Publication: Effect of different arrangements of bolt and thickness and shape of gusset plate on the rigidity of beam-to-column connection of cold-formed steel section
Date
2025-05-15
Authors
Rahima Ummi Kulsum Nadya
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Abstract
Cold-formed steel (CFS) sections are lightweight materials produced by rolling or pressing thin steel sheets at room temperature. In recent years, there has been a growth in the utilisation of CFS as a structural frame for residential constructions and multi-storey commercial buildings. This growth can be attributed to the cost-effectiveness of the material. Despite its lightweight and sustainability benefits, cold-formed steel (CFS) lacks a standardized design for load bearing connectors, as existing codes primarily address individual fasteners rather than integrated connections, resulting in design uncertainties. CFS members' thinness relative to their width makes them prone to buckling, posing a significant design challenge. Additionally, there is limited research on connection configurations, with most studies focusing on idealized connections and overlooking the semi-rigid behaviour of CFS structures. These uncertainties hinder CFS's wider adoption in major structural applications. To bridge this knowledge gap, this research investigates the load response of CFS beam-to-column connections, focusing on
how bolt arrangements, gusset plate thickness, and shape impact the behaviour and rigidity of the beam-to-column connection. The research goal was achieved through three key stages:physical testing of a reference connection, numerical analysis of diverse bolt and gusset plate configurations, and evaluation of the connection's failure behaviour, stress distribution, and buckling resistance. Testing on the laboratory model specimen has been carried out until the model has achieved its failure mode. The failure mode of the beam was identified as local buckling, with the specimen (DCC203) failing at a load of 6.9 kN with deformation of 42.17 mm on LVDT. Non-linear load-deformation behaviour was observed on the laboratory test,indicating material yield beyond a certain load threshold. The stiffness (Sj,ini) for the laboratory testing was recorded as 3235.92 kNm/rad. The laboratory-tested model served as the Base Model (BM) for our finite element analysis (FEM), confirming the experimental data's accuracy with a negligible 1.45% peak load difference. This validated the BM in FEM, allowing further
investigation on twelve additional models, each with different bolt configurations on the beam to-column sections, gusset plate thicknesses, and shapes. This study examined the influence of bolt configuration, gusset plate thickness, and shape on the behaviour of CFS beam-to-column bolted connections. It was found that increasing the number of bolts on the beam section significantly enhanced connection stiffness, while additional bolts on the column section had a
negligible effect on rigidity. While thicker gusset plates marginally improve stiffness, they also introduce a higher risk of buckling due to increased weight. In this study, thicker gusset plates did not significantly reduce z-axis deformation. NBB8 emerged as the model with the highest rigidity (3949.22 kNm/rad), an 18% increase over the baseline BM (3235.92 kNm/rad). However, SGP2 with stiffener plates exhibited the lowest rigidity and significant lateral torsional buckling. Therefore, while NBB8 offers impressive stiffness, considering factors like buckling behaviour is crucial for choosing the optimal model for specific applications. These findings provide valuable insights for optimizing CFS connection design, leading to a more efficient structure.