Collapse Analysis of Utatsu Ohashi Bridge Damaged by Tohuku Tsunami using Applied Element Method

Abstract

The 2011 Tohuku tsunami on the east coast of Japan resulted in killing more than 15,000 people and missing more than 2,500 people, washing away of more than 250 coastal bridges and loss of US$235 billion. Collapse of coastal bridges due to tsunami impact represents a huge obstacle for rescue works. Therefore, in the current study, the collapse of Utatsu Ohashi bridge is numerically studied. The analysis is carried out using the Applied element Method due to its advantages of simulating structural progressive collapse. The AEM is a discrete crack approach, in which elements can be separated, fall and collide to other elements in a fully nonlinear dynamic scheme of computations. The Utatsu Ohashi bridge collapse was successfully simulated using AEM. It was numerically found that the amount of trapped air between deck girders during tsunami had a significant effect on the behavior of the bridge. This is attributed to the buoyant force accompanied with the trapped air. A simplified method for estimating trapped air was assumed and proved to give reasonable results compared to reality. Three different solution examples for mitigating collapse of similar existing bridges were introduced and applied to Utatsu Ohashi bridge case and found to be efficient for preventing collapse.

Improvement of Tsunami Countermeasures Based on Lessons from The 2011 Great East Japan Earthquake and Tsunami — Situation After Five Years

“…To investigate the collapse of a coastal bridge in Minamisanriku, Miyagi Prefecture, Bricker and Nakayama [2014] used a shallow-water model to propagate the 2011 tsunami from its source to the beach; they then manually input the waveform at the beach into a small-scale OpenFOAM volume of fluid (VOF) CFD simulation to calculate the forces on the bridge and to thus pinpoint the factors responsible for its collapse. Azadbakht and Yim [2014] applied a similar VOF CFD simulation, while Salem et al [2014] used the applied element method (AEM). St-Germain et al [2014] ran CFD simulations using smoothed particle hydrodynamics (SPHs) to determine tsunami-induced forces on structures.…”

Progressive collapse assessment of medium-rise reinforced concrete flat slab structures

“…Therefore (and because the goal of the current study is to investigate the behavior of RC flat slab structures under severe loads resulting from column loss), it was decided that AEM is the most appropriate numerical tool for such an investigation. In the current study, the Extreme Loading for Structures (ELS) software, which is AEM‐based, was used for the investigation …”

“…AEM is a discrete crack approach in which two adjacent elements may have a discrete crack along their common faces, may be separated from each other, and may come into contact again or make contact with other elements. Therefore, AEM is capable of following the structure's behavior up to its total collapse …”

Tsunami Force Acting on Bridge Girders

“…In order to simulate the collapse of Utatsu Ohashi bridge, the Applied Element Method is introduced for its advantages of simulating structural progressive collapse 12) . The AEM is a discrete crack approach, in which elements can be separated, fall and collide to other elements in a fully nonlinear dynamic scheme of computations.…”