Failure Analysis of an Aluminum Extension Portable Ladder


The conditions of end supports of straight ladders are often the cause of major injuries. The firm and secure ladder ends against instability in general and sliding of the top and bottom ends in particular are among the check list of most ladder safety training books and manuals. However, the restraint to the free expansion of a ladder can cause a catastrophic failure due to buckling even at intermediate loads and should be presented in the latter as a serious potential hazard. This paper deals with an investigation of an extension. An analytical structural model that simulates the buckling behavior of an axially restrained ladder subjected to static and dynamic loading is developed. It compares two different ladder end conditions and shows that instability due to buckling can occur during ascension or descent in the case of an axially restrained ladder. The analytical results are supported and validated by a finite element model simulation conducted in parallel. This study may explain the root cause of similar incidents involving falls from portable ladders worldwide.

Share and Cite:

Bouzid, A. (2014) Failure Analysis of an Aluminum Extension Portable Ladder. Materials Sciences and Applications, 5, 674-684. doi: 10.4236/msa.2014.59069.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Dewar, M.E. (1977) Body Movements in Climbing a Ladder. Ergonomics, 20, 67-86.
[2] Hakkinen, K.K., Pesonen, J.P. and Rajamaki, E. (1988) Experiments on Safety in the Use of Portable Ladders. Journal of Occupational Accidents, 10, 1-9.
[3] Chang, W.R., Chang, C.C., Matz, S. and Son, D.H. (2004) Friction Requirements for Different Climbing Conditions in Straight Ladder Ascending. Safety Science, 42, 791-805.
[4] Snyder, G.A., Glancey J.L., Vinson J.R. and Cintavey, D.M. (2003) Failure Analysis of Step Ladders Manufactured from Extruded Aluminum. Proceedings of ASME 2003 International Mechanical Engineering Congress and Exposition, Washington, DC, 15-21 November 2003, 415-423.
[5] Kenner, M.T., Stevenson, M.E., Knox, E.H., Van Bree, M.P. and Wilkinson, J.A. (2011) Step Ladder Failure Analysis: A Comparison of Analytical Methods. Proceedings of ASME 2011 International Mechanical Engineering Congress and Exposition, 11-17 November 2011, Denver, 397-405.
[6] Knox, E.H., Van Bree, M.P., Kenner, M.T. and Wilkinson, J.A. (2009) Structural Stepladder Failure: Analysis of Root Cause. Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 13-19 November 2009, Lake Buena Vista, 433-441.
[7] Routley, J.G. and Bush, R. (1996) Aerial Ladder Collapse Incidents. U.S. Fire Administration. Technical Report Series, USFA-TR-081, April 1996.
[8] Ali, F.A. and O’Connor, D.J. (1996) Calculation of Axial Forces Generated in Restrained Pin Ended Steel Columns Subjected to High Temperatures. Journal of Applied Fire Science, 6, 383-394.
[9] Hozjan, T., Planinc, I., Saje, M. and Srpcic, S. (2011) Buckling of an Axially Restrained Steel Column under Fire Loading. International Journal of Structural Stability and Dynamics, 11, 451-472.
[10] Shepherd, P.G. and Burgess I.W. (2011) On the Buckling of Axially Restrained Steel Columns in Fire. Engineering Structures, 33, 2832-2838.
[11] Subramanian, R. and Venkateswara, R.G. (1987) Stability of Columns Subjected to an Intermediate Concentrated Load with One End Elastically Restrained to Move Axially. Computers and Structures, 25, 105-107.
[12] CSA-Z11-FM81 (2011) Portable Ladders. CSA Standards.
[13] ANSI ASC A14.2 (2007) Ladders—Portable Metal—Safety Requirements.
[14] Kurrer, K.E. (2008) The History of the Theory of Structures—From Arch Analysis to Computational Mechanics. Ernst &Sohn, Berlin.
[15] Young, W.C. and Budynas, R.G. (2001) Roark’s Formulas for Stress and Strain. 7th Edition, Mc-Grew-Hill, New York.
[16] Timoshenko, S.P. and Gere, J.M. (1961) Theory of Elastic Stability, 2nd Edition, McGraw-Hill, New York.
[17] CAN/CSA-S157-05/S157.1-05 (2010) Strength Design in Aluminum / Commentary on CSA S157-05—Strength Design in Aluminum. CSA Standard.
[18] ANSYS (2013) ANSYS Standard Manual Version 13.0.
[19] Glancey, J.L., Snyder, G.A., Vinson, J.R., Krisher, J. and Franklin, P. (2005) Fiberglass and Aluminum Step Ladder Performance under Dynamic loading Conditions. Proceedings of 2005 ASAE Annual International Meeting, 17-20 July 2005, Tempa, Paper Number: 055009.

Copyright © 2023 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.