Fatigue Life Of Girders Research Articles

Fatigue life of girders with trapezoidally corrugated webs: An experimental study

Corrugated steel plate has been increasingly used in the last 20years for beam webs in hybrid and composite bridges. Girders with corrugated webs have many advantages over traditional structures with flat webs, but due to the new structural layout, there are still many design questions that need to be solved. In cases with girders with trapezoidally corrugated webs, the determination of the fatigue life is rather difficult because of the complex stress field in the flanges, and the fatigue detail category has also not been elucidated. This topic has gained importance in Hungary related to a highway bridge on the Tisza River designed and constructed between 2006 and 2011. There are only a small number of investigations dealing with the fatigue behaviour of corrugated web girders in the literature. The aim of the current tests published in this paper is the analysis of the fatigue behaviour of the corrugated web girders under pure bending and combined bending and shear. Furthermore, a proposal for the fatigue detail category is developed based on the test results to support the bridge design. The tests were completed to study the effect of the corrugation profile, the normal stress ratio, the effect of the combined normal and shear stresses and the weld size on the fatigue life.

Fatigue Life of Girders with Trapezoidal Corrugated Webs

Fatigue design criteria are necessary to design steel corrugated web girders for highway bridges. The paper presents research on the fatigue life of steel bridge I-girders with trapezoidal web corrugations. Eight large-scale test girders were fabricated from HPS 485W steel and fatigue-tested in four-point bending. The web-to-flange fillet welds were made using semiautomatic gas metal arc welding (GMAW) or robotic GMAW. Fatigue cracks initiated in the tension flange at the web-to-flange fillet weld toe along the inclined web folds and adjacent bend regions, and propagated in the flange. The results demonstrate that steel corrugated web I-girders exhibit a fatigue life that is longer than that of conventional steel I-girders with transverse stiffeners. For design of corrugated web I-girders, the Category B′ design curve of the AASHTO LRFD specifications is recommended for finite life fatigue design calculations, and a value of 96.5MPa(14.0ksi) is recommended for the constant amplitude fatigue limit.

Fatigue life of girders with undulating webs

Steel girders with sinusoidally predeformed webs, commonly used in Central Europe and elsewhere, are described. A review of their static and fatigue resistance, based on tests and theoretical analyses performed at CTU in Prague, is presented. First, results of extensive static tests with local patch loading are given. The tests were statistically evaluated in accordance with Annex Z of Eurocode 3, to determine characteristic and design resistance values. The results were verified using geometrically and materially non-linear finite element analyses accounting for imperfections, and supplemented with parametrical studies. The main part of the paper reports on a vast number of tests dealing with the fatigue of undulating webs under cyclic shear and cyclic steady local patch loading. The results are summarised and statistically evaluated into fatigue curves in compliance with Eurocode 3. Finally, tests simulating moving local crane loads are described, for which the cyclic and moving strain patterns in the undulating web were achieved through a special testing rig. Evaluation of these tests and theoretical analysis of local yielding were performed using ANSYS software. Finally, some recommendations are presented for the practical fatigue design of girders with undulating webs.