Yan-Lin Guo

Experimental Investigation into Flexural-Torsional Ultimate Resistance of Steel Circular Arches

AbstractThis paper deals with experimental investigations into flexural-torsional ultimate resistance of in-plane-pinned circular steel arches. Three I-section arches with the same span but different rise-to-span ratios were tested under different loading conditions. A test rig comprising loading frames and lever beams was used to apply symmetrical three-point loads over the full span and unsymmetrical two-point loads over half the span to the arch rib. These concentrated loads are directed toward fixed points during flexural-torsional buckling of the arches. The arches are supported in such a way that their ends in plane are pinned and out of plane are semirigidly restrained. Geometric imperfections are measured before loading. The test results show that when the test arches reach their load-carrying capacity, plastic zones form in the arch rib, and the out-of-plane flexural-torsional deformation is significant. It is found that the pinned arches buckle in an asymmetric double-wave S-shaped flexural-tors...

In-Plane Failure Mechanism and Strength of Pin-Ended Steel I-Section Circular Arches with Sinusoidal Corrugated Web

AbstractThis paper investigates the global in-plane failure and local web shear failure mechanism and strength of steel I-section circular arches with a sinusoidal corrugated web. In reference to a flat web that can resist both the shear and axial forces, the sinusoidal corrugated web can resist the shear force only. As a result, the sinusoidal corrugated web may fail in an elastic-plastic shear buckling mode. This study considers pin-ended circular steel arches with a sinusoidal corrugated web under a uniform radial load or a uniform vertical load to elucidate numerically their different failure modes. It is found that local web failure occurs suddenly without warning, and all aspects pertaining to the local web shear failure are investigated thoroughly with an equation for the ultimate shear-carrying capacity of nonuniformly sinusoidal corrugated webs being proposed. It is also found that the effects of the shear deformations of corrugated web on global in-plane buckling and the strength of steel arches...

Flexural-Torsional Buckling and Ultimate Resistance of Parabolic Steel Arches Subjected to Uniformly Distributed Vertical Load

AbstractThis paper focuses on the flexural-torsional buckling and ultimate resistance of parabolic steel arches with box sections subjected to full-span uniformly distributed vertical load by using finite-element numerical analyses. First, analyses on prebuckling internal forces and flexural-torsional buckling loads are performed and compared with the existing theories. They show that parabolic arches under uniformly distributed vertical load are actually subjected to combined axial compressive and in-plane bending actions, rather than pure compression in the classic theory. Because the bending moment is substantial for shallow arches, the classic theory with the assumption of pure compression does not predict exactly the flexural-torsional buckling load. Second, the flexural-torsional ultimate resistance of parabolic arches is explored based on extensive finite-element numerical results, resulting in a design method based on a modified slenderness. The rise-to-span ratio is found to have a great effect o...

Theoretical study of ultimate load of locally buckled stub columns loaded eccentrically

Abstract This paper is concerned with the post buckling behavior and ultimate load-carrying capacity of thin-walled cold formed and welded stub columns subjected to a constant load eccentricity or a constant compression eccentricity. The analysis is based on the combined geometric and material nonlinear finite strip method in association with modified Ilushin yielding function. The emphasis is placed on the numerical studies on the effects of the loading types, load eccentricities and initial plate imperfections as well as the width-thickness ratios of the plates and the aspect ratios of the sections on the post buckling behavior and ultimate load-carrying capacity of thin-walled stub columns. The comparison of the theoretical results of this study with the experimental results conducted by X. Zhang (Ph.D. Thesis, Technical University, Darmstadt, 1989) is made and an agreement between both is very satisfactory.

Revisiting Nonlinear In-Plane Elastic Buckling and Postbuckling Analysis of Shallow Circular Arches under a Central Concentrated Load

AbstractThis paper revisits the nonlinear in-plane analysis of a shallow pin-ended circular arch under a central concentrated load. It is found that the arch may have multiple equilibrium branches and limit points, and a modified slenderness of the arch defined in the paper plays an important role in the number of the limit points and equilibrium branches. The analytical solution for the specific modified slendernesses that switch the number of equilibrium branches and limit points is derived. The analytical solutions for the load, axial force, and radial displacements corresponding to the specific modified slendernesses are also derived. This paper deepens the understanding for the geometric nonlinear analysis of circular arches and their geometric softening and stiffening behavior and provides useful benchmarks for the analyses of shallow arches. In addition, this paper extends the current solutions of nonlinear equilibrium of arches associated with axial compression to those associated with axial tensi...

