Nonlinear analysis of intermediate support regions of continuous span steel girders

The use of inelastic design methods has gained popularity in recent years due to its ability to utilize the full strength of a structure. However, until recently its use has been limited to buildings. The design of steel girder multiple-span bridges, which are inherently indeterminate structures, can greatly benefit from inelastic design methods. For continuous, statically indeterminate beams, the intermediate support regions are the areas of the maximum moment. It is therefore, this region that this research will focus.;The objective of this research is to develop inelastic moment-rotation curves for beams produced of high strength steel. The models used for analysis have compact flanges with compact and non-compact webs. The modeling of beams produced of high-strength steel, up to 70 ksi yield strength, will be used to further develop guidelines to incorporate such steels in bridge design. Bridges are inherently produced of long unsupported members prone to local yielding and buckling. The use of higher strength steels could play an important role in future design methods. Currently there exists little research in the area of inelastic moment-rotation curves for high strength steel beams. Numerical analysis of such beams would be an important step in the development of bridge design codes. The contribution of this research is to help understand the nonlinear behavior of high strength steel beams, which would reduce the cost of full or scaled models currently used in the development of the AASHTO bridge design code.;Finite element methods are used to analyze these intermediate support regions. The analysis is performed using MSC/NASTRAN nonlinear solutions. The nonlinear analysis will also examine the post-buckled behavior of these beams. Although postcritical states are usually not tolerated in structural design, the knowledge of this range provides better insight into nonlinear structural behavior such as the sensitivity to initial geometric imperfections. Geometric imperfections and residual stresses are introduced as parameters influencing load capacity and the post-critical behavior.