ORCID Profile
0000-0001-9027-6155
Current Organisations
University of Queensland
,
Charles Darwin University
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Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 07-2023
Publisher: MDPI AG
Date: 03-04-2022
Abstract: In this study, the effects of NBR polarity and organoclay addition on the curing, rheological, mechanical, and thermal properties of an NBR henolic resin blend were investigated. The s les were prepared using a two-roll mill. The results showed that rheological and tensile properties improved due to the good distribution of nanoparticles, as well as the good compatibility of nitrile butadiene rubber with phenolic resin. The addition of 1.5 phr of nanoparticles to blends containing 33% and 45% acrylonitrile increased the curing torque difference by approximately 12% and 28%, respectively. In addition, the scorch time and curing time decreased in nanocomposites. Adding nanoparticles also increased the viscosity. The addition of phenolic resins and nanoparticles has a similar trend in modulus changes, and both of these factors increase the stiffness and, consequently, the elastic and viscous modulus of the specimens. Adding 1.5 phr of organoclay increased the tensile strength of the blends by around 8% and 13% in the s les with low and high content of acrylonitrile, respectively. Increasing the temperature of the tensile test led to a reduction in the tensile properties of the s les. Tensile strength, elongation at break, modulus, and hardness of the s les increased with increasing organoclay content. In addition, with increasing nanoparticle concentration, the s les underwent lower deterioration in tensile strength and Young’s modulus at different temperatures compared to the blends. In the s les containing 1.5 phr of organoclay, the thermal decomposition temperatures were enhanced by around 24 and 27 °C for low and high acrylonitrile content.
Publisher: Elsevier BV
Date: 06-2023
Publisher: Elsevier BV
Date: 08-2018
Publisher: Elsevier BV
Date: 12-2020
Publisher: MDPI AG
Date: 17-05-2022
Abstract: Parallel strand bamboo is a composite material that demonstrates high strength and low variability compared to other timber materials. However, its use in bolted connections is limited by a tendency to fail in shear-out mode. One promising technique to prevent failure is the method of confinement, whereby the composite connection is confined laterally, inducing a compressive force perpendicular to the composite fibres, which increases the shear strength in the loading process. This paper investigates the confinement method and its effect on parallel strand bamboo connections’ strength and failure mechanisms through experimental tests and ANSYS simulation methods. It was discovered that bolted connection confinement reduces the propensity of shear-out failure by counteracting shear stresses. A comparison of graphical results revealed that confinement increased the ultimate tensile capacity of parallel strand bamboo bolted connections by up to 26%. Confinement also improved the consistency of the connection’s mechanical properties throughout the loading process. These findings assist in refining and optimising practical applications of parallel strand bamboo connections by using the method of connection confinement.
Publisher: Elsevier BV
Date: 10-2022
Publisher: Springer Science and Business Media LLC
Date: 30-08-2023
DOI: 10.1007/S12273-023-1045-X
Abstract: The application of machine learning (ML) modelling in daylight prediction has been a promising approach for reliable and effective visual comfort assessment. Although many advancements have been made, no standardized ML modelling framework exists in daylight assessment. In this study, 625 different building layouts were generated to model useful daylight illuminance (UDI). Two state-of-the-art ML algorithms, eXtreme Gradient Boosting (XGBoost) and random forest (RF), were employed to analyze UDI in four categories: UDI- f (fell short), UDI- s (supplementary), UDI- a (autonomous), and UDI- e (exceeded). A feature (internal finish) was introduced to the framework to better reflect real-world representation. The results show that XGBoost models predict UDI with a maximum accuracy of R 2 = 0.992. Compared to RF, the XGBoost ML models can significantly reduce prediction errors. Future research directions have been specified to advance the proposed framework by introducing new features and exploring new ML architectures to standardize ML applications in daylight prediction.
