Every year, new bridges are being built around the world to span further, reach higher and extend wider. This means that more time, materials and expertise are also required. How will we adapt to meet these challenges in a sustainable way? New research seeks to provide some of the answers.
A new research project pushes state-of-the-art design by enabling finite element limit analysis for solid concrete structures, resulting in significant time, material and cost savings, improved constructability and fewer environmental impacts.
"With the current state of affairs, uncertainties and disputes among engineers are often encountered in practice regarding the actual load bearing capacity of solid concrete structures and the actual amount of minimum reinforcement that is required to ensure sufficient ductility, explains Linh Cao Hoang, Professor at the Technical University of Denmark (DTU) and Project Manager of the research project.
"These uncertainties can have major societal and economic consequences and, at the same time, prevent better material utilisation in the design,” he continues.
Consequently, the project will seek to develop a theoretical basis for computer-based rigid-plastic analysis and design of solid reinforced concrete structures; uncover new knowledge on the mechanical behaviour of reinforced concrete in the tri-axial stress states; enhance the knowledge of necessary ductility; and provide valuable empirical insight into the behaviour of solid 3D structures through full scale testing.
One main challenge that the industry currently faces is the conservatism in the design methodology and the compromise between design time and material quantities. However, further optimisation of the designs for large concrete structures could reduce the environmental impact from major infrastructure schemes as cement – a key component in concrete – has a massive carbon footprint and contributes to about 7 per cent of global CO2 emissions.
"With the outcome of the research project, we will potentially make it easier to optimise the design of solid reinforced concrete structures in the future, therefore minimising the quantities of materials needed, such as cement. Thereby, we can provide clients with more sustainable designs that minimise cost and environmental impacts," states Jesper Asferg, Vice President in COWI's Bridges International department and part of the Steering Group for the research project.
The three-year project is a collaboration between DTU Civil Engineering and COWI made possible by donations from the COWI Foundation, the Innovation Foundation, DTU and COWI.