The steel arch bridge over the Virgin River at
Hurricane, Utah, is currently being rehabilitated to widen the roadway
and improve its live load capacity. In order to minimize strengthening
of structural steel members, the center hinge of the 3-hinged arch was
fixed, and a 4 ΒΌ-inch filled steel grid deck installed. To further
reduce dead load on the structure, Modjeski and Masters Consulting
Engineers used structural lightweight concrete for the grid deck fill.
The reasons for choosing lightweight concrete include the following:
1. Reduced dead load on the
entire structure.
2. Reduction of 10 lbs. sq. ft.
of bridge deck dead load.
3. Improved live load capacity.
4. Minimal strengthening of
existing riveted arch rib members required.
Previously, Modjeski and Masters used lightweight concrete for the
bridge deck replacement and widening for a mile and half long bridge
over the Hudson River.This
bridge was built for one traffic lane in each direction. After a new
parallel adjacent bridge was constructed, the original bridge had the
replacement deck widened to three lanes for single direction traffic
using a lightweight concrete deck slab, to reduce the new dead load. For
the 1000 foot long main span a steel grid deck was filled with
lightweight concrete. |
