Improvements to the analysis of floorbeams with additional web cutouts for orthotropic plated decks with closed continuous ribs

Wouter De Corte,Philippe Van Bogaert 국제구조공학회 2007 Steel and Composite Structures, An International J Vol.7 No.1

Additional cutouts in the floorbeam webs of orthotropic plated bridge decks relieve the highly stressed lower flange of the ribs passing through these floorbeam webs from possible fatigue damage. Conversely, the floorbeam webs themselves suffer from high stress concentrations, especially along the free edges of the additional cutouts. These stresses result from a combination of direct introduction of vertical traffic loads in the weakened web and from the truss action of the floorbeam. The latter differs from a simple beam action due to the presence of the openings and corresponds more to the behaviour of a Vierendeel truss. Close assessment of the appearing stresses, highly relevant for fatigue resistance, requires the use of elaborate finite element modelling. However, a full finite element analysis merely provides the results of total stresses, leaving the researcher or designer the difficult task of finding the origin of these stress components. This paper presents a calculation method for cutout stresses based on a combination of a framework analysis and a two dimensional finite element analysis of much smaller parts of the floorbeam. This method provides more insight in the origin of the stress components, as well as it simplifies any comparison of different additional cutout geometries, independent of the floorbeam topology.

Mechanical properties of curved composite box girders with corrugated steel webs

Sumei Liu,Wouter De Corte,Hanshan Ding,Luc Taerwe 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.1

Several methods derived for use on traditional concrete curved box girders (CBGs) are used in design practice. However, these typically consider only one elastic modulus and one shear modulus, and consequently cannot be applied directly to CBGs with corrugated steel webs (CSWs) due to the large shear deformations and small longitudinal stiffness of CSWs, while these shear deformations are small and usually ignored for common concrete webs. In this paper, firstly, the flexure-torsion governing differential equations considering the shear deformations and the accordion effect of CSWs, and the distortion governing differential equation considering the accordion effect of CSWs are derived for CBGs with CSWs. A practical method which can solve the deflections, torsional angles, distortional angles, stresses and internal forces of simple and continuous CBGs with intermediate diaphragms is proposed. Secondly, the results of a series of tests performed on three CBGs with CSWs, published test results, as well as finite element analysis results and theoretical results of straight box girders (SBGs) with CSWs are used to verify the correctness of the analytical method. The agreement between analytical, experimental and numerical results is good. Finally, a parametric analysis is conducted and the results show that: (a) the influence of shear deformations of CSWs on the deflections of CBGs with CSWs increases with increasing curvature radius R. For SBGs with CSWs, the deflections may increase by 30% when considering shear deformations. For CBGs with CSWs, the deflection increase ranges between 8% and 30% for concentrated loads depending on the curvature radius. (b) the distortional shear stress, which is small and typically neglected for CBGs with concrete webs, may be as big as, or larger than the flexural shear stress, and must be considered. The restrained torsional shear stress, which is also small and typically neglected for CBGs with concrete webs, can reach 9% of the flexural shear stress, and also must be considered.

Influence of the cylinder height on the elasto-plastic failure of locally supported cylinders

Arne Jansseune,Wouter De Corte,Wesley Vanlaere,Rudy Van Impe 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.12 No.4

Frequently, steel silos are supported by discrete supports or columns to permit easy access beneath the barrel. In such cases, large loads are transferred to the limited number of supports, causing locally high axial compressive stress concentrations in the shell wall above the supports. If not dealt with properly, these increased stresses will lead to premature failure of the silo due to local instability in the regions above the supports. Local stiffening near the supports is a way to improve the buckling resistance, as material is added in the region of elevated stresses, levelling these out to values found in uniformly supported silos. The aim of a study on the properties of local stiffening will then be to increase the failure load, governed by an interaction of plastic collapse and elastic instability, to that of a discrete supported silo. However, during the course of such a study it was found that, although the failure remains local, the cylinder height is also a parameter that influences the failure mechanism, a fact that is not properly taken into account in current design practice and codes. This paper describes the mechanism behind the effect of the cylinder height on the failure load, which is related to pre-buckling deformations of the shell structure. All results and conclusions are based on geometrically and materially non-linear finite element analyses.

Elastic Failure of Locally Supported Silos with U-shaped Longitudinal Stiffeners

Arne Jansseune,Wouter De Corte,Jan Belis 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.4

For practical considerations, thin-walled steel silos are often supported by a limited number of discrete equidistant supports around their circumference. In such cases, large loads are transferred to the limited number of supports, causing locally high axial compressive stress concentrations. A possible solution is to add a partial-height U-shaped longitudinal stiffener above each support. Such stiffeners create a more gradual transmission of vertical loads to the supports, increasing the maximum failure load. This paper aims to map the influence of the dimensions of such longitudinal stiffeners on the failure behaviour of a thin-walled silo. Both the parameters of the cross-section and the height of the stiffeners are discussed. All the results and the findings are based on geometrically and material nonlinear analyses - GMNA - performed with finite element software. The simulations indicate that, in general, thin-walled silos will fail by pure elastic buckling in the unstiffened silo wall above the terminations of the longitudinal stiffeners. However, this is only true if the cross-section of the stiffeners, and to a lesser degree the moment of inertia, is sufficiently large in order that the longitudinal stiffeners can absorb the supporting loads. In contrast, for longitudinal stiffeners with a small cross-section, the silo structure will fail by premature elasto-plastic collapse of the stiffeners itself at significantly lower load levels. Furthermore, the height of the stiffeners and the degree of support - the circumferential width of the supports and the stiffeners is equal to each other - are the most important geometrical parameters which are beneficial to reach a maximum load level for a specific silo. Finally, the buckling behaviour and the failure load are hardly influenced by radial width and the thickness of the longitudinal stiffeners.

The influence of convoy loading on the optimized topology of railway bridges

Arne Jansseune,Wouter De Corte 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.1

This paper presents the application of topology optimization as a design tool for a steel railway bridge. The choice of a steel railway bridge is dictated by the particular situation that it is suitable for topology optimization design. On the one hand, the current manufacturing techniques for steel structures (additive manufacturing techniques not included) are highly appropriate for material optimization and weight reduction to improve the overall structural efficiency, improve production efficiency, and reduce costs. On the other hand, the design of a railway bridge, especially at higher speeds, is dominated by minimizing the deformations, this being the basic principle of compliance optimization. However, a classical strategy of topology optimization considers typically only one or a very limited number of load cases, while the design of a steel railway bridge is characterized by relatively concentrated convoy loads, which may be present or absent at any location of the structure. The paper demonstrates the applicability of considering multiple load configurations during topology optimization and proves that a different and better optimal layout is obtained than the one from the classical strategy.