Effect of curvature and aspect ratio on shear resistance of unstiffened plates V. Broujerdian, P. Mahyar, A. Ghadami ⁎ Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran abstract article info Article history: Received 28 November 2014 Accepted 26 April 2015 Available online 5 June 2015 Keywords: Buckling Steel plate Shear strength FEM analysis Slenderness In order to investigate the effects of aspect ratio, curvature, and slenderness on the shear behavior of flat and curved plates, a parametric study is conducted. The simulations were performed by ABAQUS software. Theoretical relations were used to verify the validity of the out-coming numerical results. Comparing the results obtained from the FEM analysis with those from AASHTO, it is observed that the AASHTO shear strength of plates with aspect ratios less than 1.71 is non-conservatively more than the FEM results. For instance, in a flat plate with an aspect ratio of one, the difference between these two values is close to 8%. On the contrary, as the aspect ratio increases, the values of shear strength obtained from AASHTO are less than those derived from FEM. The difference of these two values reaches up to 11% in the case of plates with larger values of curvature. This study reveals that the curvature is a parameter which severely affects the shear behavior of plates. It is suggested that for a proper estimation of the elastic shear behavior of curved plates, this parameter must be taken into account. It is also observed that decreasing the slenderness results in lower effect of the curvature on the shear strength. Unlike the elastic range, in the plastic range of slenderness parameter, the shear strength of flat and curved plates could be considered equal. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction 1.1. Background Steel plates are widely used in engineering structures. Plate girders, gas and liquid containment structures, shelters, offshore structures, vessel fuselages, slabs, and steel plate shear walls are examples of engineering usage of such elements. On the other hand, there are some situations that curved plates are preferred to flat plates. For exam- ple need to smooth traffic transferring and restrictions on a straight path, along with the economic, environmental, and aesthetic consider- ations have resulted in wide use of curved plates for bridges [1]. Therefore, understanding the shear behavior of flat and curved steel plates has been the focus of many studies for several decades and much progress has been made in this field. 1.2. Literature review In spite of extensive literature devoted to this field, the complexity of shear behavior, arising from the interaction of geometrical buckling and material yielding, has not been solved yet. An unstiffened slender plate buckles elastically at early stages of loading and it experiences geometrical and material nonlinearities during its postbuckling behavior [2]. On the other hand, a thick plate yields before buckling. Therefore, no postbuckling capacity is expected for a thick plate. For intermediate thicknesses, there are nearly simultaneous material yielding and geometrical instability [3]. Various parameters affect the buckling behavior of the plates. Some of these parameters are: material properties, loading and boundary conditions, aspect ratio, curvature, initial imperfections, and slenderness of plates. Accordingly, during the past century, a lot of research dealt with evaluating these parame- ters. With regard to this, studies on the shear buckling behavior of plates may be categorized in the following three areas: flat plates, curved plates, and imperfection sensitivity studies. 1.2.1. Studies on shear behavior of flat plates Elastic buckling load of unstiffened flat plates was first studied by Bryan [4]. During the past century, buckling and postbuckling behav- ior of slender shear plates has been extensively studied and well documented. Timoshenko [5] utilized the energy method to study buckling of rectangular plates under the action of in-plane shear stress- es. He only considered the symmetrical buckling mode. This limitation led to an error in the prediction of critical stresses where antisymmetric buckling was the governing mode. It must be noted that if the number of out-of-plane peaks is even, buckling is called antisymmetric and if the number is odd, it is called symmetric. Stein and Neff [6] consid- ered both symmetric and antisymmetric buckling modes. Bediansky and Connor [7] applied the Lagrangian multiplier method and to compute both the upper and lower limits of the theoretical shear Journal of Constructional Steel Research 112 (2015) 263–270 ⁎ Corresponding author. Tel.: +98 912 023 5165; fax: +98 2177240398. E-mail address: Ghadami@civileng.iust.ac.ir (A. Ghadami). http://dx.doi.org/10.1016/j.jcsr.2015.04.025 0143-974X/© 2015 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Journal of Constructional Steel Research