Optimization of Trapezoidal Web Profile for Corrugated Steel Plate I Girder and A Parametric Study

Abstract

A parametric study has been carried out to know the factors affecting the optimisation of trapezoidal web profile for corrugated steel plate I girder. The influence of web ratio (ratio of flat to inclined web length portion) in a corrugated web plate girder on the strength and deflection characteristics is studied using ANSYS-FEM Software. Three corrugated web plate girders with web corrugation angles α=300 , 450 and 600 are considered in this study. In each corrugated web plate girder, the web ratio is varied from 0.2 to 1, in the increment of 0.2. These three corrugated web plate girders with corrugation angles α=300 , 450 and 600 along with their web-ratios are analyzed using ANSYS-FEM software for stresses and central deflections. A uniformly increasing central point load distributed uniformly across flange width at mid span is considered for the analysis. Load verses mid span deflection curves for various load increments are plotted. Stresses verses web ratios are also plotted. It is understood from the study that web ratio is affecting strength and deflection characteristics for any given the corrugation angle and depth of corrugation. Further analytical work has been carried out to get the optimised (efficient) trapezoidal web profile for steel plate I girder to resist lateral torsional buckling, global shear buckling, bending. In this regard, the required cubic equation to obtain the most efficient trapezoidal web profile for steel plate I girder for any given corrugation angle and depth of corrugation is derived. This cubic equation is used to get the optimised (efficient) trapezoidal web profiles for I girders in various standard example problems. The efficient web profiles obtained using this cubic equation are verified numerically by computing the lateral torsional bucking strengths, and global shear buckling strengths using the equations or formulae available in the literature. The efficient web profiles obtained using this cubic equation are also verified numerically by computing the global shear buckling strengths using formula suggested by authors. The results of all the example problems show that the presented cubic equation can be used to obtain the most efficient trapezoidal web profile for corrugated steel web plate I girder to resist lateral torsional buckling, global shear buckling for any given corrugation angel and depth of corrugation. To verify the efficient trapezoidal web profiles obtained for corrugated steel web I plate girder to resist bending, few corrugated steel I beams with trapezoidal web profiles have been fabricated and tested under uniformly increasing central point load to measure central vertical deflections and lateral displacements at supports Results show that optimised (efficient) trapezoidal web profile obtained using cubic equation derived, yields least mid span deflection and least lateral deflection. Hence optimised (efficient) trapezoidal web profile obtained using cubic equation can also be used to resist bending.