An independent distortional analysis method of thin-walled multicell box girders

Kim

et al. 2021

Metals

Self Cite

When eccentric live loads are applied on the deck overhang of steel-box girder bridges, torsional moments, comprising pure torsional and distortional moments are generated on the box sections. The torsional moment on the bridge girders distorts the box girder cross-sections, inducing additional normal stress components and causing instability of the box girder sections in severe cases. Hence, it is essential to install intermediate diaphragms in the box sections to minimize distortional behaviors. Although the applied live loads are critical parameters that influence intermediate diaphragm spacings, the effects of live load combinations have rarely been addressed in the design of intermediate diaphragm spacings. Thus, load combinations should be evaluated to design the intermediate diaphragm spacing of the box girder bridges more thoroughly. In this study, the load combination effects on the distortional behavior and adequate intermediate diaphragm spacing were evaluated through a finite element analysis (FEA). Composite rectangular box girder bridges with different cross-sectional aspect ratios (H/B) and spans (L) were analyzed in the parametric study. It was found that the truck load, which represents the concentrated load, significantly influences the distortional warping normal stress, normal stress ratio, and intermediate diaphragm spacing. In addition, the FEA results showed that the controlling load combinations could be varied with the span.

Section: Introductionmentioning

confidence: 99%

Effect of Load Combinations on Distortional Behaviors of Simple-Span Steel Box Girder Bridges

Kim

et al. 2021

Metals

Self Cite

Advances in Structural Engineering

“…In recent years, finite element method (FEM) is rapidly developed and commonly applied to analyze the relationship between the diaphragm number and the girder distortion (Choi et al, 2003;Lee et al, 2015;Li and Luo, 2010;Park et al, 2002Park et al, , 2003Park et al, , 2005aPark et al, , 2005bPark et al, , 2005cZhang, 2013), where the assumption of infinite in-plane shear stiffness for diaphragms is made for simplicity. However, this assumption is limited and doesn't fit for the thin solid or perforated diaphragms with finite shear stiffness.…”

Section: Introductionmentioning

confidence: 99%

New research for the distortion of steel box girders with inner solid diaphragms

Ren

Wang

et al. 2019

Toward estimating accurately the distortional response of box girders, in this article, distortion of steel box girders strengthened with intermediate solid diaphragms under eccentric loads is analyzed by employing the so-called initial parameter method. A new model of high-order statically indeterminate structure was established with three orthogonal redundant forces acting at the junction between the girder and diaphragms. Emphasis is put onto the interaction between the girder and diaphragms, where a hypothetical bi-moment B pi indicating all longitudinal redundant force components for diaphragm was proposed besides the moment Mpi for in-plane shear component. Simplified initial parameter method solutions for distortional angle and distortional warping stresses and displacements were derived based on the in-plane and out-of-plane compatibilities between the girder and diaphragms. Taking box girders with three and five intermediate diaphragms as an example, the proposed initial parameter method solutions have good agreement with the finite element analysis ones. Finally, distortional behavior under moving eccentric loads is investigated, resulting in a bowl-shaped curve for moment Mpi and an approximate trigonometric function for bi-moment Bpi. Results show that diaphragms have a stronger resistance on in-plane distortional shear for the loads in midspan than on ends. Plus, the thick diaphragm holds a stronger restraint on distortional warping deformations and stresses than the thin one.

Proceedings of the 2017 Global Conference on Mechanics and Civil Engineering (GCMCE 2017)

“…Based on the idea of force decomposition for thin-walled box-girder, as shown in Fig.1, which was proposed by Nakaiand Yoo [3]. When a single-cell box girder is subject to an eccentric load, the load can be resolved into flexural (symmetric load) and torsional forces (Anti-symmetric load), while torsional forces can be converted into pure torsion and distortion [2]. Sometimes, the eccentric load can not only be applied at the intersection of web and top plate.…”

Section: Introductionmentioning

confidence: 99%

Error Analysis on Force Decomposition of Applied Eccentric Load for Concrete Box-girder

Zhang¹,

Liu²,

Wang³

et al. 2017

Abstract. The paper is devoted to error analysis on force decomposition of applied eccentric load for concrete box-girder, the main parameter eccentric 'e' was considered. The stress under eccentric load, symmetric load, and anti-symmetric load is extracted from ABAQUS model, the floor stress along the cross-section and longitudinal beam were analyzed. The results show that force decomposition methodology can be used when eccentric load be 0 and b/2, when eccentric distance e=b/2, the error is zero, which means the force decomposition methodology is correct under this condition; when e=0, there is no torsion exist, the error is also very small. But when 0