An investigation on the stiffness of timber sleepers for the design of fibre composite sleepers

This paper presents an experimental investigation on timber railway sleepers with a view to select a suitable stiffness and a modulus of elasticity for the design of a fibre composite railway sleeper. Eight full size timber sleepers were tested using a four point bending test arrangement. An overview of existing material for railway sleepers is also presented. Based on the tests, it is concluded that timber sleepers have significant variation in strength and stiffness as can be inferred from the modulus of elasticity (Esleeper) which ranged between approximately 9520 MPa and 27600 MPa. It is desirable to develop a concept fibre composite sleeper within a similar range of modulus of elasticity. Based on the statistical analysis, it is proposed to use the lower tail value that is 12000 MPa as design modulus of elasticity for the fibre composite railway sleeper

Flexural behaviour of structural fibre composite sandwich beams in flatwise and edgewise positions

The flexural behaviour of a new generation composite sandwich beams made up of glass fibre-reinforced polymer skins and modified phenolic core material was investigated. The composite sandwich beams were subjected to 4-point static bending test to determine their strength and failure mechanisms in the flatwise and the edgewise positions. The results of the experimental investigation showed that the composite sandwich beams tested in the edgewise position failed at a higher load with less deflection compared to specimens tested in the flatwise position. Under flexural loading, the composite sandwich beams in the edgewise position failed due to progressive failure of the skin while failure in the flatwise position is in a brittle manner due to either shear failure of the core or compressive failure of the skin followed by debonding between the skin and the core. The results of the analytical predictions and numerical simulations are in good agreement with the experimental results

Structural evaluation of concrete expanded polystyrene sandwich panels for slab applications

Sandwich panels are being extensively and increasingly used in building construction because they are light in weight, energy efficient, aesthetically attractive and can be easily handled and erected. This paper presents a structural evaluation of Concrete-Expanded Polystyrene (CEPS) sandwich panels for slab applications using finite element modeling approach. CEPS panels are made of expanded polystyrene foam sandwiched between concrete skins. The use of foam in the middle of sandwich panel reduces the weight of the structure and also acts as insulation against thermal, acoustics and vibration. Applying reinforced concrete skin to both sides of panel takes the advantages of the sandwich concept where the reinforced concrete skins take compressive and tensile loads resulting in higher stiffness and strength and the core transfers shear loads between the faces. This research uses structural software Strand7, which is based on finite element method, to predict the load deformation behaviour of the CEPS sandwich slab panels. Non linear static analysis was used in the numerical investigations. Predicted results were compared with the existing experimental results to validate the numerical approach used

Experimental investigation on the flexural behaviour of pultruded GFRP beams filled with different concrete strengths

Glass fibre reinforced polymer (GFRP) pultruded profiles are being increasingly used in the construction industry due to their numerous advantageous over the conventional materials. However, most pultruded GFRP sections fail prematurely without utilising their high tensile strength due to their thin-walled sections. As a result, several hybrid systems made out of GFRP profiles and concrete as a filler material have been proposed in order to enhance their structural performance. Most of these studies utilised high strength concrete wherein the additional cost does not justify the enhancement in the stiffness and strength of the infilled GFRP profiles. This paper presents an experimental investigation on the effect of the compressive strength of concrete infill on the flexural behaviour of beams with a view to determine a lower cost infill for GFRP profiles. Pultruded GFRP square beams (125 mm x125 mm x 6.5mm) were filled with concrete having 10, 37 and 43.5 MPa compressive strength and tested under static four-point bending. The results showed that the capacity of the filled beam sections increased by 100 to 141% than the hollow sections. However, the compressive strength of the concrete infill has no significant effect on the flexural behaviour of the beams. The increase in concrete compressive strength from 10 to 43.5 MPa increased the ultimate moment by only 19% but exhibited an almost same flexural stiffness indicating that a low strength concrete is a practical solution to fill the GFRP profile

Industrial waste management: free trade zones in Sri Lanka

Industrial waste becomes a worldwide issue which was raise through the industrialization. Free trade zones are the one of major areas which is produced more industrial waste in Sri Lanka. Improper and isolation existing waste management practices in free trade zones create more environmental issues and spreading of deceases such as Dengue. Thus factories as well as zone management need proper system to handle the industrial waste. This study aims to explore the industrial waste management practices at Free Trade Zones in Sri Lanka in order to identify probable approaches to address the burning issues. Study was conducted through the case studies of three free trade zones which were generated highest industrial waste. Semi structured interviews were conducted with four participant of each case responsible for industrial waste management. In addition, two expert’s interviews were conducted to verify the case study findings. Findings revealed that, majority of people were not satisfied with existing isolation practices of industrial waste management due to various issues visible in existing industrial waste management process

Analysis of retrofitted corroded steel pipes using internally bonded FRP composite repair systems

Steel pipelines play an important role in the oil and gas industry. Hence corrosion of the steel pipe systems during its service life is a critical issue for the industry. Fibre reinforced composites offer solutions with broad applicability and efficiency for the internal repair of these corroded pipelines. Understanding the behaviour of internal composite repair systems against different internal pressure regimes is an important aspect in the development of a repair system. This study develops the analyses of internal composite bonded repair systems for long steel pipes with an axisymmetric defect, based on Lame’s equation. Various levels of bonding between the steel and composite are studied. Fully bonded optimum internal composite repair thicknesses are determined using biaxial carbon and glass fibre composites for different levels of corrosions, using the Von Mises yielding and Tsai-Hill failure criterion approaches. Two case studies are illustrated using the design nomographs. The analysis technique used was found to be accurate when compared with finite element modelling results

Androgens correlate with increased erythropoiesis in women with congenital adrenal hyperplasia.

