Traffic loads used in the design of highway RC bridges in Egypt

Recently, a considerable research effort has been devoted to bridge design and evaluation in Egypt. The traffic loading in the Egyptian code (ECP) gets heavier from 1963 to 2012. So, it was necessary to evaluate how much safe are the existing bridges when loaded with heavier traffic loading. For this reason, a comparative study is presented between the internal forces (bending moments) in longitudinal girders and deck slabs, in slab/girder bridges, resulting from traffic loads recommended by ECP 1963, ECP 1994 and ECP 2012. Tables and figures are displayed to show the variation in live load moments when using the three different codes for bridges with 10.5 m width (three traffic lanes) and with spans 15, 20 and 25 m. Since most highway bridges are continuous ones, the present analysis was expanded to cover the effects of the different recommended live loads on continuous bridges. The results reveal big differences between the different versions of traffic loads in the Egyptian codes. In addition, modified equations to calculate maximum moments in longitudinal girders according to ECP2012 are proposed. The proposed equations show excellent results when compared with the numerical study. Keywords: Traffic loads, Reinforced concrete bridges, Slab/girder bridges, Egyptian code ECP20