HIGHWAY TECHNET VIRTUAL EXPO STRUCTURES INDEX Bridge Design and Construction: The Ultimate Construction Kit DP-99 Bridge Design and Analysis | |
As with many other segments of civil engineering, bridge design has evolved from early art forms to a sophisticated science. A hundred years of experience have been assimilated into the engineering practice. Now modern research and development findings have been re-examined, tested, proven in service, and codified into bridge specifications and practice. Traditional design philosophies and methods, such as Working Stress Design (WSD) and Ultimate Strength Design (USD), are still used in bridge design, but recent developments in bridge design specifications have departed from the traditional approaches to incorporate more rational methods. Load Factor Design (LFD) was a first step toward implementing a bridge design code based on statistical factors that account for variability of loads, lack of accuracy in analysis, and the probability of simultaneous occurrence of different loads. Load and Resistance Factor Design (LRFD) extended the philosophy to include resistance factors that account for the variability of material properties, structural dimensions and workmanship, and uncertainty in the prediction of resistance. Properly applied, the LRFD code is expected to lead to more rational bridge designs that will produce more economical and durable highway bridges. A concerted effort to train bridge designers in the concept of load and resistance factors, as well as their applications to bridge design, is crucial to the successful implementation of the new codes. The LRFD specifications are ideal for assimilating new developments in bridge materials and construction methods, such as electroslag welding and high-performance concretes, since resistance factors can be modified as necessary to represent uncertainties in material properties. Part of this project will involve promoting new bridge materials and construction methods and will include implementing the LRFD code in bridge design software. Recent innovative developments in bridge design codes, bridge materials, and construction methods have led to the establishment of 10 milestones:
HIGHWAYTECHNET VIRTUAL EXPO STRUCTURES INDEX U.S. Department of Transportation Federal Highway Administration
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