ANALYSIS OF BRIDGES: WHAT DO THE NUMBERS REALLY MEAN?

Traditional analysis of bridges, the code-prescribed process of calculating force effects such as moments, shears, stresses of deformations from prescribed loads, introduces much uncertainty in the design of new bridges and the evaluation of existing bridges. Examples are cited that illustrate that the calculated force effects as per traditional designer assumptions and the LFRD Specifications are not necessarily accurate and precise. Two conclusions are drawn that suggest that code changes are warranted and designers' awareness should be heightened.