Yee Ling Lee

Numerical Modelling of Stiffness and Strength Behaviour of Top-Seat Flange-Cleat Connection for Cold-Formed Double Channel Section

Prediction of structural behaviour by numerical modelling can reduce the cost in conducting full-scaled experiments. This paper studies the stiffness and strength behaviour of top-seat flange-cleat connection for cold-formed steel double channel sections using finite element method. In this investigation, cold-formed channel sections are assembled back-to-back to form I-shape beam and column members. The 2 mm cold-formed bracket and 6 mm hot-rolled angle are used to connect the members. The results were collected from different beam depth ranged 150 mm, 200 mm and 250 mm. The rotational stiffness and strength obtained from the numerical modelling are then compared to the design requirements from BS EN 1993-1-8 and experimental data. The comparison of moment-rotation behaviour for top-seat flange-cleat connection has shown not more than 35% difference for strength behaviour and 50% difference for rotational stiffness behaviour between numerical modelling and experimental data. However, there is a noticeable difference between finite element models and analytical calculation. The differences are recorded from 18% to 65% for strength behaviour and between 1% and 153% for stiffness behaviour. The differences obtained between finite element analysis and experimental investigation are caused by edge stiffener while differences from finite element models and analytical models are due to strain hardening.

Effective steel area of fully embedded cold-formed steel frame in composite slab system under pure bending

In conjunction with the promote of Industrial Building System (IBS) in Malaysia building construction, precast units such as slab, beam and column were widely used. This paper reports on the determination of the effective cross sectional area of the proposed cold-formed sections that embedded in precast concrete slab. The cold-formed steel sections are single and double lipped channel section, with 100mm in depth, 50 mm width, 12 mm lips length and 1.55 mm thickness. In order to determine the flexural capacity of the composite slab system, it is necessary to identify the effective cross sectional area of the section contributes to load-carrying of the slab system. The calculation method was based on the effective width method concept from BS EN 1993-1-3 and BS EN 1993-1-5. Four types of cold-formed steel frame profiles that embedded in the concrete to form a new type of composite slab system were used to study in this paper. The four types of cold-formed steel section configuration are S1-SV, S2-SH, S3-DV and S4-DH. From the analytical calculation, S3-DV has the highest effective cross-sectional area, which it only consists of 2% ineffective area for load-carry capacity. Besides that, single lipped section S2-SH fully utilized the cross sectional in carrying load. It can be concluded that S3-DV is predicted to have highest bending resistance than other three types of configuration with condition that the reliability of the prediction need to verify as other factors such as shear bonding and shifted neutral axis happened due to combination of concrete and cold-formed section which, will also contribute the strength capacity of the composite slab system.

Comparison on Section Properties and Flexural Behaviour for Cold-Formed Steel Built-Up Section

This paper performs analytical and experimental investigation on the section properties of locally produced cold-formed steel sections. Effective width method given by BS EN1993-1-3 is used to calculate the section properties for two slender cold-formed steel channel sections, namely KS200C20 and KS250C20. Local buckling and distortional buckling are taken into account in the calculation. Effective width method has significantly reduced the full sectional area and thus gives a relative lower value for the sectional resistance of cold-formed steel channel sections. The analytical results is compared to manufacturer’s data and differences of not more than 3.37% is recorded. Experimental study on the flexural behaviour on the two types of cold-formed steel channel sections is carried out. The results show that BS EN1993-1-3 has good agreement with experimental results for flexural resistance that included local and distortional buckling consideration. It is concluded that effective width method by BS EN1993-1-3 is suitable to calculate the section properties of of locally produced cold-formed steel channel sections.

Numerical Investigation on Column Flange Thickness for Cold-Formed Steel Top-Seat Flange Cleat Connection

The large deformation of cold-formed steel bolted connection has become a significant research interest in order to construct a reliable and safe light steel frame. This paper presents a study on the influence of column flange thickness for cold-formed steel top-seat flange cleat joint using finite element method. The verified and validated modelling technique for cold-formed steel top-seat flange cleat connection is applied to the column component study. The failure of the joint is fixed at column component and the bolt pull-out from column was observed at the top tension bolt row. The increment of the thickness of column flange has improved the load-carrying characteristic by the best representation of polynomial equations at both elastic and plastic regions. The cubic polynomial equation has a good representation of initial and secant rotation stiffness in the function of the column flange thickness for cold-formed steel top-seat flange cleat joint. For relative thin cold-formed column, the thickness of open section for column flange is an important variable in the design of bolted joint in light steel framing.

Influence of angle thickness towards stiffness and strength prediction for cold-formed steel top-seat flange cleat connection

For the connection stiffness and strength prediction, Eurocode has showed an inadequacy as it will be affected by the thin-walled behaviour of cold-formed steel in actual structural performance. This paper performs a study on the connection stiffness prediction for cold-formed steel top-seat flange cleat connection with various angle thickness. Validated finite element modelling technique is applied for further advanced investigation. From the developed finite element models, it was realized that Eurocode has overestimated by the analytical stiffness prediction using component method for the studied connection which reduces the structural integrity in the design stage. A new proposal on connection stiffness prediction with influence of angle thickness for cold-formed steel top-seat flange cleat connection is presented to assist practicing engineers to design the cold-formed connection in light steel framing.