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A-Bomb Dome to be reinforced with steel in three places; work to begin this fall will make structure earthquake-resistant

by Hisashi Kawate, Staff Writer

The City of Hiroshima has decided to carry out work to make the A-Bomb Dome more earthquake-resistant for the first time, using steel to strengthen it. Built 100 years ago as the Hiroshima Prefectural Commercial Exhibition Hall, the structure will be strengthened in three places. Work will begin this fall and is intended to enable the dome, now a UNESCO World Heritage site, to withstand a quake of up to “6 Lower” on Japan’s seismic intensity scale, equivalent to the 2001 Geiyo Earthquake.

At a May 22 meeting of the Advisory Committee on Techniques for the Preservation of the A-bomb Dome, which comprises experts from the Cultural Affairs Agency and in the field of engineering, it was proposed to attach steel to the inside of the dome’s walls in three places, one on the northwest side and two on the east side. These spots were chosen for their effectiveness in strengthening the dome and because there would be little effect on the dome’s appearance. The 13 members of the committee had no major objections to this proposal.

On the other hand, no decision was made on what to do about two places on the dome’s west wall that are at risk of damage. The city proposed injecting epoxy resin, but the committee opposed the plan on the grounds that the use of advanced techniques was not appropriate for the dome and could also lead to further damage. It was also noted that the process was irreversible. The city said it would consider the matter further.

Work will begin on detailed designs for the seismic strengthening of the three spots that were decided on, and a proposed budget will be included in the supplementary budget to be submitted at the city council’s regular meeting on June 15. The city will apply to the Cultural Affairs Agency to make changes to the dome and plans to start the work in September or later.

The city has done preservation work on the A-Bomb Dome three times thus far – in 1967, 1989 and 2002. These projects included reinforcing the dome’s steel framework and repairing weakened concrete. The city’s Park Development Division said that, insofar as possible, when carrying out the necessary work the city would try to preserve the dome in the condition it was after the atomic bombing.

Analysis: Consideration for preserving cultural value

by Hisashi Kawate, Staff Writer

In considering the method of its first seismic reinforcement of the A-Bomb Dome, the city decided to attach steel to the inside of walls, keeping the reinforcement to a minimum. This plan avoids working directly on the building or the ground and emphasizes a balance that will allow the structure to be preserved indefinitely while maintaining its value as a cultural asset.

In fiscal year 2007, the city established a subcommittee of its Advisory Committee on Techniques for the Preservation of the A-bomb Dome consisting of experts in earthquake resistance measures. After carrying out surveys and research, the subcommittee established a basic policy that calls for the following: 1) in principle, no changes shall be made to the dome’s appearance; 2) the minimum necessary measures shall be implemented; and 3) insofar as possible, measures shall be reversible.

The discussions on the difficult problem of the seismic reinforcement of the decaying A-Bomb Dome were complicated. The structure, which was built of brick, sustained heavy damage in the A-bombing, and there are great variations in its strength. And because the building was built 100 years ago, the quality of the bricks and other materials is not consistent. Some of the experts recommended the atomic seismic isolation method, which is highly effective and would not change the appearance of the A-Bomb Dome, but the city rejected this idea, saying that digging in the vicinity of the dome would harm the dignity of the site. The decision on the method of the seismic reinforcement was delayed by one year.

In the 70 years since the atomic bombing, the A-Bomb Dome has continued to deteriorate. At the May 22 advisory committee meeting, the members decided to hold off on the proposal to inject epoxy resin into two of the five spots needing reinforcement, citing the method’s irreversibility. The question of how to preserve the A-Bomb Dome, which silently tells of the horrors of the atomic bombing, will remain an issue.

(Originally published on May 23, 2015)

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