Learning from Earthquakes: First person reports


FHWA/UJNR/EERI Reconnaissance Team for Bridge Damage Investigation

June 8, 2011 by
Filed under EERI Team Field Blog, Geotechnical, Images and Videos, Structural, Tsunami

US Team
W. Philip Yen, US side Chair of T/C G, Federal Highway Administration
Ian Buckle, Professor, University of Nevada, Reno
David Frost, Professor, Georgia Institute of Technology, Atlanta
Lee Marsh, Senior Project Manager, Berger/ABAM Engineers, Seattle
Shideh Dashti, Assistant Professor, University of Colorado, Boulder
Eric Monzon, Research Assistant, University of Nevada, Reno

Japan Team
Tetsuro Kuwabara, Japan side Chair of T/C G, Director of Bridge Structure Research Group, CAESAR, PWRI
Keiichi Tamura, Japan side Secretary General of UJNR Panel on Wind and Seismic Effect, Research Coordinator for Earthquake Engineering, PWRI
Jun-ichi Hoshikuma, Chief Researcher, CAESAR, PWRI
Taku Hanai, Senior Researcher, CAESAR, PWRI
Hideaki Nishida, Senior Researcher, CAESAR, PWRI
Shigeki Unjoh, Research Coordinator for Earthquake Disaster Prevention, Research Center for Disaster Risk Management, NILIM, MLITT
Kazuhiko Kawashima, Professor, Tokyo Institute of Technology

Disclaimer: All comments/opinions/observations are preliminary and my own (Eric Monzon) and do not necessarily represent the views of all the reconnaisance members.

Day 1 (June 3, 2011)

After a brief breakfast meeting with the US Team, we checked out of Hilton Narita and met up with the Japanese Team. We headed to Tokyo via the Narita Express and then to Sendai on Shinkansen. Arrived Sendai at noon then checked in at the Koyo Grand Hotel.

Our first stop was at the office of Tohoku Regional Bureau of the Ministry of Land, Infrastructure, Transport and Tourism (MLITT) where the director gave a brief presentation on the critical role of the MLITT on rescue, structure inspection, rehabilitation, and supporting local governments and victims.

Next stop was the Sendai-Tohbu viaduct, our first bridge. Nexco engineers working on the bridge repair were kind enough to give us an overview of the structure damage and provided plans of the bridge. Damage to the elastomeric bearings were mainly concentrated at Piers 52 and 56 where the superstructure changes from steel I-girders to steel box girders. The substructure also changes from single-column piers to two-column piers. The damage to Pier 56 includes buckling of girder web and cross-frame.

Day 2 (June 4, 2011)

We left the hotel at 8:30AM and headed to the coastal areas to see the bridges that were damaged by tsunami. At 11:10AM, we arrived at Koizumi O-hashi – a 6-span steel I-girder bridge. The piers are still standing (except the one that collapsed possibly due to scouring) but the superstructure was washed away about ¼ mile upstream of the river. Several spans of the railway bridge that runs perpendicular to the bridge were also washed away by the tsunami. Houses were lifted onto the deck of the railway bridge.

Next stop was the Sodeo-gawa hashi – a 4-span curved bridge. The main deck survived the tsunami but the deck of the adjacent pedestrian bridge was washed away. Since the deck of the pedestrian bridge was not tied to the substructure, the deck was lifted by the tsunami waves and was swept away about 300 ft upstream of the river.

Next bridge was the Nijyu-ichihama hashi. This is a single span bridge with pedestrian bridges added on both sides of the main deck. The bridge is still standing but all the abutment backfill were washed away. The same is true for the nearby railway bridge.

Volunteers are on the area helping on the cleanup.

About 12 minutes drive south of Nijyu-ichihama is Utatsu O-hashi. Several spans of the bridge deck were swept away but the columns are still standing. Inclined cracks were observed on the concrete I-girders of the spans that are still standing. This could be due to the torsion in the girders as the tsunami waves pushed the superstructure.

Last stop was the Shida hashi – a multispan steel girder bridge built in 1957. The approach slab settled by about 6 in. and cracks were found on the abutment backwall. At Piers 1 and 6 (two-column bents), there are cracks at the bottom and at the top (about 3 ft measured from haunch) of the columns. Pier 6 is close to the river and liquefaction most likely happened while Pier 1 is next to the abutment where the approach slab settled. In addition, the anchor bolts of the steel bearings on Piers 1 and 6 have yielded.

Day 3 (June 5, 2011)

Prof. Kawashima joined the recon team then we headed to Sendai O-hashi. On the bus, Hoshikuma-san briefed us about the bridge – built in 1965, was damaged by the 1978 Miyagi Earthquake, was retrofitted with fiber wrap, and the bridge performed well during the earthquake. There are sink holes (about 2 ft by 3 ft) near the base of the pier that is close to the river.

Next stop was the Yuriage O-hashi that spans the Natorigawa River. The main span is reinforced concrete box while the end spans are concrete I-girders. The bearings at the joint between the exterior spans and main spans were severely damaged. The longitudinal movement is about 15 in.

Dr. Frost was leaving to US on that day. We dropped him off at the Shinkansen station in Sendai before heading to Ezaki O-hashi which is about 2.5 hours drive north. This is 9-span steel girder bridge that was designed based on the pre-1980 code but was constructed in 1982. The shorter piers, Piers 5, 6, 7, and 8, were damaged by main shock but have been repaired.

Last stop was at Fuji hashi, about 25 minutes drive south of Ezaki O-hashi. The bridge was not damaged by the main shock but was damaged by the aftershocks because the epicenters are closer to the bridge. Pier 6 is being retrofitted with reinforced concrete jacket while Pier 7 has been retrofitted with fiber wrap to increase their shear capacity.

Day 4 (June 6, 2011)

At 8:30AM we checked out of Koyo Grand Hotel then took the Shinkansen to Tokyo. Dr. Buckle and Dr. Yen transferred to Narita Express because they were leaving to US that day. After lunch at a Mexican restaurant, we headed to Arakawa Wangan bridge. This is a long span steel truss bridge where the joint connections were damaged during the earthquake. Actually, before the earthquake, the bridge was being retrofitted by adding dampers, increasing the member strength, and replacing the bearings. Some of the gusset plates buckled and some were fractured. The bridge was closed for about 11 days while the damaged gusset plates were being repaired or replaced. We were told by the Metropolitan Expressway engineers that the average daily traffic on the bridge is about 80,000 vehicles.

Last stop of the recon team was at Urayasu-shi of Chiba Prefecture, a residential area, where extensive liquefaction occurred. In the area that we visited, the ground settlement is up to 20 in.

Day 5 (June 7, 2011)

Back to Reno via San Francisco. Many thanks to FHWA, EERI, and members of US and Japan Team.

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