Bridge Evaluation for Multipresence of Vehicles

Abstract

It is customary in North America to evaluate a short‐span bridge on a busy highway exactly the same way as a bridge on a lightly travelled road. This paper proposes that multipresence reduction factors can be used as the means for taking account of volume of traffic. These factors, strictly speaking, are applicable only to bridges that carry a high volume of traffic; however, in bridge‐design codes such as AASHTO and OHBDC, they are used for all bridges irrespective of the volume of traffic. New multipresence‐reduction factors, to be used in conjunction with AASHTO, Ontario, and CSA codes, are proposed for different classes of highways. In addition, the paper presents simplified methods of transverse load distribution that incorporate the proposed reduction factors in such a way that the designer or evaluator can see immediately the effect of volume of traffic on live load responses without having to perform extra calculations.