Publisher: Elsevier BV
Date: 07-2023
Publisher: Springer Science and Business Media LLC
Date: 07-2023
DOI: 10.1617/S11527-023-02201-0
Abstract: The preliminary findings of cyclic tests conducted on a series of half-scale unstrengthened and strengthened masonry walls are presented. Reinforced walls were strengthened by (i) non-prestressed near surface mounted (NSM) glass fibre reinforced polymer (GFRP) bars and (ii) prestressed NSM GFRP. Walls were strengthened symmetrically by vertical bars passing through both mortar and bricks. The structure was subjected to concurrent sustained uniformly distributed vertical loads and static cyclic horizontal loads. Each reinforcement method was evaluated for its loading capability and ductility efficiency. The experimental results showed a considerably higher ultimate load-carrying capability and ductility of strengthened walls compared to the unstrengthened wall. This was more pronounced for walls reinforced with prestressed GFRP bars. The ultimate strength of the strengthened walls compared to the un-reinforced masonry (USM) wall was 38% for the wall strengthened with the non-prestressed NSM technique and 58% for the wall strengthened with the prestressed NSM technique. The horizontal failure displacement was improved by about 64% in the non-prestressed NSM technique and 127% in the prestressed NSM technique compared to the USM wall.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [Hossein Kanani] Last name [kashani]. Also, kindly confirm the details in the metadata are correct. Author 4 Given name: [Seyed Mohammad] Last name [Hosseini]. Also, kindly confirm the details in the metadata are correct. Author 5 Given name: [Seyed Mohammad Reza] Last name [Mortazavi]. Also, kindly confirm the details in the metadata are correct.All confirmed!Please check and confirm the corresponding affiliation is correctly identified.Confirmed!
Publisher: Elsevier BV
Date: 09-2022
Publisher: American Society of Civil Engineers (ASCE)
Date: 02-2023
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 08-2023
Publisher: American Society of Civil Engineers (ASCE)
Date: 12-2023
Publisher: Springer Science and Business Media LLC
Date: 12-2017
Publisher: Elsevier BV
Date: 09-2023
Publisher: Elsevier BV
Date: 03-2023
Publisher: SAGE Publications
Date: 05-08-2020
Abstract: This article presents an investigation on the durability of different glass-fibre-reinforced polymer composites when subjected to harsh outdoor conditions, including freeze/thaw cycles, ultraviolet radiation and moisture, as well as when used with seawater sea-sand concrete for construction applications. To achieve this, the effects of a number of parameters, including the environment of exposure, exposure time, profile cross-sectional configuration and orientation of fibres, on the mechanical properties of different glass-fibre-reinforced polymer composites were studied. To investigate the degradation of the mechanical properties, three-point bending, compression and tension tests were conducted on both reference and conditioned s les. Moreover, scanning electron microscopy analyses were performed to examine the contribution of microstructural deterioration to the damage mechanisms of the conditioned composites. Finally, the test results were used to develop empirical regression models to predict the level of retention of mechanical properties of different composites under different environmental conditions. The findings showed the maximum flexural, compressive and tensile strength reductions to be 35%, 48% and 37%, respectively, with regards to the pultruded profiles exposed for 3000 h to freeze/thaw cycles followed by 90 days of seawater sea-sand concrete immersion, while the flexural strength reductions recorded for the vacuum-infused s les subjected to 2000 h of freeze/thaw cycles followed by 90 days of seawater sea-sand concrete immersion were 28%, 72% and 56% for the unidirectional, woven and chopped strand mat laminates, respectively.
