James Gendall discusses the current challenges impacting high rise structural design
Article posted on: 17 February 2021
James Gendall, Divisional Director at Clancy’s Liverpool office, leads some of the businesses’ largest high-rise residential schemes. Here he discusses the challenges encountered during the design phase and construction techniques.
The structural design of high-rise buildings requires a different skill set to that of traditional building design. A greater appreciation of materials properties, construction sequencing and planning, plus the effects of design decisions of other members of the design team is crucial to the successful delivery of the project.
As buildings have become taller, and increasingly more slender, the materials and load bearing structural elements that support and stabilise the building are required to work harder. A deeper understanding of the materials science and behaviour under loading is required to predict how the building will behave, influencing construction techniques and design choices. The effects of creep, axial shortening, thermal movement, foundation settlement and shrinkage can all have a significant impact on the long-term performance of the building and need to be a primary consideration from the concept design of tall buildings. Despite the best efforts of the setting out engineer and construction team, the methods used in the construction of the building, and their effect on tolerance, also needs to be factored into the overall building design from concept stage. The tolerances achieved using different construction techniques, combined with the prediction of long-term movement, can often have a significant impact on the design of follow-on trades such as facades, partitioning, M&E installation and lifts. Early consideration of this enables better design decisions to be made and ultimately allows for a more cost-effective building solution.
Perhaps the biggest challenge for most tall buildings is overcoming the effects of the wind, which are significantly increased the taller the building becomes. Typically, at around 20-25 storeys, wind induced vibration starts to govern the structural design of the lateral stability system. Limiting this lateral acceleration due to wind loading prevents occupants of the building feeling motion which may cause alarm or motion sickness. The use of wind-tunnel studies helps with this but, importantly, starting from a sound basis of design reduces this iterative process of fine-tuning the lateral stability systems performance and reduces the overall design period. A good starting point for the lateral stability system reduces the overall time from concept to starting on site, providing investment benefits and reduced costs to the project. Due to our significant experience of designing high-rise structures at Clancy, the team has developed in-house systems to predict tall building behaviour, allowing for a quicker design process, with better upfront information to allow design decisions to be made quicker. The use of our in-house developed iterative scripting, in conjunction with market leading structural analysis software, allows for the rapid assessment and stability system optimisation.
Find out more about our experience in the high rise residential sector, or contact James, or any of the senior team, to discuss your project.