Bridge 1-351 over Muddy Run: Design, Testing, and Erection of an All-Composite Bridge

Abstract

Bridge 1.351 on Business Route 896 in Glasgow, Delaware, was replaced with one of the first state-owned all-composite bridges in the nation. Composites are lightweight construction materials that do not corrode, which results in benefits such as ease of construction and reduced maintenance costs. A summary of the design, large-scale testing, fabrication, erection, and monitoring of this bridge is presented. The bridge was designed to AASHTO load and resistance factor design specifications. A methodology was developed to incorporate the engineering properties of these unique composite materials into the design. The bridge consists of two 13 × 32 ft (3.96 × 9.75 m) sections joined by a unique longitudinal joint. The sections have sandwich construction consisting of a core [28 in. (71.12 cm) deep] and facesheets [0.4 to 0.6 in. (10.16 to 15.24 mm) thick] that provide shear and flexural rigidity, respectively. The composite bridge was fabricated with E-glass preforms and vinyl-ester resin, which offers excellent structural performance and long-term durability. Each of the sections was fabricated to near-net shape in a single step by a vacuum-assisted resin transfer molding process. The overall structural behavior has been accurately predicted with simple design equations based on sandwich theory for anisotropic materials. Large-scale testing of full-sized subcomponents was conducted to prove that the design satisfied deflection, fatigue, and strength limit states. A redundant longitudinal joint was designed that consisted of both an adhesively bonded vertical joint between sections and splice plates. Assembly procedures were developed, and transverse testing of the full-sized joint was conducted. Final bridge sections were proof-tested to the strength limit state. The construction phase included section positioning, joint assembly, and application of a latex-modified concrete wear surface. The bridge was reopened to traffic on November 20, 1998. Results from the long-term monitoring effort will be documented.