Publisher: MDPI AG
Date: 26-08-2019
Abstract: The present study indicates the importance of using glass fiber reinforced polymer (GFRP) laminates with appropriate thickness and fibers orientation when exposed to harsh environmental conditions. The effect of different environmental conditions on tensile properties of different GFRP laminates is investigated. Laminates were exposed to three environmental conditions: (1) Freeze/thaw cycles without the presence of moisture, (2) freeze/thaw cycles with the presence of moisture and (3) UV radiation and water vapor condensation cycles. The effect of fiber configuration and laminate thickness were investigated by considering three types of fiber arrangement: (1) Continuous unidirectional, (2) continuous woven and (3) chopped strand mat and two thicknesses (2 and 5 mm). Microstructure and tensile properties of the laminates after exposure to different periods of conditioning (0, 750, 1250 and 2000 h) were studied using SEM and tensile tests. Statistical analyses were used to quantify the obtained results and propose prediction models. The results showed that the condition comprising UV radiation and moisture condition was the most aggressive, while dry freeze/thaw environment was the least. Furthermore, the laminates with chopped strand mat and continuous unidirectional fibers respectively experienced the highest and the lowest reductions properties in all environmental conditions. The maximum reductions in tensile strength for chopped strand mat laminates were about 7%, 32%, and 42% in the dry freeze/thaw, wet freeze/thaw and UV with moisture environments, respectively. The corresponding decreases in the tensile strength for unidirectional laminates were negligible, 17% and 23%, whereas those for the woven laminates were and 7%, 24%, and 34%.
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 08-2016
Publisher: MDPI AG
Date: 25-01-2022
Abstract: Several experimental and numerical studies have been conducted to address the structural performance of FRP-reinforced/strengthened concrete structures under and after exposure to elevated temperatures. The present paper reviews over 100 research studies focused on the structural responses of different FRP-reinforced/strengthened concrete structures after exposure to elevated temperatures, ranging from ambient temperatures to flame. Different structural systems were considered, including FRP laminate bonded to concrete, FRP-reinforced concrete, FRP-wrapped concrete, and concrete-filled FRP tubes. According to the reported data, it is generally accepted that, in the case of insignificant resin in the post curing process, as the temperature increases, the ultimate strength, bond strength, and structure stiffness reduce, especially when the glass transition temperature Tg of the resin is approached and exceeded. However, in the case of post curing, resin appears to preserve its mechanical properties at high temperatures, which results in the appropriate structural performance of FRP-reinforced/strengthened members at high temperatures that are below the resin decomposition temperature Td. Given the research gaps, recommendations for future studies have been presented. The discussions, findings, and comparisons presented in this review paper will help designers and researchers to better understand the performance of concrete structures that are reinforced/strengthened with FRPs under elevated temperatures and consider appropriate approaches when designing such structures.
Publisher: Elsevier BV
Date: 04-2018
Publisher: Elsevier BV
Date: 04-2020
Publisher: Elsevier BV
Date: 09-2017
Publisher: Elsevier BV
Date: 12-2023
Publisher: Elsevier BV
Date: 10-2023
Publisher: MDPI AG
Date: 18-03-2022
Abstract: This study carried out a comparison between cement grouting and chemical grouting, using epoxy and polyurethane, with respect to their effects on the shear behavior of joints. Joint replicas, with three different grades of surface roughness, were molded and grouted by means of cement and epoxy grouts of various mixtures. To investigate their shear behavior, s les were subjected to direct shear tests under constant normal load (CNL) condition. According to the results obtained, grouting improves the overall shear strength of the rock joints. All the grouted s les yielded higher maximum and residual shear strength in comparison with the non-grouted joint. Grouting resulted in an improvement in the cohesion of all the s les. However, a fall in friction angle by 5.26° in the s le with JRC of nine was observed, yet it was reduced by 2.36° and 3.26° for joints with JRC of 14 and 19, respectively. Cement grouts were found to have a more brittle behavior, whereas the chemical grouts were more ductile. Higher amounts of cement used in the grout mixture do not provide as much cohesion and only increase the brittleness of the grout. As a result of being more brittle, cement grout breaks into small pieces and joint planes are in better contact during shearing consequently, there would be less of a fall in friction angle as opposed to epoxy grout whose ductile characteristic prevents grout chipping therefore, joint planes are not in contact and a greater fall in the friction angle occurs. There was no noticeable change in the cohesion of the larger grouted joints. However, the friction angle of both natural and grouted joints increased in the larger joint. This can be related to the distribution of random peaks and valleys on the joint surface, which increases with the joint size.
