Recommendations for Dynamic Allowance in Bridge Assessment

This paper summarises the developments in the dynamic response of bridges to traffic loading based on a large amount of simulations and field tests carried out within the 6th EU framework ARCHES (2006-2009). When assessing the total traffic load effect on a bridge, there is a number of alternatives to characterise the associated dynamic component depending on the information available to the engineer. The simplest approach is to adopt the conservative values provided in bridge codes covering for many uncertainties. Nevertheless, if bridge drawings, bridge properties, updated weigh-in-motion data and road profile were known, then validated vehicle-bridge finite element interaction models can be used to reduce these uncertainties. Dynamic allowance can also be experimentally derived from measured total load effects using modern bridge weigh-in-motion technology. Guidelines are provided on how to obtain a site-specific value of dynamic allowance, both numerically and experimentally.