When knowledge of mathematics, computer science, structural mechanics and materials engineering come together, designers and experts get software that calculates how long a 1932 bridge will last or helps design and plan maintenance of a new structure to make it economical and safe for as long as possible.  

Scientists from the Institute of Structural Mechanics at the Faculty of Civil Engineering of Brno University of Technology have developed a tool to calculate the reliability, load-bearing capacity and service life of reinforced concrete bridge structures. Predict-C uses the so-called semi-probabilistic method, assesses the ultimate and serviceability limit states, and also takes into account the effect of concrete degradation and reinforcement corrosion. All this is integrated into a user-friendly program environment where designers can easily simulate the evolution of the load-bearing capacity and reliability of structures over time and design them in a safer and economically rational way.  

"When modelling degradation processes, we focused on reinforcement corrosion caused by concrete carbonation. The action of airborne carbon dioxide on calcium hydroxide and other hydration products gradually lowers the pH of the protective layer of the iron elements in the structure, which then corrode. The mathematical models of carbonation are based on the diffusion of carbon dioxide in the concrete pore system, which we describe using Fick's second law," explains David Lehký from the research team, adding: "The corrosion of the reinforcement not only reduces the effective area of the reinforcement, but the emerging corrosive products cause an increase in tensile stress in the surrounding concrete, resulting in longitudinal cracks and spalling of the concrete cover." It is these visible defects on the surface of structures that affect their durability and, in terms of user perception, often their serviceability.  

Calculating the reliability and durability of reinforced concrete structures as accurately as possible is also crucial when planning structural renovations. Large bridges or stadiums must above all be safe for users, therefore Predikt-C works with the valid building standards. It refines the calculation models using data from real measurements on site. During the development process, the researchers continuously verified the accuracy of the results obtained on selected examples of bridges of different sizes, types and ages.  

The software was developed in cooperation with MORAVIA CONSULT Olomouc a.s. within the EPSILON programme for the support of applied research and experimental development funded by Technology Agency of the Czech Republic. The research team continues the development. Gradually, the model will include calculations for other areas, such as the effect of chloride ions that penetrate structures during the winter salting of roads.  

  

Fick's laws mathematically describe the diffusion of liquids using equations to characterise changes in concentration over time.