Effectiveness of Skewness on Dynamic Impact Factor of Concrete Multicell Box-Girder Bridges Subjected to Truck Loads

Abstract

Evaluation of the dynamic response of bridge–vehicle interaction is an interesting topic in bridge engineering. It is an effective way to develop the accuracy of a new generation of reliability-based bridge design specifications. Traditionally, to consider the effect of moving loads on bridge design, the response of bridges using static loads is amplified by a dynamic load factor (dynamic impact factor). Although a considerable amount of studies has been conducted to determine the dynamic impact factor of bridges, it still remains as a controversial issue. The dynamic impact factor is dependent on the dynamic properties of the superstructure and vehicle such as natural frequency, vehicle speed, and many other parameters, which are difficult to take into account. Underestimating the effect of each parameter on the development of new expressions for dynamic impact factor may lead to substantial problems. Hence, the present study focused on the dynamic behavior of multicell box-girder bridges under moving loads. Firstly, the related literature on the effect of vehicle loads on bridges was reviewed to get closer insights into the dynamic behavior of bridges. The effects of various parameters of bridge on dynamic responses are considered. Dynamic impact factor expressions for skew bridges are deduced based on upper bound values of finding results. The comparisons indicate that the current bridge codes unable to estimate accurate values for dynamic responses of skew bridges.