In-Plane Failure and Strength of Pin-Ended Circular Steel Arches Considering Coupled Local and Global Buckling

AbstractLittle research has been reported that investigates the effects of plate local buckling and postbuckling on the in-plane behavior and strength of steel arches, and hitherto there has been no corresponding design guidance available. This paper presents a numerical investigation of the structural behavior of steel arches, and proposes a strength design method against their in-plane failure by considering plate local elastic-plastic buckling and postbuckling coupled with global elastic-plastic buckling. The failure modes of pin-ended steel circular arches having a box section under a uniformly distributed radial load are analyzed by using a large deformation elastic-plastic finite-element formulation. It is found that plate local buckling significantly influences the in-plane failure mode and strength of a steel arch. The arch may fail owing to local elastic-plastic buckling of its plates, global elastic-plastic buckling of the arch, or coupled local and global elastic-plastic buckling. The failure m...

Out-of-Plane Elastic Buckling of Circular Arches with Elastic End Restraints

Circular arches subjected to in-plane loading are restrained with discrete lateral bracings to improve their out-of-plane stabilities in many cases. The arch segment between two adjacent bracings may buckle out of plane if the effective length of the arch segment is sufficiently large. During out-of-plane buckling, adjacent arch segments may provide elastic restraints which increase the out-of-plane stability of the arch segment significantly. This paper is concerned with out-of-plane elastic buckling of circular arch segments with elastic end restraints. The analytical method for deriving the out-of-plane buckling loads of circular arches with equal rotational restraints or equal warping restraints at both ends is formulated. For the convenience of structural designers, simple approximate formulas for predicting the out-of-plane buckling loads of these arches are developed by the curve-fitting method. As for circular arches with unequal rotational restraints, the approximate formula for the buckling load of the arch with equal rotational restraints is modified with a reduction factor. Comparisons with the finite-element results and the analytical solutions show that the predictions by approximate formulas are sufficiently accurate.

Subassemblage tests and design of steel channels assembled buckling-restrained braces

This study investigates the load-carrying behavior of a proposed all-steel buckling-restrained brace (BRB) under seismic loading. The proposed steel channels assembled BRB (SCA-BRB) consists of a steel core plate encased by four steel channels assembled by high-strength bolts. Self-weight of an SCA-BRB is relatively small since the use of concrete is eliminated, leading to easier transportation and erection of the BRB. Firstly, by simplifying the restraining system of an SCA-BRB into a 2-chord battened column, the reduction factor of the elastic buckling load of the restraining system considering the discrete connection of bolts was derived. On this basis, the formulas in predicting ultimate resistance of an SCA-BRB were deduced along with the formulas of the lower limit of restraining ratio, and the upper limit of bolt spacing. Then, subassemblage test results of four specimens were reported. All the test specimens maintained stable load-carrying capacity during the loading process, and satisfactory energy-dissipating ability was achieved. Finite element (FE) models were established, and they well predicted the hysteretic responses of the test specimens. A total of 25 additional FE models was analyzed to perform a parametric study, verifying the effect of the member length, number of bolts, steel grade, gap size and geometrical imperfection on the hysteretic response and ultimate resistance of BRB. Finally, a design procedure of the SCA-BRB was proposed based on theoretical formulas, which have been validated by tests and FE results.

Strength and Design of Pin-Ended Circular Arches with Sinusoidal Corrugated Web under Combined In-Plane Loads

AbstractThis paper presents numerical and experimental investigations of the in-plane strength and design of pin-ended circular arches having a sinusoidal corrugated web under combined in-plane loads. Finite-element models are developed that account for the effects of the corrugated web, initial geometric global and local imperfections of the arch and its web and flanges, residual stresses, the included angle and curvature of the arch, and different combined load cases. These are validated by test results and used together with the experiments to investigate the failure modes and strengths of such arches. It is found that an I-section arch with a corrugated web may fail in a global mode or in a web shear buckling mode. There are two types of global failure modes for arches under combined loads. In most cases, corrugated arches may fail in an elastoplastic buckling mode. However, when wind load plays an important role in the combined loads, corrugated arches may fail in a plastic yielding mode. An interact...

Threshold Stiffness of Discrete Lateral Bracing for Out-of-Plane Buckling of Steel Arches

AbstractSteel arches are often restrained by elastic lateral braces to improve their out-of-plane stability. Because in real structures, the braces are not infinitely elastic and the strength consideration can have an effect on the stiffness requirement of the braces, it is important for the lateral braces to have sufficient stiffness and to be configured properly. This paper presents an investigation of the threshold stiffness and arrangement of discrete lateral braces required for preventing steel arches from buckling out of their plane. An energy approach is used to derive the elastic threshold stiffness for discrete lateral braces, and the effect of out-of-plane geometric imperfections on the elastic threshold stiffness of the lateral bracing is also studied. The number of lateral braces and the length of the arch segment between adjacent braces are also derived analytically by comparing the in-plane buckling loads of the entire arch and the out-of-plane buckling loads of the arch segment between adja...