Structural instability of multi-storey door-type modular steel scaffolds

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Abstract

Modular steel scaffolds are commonly used as supporting scaffolds in construction, and structural instability is always an important design consideration for their safe and effective use. This paper presents a systematic study on the structural behaviour of multi-storey door-type modular steel scaffolds through both experimental and numerical investigations. Three one-storey and three two-storey modular steel scaffolds were built and tested to failure in order to examine the structural behaviour of typical multi-storey door-type modular steel scaffolds. Test data from literature on three-storey door-type modular steel scaffolds with similar member configuration and geometrical dimension were also adopted for investigation. An advanced non-linear finite element model with high performance beam-column elements was established to evaluate the load carrying capacities of these scaffolds under idealised boundary conditions. Moreover, in order to provide practical design guidance on the safe and effective use of multi-storey door-type modular steel scaffolds, the structural behaviour of these scaffolds under a wide range of positional and rotational restraints at the top and the bottom of the scaffolds is also examined through an extensive parametric study. It is demonstrated that the load carrying capacities of these scaffolds are sensitive to both the types and the magnitudes of restraints provided at the top and the bottom of the scaffolds, and also to the presence of cross-bracings. Hence, the load carrying capacities of two-storey and three-storey modular steel scaffolds are only 85 and 80% of those of one-storey modular steel scaffolds respectively. Moreover, depending on the boundary conditions provided at the top and the bottom of the modular steel scaffolds, the load carrying capacities are found to vary from 50 to 120% of those obtained from tests. Engineers are thus urged to design, specify and erect multi-storey door-type modular steel scaffolds with caution. Careful interpretation on test results and safe load data is essential to the safe use of these scaffolds on sites, in particular, for those scaffolds with boundary conditions significantly different from those adopted in tests.
Original languageEnglish
Pages (from-to)867-881
Number of pages15
JournalEngineering Structures
Volume26
Issue number7
DOIs
Publication statusPublished - 1 Jun 2004

Keywords

  • Column buckling design
  • Equivalent effective length
  • Modular steel scaffolds
  • Partially restrained scaffolds
  • Structural instability

ASJC Scopus subject areas

  • Civil and Structural Engineering

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