The Beveridge Suspension Bridge has won the National Steel Bridge Alliance Prize Bridge Competition Merit Award.
The Beveridge Bridge is an historic parallel wire suspension bridge located in San Saba County, Texas on China Creek Road over the San Saba River, just northwest of the city of San Saba.
Built in the late 1800s, the bridge was eventually closed due primarily to the deteriorating main cable. The Texas Department of Transportation (TxDOT), while recognizing the need for a transportation crossing more suitable to the area’s agricultural community, also recognized the uniqueness of the historic suspension bridge and developed a plan to preserve it. TxDOT initiated a preservation plan to remove the structure from vehicular service permanently, restore it as nearly as possible to its 1938 condition, and leave it in its original location as a pedestrian access structure.
The Beveridge Bridge is a stayed catenary bridge with parallel wire cables. The suspended span is 133 ft. The ground-anchored cables dated from a 1938 reconstruction, and the site investigation revealed that the cables were severely corroded at the ground line. In addition, approximately 40% of the wires at mid-span were severed from vehicular impact.
The original pier towers dated from 1896. The piers consist of a metal pipe tripod, trussed by a through-bolted framing system designed by the original builder. From contemporary newspaper accounts, the tripod is thought to be founded on a sandstone block footing approximately 18 ft below the ground line. At the ground line the metal pipes exhibited localized pinhole corrosion.
Complete replacement of the main cables was necessary to restore the suspended span. A new cable anchorage was designed to be placed below ground, founded on drilled shafts that straddled the existing anchorage. The straddle cap was designed for torsion and situated so that only the upper surface was out of the ground. Welded steel, cable link plates were attached to the upper surface of the anchorage. This allowed the anchorage to be as visually unobtrusive as the original, but kept the new cables out of the ground and subject to less corrosion.
To stabilize the 1886 pipe towers, concrete footings founded on drilled shafts were designed.
The drilled shafts were placed outside the limits of the existing stone footings. The new footings were designed to cantilever from the drilled shafts and wrap around the existing pipe towers. Steel shoes were designed to be welded to the tower legs so as to transmit any added tower load to the new footing.
The original piers and footings were left intact and functional through the footing and below the ground line.
A new cable layout was prepared, which allowed the cable and deck stays to be pre-spun as a single prefabricated unit. Sample cables were prepared and tested to verify the ability of the socket to develop the strength of the wire. The cables were spun and banded at a remote location and shipped to the job site.