Effects of Radial Imperfection on the Load Capacity of Round HSS Columns


1 Faculty of Engineering, Urmia University, Urmia, Iran

2 Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran


Geometric imperfections such as radial imperfection, diamond shape, and local dimples could affect the buckling mode and load carrying capacity of axially compressed steel tubular columns. This paper experimentally investigates the effect of radial imperfection on the load carrying capacity of tubular columns. Test samples include 100 specimens with different values for diameter, length, thickness, imperfection amplitude and imperfection location. Considering applications of columns in buildings, bridges, and offshore jackets, diameter to thickness and slenderness ratios were varied between 20-90 and 17-181, respectively. Results showed that depending on the slenderness ratio and the severity of the imperfection, there was a significant difference between buckling loads of perfect and imperfect specimens.


1.     Timoshenko S.P., Gere J.M., “Theory of elastic stability”, 2nd ed. Singapore, McGraw-Hill, (1965).
2.     Starnes, Jr. J. H., “The effects of cutouts on the buckling of thin shells”, Thin-shell structures, Prentice-Hall, (1974), 289-304.
3.     Horton, W.H. and Durham, S.C., “Imperfections, a main contributor to scatter in experimental values of buckling load”, International Journal of Solids and Structures, Vol. 1, No. 1, (1965), 59-62, IN1-IN2, 63-70, IN3, 71-72.
4.     Koiter, W.T., “The effect of axisymmetric imperfection on the buckling of cylindrical shells under axial compression”, Academia van Wetenschappen-Amsterdam, Series B,No. 66, (1963), 265-279.
5.     Chajes, A., “Post-buckling Behavior”, Journal of Structural Engineering, 109, (1983), 2450-2462.
6.     Nishimori, F.  “Influential mode of imperfection on carrying capacity of structures”, Journal of Engineering Mechanics, Vol. 115, (1989), 2150-2165.
7.     Koiter, W.T., “About the stability of the elastic balance (in Dutch)”, Thesis Delft, Amsterdam, (1945).
8.     Hutchinson, J. W. and Koiter, W. T., “Postbuckling theory”, Applied Mechanics, Rev. 23, (1970), 1353-1366.
9.     Krishnakumar, S. and Foster, C.G., “Axial load capacity of cylindrical shells with local geometric defects”, Experimental Mechanics, (1991), 104-110.
10.   Tafreshi, A., and Colin, G.B., “Instability of imperfect composite cylindrical shells under combined loading”, Composite Structures, Vol.80, No. 1, (2006), 49-64.
11.   Chan, T. M., and Gardner, L., “Flexural buckling of elliptical hollow section columns”, Journal of Structural Engineering, (2009), 546-557.
12.   Shariati, M., and Mahdizadeh Rokhi, M., “Buckling of steel cylindrical shells with an elliptical cutout”, International Journal of Steel Structures, Vol. 10, No. 2, (2010), 193-205.
13.   Shu, G., Zheng, B., and Shen, X., “Experimental and theoretical study on the behavior of cold-formed stainless steel stub columns”, International Journal of Steel Structures, Vol. 13, No. 1, (2013), 141-153.
14.   Ghanbari Ghazijahani, T., Jiao, H., and Holloway, D., “Plastic buckling of dented steel circular tubes under axial compression: An experimental study”, Thin-Walled Structures, Vol. 92, (2015), 48-54.
15.   Guo, L., Liu, Y., Jiao, H., and An, S. “Behavior of thin-walled circular hollow section stub columns under axial compression”,  International Journal of Steel Structures, Vol. 16, No. 3, (2016), 777-787.
16.   Kalantari, Z., and Razzaghi, M. S., “Predicting the buckling Capacity of Steel Cylindrical Shells with Rectangular Stringers under Axial Loading by using Artificial Neural Networks”, International Journal of Engineering (IJE), Transactions B: Applications, Vol. 28, No. 8, (2015), 1154-1159.
17.   Rastgar, M., and Showkati, H., “Field Study and Evaluation of Buckling Behavior of Cylindrical Steel Tanks with Geometric Imperfections under Uniform External Pressure”, International Journal of Engineering, Transactions C: Aspects, Vol. 30, No. 9, (2017), 1309-1318.
18.   “Specification for structural steel buildings”, American Institute of Steel Construction, Chicago: ANSI/AISC 360-16, (2016).
19.   Salmon, C.G., Johnson, J.E., and Malhas, F.A., “Steel structures design and behavior”, Prentice-Hall, (2009).
20.   Greschik, G., “Global imperfection-based column stability analysis”, 48th structures, structural dynamics, and materials conference, April 23-26, (2007).
21.   Gavrilenko, G.D., “Stability of cylindrical shells with local imperfections”, International Applied Mechanics, Vol. 38, No. 12, (2002), 1496–1500.
22.   Schneider, W. “Stimulating equivalent geometrical imperfections for the numerical buckling strength verification of axially compressed cylindrical steel shells”, Computational Mechanic, Vol. 37, No. 3, (2006), 530–536.
23.   Teng, J.G., and Rotter, J.M., “Buckling of pressurized axisymmetrically imperfect cylinders under axial loads”, Journal of Engineering Mechanics, Vol. 118, (1992), 229-247.
24.   Wullschleger, L., and Piening Meyer, H.R., “Buckling of geometrically imperfect cylindrical shells-definition of a buckling load”, International Journal of Non- Linear Mechanics, (2002), 645–57.
25.   Gavrilenko, G.D., and Krasovski, V.L., “Stability of circular cylindrical shells with a single local dent”, Strength of Materials, Vol. 36, No. 3, (2004), 260–268.
26.   Jiao, H., and Zhao, X.L., “Imperfection, residual Stress and yield slenderness of very high strength (VHS) circular steel tubes”, Journal of Constructional Steel Research, Vol. 59, (2003), 233-249.
27.   Bjornsson, T., “Structural analysis of columns with initial imperfections”, M.Sc. thesis, Faculty of Civil and Environmental Engineering, University of Iceland, (2017).
28.   Somodi, B., “Flexural buckling resistance of high strength steel welded and cold-formed square closed section columns”, Thesis of dissertation, Faculty of Civil Engineering, Budapest University of Technology and Economics, (2017).