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The worldwide biomedical polymeric waste (BPW) production from dialysis treatment is estimated to be reached about 1.6 million tons/year by 2025, dramatically raising financial, environmental, and ecological concerns. Thanks to new technologies, the waste is disinfected for being discarded as non-hazardous waste, incinerated or landfilled, making the disinfection process redundant and increasing the disposal costs. This study takes advantage of BPW to improve water sorptivity and electrical resistivity of concrete and lightens the way towards environmental-friendly disposal of BPW. Three Hybrid, Soft, and Hard BPW were added to concrete from 0% to 9% by weight of cement in 13 different mixtures. Afterwards, electrical resistivity, long-term capillary water absorption tests were conducted. Predictive models were then developed in three time periods. The addition of Hybrid and Hard BPW improved the capillary absorption and sorptivity by 28%, but, surprisingly, Soft BPW addition showed an adverse effect. Electrical resistivity also improved up to 22.1% after BPW addition. Considering the results, utilising Hybrid BPW in concrete eliminates the waste separating phase and can improve the concrete’s durability, saving time and costs.
Saman Rahimireskati; Kazem Ghabraie; Estela Oliari Garcez; Riyadh Al-Ameri. Improving sorptivity and electrical resistivity of concrete utilising biomedical polymeric waste sourced from dialysis treatment. International Journal of Sustainable Engineering 2021, 14, 820 -834.
AMA StyleSaman Rahimireskati, Kazem Ghabraie, Estela Oliari Garcez, Riyadh Al-Ameri. Improving sorptivity and electrical resistivity of concrete utilising biomedical polymeric waste sourced from dialysis treatment. International Journal of Sustainable Engineering. 2021; 14 (4):820-834.
Chicago/Turabian StyleSaman Rahimireskati; Kazem Ghabraie; Estela Oliari Garcez; Riyadh Al-Ameri. 2021. "Improving sorptivity and electrical resistivity of concrete utilising biomedical polymeric waste sourced from dialysis treatment." International Journal of Sustainable Engineering 14, no. 4: 820-834.
With the growing global tendency towards sustainable construction techniques, the use of renewable material regains attention from the industry. Cross laminated timber (CLT), as a relatively new engineered timber product, is recognized as a viable alternative to some traditional materials for various of structures. Based on the source of original raw materials, structural responses of CLTs could vary significantly between species. In Australia, locally planted Radiata Pine (Pinus radiata D. Don) is used to manufacture CLT panels by XLam. For panel-to-panel connection in CLT buildings, self-tapping screws (STS) are most used and are typically recommended by CLT producers as a result of their superb resistances and easy installation process. In the current study, Rothoblaas VGS11 STSs were used to investigate their pull-out responses from three-layer CLT panels with overall thickness of 105 mm and 135 mm. STSs were inserted on the narrow face of the considered XLam CLT panels both parallel to the grain direction and perpendicular to the grain direction. Different penetration depth or embedment length were considered to observe the effect of bond area on the bond strength of the STS-to-CLT interface. Typical failure modes and load vs slip curves were recorded during experiment, and were compared with available design rules for predicting withdrawal resistances. It was observed that the theoretical models are quite conservative in terms of predicting withdrawal capacity and strength. The available theoretical models yield an error of up to 57% and 43% when calculating withdrawal resistance and strength, respectively.
Xin Li; Mahmud Ashraf; Mahbube Subhani; Kazem Ghabraie; Haitao Li; Paul Kremer. Withdrawal resistance of self-tapping screws inserted on the narrow face of cross laminated timber made from Radiata Pine. Structures 2021, 31, 1130 -1140.
AMA StyleXin Li, Mahmud Ashraf, Mahbube Subhani, Kazem Ghabraie, Haitao Li, Paul Kremer. Withdrawal resistance of self-tapping screws inserted on the narrow face of cross laminated timber made from Radiata Pine. Structures. 2021; 31 ():1130-1140.
Chicago/Turabian StyleXin Li; Mahmud Ashraf; Mahbube Subhani; Kazem Ghabraie; Haitao Li; Paul Kremer. 2021. "Withdrawal resistance of self-tapping screws inserted on the narrow face of cross laminated timber made from Radiata Pine." Structures 31, no. : 1130-1140.
