Dynamic wheel loads from bridge strains

Earlier impact studies on a small span bridge under service loads gave impact fractions much higher than those specified by AASHTO. This paper represents the first stage of a programme to identify the high impact vehicles. It describes theoretical studies which use bridge measurements to estimate not only the equivalent static loads but also their dynamic variation with time. Acceptable estimates have been obtained. The use of measured bending moments gives better results than measured deflections. The correct selection of nodal spacing and arrangement is important (a).