total precast system starts with the precast column. All of the beams, slabs, walls and stairs in the building ultimately transfer back to the ground through those columns. If they are correct in size, accurate in detail and produced to a confirmed quality, everything in the system will operate as intended.