The Burj Dubai represents the state-of-the-art in tall building design. Once completed, it will be not only the world's tallest building but the tallest man-made structure ever created.

From the project's initial concept design through construction, the combination of several important technological innovations results in a building of unprecedented height.

The following is a description of some of the innovative structural design methods which enable the creation of a superstructure that is both efficient and robust.

Designing the wind

The primary concern in the engineering of tall buildings is the effect of the wind on the building's structure. The shape of the Burj Dubai is the result of deliberate cooperation between SOM's architects and engineers to vary the shape of the building along its height, thereby minimising wind forces on the building.

In effect, each uniquely-shaped section of the tower causes the wind to behave differently, preventing it from becoming organised and minimising lateral movement of the structure.

Modular Y-shaped

The modular Y-shaped structure, with setbacks along each of the three wings, was part of the original concept entered in an invited design competition at the beginning of the project.

From this starting point, the SOM team refined the tower's shape over several months of extensive wind tunnel tests. Through these tests, the team determined the harmonic frequency of wind gusts and eddies under various conditions. This information was used to set targets for the building's natural frequencies, thereby "tuning" it to minimise the effects of the wind.

Concurrent with the wind tunnel studies, the team performed a detailed climatic study which considered the unique meteorological conditions of the Dubai wind climate. These studies considered both frequently occurring and rare wind events to address occupant comfort and building strength.

Together, the wind tunnel testing and climatic studies resulted in an engineered solution that is appropriate for the Dubai wind climate.

Buttressed core system

As a residential tower, the Burj Dubai requires floor plates with shallow lease spans that maximise the amount of exterior window area (and therefore natural light) in the living spaces. As a very tall tower, it requires a wide footprint to provide sufficient stability to resist high wind loads. The Y-shaped arrangement of reinforced concrete shear walls around a central hexagonal reinforced concrete core satisfies both of these requirements. The resulting "buttressed core" is an extremely efficient solution to the potentially conflicting structural requirements of a super tall residential tower.

Core walls in each wing are arranged in a nine-metre module that matches the setbacks of the tower. This allows the building to be shap-ed without transfers; the columns in the nose of each setback sit directly on the walls below. The result is an easily constructed system that is significantly less expensive to build than one requiring transfers.

The perimetre columns on the sides of each wing match the width of the adjacent shear walls, thus permitting them to be engaged by infill walls at each mechanical level. This engagement of the perimeter columns leads to high levels of structural efficiency in resisting loads as well as a high degree of redundancy.

High performance materials

The specified material and the configuration of the structural elements utilise the high performance concrete and formwork systems readily available in Dubai. Very strong, high density concrete composed of Portland cement in combination with silica fume, fly ash, and ground granulated slag is available and results in a structure which is stiff, strong and highly constructible.

Reinforces foundations

The superstructure is supported by a large reinforced concrete mat, which is in turn supported by bored reinforced concrete piles. The design of these elements is based on extensive geotechnical and seismic investigations and analysis.

The high density and low permeability of the concrete used for the foundations minimise the detrimental effects of high chlorides and sulphate content in the local ground water. The foundations are further protected by waterproofing and cathodic protection systems.

The expected effects of a seismic event on the tower are modest. As is the case with most tall buildings, the long vibration period of the Burj Dubai is quite different from the high frequency vibrations of an earthquake and therefore the structure will not generate large forces in a seismic event.

Extensive peer review process

The Burj Dubai represents a groundbreaking design of an extremely important building. For this reason, the team implemented an extensive program of peer reviews. All major technical aspects of the project were examined by experts in tall building design to confirm the safety and effectiveness of the structural systems. This extensive program included three separate peer review programs on the project's geotechnical engineering, wind engineering/ testing and structural engineering.

State-of-the-art structure

The Burj Dubai structure represents the state-of-the-art in super tall buildings. It capitalises on the latest advances in wind engineering, structural engineering, structural systems, construction materials and construction methods to result in a structure that goes beyond anything that has been achieved before. The tallest structure ever built, it realises the aspirations of mankind to reach to the sky.

The writer is the Structural Engineering Partner of Skidmore, Owings and Merrill (SOM).