Regarding the design defect in the Ami Viaduct on the Ken-o Expressway (in front of Yoshiwara, Ami-cho, Inashiki-gun, Ibaraki Prefecture)

Recently, during the construction of the Ami Viaduct of the Ken-o Expressway Yoshiwara site in Ami-cho, Inashiki-gun, Ibaraki Prefecture, a design defect was discovered.

For this reason, the Kanto Regional Development Bureau, as of August 18, 2008, is the contractor for the Ami Viaduct construction, Nittetsu Bridge Co., Ltd., and Kubota Koken Co., Ltd. I requested a "kashi repair" from the construction consortium of different construction types.

There is no problem with normal traffic.

Overview

Yoshihara, Ami-cho, Inashiki-gun, Ibaraki Prefecture The construction of the Ken-o Expressway (Ken-O Road) Ami Viaduct is designed and ordered by the Joso National Road Office of the Kanto Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism. The order was placed by Nippon Steel Engineering/Kubota Engineering Construction Co., Ltd. construction company, completed in September 2006, and in use on March 10, 2007.

It has now been discovered that there is a mistake in the design horizontal seismic intensity in the seismic design of the substructure of this bridge.

As a result of the check, seismic performance against Level 1 earthquake motion (earthquake motion that is likely to occur during the service period of the bridge) is secured, We have confirmed that there are no obstacles to normal traffic. Also, as a result of the inspection, there is no abnormality in the relevant bridge, so there is no problem in driving safety.

For Level 2 earthquake motion (earthquake motion that has a high intensity but is unlikely to occur during the service period of the bridge), Not seriously damaged but may take time to recover if damaged Therefore, we are currently considering the necessary measures.

Construction name
Ami viaduct construction

Construction period
From January 22, 2005 to September 30, 2006

Builder
Ami Viaduct Nippon Steel Engineering/Kubota Engineering Construction

Situation
The seismic design of the Ami Viaduct is carried out by the joint venture of the Ami Viaduct, Nippon Steel Engineering/Kubota Engineering and Construction of different works, which received an order for the design and construction at once.

When performing a seismic design of a bridge, seismic motions (Level 1) that have a high probability of occurring during the service period of the bridge, and earthquake motions (Level 2) that have a low probability of occurring during the service period of the bridge but have a high intensity (Level 2) , It is decided to provide both with seismic performance.

For level 1, performance that does not impair the soundness of the bridge due to the earthquake, and for level 2, performance that can quickly recover the function as a bridge with only limited damage due to the earthquake, Must have.

In this case, the seismic performance for Level 1 is secured, and it is safe to pass in the event of a normal earthquake.

When performing seismic design against Level 2 seismic motion, the seismic force that originally had to act on the bridge was set too low. Therefore, there is a concern that it will take time to recover in the event of a large-scale earthquake.

Therefore, the seismic resistance will be verified again, and necessary measures will be examined.