Abstract: A five-level parking garage was being built with precast concrete parts, including 6-ft-wide by 10-ft-high wall panels set one on top of the other and screwed together with two 2-ft-long-0.75-in.-diameter rebar. Each panel had a haunch at varying levels to support the ends of 58 ft long by 9 ft wide slabs fastened to the panels by two connectors made of rebar and steel plates welded together. The panels were held plumb by a telescoping pipe brace where the floor slabs had been set and one connector had been welded. The second weld could not be made until the next slab was set and aligned vertically and the crane was entirely free. One connector had been welded between the panel below and its double tee bracket. Employees #1 and #2, both iron workers, were plumbing the panel, one with a level at the panel and the other rotating the pipe brace, which had a jackscrew at one end. As plumb was reached and the tension was momentarily released, the panel was struck from below and the rebar popped out of the tee. Both panels fell to the ground and the slab fell 8 ft, striking Employees #1 and #2. They were injured and required hospitalization.