Case Studies

Lap Splice Retrofit

The 2150 Shattuck seismic upgrade included adding fiber wrap to strengthen concrete shear walls and adding through-bolted headed studs to improve confinement of the concrete. The objectives were to overcome inadequate shear strength in the existing walls and inadequate lap splices of the existing vertical reinforcement. A physical test program was conducted at McGill University under the direction of Professor Denis Mitchell to ascertain the effectiveness of the novel approach.

The as-built test specimens were designed to have similar properties to the wall in the as-built structure chosen to simulate the most critical portions of the structure.

Companion specimens were constructed with details identical to those of the as-built specimens. These panels were then retrofitted with headed reinforcement to increase shear capacity and add confinement . The retrofit included additional reinforced concrete to thicken the base of the wall over the lap length of the vertical reinforcement. The wall was strengthened with bands of externally applied carbon fiber. The test results demonstrated that the headed bolts were effective in confining the concrete and preventing premature lap-splice failures. The experiment also demonstrated that the effectiveness of carbon-fiber wrap.

The tests were sponsored by Headed Reinforcement Company (HRC) and Fyfe Company.