Since between 1.5 and 8 kg (400 kg/patient/year) of biomedical polymeric waste (BPW) is usually discarded by landfilling or combusting after each dialysis treatment, this study provides evidence for safe and environment-friendly utilisation of BPW, sourced from dialysis treatment and donated by the health and industrial partners, by incorporating it in high-strength concrete. Moreover, the paper aims to provide engineers, designers, and the construction industry with information regarding the mechanical performance of high-strength concrete containing BPW, and the susceptibility of the current international codes and standards on the prediction of the mechanical performance. A new concrete mix design incorporating BPW was proposed and verified by several trial mixes. Three Soft, Hard, and Hybrid BPW were added to the conventional high-strength concrete in different percentages ranging from 1.5% to 9% by weight of cement. Afterwards, the fresh and hardened concrete properties, namely slump, density, compressive strength, tensile strength, modulus of elasticity, and Scanning Electron Microscopy (SEM), were investigated, and existing prediction models were employed to verify their suitability for the new concrete. Generally, adding Hybrid BPW resulted in better mechanical performance than soft or hard BPW addition, while eliminating the waste separation phase. The results also showed that the mechanical performance of BPW-containing concrete is predictable by current codes, addressing possible engineering design limitations. New higher accuracy regression-based models were also proposed to reach better engineering interpretations.
Saman Rahimireskati; Kazem Ghabraie; Estela Garcez; Riyadh Al-Ameri. Prediction of the Mechanical Performance of High-Strength Concrete Containing Biomedical Polymeric Waste Obtained from Dialysis Treatment. Applied Sciences 2021, 11, 2053 .
AMA StyleSaman Rahimireskati, Kazem Ghabraie, Estela Garcez, Riyadh Al-Ameri. Prediction of the Mechanical Performance of High-Strength Concrete Containing Biomedical Polymeric Waste Obtained from Dialysis Treatment. Applied Sciences. 2021; 11 (5):2053.
Chicago/Turabian StyleSaman Rahimireskati; Kazem Ghabraie; Estela Garcez; Riyadh Al-Ameri. 2021. "Prediction of the Mechanical Performance of High-Strength Concrete Containing Biomedical Polymeric Waste Obtained from Dialysis Treatment." Applied Sciences 11, no. 5: 2053.
The smooth design of self-supporting topologies has attracted great attention in the design for additive manufacturing (DfAM) field as it cannot only enhance the manufacturability of optimized designs but can obtain light-weight designs that satisfy specific performance requirements. This paper integrates Langelaar’s AM filter into the Smooth-Edged Material Distribution for Optimizing Topology (SEMDOT) algorithm—a new element-based topology optimization method capable of forming smooth boundaries—to obtain print-ready designs without introducing post-processing methods for smoothing boundaries before fabrication and adding extra support structures during fabrication. The effects of different build orientations and critical overhang angles on self-supporting topologies are demonstrated by solving several compliance minimization (stiffness maximization) problems. In addition, a typical compliant mechanism design problem—the force inverter design—is solved to further demonstrate the effectiveness of the combination between SEMDOT and Langelaar’s AM filter.
Yun-Fei Fu; Kazem Ghabraie; Bernard Rolfe; Yanan Wang; Louis N. S. Chiu. Smooth Design of 3D Self-Supporting Topologies Using Additive Manufacturing Filter and SEMDOT. Applied Sciences 2020, 11, 238 .
AMA StyleYun-Fei Fu, Kazem Ghabraie, Bernard Rolfe, Yanan Wang, Louis N. S. Chiu. Smooth Design of 3D Self-Supporting Topologies Using Additive Manufacturing Filter and SEMDOT. Applied Sciences. 2020; 11 (1):238.
Chicago/Turabian StyleYun-Fei Fu; Kazem Ghabraie; Bernard Rolfe; Yanan Wang; Louis N. S. Chiu. 2020. "Smooth Design of 3D Self-Supporting Topologies Using Additive Manufacturing Filter and SEMDOT." Applied Sciences 11, no. 1: 238.
