Cher Siang Tan

Review on Cold-Formed Steel Connections

The concept of cold-formed light steel framing construction has been widespread after understanding its structural characteristics with massive research works over the years. Connection serves as one of the important elements for light steel framing in order to achieve its structural stability. Compared to hot-rolled steel sections, cold-formed steel connections perform dissimilarity due to the thin-walled behaviour. This paper aims to review current researches on cold-formed steel connections, particularly for screw connections, storage rack connections, welded connections, and bolted connections. The performance of these connections in the design of cold-formed steel structures is discussed.

Maximum local thermal effects carpet plot for symmetric laminated composite plates

Maximum local thermal effects carpet plots for symmetric laminated composite plates used in the design and optimization for material under heat loads are produced and demonstrated. The independent variables considered in this paper are the proportions of 0, 45, and 90 degrees ply orientations in the laminates. The carpet plots are presented in such a way that when the failure stress or strain of a composite lamina is known, all possible safe ply orientation proportion can be determined. In addition, the dependency of the carpet plots in correspondence to the temperature change is investigated. It is found that the shapes of both thermal stress and strain plots are practically identical.

Properties of Foamed Mortar Prepared with Granulated Blast-Furnace Slag

Foamed mortar with a density of 1300 kg/m3 was prepared. In the initial laboratory trials, water-to-cement (w/c) ratios ranging from 0.54 to 0.64 were tested to determine the optimal value for foamed mortar corresponding to the highest compressive strength without compromising its fresh state properties. With the obtained optimal w/c ratio of 0.56, two types of foamed mortar were prepared, namely cement-foamed mortar (CFM) and slag-foamed mortar (SFM, 50% cement was replaced by slag weight). Four different curing conditions were adopted for both types of foamed mortar to assess their compressive strength, ultrasonic pulse velocity (UPV) and thermal insulation performance. The test results indicated that utilizing 50% of slag as cement replacement in the production of foamed mortar improved the compressive strength, UPV and thermal insulation properties. Additionally, the initial water curing of seven days gained higher compressive strength and increased UPV values as compared to the air cured and natural weather curing samples. However, this positive effect was more pronounced in the case of compressive strength than in the UPV and thermal conductivity of foamed mortar.

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.

Experimental and analytical study of various shear connectors used for cold-formed steel-ferrocement composite beam

This work presents the experimental tests carried out to evaluate the behaviour of different types of shear connectors proposed for cold formed steel (CFS) section integrated with ferrocement slab as potential used for composite beam. Ten push-out test specimens of cold-formed steel lipped channel sections connected with ferrocement slab were tested. Three types of shear connectors were studied comprised of bolts, self-drilling-screw and bar angle. The connection behavior is analysed in terms of its load-slip relationship and the failure mode. The parametric studies were performed to investigate the effect on the shear connector’s capacity by varying the number of layers of wire mesh used in ferrocement slab and types of shear connector used. A theoretical analysis (Eurocode 4) was carried out to verify the experiment results. The results show that the experimental and theoretical proved to have good agreement with each other.

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.

Experimental investigation of end-plate connection with cruciform column section

This paper presents an experimental investigation on typical end-plate connection with reduced beam-to-end plate welding, connected to cruciform column (CCUB) section. The study aims to reduce the cost of fabrication and materials. Two tests were conducted to study the behavior of the proposed connections and evaluate the failure modes, moment resistance, initial stiffness and rotational capacity of the connections. The experimental results indicated that the failure mechanisms for the tested specimens begin with the end-plate yielding followed by bolt slippage that was limited to the tension region of the joint due to the tension forces exerted through the top bolt rows. The experimental results will then be used to validate the theoretical model for the T-stub idealization of the tension zone.

Experimental Investigation on Slip-in Connection for Cold-formed Steel Double Channel Sections

The application of cold-formed steel in light steel framing design can become a popular choice of Industrialized Building System, by moving huge amount of construction work to the factory and leaving the construction site cleaner and safer. However the joints behaviour for primary structures, particularly the partial strength semi-rigid beam-to-column connection has not been studied in depth. This paper presents the isolated joint test on slip-in connection using 6 mm hot-rolled steel gusset plate. Two cold-formed lipped channel sections were placed back-to-back to form beam and column members. Three specimens with the depth of beam ranging from 150 mm to 250 mm were tested. From the experimental results, it is observed that the ratio of moment resistance of joint to the moment resistance of the connected beam increases in the range of 0.46 to 0.70. The rotational capacities of the joints exceed 30 mRad. The rotational stiffness achieves 511 kNm/rad to 1671 kNm/rad. It is concluded that the proposed connections could be classified as partial strength connection.

Tension Behaviour on the Connection of the Cold-Formed Cut-Curved Steel Channel Section

Cold-formed steel (CFS) are utilised as a non-structural and structural element in construction activity especially a residential house and small building roof truss system. CFS with a lot of advantages and some of disadvantages such as buckling that must be prevented for roof truss production are being studied equally. CFS was used as a top chord of the roof truss system which normally a slender section is dramatically influenced to buckling failure and instability of the structure. So, the curved section is produced for a top chord for solving the compression member of the roof truss. Besides, there are lacked of design and production information about the CFS curved channel section. In the study, the CFS is bent by using a cut-curved method because of ease of production, without the use of skilled labour and high cost machine. The tension behaviour of the strengthening method of cut-curved or could be recognised as a connection of the cut-curved section was tested and analysed. There are seven types of connection was selected. From the testing and observation, it is shown the specimen with full weld along the cut section and adds with flange element plate with two self-drilling screws (F7A) was noted to have a higher value of ultimate load. Finally, there are three alternative methods of connection for CFS cut-curved that could be a reference for a contractor and further design.

Evaluation of Material Properties of Cold-formed Steel Channel Section with Different Thickness

Cold-formed steel channel (CFSC) section is a popular material that used broadly in construction, especially in the roof truss system and non-structural elements. CFSC with a variety of sizes, shapes, thicknesses and grades is becoming admired because it offers several advantages such as lightweight, easy fabrication, fast installation, no formwork, termite resistance and corrosion resistance. The main objective of the study is to investigate the CFSC material properties with a variety of thicknesses. When the CFSC is utilised as in construction structural material, the CFSC material properties must be evaluated for further work, especially in design, failure capacity information and modelling intention. The thickness of the CFSC is important in study to check the failure mode and mechanical properties of the material. The material properties of CFSC are examined by using tensile coupon test specimens and universal tensile testing machine. The CFSC that be used in the study is CFSC 1.0 and CFSC 1.2 with the thickness of 1.0 and 1.2 mm respectively for grade G450. The CFSC is selected by having intermediate end stiffener and lipped. The specimen of tensile coupon test is located on flange, web, upper corner and bottom corner of overall section. From the results, the yield stress, elastic modulus and ultimate stress of the CFSC 1.2 is found higher than of CFSC 1.0.