OBJECTIVE: Hyperandrogenism in congenital adrenal hyperplasia (CAH) provides an in vivo model for exploring the effect of androgens on erythropoiesis in women. We investigated the association of androgens with haemoglobin (Hb) and haematocrit (Hct) in women with CAH. DESIGN: Cross-validation study PATIENTS: Women with CAH from Sheffield Teaching Hospitals, UK (cohort 1, the training set: n=23) and National Institutes of Health, USA (cohort 2, the validation set: n=53). MEASUREMENTS: Androgens, full blood count and basic biochemistry, all measured on the same day. Demographic and anthropometric data. RESULTS: Significant age-adjusted correlations (P<0.001) were observed for Ln testosterone with Hb and Hct in cohorts 1 and 2 (Hb r=0.712 & 0.524 and Hct r=0.705 & 0.466), which remained significant after adjustments for CAH status, glucocorticoid treatment dose and serum creatinine. In the combined cohorts Hb correlated with androstenedione (P=0.002) and 17-hydroxyprogesterone (P=0.008). Hb and Hct were significantly higher in cohort 1 than those in cohort 2, while there were no group differences in androgen levels, glucocorticoid treatment dose or body mass index. In both cohorts, women with Hb and Hct in the highest tertile had significantly higher testosterone levels than women with Hb and Hct in the lowest tertile. CONCLUSIONS: In women with CAH, erythropoiesis may be driven by androgens and could be considered a biomarker for disease control

Challenges of teaching engineering analysis software to distance education students

CONTEXT Engineering analysis software packages are regularly used in industry for solving problems. Therefore, it has become a necessity for the engineering academics to teach the students how to use software for solving problems. Academics face considerable challenges while teaching distance education students. The challenge arises not only from teaching the students we cannot see but also how the students access and use the software from home. In fact, providing proper software access to off-campus students (up to the students’ satisfaction) is not an easy task. The access process involves multiple technical issues. Diverse and dispersed student cohorts working in another part of the world at a different time zone, make the situation even trickier. The complexity increases further depending on how easy it is to learn the software and how technically involved the software is. PURPOSE In this paper, we present an example of how we are teaching the Strand7 software to our off-campus students at the University of Southern Queensland (USQ). The challenges we had faced over the years and the performances of various technologies that we have implemented, the learning and teaching activities we have designed, are discussed in detail. This paper can serve as a guide for options to teach software online. APPROACH We have implemented various technologies for providing remote access, and have designed learning and teaching activities for online teaching. In addition, we have provided recordings of live video tutorials as learning resources showing how to use the software Strand7. The performance of each technology was judged based on students’ satisfaction and whether the intended learning outcomes were achieved or not. RESULTS Progressively, we have implemented various technologies including Virtual Desktops, Remote Access Laboratories (RALs) and Virtual Private Networks (VPNs) for providing remote access. We have found that multiple technical factors, some of them beyond our control, affected the system performance badly. These technologies failed to provide viable long-term options for the online teaching of engineering analysis software. Therefore, we have explored other avenues. The current option in which the Strand7 Company provides the service to the students for a nominal charge is perhaps one of the best. Other options including the software CD provided by the Company for a limited period or the Student Version/Open Source software packages are also good. CONCLUSIONS Teaching online students how to use engineering analysis software packages comes with an additional challenge of providing remote access. We have trialled various technologies for providing this service with limited success. We found that other options including the service provided by the Company or Student Versions/Open Source software packages are perhaps better alternatives. We found that our designed learning and teaching activities along with the video tutorials helped the distance education students to achieve similar learning outcomes as the face-to-face students

Behavior of pultruded multi-celled GFRP hollow beams with low-strength concrete infill

The structural performance of multi-celled GFRP hollow beams is highly affected by the local buckling failure. Therefore, this study introduces pultruded multi-celled GFRP beams filled with low strength concrete. The flexural behaviour of beams made up of 1, 2 and 3 pultruded GFRP square sections (125 mm x125 mm x 6.5mm) and filled with concrete having low compressive strength was investigated. The composite beams were subjected to four-point static bending test to determine the strength, stiffness and failure mechanisms. The results of the experimental investigations showed that the failure stress of 2 and 3 cells beams is 98% and 85% compared with single cell beam, respectively. However, the filling percentages are 50% and 33%, respectively. All the tested beams were failed due to compression failure of the GFRP profile. Furthermore, the effective stiffness of 2 and 3 cells is 95% and 96%, respectively compared with single cell section