Live‐Load Moments for Continuous Skew Bridges

Abstract

This paper presents a method for determining moments in continuous normal and skew slab‐and‐girder bridges due to live loads. Using the finite element method, 112 continuous bridges are analyzed, each having five pretensioned Igirders. The spans vary between 24.4 and 36.6 m (80 and 120 ft), and are spaced between 1.8 and 2.7 m (6 and 9 ft) on center. The angle of skew, α, varies between 0 and 60°. A convergence study is also performed on a control bridge to ensure reliable results. Design parameters are identified and their influence on the load distributions studied. For a skew angle of 60°, maximum moment in the interior girder is approximately 71% of that in a normal bridge; and reduction in maximum bending moment is 20% in the exterior girders, which control the design for a bridge with long span, small girder spacing, and small relative stiffness of girders to slab. It is concluded that the AASHTO distribution of wheel loads for exterior girders in normal bridges underestimates the bending moments by as much as 28%.