Poi Ngian Shek

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.

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.

Compressive strength of ground waste seashells in cement mortars for masonry and plastering

For environmental protection and sustainable development, many research studies have been carried out on the utilization of waste materials in construction such as fly ash, mine tailings, slags, construction and demolition waste, wood sawdust, rice husk ash, crumb rubber and etc. In this study, two types of waste seashells; green mussel and cockle were tested experimentally to replace fine aggregate in cement mortar. The compressive strength of the cement mortar with seashells were compared with those of a control mortar that was made of a conventional river sand. The main parameter of this study was the proportion of ground seashells used as sand replacement (25%, 50%, 75% or 100% by weight). Incorporation of cockle in cement mortar resulted in higher compressive strength as compared to conventional mortar up to 110 percent. However, incorporation of green mussel resulted in decrement in compressive strength by 67 percent. The results indicate that ground seashells can be applied as a sand replacement in mortar mixes and may improve the compressive strength of rendering and plastering mortar.

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.

Economic aspect of square hollow section in the design of multi-storey unbraced steel frame

Abstract The use of structural hollow sections as column members exhibits a number of advantages as compared with other open sections in terms of structural efficiency, robustness and aesthetic appeal. In this study, the square hollow section is chosen as column member to design the semi-rigid multi-storey unbraced steel frame. Structural design was conducted by selecting the optimum steel section for the vertical and horizontal members of the steel frames. The selection was carried out in such a way that the behaviour and performance of the structure is within the limitations in accordance with Eurocode 3. This study compares the design in an unbraced plane frame. The steel weight of each plane frame was calculated and the economic aspect by using square hollow section was investigated. The study concluded that steel weight savings can be achieved by using square hollow section with savings ranging from 12 to 34%.

Uniaxial compressive stability of laminated composite plate with localised interfacial degeneration

Abstract Motivated by general observation that it is practically impossible to achieve a perfect attachment between two originally separated materials, this paper examines numerically the influence of localised imperfect bonding at interface on the buckling response of fully fixed laminated composite plates, in the existence of uniaxial compression. The present work focuses on the buckling analysis of a two-layered laminate using the finite element formulation, in which each layer was meshed employing a locally contributing lamina sub-element, whereas the interface lied in between was modelled using a well-defined virtually zero-thickness interface element. To simulate the interfacial degeneration, a degeneration ratio R was conveniently prescribed. The present work has an advantage of permitting the simulation of deteriorated interface in a locally perturbed manner, differs from existing literatures that modelled mostly in a global sense. It is found from the current study that the normalised critical buckling load decreases, which indicates an increased degree of instability, corresponding to the rise in the degeneration ratio. Also, delaminated condition (R = 1), either isolated or otherwise, is the most critical scenario with an approximately 70% performance discount from that of R = 0·9. There exist, in addition, a variety of stability reduction trends when inducing different fibre orientations for the top lamina relative to that of the bottom. High dependencies of buckling modes on the degenerated area (Ar) and distance ratios () have also been exhibited.

Flexural Behavior of Steel Reinforced Brick Beam Utilizing Interlocking Brick System

This paper presents the full-scale experimental tests on steel reinforced and non-reinforced interlocking brick beam utilizing interlocking brick system. Two specimens were tested with and without steel reinforcement embedded in the beam formed using interlocking brick. The purpose of this study is to investigate the performance of beam utilizing interlocking brick subjected to bending. The flexural behavior of the beam will be studied and discussed in this paper. It is concluded that the use of steel reinforcement in the beam has significantly influenced the flexural capacity. The results obtained from this study can be applied in the design of structure utilizing interlocking brick. Future recommendations are proposed in this paper for further improvements.