Modelling of precast concrete composite slab using finite and interface elements

This study presents an efficient finite element analysis technique which shows great versatility in modelling of precast composite flooring system subjected to static loadings. The method incorporates sliding and opening in the analysis of composite structures using the interface element which was specifically designed to simulate the actual behaviour at the interfaces between contacting materials. A three-dimensional finite element model of the precast composite slab which exhibits discontinuous behaviour was performed to demonstrate the potential and applicability of the proposed method of analysis. The results of the analysis demonstrate that the overall response of a discontinuous system to external loading is significantly affected by the bonding condition at the interfaces between the contacting materials

Software development for optimal design of different precast slabs

Precast concrete technology forms an important part in the drive towards a full implementation of the Industrialized Building System (IBS). The IBS requires building components and their dimensions to be standardized, and preferably cast off site. Slabs are major structural elements in buildings, other than beams and columns. Standardized and optimized slabs can significantly enhance the building industries in achieving the full implementation of the IBS. Nevertheless, this requires computer techniques to achieve standardized and optimized slabs which can satisfy all building design requirements, including the standards of architectural and structural design standards. This study proposed a computer technique which analysed and designed five different types of slabs which will satisfy all the requirements in design. The most commonly used slabs included in this study were the solid one way, solid two way, ribbed, voided and composite slabs. The computer techniques enable the design of the most optimized sections for any of the slab types under any loading and span conditions. The computer technique also provides details for the reinforcements required for the slabs

The recent advances in the nanotechnology and its applications in food processing : a review.

The objectives of this paper was to discuss the latest development of nanotechnology, especially in food industries, to give clearer picture about the effect of nanotechnology in food industries and to highlight the latest applications of nanotechnology in food processing industry. However, the risk issues involving the use of nanotechnology in food were also explored. The outcome of this research revealed that the nanotechnology could be useful for controlling and manipulating the matter at the nanoscale level during processing. On the other hand, nanotechnology could also help the consumers to modify the food depending on their own nutritional needs and tastes. However, from health viewpoint, the potential risks of nanoscale materials and the possibility of the accumulation and translocation of nanoparticles in the body should be avoided

Influence of torsion on the inelastic response of three-dimensional r.c. frames

A three-dimensional reinforced concrete framed building was modelled using finite element method. Two types of elements, the beam-column element and flat shell element were used for modelling the frame and floor slabs, respectively. A computer program has been developed for the analysis of 3D framed building by integrating the finite element and stiffness method. The lumped inelasticity model with three-dimensional point hinges at the ends of the beam-column element was implemented. A yield surface for a reinforced section of the member subjected to simultaneous actions of biaxial bending, torsion and axial forces was evolved. The developed yield surface integrated with the theory of plasticity was used to develop a suitable procedure for inelastic analysis of three-dimensional problems with the floor slab assumed to remain elastic throughout the analysis. The inelastic procedure is able to predict the sequential formation of plastic hinges in the frame members and the continuous deterioration of the stiffness of the frame. A single storey one bay reinforced concrete space frame was analysed for twist loading to study the inelastic response of the reinforced concrete frame. The results indicate that, the consideration of torsion in defining the yielding surface plays a significant role in the inelastic behaviour and estimation of failure load for reinforced concrete frames under torsional loading

Comparative nutritional and toxicity analyses of beverages from date seed and barley powders as caffeine-free coffee alternatives

Coffee is one of the most preferred beverages due to its flavour and aroma, which is partially contributed by the presence of caffeine. However, there are many negative effects of caffeine on human health. Alternative products like date seed and barley beverage have become an interest to switch from caffeine to caffeine-free beverages. The present work thus aimed to evaluate the nutritional properties and toxicity of date seed and barley powders as compared to Arabica coffee powder. Samples were analysed for its caffeine content, antioxidant activity, and toxicity activity from boiled water extract, whereas the nutrition compositions and heavy metal contents were analysed based on respective extraction method performed. A mass spectral peak of caffeine was detected in the Arabica coffee but not in the date seed and barley powders. All three samples were shown to possess antioxidant activities with Arabica coffee yielding the highest. Arabica coffee, however, exhibited a moderate level of toxicity to human lung fibroblast (MRC-5) cell line with IC50 of 230 ± 40 µg/mL at the extract concentration. There was no inhibition on 50% MRC-5 cell viability showed by the date seed and barley powders up to 10 mg/mL extract concentration. The abundance of heavy metals detected in all samples was lower than the regulatory limits. Our findings therefore further supported the advantages of date seed and barley powders as alternatives to coffee beverage as both contained undetected amount of caffeine, low fat and high carbohydrate contents, and possessed good antioxidant activity with low potential health risks

