Seismic Damage of a Building Caused by Post-installed Anchors Intended to Increase Shear Strength of Structural Wall

A building was severely damaged during the 2011 Tohoku Earthquake in spite of having been strengthened before the event and having withstood a comparable event before with only minor damage. An experimental study was conducted to test the hypothesis that damage to the building may have been triggered by cone breakout failure of anchors installed during the strengthening program leading to a strain concentration at the third story. Specimens were tested which represented portions of shear wall boundary columns either before or after the strengthening program. Observed damage in the specimens representing the boundary columns after strengthening was similar to the damage observed in the building after the 2011 Tohoku earthquake. Projections of the test results suggest that the strengthening program may have reduced the drift capacity of the building.