Publisher: Elsevier BV
Date: 04-2023
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 08-2022
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 10-2020
Publisher: American Society of Civil Engineers (ASCE)
Date: 02-2018
Publisher: Springer Science and Business Media LLC
Date: 11-2022
DOI: 10.1617/S11527-022-02074-9
Abstract: Anchor heads could efficiently address the bond weakness between Fibre-Reinforced Polymer bars and concrete. This experimental study enhanced the bond behaviour between GFRP bars and concrete using three innovative anchorage systems made from glass fibre cloth and epoxy resin. A direct pullout test was used to study the bond-slip performance between the bar and the concrete. Test variables were GFRP bar diameter (3 diameters), concrete compressive strength (20.4 and 40.2 MPa), and anchor system (three different types). Based on the test results, in low-strength concrete (i.e. 20.4 MPa) s les, the anchor system efficiency was not promising, and the failure occurred between the concrete and anchors. However, for higher strength concrete (i.e. 40.2 MPa) s les, the ultimate developed tensile load increased between 14 and 68% for different bar sizes and anchorage systems compared to the unanchored control specimens.
Publisher: Elsevier BV
Date: 12-2022
Publisher: Elsevier BV
Date: 05-2018
Publisher: Elsevier BV
Date: 08-2022
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 07-2020
Publisher: Elsevier BV
Date: 03-2019
Publisher: Springer Science and Business Media LLC
Date: 29-03-2023
DOI: 10.1617/S11527-023-02153-5
Abstract: The lower bond strength of FRP bars to concrete compared to steel bars has remained an unsolved barrier to the widespread use of FRP-reinforced concrete under extreme loading. Additionally, the degradation of the bond between FRP reinforcement and concretes in aggressive environments adds to the existing concern. In this study, an innovative anchorage system comprised of polypropylene pipe was used to strengthen the bond between seawater concrete and GFRP bars after 250 days of exposure to offshore environmental conditions. As material factors, two types of GFRP bars (sand-coated and ribbed) and two types of concrete (normal and seawater concrete) were evaluated. Four distinct environmental conditions were used to assess the s les: (i) ambient environment (control), (ii) tap water, (iii) seawater, and (iv) wet-dry cycles in seawater. According to the findings of the direct pull-out tests, the suggested anchor system strengthens the bond and shifts the failure mode from bond failure to bar rupture. Additionally, after exposure to 250 days of seawater wet-dry cycles, GFRP-reinforced seawater concrete lost 5% of its maximum bond strength (developed bar tensile stress). All other s les exposed to different environmental conditions either increased or decreased in bond strength by less than 5% after 250 days, compared to the control s les.
Publisher: MDPI AG
Date: 05-11-2020
Abstract: Fibre-reinforced polymer (FRP) composite is one of the most applicable materials used in civil infrastructures, as it has been proven advantageous in terms of high strength and stiffness to weight ratio and anti-corrosion. The performance of FRP under elevated temperatures has gained significant attention among academia and industry. A comprehensive review on experimental and numerical studies investigating the mechanical performance of FRP composites subjected to elevated temperatures, ranging from ambient to fire condition, is presented in this paper. Over 100 research papers on the mechanical properties of FRP materials including tensile, compressive, flexural and shear strengths and moduli are reviewed. Although they report dispersed data, several interesting conclusions can be drawn from these studies. In general, exposure to elevated temperatures near and above the resin glass transition temperature, Tg, has detrimental effects on the mechanical characteristics of FRP materials. On the other hand, elevated temperatures below Tg can cause low levels of degradation. Discussions are made on degradation mechanisms of different FRP members. This review outlines recommendations for future works. The behaviour of FRP composites under elevated temperatures provides a comprehensive understanding based on the database presented. In addition, a foundation for determining predictive models for FRP materials exposed to elevated temperatures could be laid using the finding that this review presents.
