John M. Hooks, Federal Highway Administration
The Innovative Bridge Research and Construction (IBRC) program was established under the Transportation Equity Act for the 21st Century. The intent of the IBRC program is to develop and promote applications of innovative (high performance) materials for bridges. The IBRC program is funded for six years through fiscal year 2003 at a total authorized level of $102 million. As of fiscal year 2001, 157 projects have been selected for funding. By the time the program expires, IBRC funds will have supported the construction or rehabilitation of an estimated 250 bridges with innovative materials. Eighteen states have used IBRC funds to design, build, and monitor the performance of high performance concrete (HPC) in bridges. Twenty-nine HPC projects have been approved and include applications in deck slabs, substructure elements, concrete I-girders, concrete box beams, and bridge railings. Nineteen of the 29 projects include HPC in the bridge deck slab; this reflects the concern with durability and service life of concrete bridge decks, especially those subjected to deicing chemicals in ice and snow areas. It also reflects the expectation that low permeability HPC will produce decks with significantly longer service lives.
The true value of the IBRC program is in advancing technologies that will enable all bridges to last longer at a lower total cost. IBRC funds are being used for special engineering studies, materials testing and evaluation, mix designs, and instrumentation and post-construction monitoring of performance of the HPC components of the bridges. Under normal circumstances, agencies might not be able to afford these extra efforts because of the shortage of staff, pressure of project schedules, or lack of funds. IBRC funds can fill this gap and are often used to enlist the services of local universities to conduct the necessary studies.
The Virginia Department of Transportation (VDOT), with funding from the IBRC program, initiated a project to evaluate the use of structural lightweight, high performance concrete in prestressed concrete bridge girders. The project includes the fabrication of three AASHTO Type II girders with deck slabs for measurement of transfer length, development length, and flexural strength and two AASHTO Type IV girders for monitoring long-term prestress losses and camber. Three girders in the actual bridge will be instrumented for long-term monitoring of concrete strains. As a result of this study, VDOT hopes to benefit from a reduction in dead load as well as the other strength and durability advantages of HPC.
IBRC funding allowed the New Hampshire Department of Transportation (NHDOT) to collaborate with the University of New Hampshire (UNH) on the use of innovative materials in bridges. The project involved the development of HPC mixtures and design details for fiber-reinforced plastic reinforcement. The funding supported experimental research at UNH. The results were immediately implemented by NHDOT in a bridge.
Both innovative materials will enable the NHDOT to design more durable bridges. The actual performance of the HPC and FRP materials in the bridge is being monitored. Test results will be used to refine the predictive models. This program is allowing practitioners to gain confidence with advanced materials and, by doing so, is incrementally advancing the state-of-the-art in both HPC and FRP.
Summary
The IBRC program provides funds to offset additional engineering and monitoring costs and increases confidence in new materials. IBRC funds also help offset the risks and premium costs of experimenting with innovative materials. The next project solicitation will be announced on March 15, 2001, with project applications due by July 15, 2001. For further information on the IBRC program, visit the IBRC website at http://ibrc.fhwa.dot.gov.