Investigating measures to improve seismic performance of stone arch bridges using larger filling stones

Stone arch bridges in Japan consist of ring stones, wall stones, and filling material. Some stone arch bridges have a filling material of small size, while others have a filling material of large size. During past earthquakes, the filling material collapsed and made the wall stones to collapse together, therefore, the stability of the filling material itself seems to have an important influence on the seismic performance of stone arch bridges. However, few studies have investigated the filling material. This study focused on the effect of the filling material size on the seismic performance of stone arch bridges. The seismic behavior of stone arch bridges with large or small crushed stones as the filling material was compared through shaking table tests and numerical simulation using the refined distinct element method. The shaking table test revealed that the natural frequencies and resonance curves of stone arch bridges with large and small crushed stones are similar. However, the seismic performance was different depending on the size of crushed stone. The stone arch bridge with larger crushed stones withstood the earthquake shaking for longer time. The post-collapse appearance of the test specimen revealed that large crushed stones were more stable than small crushed stones, because large crushed stones stabilized with a steeper slope angle. The numerical simulation revealed a trend similar to that in the shaking table test. The results revealed that replacing the filling material with larger stones is expected to improve seismic performance in the maintenance of stone arch bridges.