International Journal of Civil Engineering and Technology (IJCIET) Volume 10, Issue 04, April 2019, pp. 1715-1721, Article ID: IJCIET_10_04_180 Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=04 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication Scopus Indexed FURTHER ASSESSMENT OF BUCKLING STABILITY OF STEEL PLATES Farhad Riahi Dept. of Civil Engineering, Mahabad Branch, Islamic Azad University, Mahabad, Iran Dept. of Civil Engineering, Boukan Branch, Islamic Azad University, Boukan, Iran Vahed Mam Ghaderi Dept. of Civil Engineering, Mahabad Branch, Islamic Azad University, Mahabad, Iran Tadeh Zirakian* Dept. of Civil Engineering and Construction Management, California State University, Northridge, CA, USA Bijan Sanaati Dept. of Civil Engineering, Boukan Branch, Islamic Azad University, Boukan, Iran * Corresponding Author; Tel.: +1-818-677-7718, E-mail: tadeh.zirakian@csun.edu ABSTRACT: Thin plates are commonly-used structural members with wide range of applications. In spite of the proliferation of research on the buckling behavior of such members, further detailed investigations are still required for the performance assessment and improvement of such structural members. On this basis, the buckling behavior of thin steel plates subjected to uniaxial compressive loading is further investigated in this research endeavor via detailed numerical simulation by considering some key factors including the support conditions, aspect ratio, and slenderness. The results and findings of this study can provide further insight into the efficient design and application of such important structural members. Keywords: Plate, Steel, Buckling, Numerical simulation Cite this Article: Farhad Riahi, Vahed Mamghaderi, Tadeh Zirakian and Bijan Sanaati, Further Assessment of Buckling Stability of Steel Plates. International Journal of Civil Engineering and Technology, 10(04), 2019, pp. 1715-1721 http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=04 \http://www.iaeme.com/IJCIET/index.asp 1715 editor@iaeme.com Further Assessment of Buckling Stability of Steel Plates 1. INTRODUCTION Plates and shells are important structural elements in engineering and their buckling is a major aspect of structure damage. The buckling problem of a thin plate subjected to in-plane compressive and/or shear loading is important in the construction industry. The buckling of plates under distributed edge forces has been studied by numerous investigators, including Timoshenko (1910), Leggett (1937), Zetlin (1955), White and Cottingham (1962), Bulson (1969), Hopkins (1969), Khan and Walker (1972), Khan et al. (1977), and Young and Lui (2005). The first work in this area was perhaps reported by Van der Neut (1958), which considered a uniaxial compressive loading with a half sine distribution. Later, Benoy (1969) considered a uniaxial compressive loading with a parabolic distribution and obtained an energy solution. Shakerley and Brown (1996) investigated elastic buckling of simply supported and fully fixed plates with eccentrically placed rectangular cutouts using conjugate method. Their results were given for uniaxial compression and shear loading. Bert and Devarakonda (2003) studied the buckling of rectangular plates subjected to non-linearly distributed in-plane loading using analytical solution method. They considered a rectangular plate subjected to parabolic loads along with the removal of some deficiencies of earlier reported work. Zhong and Gu (2006) reported a study on the buckling analysis of simply supported rectangular plates subjected to linearly varying edge loads. An analytical solution to buckling problem was developed and the effect of load intensity variation on the critical load was investigated. Recently, MijuškoviΔ et al. (2014) presented an accurate buckling analysis for thin rectangular plates under locally-distributed compressive stresses. Interestingly, Wang et al.’s (2007) and Wang’s (2015) studies have also shown that the differential quadrature method can yield accurate buckling loads for rectangular plates under uniformly or non-uniformly distributed edge compressions. It is also noteworthy that some other researchers have conducted comprehensive research, most recently, on the buckling of shells and plates, e.g. McCann et al. (2016), Riahi et al. (2017 and 2018), and Vu et al. (2019). In this paper, the buckling behavior of rectangular steel plates subjected to uniaxial compression is investigated by considering some key parameters including the support conditions, aspect ratio, and slenderness. The current numerical study intends to provide a better understanding of effects of the aforementioned significant geometrical properties on the buckling stability performance of thin steel plates, which can consequently result in efficient design and application of such commonly-used and important structural members. 