Seismic Reinforcement (Retrofitting)

The Fuji Fire and Marine Insurance Building in Ginza is a 10-story steel office building that was constructed in 1974, and it was seismically evaluated right after the Southern Hyogo Prefecture Earthquake. Results indicated that the entire building lacked 5 to 23% of its horizontal load-bearing capacity along its shorter side. In order to meet current standards, its bearing capacity had to be increased and girders and column and girder connections had to be reinforced. With a steel building, however, increasing the load-bearing capacity of fireproofed clad girders and connections to the required level has been a difficult task.

Instead of reinforcing the structural members to increase their load-bearing capacity, a method of retrofitting to reduce the seismic response with wall-type dampers was used.

Four to eight wall-type dampers were installed on each floor, with an emphasis on balance to prevent eccentricity. The wall-type dampers were configured to perform so that the response of each floor is less than the horizontal load-bearing capacity in response to a seismic input with a maximum acceleration of 400 gals.

S and SRC construction, 10-story building with a basementWall-type damper48 units
Design: Kume Sekkei Installation: Shimizu Corporation