Experimental investigation on cold-formed steel beams under pure bending

This paper presents the flexural behaviour of cold-formed double lipped channels beams under pure bending action. Two channel sections are bolted back-to-back to form an I-shape structural beam member. A series of six experiment tests were carried out on beam specimens DC200 and DC250, each with 200 mm depth and 250 mm depth respectively. The thickness of beam section is 2 mm and the design yield strength is 350 N/mm2. All beams failed at local buckling at top-flange due to lateral instability of the cold-formed steel structural members. The moment resistance for DC200 is 17.87 kNm and DC250 is 31.53 kNm. The experimental results are compared to theoretical resistance prediction based on British Standard and Eurocode. The comparison showed that the experimental moment capacity is lower than the theoretical bending moment resistance but higher than theoretical buckling moment resistance from Eurocode. This showed that a better agreement is achieved between experimental data and Eurocode buckling moment resistance for cold-formed steel beam under pure bending

Capacity of interlocking stub column with cement mortar infill under axial compression load

This paper presents an experimental investigation on interlocking stub column with cement mortar infill subjected to axial compression load. The interlocking stub column is produced by using load bearing interlocking blocks arranged in vertical direction to form a square shaped column section. The objective of this study is to investigate the compression capacity and failure mode of the column. Six specimens were tested in this study under axial compression load using universal testing machine. From the experiments, all specimens failed in crushing of interlocking blocks. The ultimate load carrying capacity for all tested specimens are in the range of 461.6kN to 577.6kN

Perception Analysis of Industrialized Building System (IBS) Implementation for G7 Contractors in Kuching, Sarawak

Industrialized Building System (IBS) is one of the initiatives underpinning the green construction zeitgeist. A myriad of advantages can be associated with adopting IBS in construction, including inter alia, improved construction quality and productivity, minimisation of construction waste, optimisation of construction materials on-site, enhanced environmental sustainability, and many others. In spite of these advantageous propositions, there is exist a gap in the exposure towards IBS construction methods, particularly in the city of Kuching, Sarawak, as compared to more familiar conventional methods. Thus, the purpose of this study is to identify the issues and challenges experienced by contractors in their IBS endeavour as well as to propose a framework of solution. Moreover, this study investigated the impact of IBS adoption by G7 contractors registered with the Construction Industry Development Board (CIDB) of Sarawak. Data of this study was collected via questionnaires distributed to the G7 contractors and subsequently analysed using descriptive and mean analysis. Results obtained from the study suggested that IBS construction method enhances the efficiency of construction for speedier completions, which recorded the highest ranking. Conversely, lowering the costs of construction through optimisation of materials registered the lowest ranking, suggesting that contractors do not necessarily perceive IBS as having a cost-saving ability. This study showed that IBS helps to improve the efficiency of the construction process. However, respondents were still uncertain that adopting IBS can reduce costs. This corresponds to the finding in which the most significant challenge perceived by the contractors was related to cost. This suggested a lack of integration between the different stakeholders, especially during the design stage, often resulting in the need for redesign works that required additional costs when IBS is to be adopted. In this regard, it was not a surprise to find that “promotions” obtained the top ranking as a solution in overcoming the IBS challenges. Hence, support from both the government and the private sector needs to be garnered and diligently promoted, so that the adoption of IBS in the Sarawak construction industry can be properly enhanced

Numerical modelling and validation of light gauge steel top-seat flange-cleat connection

This paper presents the numerical investigation on the moment-rotation behaviour of cold-formed top-seat flange-cleat connection, a type of light gauge steel connection which structural connection has sparked a wide range of research interest. The cold-formed channel sections were assembled back-to-back to form I-shape beam and column members. Two components were used to connect the members, notably the 2 mm cold-formed bracket and the 6 mm hot-rolled angle. The results were collected from different beam depths, namely 150 mm, 200 mm and 250 mm. The rotational stiffness and strength obtained from the numerical modelling were then compared with design requirements from BS EN 1993-1-8 and experimental data. The comparison showed not more than 35 % difference in strength and about 50 % difference in rotational stiffness between numerical modelling and experimental data. However, there was a noticeable difference between finite element models and analytical calculation. The differences were from 18 % to 66 % for strength and between 1 % and 145 % for stiffness. Finite element models showed a better agreement with experimental data as compared to analytical study. Edge stiffener of numerical model and theoretical stiffness calculation had caused significant difference in comparison

Analytical Model of Nonlinear Semi-rigid Frames Using Finite Element Method

Performance-based design for a constructional steel frame in nonlinear-plastic region requires an improvement in order to achieve a reliable structural analysis. The need to explicitly consider the nonlinear behaviour of structures makes the numerical modelling approach much more favourable than expensive and potentially dangerous experimental work. The parameters considered in the analysis are not limited to the linear change of geometry and material yielding, but also include the effect of large deformations, geometrical imperfections, load eccentricities, residual stresses, strain-unloading, and the nonlinear boundary conditions. Such analysis requires the use of accurate mathematical modelling and effective numerical procedures for solving equations of equilibrium. With that in mind, this paper presents the mathematical formulations and finite element procedures of nonlinear inelastic steel frame analysis with quasi-static semi-rigid connections. Verification and validation of the developed analytical procedures are conducted and good agreements are obtained. It is an approach that enables the structural behaviour of constructional steel frames to be traced throughout the entire range of loading until failure. It also provides information on the derivation of the structural analysis by using finite element method

