The short answer is yes and UAE contractors have been doing just that for years. Residential towers, commercial office buildings, parking structures, schools and industrial buildings are already built using precast concrete columns in Dubai, Abu Dhabi and other areas. This is not an ideal application that has yet to be implemented — it is already the norm on a majority of the area’s multi-storey schemes.
This guide explores the structural logic behind how it works, real height and connection possibilities, the UAE regulatory framework and the ever growing need for precast columns for multi-storey construction.
The Only Real Question Here is Why Precast Columns are Effective for Multi-Storey Buildings
Precast column is a vertical structural member that is designed to transmit loads from the floor and beam above to the foundation, and is cast in the factory. The true engineering problem on any multi-storey building is not if the column can support vertical loading, but if the entire frame can resist the lateral forces of wind, sway and, in appropriate areas, seismic loading.
The answer to this question is frame type. Generally, the most economical and structurally efficient method of multi-storey precast construction is a pin-jointed braced frame where the shear walls or diagonal bracing provide the sidesway resistance rather than the columns themselves. The Precast/Prestressed Concrete Institute’s structural engineering literature indicates that unbraced frames are only practical up to approximately three storeys whereas the practical limit of braced frames is around 20 storeys.The Precast/Prestressed Concrete Institute’s structural engineering literature suggests that unbraced frames may be used up to approximately three storeys, whereas braced frames can reasonably be extended to approximately 20 storeys.
It’s the structural logic that underlies most multi-storey precast systems: the columns are designed to resist gravity loads, and the shear walls or cores are typically located around lift shafts and stairwells and designed to resist lateral loads. The two systems function as one and do not demand that one element perform two functions.
Just How Tall Can Precast Columns Get?
It is one of the most frequently asked questions by engineers and it is usually not what one would expect. Precast columns can be cast in a single continuous pour of approximately 18m, covering approximately 5 storeys, which would not have an inter-column splice point.Precast columns can be cast in a continuous pour of approximately 18m or between 5 storeys without any inter-column splicing point.
If the structure is taller, the connections between the columns go up that height. Depending on the structural design, columns can be connected by threaded rod connectors with concrete cast around the joint or through bars embedded in grouted sleeves with a thin stitch between column segments. This connection detailing is significant enough to be regulated by international standards, specifically ISO 20987:2019 which refers to joints between column segments in multi-storey precast structures, and column-to-foundation joints designed for fixed support.
Using appropriate bracing and connection detailing, a well-designed precast column system can be realistically used for buildings in the 15-20 storey range. In addition, precast columns that take gravity loads are typically used in conjunction with cast in place concrete cores that offer the lateral stiffness that taller buildings require.
Precast Columns Across the UAE Multi-Storey Market
But in the UAE, the answer to the question “can this be done?” is already known, because that is what is being built. Precast beams and columns are ideal for fast-track and conventional projects and are produced by manufacturers throughout the country for low-rise projects to high-rise towers, parking structures and bridges.
In this application UAE suppliers document it themselves in their technical materials. As more and more concrete is being used in taller structures, the ability to meet speed and quality requirements makes precast concrete an attractive option for high-rise towers, office and institutional projects — especially when open floor layouts are important. Precast beams and columns are also routinely used for parking structures and mixed commercial/residential projects, frequently used in conjunction with wall panels, hollow core slabs and double tees for a complete precast package.
Using Column Types and Shapes for Multi-Storey Applications
Not all column profiles are appropriate for every project, and therefore, it is important to have an understanding of the range, in order to specify early on in the project.
Rectangular Columns
Rectangular columns still are the main workhorse of the building industry, easy to produce, easy to join and work with most beam systems for all levels of multi-storey construction.
Circular Columns
Circular columns are clearly superior in appearance in areas of the building where they will be seen such as the car park entrance, podium level or building lobby, yet maintain the structural performance.
L-Shaped and T-Shaped Columns
L-shaped and T-shaped columns are used in more complex structural situations, such as connecting columns with beams, where corbels are needed, or in a particular architectural design to use non-standard column profiles.
Prestressed Columns
Prestressed columns are used where architectural considerations require extremely thin cross-sections or when a column is required to provide more than the normal amount of uplift for a given reinforced cross-section.
For the Past Decade, They Have Been Working Together on the Same Projects.They Have Worked on the Same Projects for the Past Ten Years
Unless someone has a brilliant new idea for handling the connection of multi-storey precast columns, I don’t know of any other aspect of the design that is worth an engineering look at. A column supported by a foundation must be securely joined to the foundation. A column that is connected to the one above must have a joint that will transfer the force and moment reliably.
The connections at the ends of precast beams are also important — either a base plate on the column or reinforcing bars from the end of the beam through sleeves that are filled with grout. When erecting columns, temporary bracing is necessary until all beam and slab connections are made and the stability of the frame is as desired.
The capacity to deliver good results vs expensive results is really the place the difference lies between supplier capability. If the manufacturer does not provide technical engagement, and leaves the connection engineering solely to you, that will bring real risk and time to the project. The stronger UAE suppliers enter the design process early as structural engineers and create the complete shop drawings prior to any component entering production.
The UAE Regulatory Framework
The UAE has a well-defined regulatory framework for precast concrete design of multi-storey buildings, and it is not just optional guidance; it’s the requirement for compliance. Dubai’s adopted building code is based on the principles of the International Building Code (IBC) which include wind, seismic and live load calculations, with detailed seismic analysis required for high-rise buildings under Dubai’s overlaid Seismic Design Code requirements.
Before ordering, it’s important to make sure the certificate is still valid, as a certificate that has expired months ago will not be valid again just because the company has been continuing operations.It is important to ensure that before ordering the products, the certificates are not expired, as an expired certificate months ago will not be valid anymore, even if the company keeps on operating.
Why Demand Keeps Rising
There are four practical reasons why precast columns continue to grow in popularity on UAE multi-storey projects.Precast columns continue to grow in popularity on UAE multi-storey projects for the following four practical reasons.
The top three, in order: speed. The difference that can make the difference in a multi-storey construction program is the fact that factory-cast columns are ready for installation without the need for formwork, pouring, curing and stripping.
Controlled factory production leads to consistent quality. In UAE summer temperatures, on-site concrete curing is indeed unpredictable because of the impact of extreme high temperatures on hydration, finishing and strength development which is avoided in factory controlled curing.
Design flexibility is more than meets the eye of most developers. Precast concrete skeletal frame systems have been documented supporting buildings that are taller than the typical mid rise; thus, more room is available for architects and structural engineers to work than justifying the “precast means boxy” assumption.
When it comes down to it, all that’s left is cost efficiency. The elimination of standardized molds, repeatable labor processes, and material waste make factory production a real competitor to cast-in-place methods, and the savings in schedule directly impact developers of both commercial and residential projects.
Final Thoughts
Multi-storey construction using precast columns has already been proven and popular in the UAE, and it is not just a solution for an unusual project, but a necessary solution. It is supported by the structural engineering literature, has been well documented by the UAE’s big manufacturers and the buildings seen in every emirate.
The four keys to getting it right are: the right approach to bracing for your building height, early proper engineering of connections, and a DM-certified supplier that offers real technical support, and a structural engineer from the onset. With the right four elements, precast columns provide exactly what UAE developers require – speed, quality and durability – whether the project is a small residential building or a true high-rise.