This was the fourth and final construction contract for the seismic safety retrofit of the Queensborough Bridge. Previous contracts retrofitted the main river spans, approach spans and densified soils on the south side of the river. During the third contract for the retrofitting of the approach spans, field pachometer measurements indicated that reinforcement ties were missing from the tops of the columns to several bents. Nonlinear pushover analyses revealed one bent to be deficient in shear at the tops of the columns, which could lead to failure in an earthquake. The retrofit of the bent to increase the shear capacity used a carbon fibre wrapping system. The photo in the fact sheet shows the installed wrap, the restrainers installed in Contract #3, and the drain downpipe that needed disconnecting during wrapping of the column.

View the full factsheet here.