Optimized design of precast concrete shear walls with consideration of future modification scenarios

Abstract

One way to decrease the carbon emissions from concrete structures is to make smarter and more optimal structural designs. Prefabricated concrete walls are widely used in building structures. However, buildings made of traditional precast wall elements contain very little flexibility if you need an opening like a door hole or a larger opening in the wall in the future. To enable circular use of buildings with concrete walls, a new optimized concept for precast concrete walls is suggested in this paper. It is called a modifiable concrete wall and consists of two zones: a frame zone and a flexible zone. A new opening can be cut in the flexible zone without, or with little, strengthening of the structure. This will potentially prolong the lifespan of the building and reduce carbon emissions (CO2e) in the long run. To also reduce carbon emissions in the short run, the carbon footprint from the materials of the wall is minimized. This is done by allowing a very low concrete strength and small amount of reinforcement in the flexible zone. Furthermore, a material optimization framework using finite element limit analysis (FELA) is developed. For one or more given load cases, the optimization framework finds the optimal concrete strength and amount of reinforcement, which minimizes the carbon footprint. A realistic example of a wall structure of a five‐floor apartment building is made. The carbon footprint of the optimized modifiable concrete element is compared to a standard wall element, and reductions in the order of 40%–60% are found.