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 05-2022
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 09-2021
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 07-2023
Publisher: Elsevier BV
Date: 11-2023
Publisher: MDPI AG
Date: 12-09-2022
DOI: 10.3390/JMSE10091286
Abstract: Ocean energy is an underutilized renewable energy source compared with hydropower and wind power. Therefore, the development of economical and efficient wave energy converters (WECs) is important and crucial for offshore power generation. The mooring tensioner is a critical device that can be used in point-absorber-type WECs, semisubmersible floats for oil and gas drilling, and floating wind turbines. A mooring tensioner is a system used to create, reduce, or maintain tension within the mooring lines by applying a force to the mooring line. Composite springs as mooring tensioners have several advantages compared to metal springs, such as corrosion resistance, high specific strain energy, appropriate fatigue performance, and the ability to flexibly adjust the spring constant without changing the overall dimensions. This paper reviews in detail the fatigue performance, seawater durability, and manufacturing methods of different composite materials as well as the current and potential applications of composites springs. In addition, recommendations for future research and opportunities for composite mooring tensioners are presented.
Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 06-2022
Publisher: Elsevier BV
Date: 06-2020
Publisher: Elsevier BV
Date: 12-2017
Publisher: MDPI AG
Date: 31-01-2023
Abstract: The present study investigates the phenomena of creep in a bamboo composite. The material was tested under tensile and compressive loading and simulated in finite element analysis software to estimate the creep coefficients. The presented findings have displayed the material’s propensity to fail at loads lower than the recorded ultimate strength, as early as 65% of this strength within 100 h, showing the importance of considering creep when designing structural components. Larger resistance to creep was observed under tensile stresses. Coefficients of the time-hardening creep model were estimated, which were found to be different under compression and tension. The findings provide insight into the reliable strength value of the Bamboo Composite. They could be also essential in estimating the long-term deflations in Bamboo Composite structures.
Publisher: MDPI AG
Date: 14-01-2022
DOI: 10.3390/FIB10010008
Abstract: Using fibre-reinforced polymers (FRP) in construction avoids corrosion issues associated with the use of traditional steel reinforcement, while seawater and sea sand concrete (SWSSC) reduces environmental issues and resource shortages caused by the production of traditional concrete. The paper gives an overview of the current research on the bond performance between FRP tube and concrete with particular focus on SWSSC. The review follows a thematic broad-to-narrow approach. It reflects on the current research around the significance and application of FRP and SWSSC and discusses important issues around the bond strength and cyclic behaviour of tubular composites. A review of recent studies of bond strength between FRP and concrete and steel and concrete under static or cyclic loading using pushout tests is presented. In addition, the influence of different parameters on the pushout test results are summarised. Finally, recommendations for future studies are proposed.
Publisher: Elsevier BV
Date: 05-2019
Publisher: MDPI AG
Date: 12-07-2022
DOI: 10.3390/FIB10070059
Abstract: Interlaminar shear strength in bamboo composite (BC) is mainly provided by epoxy resin as the matrix in BC. This may greatly change due to humidity. This study aims at evaluating the shear strength of BC by testing and developing probabilistic relationships. The interlaminar shear strength of bamboo composite (BC) in different moisture conditions was tested according to ASTM D2344. The results show that the maximum shear stress does not generally occur at the centroid of s les, which could be associated with imperfections in BC layers. An extreme value theory-based model is suggested to evaluate the probability of shear failure in BC s les. The shear capacity decreased from 20.4 MPa to 14 MPa as the humidity increased from 60% to 90%. A summary of findings is as follows: It was found that under transient moisture conditions, local failure is likely to happen before the first significant crack occurs. Local failure is suggested to be considered in the design for serviceability. Stress drop caused by the local failure could exceed 10% of total shear strength and, therefore, should be regarded as a serviceability design. The probabilistic model developed in this study could be used for developing structural design safety factors.
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