Traffic Load Effect on a Highway Bridge

Abstract

Bridge plays an important role in a transportation system, and is directly linked to the country’s development as well as people’s daily living. However, it is subjected to the damaging effects of the daily traffic and freight trains. Experience shows that bridges with fundamental natural frequencies in the range f=2.0...4.0 Hz respond more strongly to the dynamic action of heavy commercial traffic than other bridges. To achieve better insight into the processes occurring during the passage of a vehicle over a highway bridge with a critical natural frequency dynamic load tests have been performed. This article is about the dynamic analysis of bridges under moving vehicles. In the first phase, dynamic equation of motion with the moving load for simply supported beam is solved by the analytical method of moments and then the results are compared with the time domain method. Secondly experimental analysis is presented in which the beam is divided into 20 stations and the deflection at mid-span is recorded while the mass moves at constant velocity through different stations with the help of oscilloscope. The result obtained is plotted in the form of graphs for different velocities of mass. Finally the dynamic amplification of displacements was extracted and compared with recommendations of current design codes.