2. GEOMETRICAL AND MATERIAL PROPERTIES OF THE PLATE MODELS The considered boundary conditions of the plates are illustrated in Fig. 1, which include CCCC: clamped along all edges; SSSS: simply-supported along all edges; CFFS: clamped along the free edges and simply-supported along the loaded edges; SFCC: simply-supported along the free edges and clamped along the loaded edges. The letters S, C, and F respectively stand for simple, clamped, and free edges. All plate models are subjected to uniaxial compressive loading, as shown in Fig. 2. Figure. 1. Boundary conditions of the plate models http://www.iaeme.com/IJCIET/index.asp 1716 Figure. 2. Geometry and loading editor@iaeme.com Farhad Riahi, Vahed Mamghaderi, Tadeh Zirakian and Bijan Sanaati As it is seen in Fig. 2, the plate length (a) lies along the x-axis, the plate width (b) lies along the y-axis, and the plate thickness (t) is constant along the z-axis. It was assumed that midplane of the plate is coinciding with the x-y plane. The plate length (a) was considered to vary between 500 mm and 4000 mm. Moreover, the plate width (b) was considered to vary between 500 mm and 1000 mm, and also the plate thickness was taken as 1 mm and 2 mm. Thirty-two plate models, in total, were considered for the purpose of this research. The resulting thirtytwo models were divided into four groups based on the considered boundary conditions. The geometrical properties of the plate models are summarized in Table 1. Table 1. Geometry of specimens Plate model Geometrical property Plate width (b) [mm] Plate length (a) [mm] Plate thickness (t) [mm] Length/width ratio (a/b) P500 500 500 1000 1500 1 1 2 3 500 500 1 1 500 2000 1 4 P1000 1000 1000 2000 3000 2 2 2 3 1000 1000 2 1 1000 4000 2 4 The mechanical properties of the adopted steel material include: yield stress = 355 MPa, Poisson’s ratio = 0.3, Young’s modulus = 2.1×105 MPa, and bulk density = 7850 kg/m3. 3. FORMULATION OF THE PROBLEM As illustrated in Fig. 2, an isotropic thin rectangular plate with length (π), width (π), and thickness (π‘), subjected to uniaxial compressive loads π(π₯) was considered for the purpose of the current investigation. On this basis, the displacement field could be expressed as: ππ€ π’Μ (π₯, π¦, π§) = −π§ ππ₯ , ππ€ π£Μ (π₯, π¦, π§) = −π§ ππ¦ , π€ Μ (π₯, π¦, π§) = π€(π₯, π¦) (1) Where, (π’, π£, π€) are the displacement components along the x, y, z coordinate directions, respectively, and π€ is the transverse deflection of a point on the mid-plane, i.e. z = 0. Assuming the material of the plate to be isotropic and to obey Hooke’s law, the stress-strain relations can be given by πΈ πΈ πΈ ππ₯π₯ = 1−π2 (ππ₯π₯ + πππ¦π¦ ), ππ¦π¦ = 1−π2 (ππ¦π¦ + πππ₯π₯ ), ππ₯π¦ = πΊπΎπ₯π¦ = 2(1+π) πΎπ₯π¦ (2) Where, πΈ = Young’s modulus, πΊ = shear modulus, and π = Poisson’s ratio. Eqs. (1) to (3) constitute the mathematical formulation of the problem under consideration. Timoshenko and Gere (1961) investigated the buckling behavior of a simply supported rectangular plate subjected to uniform loading. The elastic critical buckling load (πππ ) of such thin plates can be calculated using Eq. (3): ππ2 πΈπ‘ 3 π πππ = 12(1−π£2 )β2 (3) Where, β = depth of plate, π = buckling coefficient of plate subjected to edge loading, π = plate length, and π‘ = plate thickness. The buckling coefficient is calculated against the plate aspect ratio a/b. An approximate analytical solution was provided by Timoshenko and Gere (1961), as given in Eq. (4). π = 0.456 + (π⁄π)2 http://www.iaeme.com/IJCIET/index.asp (4) 1717 editor@iaeme.com Further Assessment of Buckling Stability of Steel Plates 4. NUMERICAL ANALYSIS ABAQUS (2016) software was used for numerical simulation of the plate models. Thirty-two axisymmetric plate models with geometrical and material nonlinearities were developed. The plates were modeled using the eight-node SHELL element S8R5 with six degrees of freedom at each node including three translations and three rotations. An irregular mesh in finite element modeling was employed for simulation of the plates in which the element size was selected to be b/30 along the plate width. Linear and nonlinear buckling analyses were performed to obtain the buckling mode shapes, capacities, and deformations of the plate models. Fig. 3 shows typical buckling mode shapes of plates. Fig. 4, also, illustrates some typical analysis results on the large deflection collapse of the plate models. Figure. 