Analysis of skew box girder bridges

The number of bridges in cities and on highways is increasing as a result of theincrease in traffic volume. A large number of these bridges are built on skew supports dueto the topology of the site and the economic and structural requirements. This study isdesigned to provide information about the behavior of skew box girder bridges. Thereforelinear as well as nonlinear finite clement analysis is used to judge the credihility of thelinear analysis when used as a tool for design of such structures. The linear and nonlinearanalyses use a three dimensional eight node shell elements with six degrees of freedom ateach node. The reinforced concrete modelling is accomplished hy comhining the standardelements using a plain concrete model with rebar elements embedded in oriented surfaces.Effects associated with the rebar-concrete interaction are simulated using tensionstiffening. Cracking is assumed to occur when the stress reach a failure surface which iscalled the crack detection surface. The prestressing cables are modelled using threedimensional three node curved truss elements. The ABAQUS code version 5.5 is usedhere for the linear, and the nonlinear analyses under the academic license of the Universityof Calgary, Alberta, Canada.The study includes both simple and continuous bridges. Parametric studies arecarried out in which the following parameters have been investigated: angle of skew, span,’shape of the section (vertical and inclined webs) and number of cells. The models wereanalyzcd for different dead and live load cases. The case of differential settlement of thesupports is also studied. Reinforced as well as prestressed concrete bridges with differentcable profiles are studied. To verify the results of the theoretical analysis; experimentalwork was carried out on a single cell, simple span, I!lO scale model of reinforcedconcrete with 45 0 angle of skew. The total length of the model is 3040 mm, while thetested span is 2640 mm. The model has an overall depth of 300 mm. The model was testedto failure under two concentrated loads over each web. The test results together withcomparisons with the results of the linear and the nonlinear analyses are presented.