Advanced Steel Construction

Vol. 13, No. 4, pp. 412-426 (2017)




Guo-Qiang Li1,2, Ke Cao1, Ye Lu1,2,* and Jian Jiang1

1College of Civil Engineering, Tongji University, Shanghai 200092, PR China

2State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, PR China

*(Corresponding author: E-mail:This email address is being protected from spambots. You need JavaScript enabled to view it.)

Received: 8 February 2016; Revised: 27 January 2017; Accepted: 25 February 2017





Prefabrication by off-site manufacturing (OSM) leads to faster construction, improved quality, and reduced resources and waste. As a specific type of off-site structure, modular steel buildings consisting of volumetric modular units is a relatively new structural form in comparison with traditional steel frames with fixed or flexible beam-to-column connections. For multi-strorey modular steel buildings, additional lateral force-resisting systems are commonly used to prevent the structural side sway. In order to rationally evaluate the stability of columns in the non-sway modular steel buildings, the governing equations for determining the effective length factor (K-factor) of columns are derived using the three-column sub-assemblage model. A simplified method based on the French rule is proposed to determine K-factors. Its accuracy and effectiveness are verified against governing equations (maximum error within 6%) and finite element simulation of a six-storey modular steel frame (maximum error within 9%). The influencing factors on the K-factor are studied. The results show that the available methods such as the alignment chart and French rule cannot be directly applied to determine K-factors for the modular steel buildings. It is found that the boundary restraint parameters and their relative values affect the K-factor. The assumption of pinned connections between modular units is found to be non-conservative. It is recommended to check and strengthen the flexible connections for the design of modular steel buildings with too small or too large relative stiffness of the connections between modules.



Effective length factor, column buckling, semi-rigid connection, non-sway modular steel building, simplified method


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