Damage to Teluk Palu Bridge in the 2018 Sulawesi Earthquake, Indonesia

¹ Kyushu Institute of Technology, Sensui 1-1, Tobata, Kitakyushu, Fukuoka, 804-8550 Japan
² Tadulako University, Bumi Tadulako Tonda Campus, Palu, Central Sulawesi, 941182 Indonesia
³ Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192 Japan
⁴ Tottori University, Koyamacho Minami 4-101, Tottori, 680-8552 Japan
⁵ National Institutte of Technology, Fukui College, Geshi, Sabae, Fukui, 916-8507 Japan

^* Corresponding author: kosa.kenji383@mail.kyutech.jp

Abstract

The authors conducted a field survey in the affected area of the 2018 Sulawesi Earthquake, mainly focusing on the damage occurred to the Teluk Palu Bridge in Palu City. It was found that the area around the bridge received approximately 200 gal acceleration and 3 to 6 m tsunami height. From the traces of the tsunami, we estimated that the tsunami reached up to the girder but not up to the arch rib of the bridge. The arch ribs sustained buckling and displaced 2 to 5 m into the water. The main cause of bridge collapse was the earthquake force as local eyewitnesses said the bridge collapsed immediately after the earthquake and before the arrival of the tsunami. In terms of earthquake-resistant design, the following three problems were identified regarding this arch bridge: resisting capacity of the arch rib, resisting capacity of the bearing system, and design concept about the seating length at the pier.