The influence of semi-rigid connections on the non-linear behaviour of pallet rack and scaffold structures

Traditional analyses of framed structures have assumed that the connections between uprights and beams are either rigid or pinned. In reality all joints exhibit flexibility and can be considered as semi-rigid. The published work in this thesis provides some of the most extensive work on the effects of semi-rigid connections on the behaviour of slender, thin-walled structures. In particular, the three papers on scaffold structures present the first analyses of large scaffold structures available in the literature in which all joint connections are semi-rigid. They provide analytical models upon which designs of large scaffold structures have been, and will be, made in the future. The papers show the importance of correctly modelling joint behaviour on the overall stability and performance of scaffold structures. They show that when the interaction between adjacent parallel sub-frames is included, two-dimensional and three-dimensional models can be used with equal accuracy. In addition, they show the influence of splices and member and out-of-plumb imperfections on the scaffold behaviour. The papers on pallet rack structures provide information on the influence of semi-rigid connections in pallet rack performance. The paper describing the numerical modelling of boltless connectors is the first reported research into analysing these connections theoretically. The influence of spring connection stiffness illustrates that for only a small range of stiffnesses can these connections be considered semi-rigid. This influence is also shown in the third scaffold paper and in the papers analysing pallet rack splices. One of the papers reports the apparently anomalous result that under certain loading conditions a rack supported on a semi-rigid base cannot carry as much load as the same rack supported on a pinned base and gives examples of the occurrence. The two papers on splices provide analytical procedures for modelling spliced, pallet rack structures. No previous procedures are available. The papers use a single column model, based on stability functions. To ensure an efficient algorithm modified slope-deflection equations are derived for elements of the pallet rack containing splices. The analysis programs are then able to use efficient tri-diagonal symmetric Gauss Elimination procedures to solve the resulting equations quickly. A computer algebra program was used to derive the modified equations. The resulting program was compared with finite element analyses with excellent agreement. Special cases of zero-stiffness splices and splices at, or near to, beam-column intersections are investigated and their influence on rack performance shown. The results of the analysis show the importance of the position of the splice on rack performance and give recommendations for splice design and placement for designers. The two papers on the pallet program show how single column models, incorporating splices, can be included in efficient programs for the analysis and design of storage structures according to the code of the Federation Europeenne de la Manutention. They also provide efficient algorithms to determine the maximum load carrying capacity of a given rack structure and to determine performance tables for rack structures. The papers show that the pallet program is also able to determine all combinations of beam and upright that satisfy a given payload. The papers also contain algorithms for pattern loading and accidental loading not given in the two analysis papers. The remaining paper shows the importance of using a yield-line mechanism which incorporates internal shear forces. A channel section under pure bending was re-analysed using Bakker’s mechanism and the results compared with experiment with excellent agreement. Overall, the thesis demonstrates the author's contribution to the analysis of slender structures with particular reference to the influence of splices and rotational gaps on the overall structural behaviour.

Grantor dc:publisher

Oxford Brookes University

Author dc:creator

• Beale, Robert

Contributors dc:contributor

• Hutchinson, Allan

Statement dc:rights

• All rights reserved

Language dc:language

en

DOI dc:identifier

https://doi.org/10.24384/wyx2-t218

OAI identifier oai:identifier

tle:68a5e483-2b94-41e0-9da4-76b330e809e2:d6bd9758-527a-46cd-bfe2-c433766e8fca:1