Fibre-reinforced polymer (FRP) rebar and geopolymer concrete (GPC) are relatively new construction materials that are now been increasingly used in the construction sectors. Both materials exhibit superior structural and durability properties that also make them a sustainable alternative solution. Due to the absence of any design standard for an FRP-reinforced GPC beam, it is important to validate the efficacy of available standards and literature related to other materials, e.g., FRP-reinforced conventional concrete or GPC alone. Four theories/design standards are considered for this comparison—ACI440.1R-15, CAN/CSA S806-12, parabolic stress block theory, and equivalent rectangular stress block theory for GPC under compression. The accuracy of these four approaches is also examined by studying the flexural performance of both the glass FRP (GFRP) and carbon FRP (CFRP). The FRP-reinforced beams are designed against the actual load they will be subjected to in a real-world scenario. It is concluded that parabolic stress block theory over-estimates the capacity, whereas CSA S806-12 yields the most accurate and conservative results. In addition, the flexural performance of the FRP-reinforced beams is evaluated in terms of ultimate, cracking, and service moment capacity, along with serviceable, ultimate, and residual deflection.
Janeshka Goonewardena; Kazem Ghabraie; Mahbube Subhani. Flexural Performance of FRP-Reinforced Geopolymer Concrete Beam. Journal of Composites Science 2020, 4, 187 .
AMA StyleJaneshka Goonewardena, Kazem Ghabraie, Mahbube Subhani. Flexural Performance of FRP-Reinforced Geopolymer Concrete Beam. Journal of Composites Science. 2020; 4 (4):187.
Chicago/Turabian StyleJaneshka Goonewardena; Kazem Ghabraie; Mahbube Subhani. 2020. "Flexural Performance of FRP-Reinforced Geopolymer Concrete Beam." Journal of Composites Science 4, no. 4: 187.
Cross-laminated timber (CLT) is an engineered wood product made up of layers of structurally graded timber, where subsequent layers are oriented orthogonally to each other. In CLT, the layers oriented in transverse direction, generally termed as cross-layer, are subjected to shear in radial–tangential plane, which is commonly known as rolling shear. As the shear modulus of cross-layers is significantly lower than that in other planes, CLT exhibits higher shear deformation under out-of-plane loading in contrast to other engineered wood products such as laminated veneer lumber (LVL) and glue laminated timber (GLT). Several analytical methods such as Timoshenko, modified gamma and shear analogy methods were proposed to account for this excessive shear deformation in CLT. This paper focuses on the effectiveness of Timoshenko method in hybrid CLT, in which hardwood cross-layers are used due to their higher rolling shear modulus. A comprehensive numerical study was conducted and obtained results were carefully analyzed for a range of hybrid combinations. It was observed that Timoshenko method could not accurately predict the shear response of CLTs with hardwood cross layers. Comprehensive parametric analysis was conducted to generate reliable numerical results, which were subsequently used to propose modified design equations for hybrid CLTs.
Tanvir Rahman; Mahmud Ashraf; Kazem Ghabraie; Mahbube Subhani. Evaluating Timoshenko Method for Analyzing CLT under Out-of-Plane Loading. Buildings 2020, 10, 184 .
AMA StyleTanvir Rahman, Mahmud Ashraf, Kazem Ghabraie, Mahbube Subhani. Evaluating Timoshenko Method for Analyzing CLT under Out-of-Plane Loading. Buildings. 2020; 10 (10):184.
Chicago/Turabian StyleTanvir Rahman; Mahmud Ashraf; Kazem Ghabraie; Mahbube Subhani. 2020. "Evaluating Timoshenko Method for Analyzing CLT under Out-of-Plane Loading." Buildings 10, no. 10: 184.
