PSI - Issue 70

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ScienceDirect

Procedia Structural Integrity 70 (2025) 35–42

Structural Integrity and Interactions of Materials in Civil Engineering Structures (SIIMCES-2025) Experimental investigations on looseness in beam-to-upright connections of CFS storage racks

Umeshkumar T. Mourya a,* , S. Arul Jayachandran a a Civil Engineering, Indian Institute of Technology Madras, Chennai - 600036, India

Abstract This paper presents an experimental investigation into the looseness observed in boltless beam-to-upright connections of cold formed steel storage racks. These connections, formed by tab-insertion mechanisms, are inherently semi-rigid and prone to looseness due to oversize perforations in the uprights, resulting in discontinuities in their structural response under cyclic loading. A total of twelve connection configurations with variations in upright, beam and end-connector geometries were evaluated through single cantilever bending tests as recommended by EN15512. The tests involved alternating sagging and hogging moments to simulate reversal loading conditions, and the looseness was quantified by measuring relative displacements in the connection. Results demonstrated that looseness values ranged from 0.005 to 0.028 radians, correlating to imperfection amplitudes between 1/200 and 1/35. The number of tabs in the end-connector, as well as upright thickness and geometry, significantly influenced the looseness. The study highlights the importance of accounting for connection looseness in rack frame design, as even minor geometric variations can substantially affect connection behavior. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of International Conference on Structural Integrity Organizers

Keywords: Bending test; imperfection; storage rack; looseness; cold-formed steelIntroduction

1. Introduction Boltless beam-to-upright connections in cold-formed steel (CFS) storage racks are the essential components in the which provide stability to storage racks in down-aisle direction with their semi-rigid action. The connections are formed with the help of tabs in the end-connector that fit into the perforations of the uprights to form the semi-rigid

* Corresponding author. Tel.: +91 44 2257 5308; +91-9910163168 E-mail address: umourya.iitm@gmail.com

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of International Conference on Structural Integrity Organizers 10.1016/j.prostr.2025.07.023