Joe Robbie Stadium, home of the Miami Dolphins, was designed with eight 29-foot-wide pedestrian ramps. The fans pour down the ramps, emptying the 73,000-seat stadium in just a few minutes. Each quadrant of the stadium has a pair of ramps, one ramp on each side of a pair of escalators. The left-hand ramp of a pair spirals downward clockwise and the right-hand ramp spirals down counterclockwise. For that reason two complete sets of formwork, one for each type of spiral, were needed. Each set of formwork was used to form four ramps.
THE PROBLEMS OF FORMING SPIRALS
The spiral shape of the ramps presented several forming problems. Forms for the ramps' slab-joist system had to be wider at the outer edge of the spiral than at the inner edge, and the forms had to provide for the slope of the ramp. To meet these requirements, custom dome pans were fabricated of glass-fiber-reinforced plastic. The pans were trapezoidal in shape and warped about the radial centerline to provide the steeper slope needed at the inner edge. After the first revolution, formwork had to be supported on the structure below. Also, the formwork had to be designed to be removed readily from one section and flown by crane to another section for reuse. These problems were solved by assembling a number of modules, each consisting of a beam table section and its shoring. The shoring incorporated adjustable scaffold frames that could be lowered 6 to 8 inches to facilitate stripping of concrete and repositioning of the module at another level.