IMPACT OF ENVIRONMENT AND CLIMATE CHANGE ON SEISMIC RESISTANCE OF CONCRETE BRIDGES

In seismic design and assessment, it is often assumed that the seismic resistance of the structure remains constant over time, although it is subject to deterioration processes. However, structure exposure to its environment and local climate lead to several degradation mechanisms, which impact structure durability and load-bearing capacity. By neglecting the influence of the environment and changing climate during the service life, the structure resistance can be significantly overestimated, especially in extreme events such as an earthquake. The focus of this article is on concrete bridges exposed to aggressive environmental and climate conditions (de-icing salts, sea, carbon dioxide concentration in air, high winds, floods, etc.). Concrete bridges and similar structures without surface protection such as facades, coatings, etc. are susceptible to many degradation processes caused by their environment and the local climate. Since corrosion of reinforcement in concrete is the most important degradation process of concrete structures, its effects on seismic resilience are analysed in more detail. In the first part of the article, an overview of numerical and experimental investigations is given to explain and quantify how much the corrosion process can reduce the seismic capacity of the structure. The second part of the article discusses the effects of climate change on the durability and seismic resistance of concrete bridges in the future. In the third part, several bridges in Croatia are presented as case studies where a combination of deterioration processes and seismic action led to damage of the structure. Finally, recommendation for optimal assessment and management of concrete bridges exposed to multi-hazard environment (earthquake, climate change, aggressive environment) will be given in conclusion.