Thermal Performance of Structural Lightweight Concrete Composites for Potential Energy Saving

Residential consumption dominates the energy expenditure of heating and cooling systems, especially in tropical climates where building envelopes play an important role in energy efficiency. The thermal properties of concrete that are commonly employed as the building envelope material affect directly human comfort in a building. In addressing both the concrete thermal performance and industrial waste issues, this paper experimentally studies the concrete compressive strength and thermal properties used later for comparative energy analysis for human comfort. Four design mixes and a conventional concrete as control specimen are considered utilizing industrial wastes; palm oil fly ash (POFA), lightweight expanded clay aggregate (LECA), oil palm shell (OPS), and quarry dust, as constituents. These mixes are cast for cube compressive strength (to ensure the achievement of structural concrete requirement) and small-scaled wall tests. The measurement of surface temperatures of scaled wall tests is conducted in a polystyrene box to determine the concrete time lag and decrement factor. It is found that the density of concrete governs the compressive strength and that air pockets in the concrete matrix play an essential role as far as the thermal properties are concerned. From the energy analysis, structural lightweight concrete may save approximately 50% of the residential energy consumptio

Mechanical properties prediction for cold-formed steel angle connection with various flange cleat thickness

Connection is an important element in structural steelwork construction. Eurocode does not provide adequate design information for mechanical properties prediction of top-seat flange cleat connection, especially for thin-walled cold-formed steel structures. Adopting hot-rolled design with neglecting thin-walled behaviour could lead to unsafe or uneconomic design. This research aims to provide accurate mechanical properties prediction for bolted top-seat flange cleat connection in cold-formed steel structures. The scope of work focuses on the effect of various thickness of the flange cleat to the rotational stiffness and strength behaviour of a beam-to-column connection. Experimentally verified and validated finite element modelling technique is applied in the parametric investigation. Two categories of flange cleat thickness, ranged from 2 mm to 40 mm are studied. From the developed numerical models, it is observed that Eurocode has overestimated the initial rotational stiffness prediction, calculated with component method. The over-estimation would influence the overall stiffness of structures and force distribution within the components. As a conclusion, a set of newly proposed accurate predictions for initial rotational stiffness and strength of cold-formed steel top-seat flange cleat connection, with the influence of the thickness of flange cleat is presented

Compressive and Flexural Strengths of Mortar with Silica Aerogel Powder

Excessive usage of sand in construction industries has generated many environmental issues. Silica aerogel, is able to minimise environmental issues while providing thermal resistance for building materials. Silica aerogel has properties such as lightweight, nano-porous and very low thermal conductivity compared to sand in the mortar matrix. This paper studied the compression and flexural strengths of mortar with silica aerogel as a sand replacement. Cement to sand ratio of 1:3 was used and sand was replaced with silica aerogel in the volumes of 15%, 20% and 25%. 15% volume of sand replacement with silica aerogel powder was the optimum ratio as it possessed the highest strength during experimental work. All the specimens were able to achieve the minimum strength for Type N non load bearing wall with the optimum ratio of 15% volume silica aerogel powder. In conclusion, silica aerogel mortar achieved the minimum strength of type N mortar

Flatwise and edgewise compression strengths of sandwich panel with silica aerogel mat

Facade of building are mainly made up from red clay brick and concrete block. However, both materials are having high thermal mass and promote high indoor thermal discomfort level. Therefore, it is necessary to invent new building material that have low thermal mass and able achieve strength required. Silica aerogel possesses properties of lightweight and low thermal conductivity as compared to other construction materials. In this study, sandwich panel with silica aerogel mat was studied where the properties of sandwich panel silica aerogel mat are rarely found in previous investigations. Before checking its reliability as thermal insulation panel, the mechanical properties of this panel was investigate. The panel was made-up by concrete wythes with type N mortar and the silica aerogel mats with different thickness. Both concrete wythes were casted and then attached together with silica aerogel mat as the cover. 3 types of panel with different insulation thickness were then tested for flatwise and edgewise compression test. From the results, it was found that core thickness of silica aerogel mat has less influence in flatwise and edgewise compression strengths of the sandwich panel. All specimens achieved minimum strength of type N mortar. Therefore, it is recommended to be used in construction that has equivalent application of type N morta

A study on the challenges of implementing green building concept in Sarawak, Malaysia

Malaysia is looking forward in achieving developed country status which drives several strategic plans in construction, as it plays a vital role in country‟s economic growth and development. Construction Industry Transformation Programme (CITP) has been introduced to boost its performance with sustainable construction. However, most of the construction industry players are not involved in sustainable construction especially on green building concept and thus decelerating the development. Therefore, this study is conducted to identify the drivers and challenges faced by the construction industry players through questionnaire survey where the market demand from stakeholders is placed primarily in implementing green building. The findings showed that awareness and understanding of the stakeholders about green building concept are lacked due to unforeseen circumstances. Detail explanations or descriptions on the benefits and contributions from green building application are needed to be delivered to stakeholders. A framework is proposed for future implementation by improving the education and delivered information, as well as providing the mechanism of promoting the green building concept among the stakeholders