Bridge traffic loading: the implications of some recent findings
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The maintenance of highway infrastructure requires major expenditure in many countries. By minimizing the repair or replacement of highway bridges in particular, this cost can be reduced significantly. Of the two bridge assessment components, loading is more difficult to estimate than strength, due to its more variable nature. Consequently, bridge traffic loading has been an area of intensive research in recent years. Recent research has focused on assumptions inherent in previous work and the results are presented and discussed. In this paper, the latest statistical analyses adapted for use in the bridge traffic loading problem are reported. Comparisons to the previous state of the art are made and it is shown that a revised approach reflects the underlying phenomenon of bridge traffic loading more accurately. A method which is shown to reduce the variability of the statistical extrapolation process is also presented. Of more significance, a statistical approach which joins the dynamic and static effects of traffic loading is presented. An assumption inherent in much previous research in this area is that free-flowing traffic with coincident dynamic effects is more critical than congested traffic (which has practically no dynamic effect) for short-to-medium-length bridges. Given that about 90% of bridge stock is of this length, the assumption has critical implications for the expenditure on bridge rehabilitation. A sample application of the proposed statistical method is presented and the results are shown to be of great significance. It is shown that the level of dynamic interaction is not sufficient for the flowing traffic to govern and that it is congested traffic that may govern the vast majority of bridges. The implications of the cumulative effect of these various findings are discussed with reference to the future direction of research into bridge traffic loading and current practice in bridge assessment for traffic loading.
Caprani, Colin C. and Rattigan, Paraic H.: Bridge traffic loading: the implications of some recent findings. Paper given at Bridge and Infrastructure Research in Ireland Symposium 2006.