Bridge failures mostly occur due to erosion of the ground that surrounds a bridge foundation, a procedure known as scouring. Bridge scour is enabled when water removes soil material around the foundation, leaving holes that affect the stability of the structure.
Researchers, Dan M. Frangopol, Professor of Civil and Environmental Engineering at Lehigh University and Fazlur R. Khan Endowed Chair of Structural Engineering and Architecture, and David Y. Yang, Post-Doctoral Research Associate at Lehigh University, evaluated the scouring effect on bridges by quantifying the impact of temperature rise and increased precipitation caused by climate change. “We know climate change will increase the frequency and intensity of natural hazards like hurricanes, heatwaves, wildfires, and extreme rains,” Dr. Yang, stated.
In particular, scientists converted the climate simulation data into flow discharge by applying hydrologic modeling. Due to the fact that predicting the future climate involves numerous uncertainties, a group of different climate future models and global climate models was considered. The long-term hazard of bridge scour is evaluated using climate models under 3 climate change scenarios. Their approach was applied in the bridges of the Lehigh River.
According to Dr. Yang, it is the first attempt to evaluate climatology, hydrology, structural engineering, and risk assessment to quantify the impact of climate change on bridge safety.
Authors had to back-calculate the foundation depth of older bridges that exist along the Lehigh River as data is unavailable. They developed a method that includes utilizing the bridge condition rating provided by the National Bridge Inventory.
The analyses also considered regional data and life-cycle of the bridges, parameters that are significant to derive a general trend. “Bridges have a lot of microenvironments, and if you only look at one bridge, it’s really hard to capture the trend and get the increased risk from climate change. So we broadened this analytical horizon both spatially and temporally to capture long-term trends,” Dr. Yand, added.
The most significant finding of the analyses was the fact that flooding frequency is rapidly changing and, therefore, infrastructure may suffer unanticipated damage. “We realized that a 20-year flood may now become a 13-year flood at the end of the century, so that frequency nearly doubled. This is why climate change may induce an increased risk to infrastructure,” Dr. Yang concluded.
Scientists are willing to share their model in order to evaluate bridge vulnerability in more regions.
Source: Lehigh University