3. Typical buckling modes of plates Figure. 4. Large deflection collapse of the plates under uniaxial compression 5. DISCUSSION OF RESULTS 5.1. Effects of Boundary Conditions and Aspect Ratio on Buckling Capacity The buckling capacities of plates with various aspect ratios and support conditions are illustrated in Fig. 5. In general, these results demonstrate the increasing of the buckling capacity of the plates as the aspect ratio increases beyond unity. This is indicative of effectiveness of the aspect ratio on the capacity performance of the plates. It is observed that the amount of fixity of the plate edges, as in CCCC and SFCC cases, plays an important role in improving the buckling capacities of the plates. Plates with CCCC support conditions possess the highest buckling strengths. In cases of SSSS and CFFS support conditions, it is evident that the aspect http://www.iaeme.com/IJCIET/index.asp 1718 editor@iaeme.com Farhad Riahi, Vahed Mamghaderi, Tadeh Zirakian and Bijan Sanaati CCCC SSSS CFFS SFCC 24 22 20 18 16 14 12 10 8 6 4 2 0 1 buckling load (*10^5 N/m) buckling load (*10^5 N/m) ratio parameter has a minimal effect on the buckling capacity of the plate. Plates with CFFS support conditions have the lowest performance due to the possession of two free edges; this can be quite important in the seismic applications of plates with free edges, for instance, the beam-attached infill panels in steel plate shear wall (SPSW) systems which requires the designer’s proper and adequate assessments. 2 a/b 3 24 22 20 18 16 14 12 10 8 6 4 2 0 4 CCCC SSSS CFFS SFCC 1 2 a/b (a) P500 3 4 (b) P1000 Figure. 5. Effects of plate aspect ratio and boundary conditions on buckling capacity 5.2. Effects of Boundary Conditions an Aspect Ratio on Maximum Displacement 0.10 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 0.14 CCCC SSSS CFFS SFCC 1 Maximum displacement-U3(m) Maximum displacement-U3(m) The maximum out-of-plane displacements of the models with various geometrical properties were obtained from the nonlinear static analyses for further stability (and serviceability) performance(s) assessment of the plates. These results are illustrated in Fig. 6. It is found that by increasing of the a/b aspect ratio from 1 to 4, the plate maximum displacement increases as well, consistent with all cases. The highest and the lowest maximum displacement values are associated with the SFCC and CCCC support conditions, respectively. Despite the scatteredness of the results, it may be concluded that fixity and proper arrangement of the plate edges, especially the free edges by considering the loading conditions in structures, can improve the out-of-plane displacement (and serviceability) performance(s) of plates. 2 a/b 3 4 (a) P500 CCCC SSSS CFFS SFCC 0.12 0.10 0.08 0.06 0.04 0.02 0.00 1 2 a/b 3 (b) P1000 Figure. 6. Effects of plate aspect ratio and boundary conditions on maximum displacement http://www.iaeme.com/IJCIET/index.asp 1719 editor@iaeme.com 4 Further Assessment of Buckling Stability of Steel Plates 6. CONCLUSION In this paper, the buckling stability performance of steel plates with different support conditions, aspect ratios, and slenderness values, subjected to uniaxial compression was investigated through detailed numerical simulations. Linear and nonlinear buckling analyses were performed and the buckling capacities and maximum out-of-plane displacements of the plate models were obtained. It was shown that the edge fixity can be instrumental in improving the buckling stability performance of plates. More importantly, accurate and careful assessment of the loading conditions in structures and accordingly proper placement of plates with different edge supports can improve the performance of the plate elements and indeed the main objective of this study was to provide the engineers and designers with more insight into the efficient design and application of plates as commonly-used structural members. 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