Strength Estimation of Concrete in Different Environments Using UPV

Deterioration of concrete in a structure is a result of several internal and external degradation mechanisms which decrease the strength or the integrity of the structure. This paper presents results of use of non-destructive ultrasonic pulse velocity tests (UPV) to determine the strength of concrete in three different environments, namely oven-dry, air-dry and saturated conditions, as the full potential of UPV in different environments is still not fully explored. Moisture is known to have a significant effect on ultrasonic pulse velocity. In order to improve the efficiency of UPV in estimating the concrete strength, the degree of moisture present in the concrete i.e. the physical condition of the concrete is to be considered. Pulse velocity path in the different physical conditions of concrete also has to be examined. In the present investigations, four different grades of concrete in three different environments were considered. Extensive series of tests were carried out in the laboratory to obtain a correlation of the UPV test results with the actual compressive strength of concrete. A total of 108 cubes were cast. The cement used was the ordinary Portland cement and the coarse aggregate consisted of granite with the maximum aggregate size of 19mm as is generally used in conventional RC structures. The DOE-method of mix-design was used to design four different grades of concrete in order to simulate concrete strengths found in practice. Test results indicated that the presence of moisture in concrete changes the UPV values significantly. The UPV tests through the direct transmission measurements display better estimates compared to the indirect measurements. Exponential expressions have been proposed for the strength estimation of concrete under oven dry and air dry conditions

Development of portable magnetic clampingfor lathe machine

Chuck is a device used to clamp any material that operates with the turning of the machine and it is connected to the headstock spindle of the lathe. However, the limitation is that the thickness of the workpiece must not be less than the area of clamping on the chuck. In this a new magnetic clamping for attaching and detaching the workpiece on the chuck and is able to clamp small and thin workpieces is developed. The chuck is made by using mild steel and has a few intercepts with brass. Magnetic mechanism is placed in the chuck. Several cutting processes were done with the convectional chuck and the magnetic clamping on a different thickness of workpiece. Next, all the workpieces were tested with several parameters on specimen and perform surface roughness testing to compare and finalize the effectiveness of the magnetic clamping. From the obtained result, the use of the magnetic clamping produces much better result of surface roughness on thin workpiece. Thus, using magnetic clamping as the clamping method for thin workpiece is much effective in turning machine

Seismic response analysis of linked twin tall buildings with structural coupling

Effect of structural links on seismic responses for a linked building system has been investigated in this paper by using finite element modeling technique. The linked building system in this study is represented by twin 40-story reinforced concrete frame-wall structures horizontally coupled by structural links. It is assumed that the two adjacent buildings were similar in this linked building system, so the two adjacent stories could be linked at the same height by an inter-building link. The linked building system is modeled as a rigid floor diaphragm for towers and as a beam for each link fixedly linked to the perimeter structural framework of the buildings. By employing earthquake time history excitation, the seismic responses of the twin towers were computed at different locations for the link. The responses of structures were evaluated and compared. The analysis outcomes indicated that the link could effectively change the structural responses of the linked building system. The structural responses have been decreased in some cases compared to the single tower, referring to the extra link stiffness as gathering the single tower to withstand seismic excitation. While the responses have been increased in other cases, attributing to the additional mass of link. Thus, in the design of seismic-resistant linked building systems, care must be taken. Particularly regarding properties of the link, specifically mass, stiffness, and location, as well as the link resistance with respect to the strength of the link and/or the structural elements composing the link to obviate undesired structural responses

Causative failure factors of communications management in mixed-use development projects in Malaysia

Construction delay has been a persistent challenge for the Malaysian construction industry. This has resulted in many issues, including public complaints, government loss of reputation and income and a decline in the gross domestic product output of the industry. Furthermore, the construction industry is a complex business with several stakeholders continually sharing information. Hence, ensuring project success has to be the utmost important task of a project manager. Often the construction industry is marred by high cases of delays, overruns, poor quality, health and safety issues, emissions and sustainability issues as a result of ineffective communication practices. Therefore, this paper aims to examine causative failure factors of communications management in mixed-use development projects in Malaysia. Based on the literature review, 11 factors and 44 items were identified. These factors and items were evaluated by 141 respondents from the Malaysian construction industry. Data analysis was done using SPSS 23.0. This study found that the most critical causative failure factor is team meeting discussions. The respondents believe that there is lack of stakeholder cooperation due to poor representation during the discussions, which also reflects the inadequacy of mutual respect, confidence and trust among stakeholders. As a recommendation, frequent team meeting discussions provide a platform for effective information exchange, thus help to reduce mixed-use project failures in Malaysia

Development of an innovative interlocking load bearing hollow block system in Malaysia

The paper describes the development of a new interlocking hollow block masonry system appropriate for load bearing masonry wall construction. The developed system is an alternative to the traditional bonded masonry system where the blocks in the wall are integrated through mortar layers. In the system developed, the blocks are stacked on one another and three-dimensional interlocking protrusions are provided in the blocks to integrate the blocks into walls. This paper includes the background, concept and procedure used to develop an efficient interlocking hollow block system, which may be used in the construction of load bearing walls. Twenty-one different block models have been investigated and analysed with respect to weight, bearing and shear areas, shape, ease of production, ability to accommodate vertical and horizontal reinforcing stabilising ties and efficiency of the interlocking mechanism under imposed loads. The blocks, developed under the name ‘PUTRA BLOCK’, have been used to construct a single-storey house at Universiti Putra Malaysia. The system provides a fast, easy and an accurate building system