Element-based topology optimization algorithms capable of generating smooth boundaries have drawn serious attention given the significance of accurate boundary information in engineering applications. The basic framework of a new element-based continuum algorithm is proposed in this paper. This algorithm is based on a smooth-edged material distribution strategy that uses solid/void grid points assigned to each element. Named Smooth-Edged Material Distribution for Optimizing Topology (SEMDOT), the algorithm uses elemental volume fractions which depend on the densities of grid points in the Finite Element Analysis (FEA) model rather than elemental densities. Several numerical examples are studied to demonstrate the application and effectiveness of SEMDOT. In these examples, SEMDOT proved to be capable of obtaining optimized topologies with smooth and clear boundaries showing better or comparable performance compared to other topology optimization methods. Through these examples, first, the advantages of using the Heaviside smooth function are discussed in comparison to the Heaviside step function. Then, the benefits of introducing multiple filtering steps in this algorithm are shown. Finally, comparisons are conducted to exhibit the differences between SEMDOT and some well-established element-based algorithms. The validation of the sensitivity analysis method adopted in SEMDOT is conducted using a typical compliant mechanism design case. In addition, this paper provides the Matlab code of SEMDOT for educational and academic purposes.
Yun-Fei Fu; Bernard Rolfe; Louis N. S. Chiu; Yanan Wang; Xiaodong Huang; Kazem Ghabraie. SEMDOT: Smooth-edged material distribution for optimizing topology algorithm. Advances in Engineering Software 2020, 150, 102921 .
AMA StyleYun-Fei Fu, Bernard Rolfe, Louis N. S. Chiu, Yanan Wang, Xiaodong Huang, Kazem Ghabraie. SEMDOT: Smooth-edged material distribution for optimizing topology algorithm. Advances in Engineering Software. 2020; 150 ():102921.
Chicago/Turabian StyleYun-Fei Fu; Bernard Rolfe; Louis N. S. Chiu; Yanan Wang; Xiaodong Huang; Kazem Ghabraie. 2020. "SEMDOT: Smooth-edged material distribution for optimizing topology algorithm." Advances in Engineering Software 150, no. : 102921.
Topology optimization has emerged as a powerful tool for generating innovative designs. However, several topology optimization algorithms are finite element (FE) based where mesh-dependent zigzag or blurry boundaries are rarely avoidable. This paper presents a continuum topological design algorithm capable of obtaining smooth 3D topologies based on elemental volume fractions. Parametric studies are thoroughly conducted to determine the proper ranges of the parameters in the proposed algorithm. The numerical results confirm the robustness of the proposed algorithm. Furthermore, it is shown that very small penalty coefficients can be used to obtain clear and convergent topologies. The effectiveness of the proposed algorithm is further proven via numerical comparison with a well-established topology optimization framework. Because of the smooth boundary representation, optimized topologies are suitable for additive manufacturing (AM) without redesign or post-processing.
Yun-Fei Fu; Bernard Rolfe; Louis N.S. Chiu; Yanan Wang; Xiaodong Huang; Kazem Ghabraie. Smooth topological design of 3D continuum structures using elemental volume fractions. Computers & Structures 2020, 231, 106213 .
AMA StyleYun-Fei Fu, Bernard Rolfe, Louis N.S. Chiu, Yanan Wang, Xiaodong Huang, Kazem Ghabraie. Smooth topological design of 3D continuum structures using elemental volume fractions. Computers & Structures. 2020; 231 ():106213.
Chicago/Turabian StyleYun-Fei Fu; Bernard Rolfe; Louis N.S. Chiu; Yanan Wang; Xiaodong Huang; Kazem Ghabraie. 2020. "Smooth topological design of 3D continuum structures using elemental volume fractions." Computers & Structures 231, no. : 106213.
Incorporating additive manufacturing (AM) constraints in topology optimisation can lead to performance optimality while ensuring manufacturability of designs. Numerical techniques have been previously proposed to obtain support-free designs in AM, however, few works have verified the manufacturability of their solutions. Physical verification of manufacturability becomes more critical recalling that the conventional density-based topology optimisation methods will inevitably require post-processing to smooth the boundaries before sending the results to a 3D printer. This paper presents the smooth design of self-supporting topologies using the combination of a new Solid Isotropic Microstructure with Penalisation method (SIMP) developed based on elemental volume fractions and an existing AM filter. Manufacturability of selected simulation results are verified with Fused Deposition Modeling (FDM) technology. It is illustrated that the proposed method is able to generate convergent self-supporting topologies which are printable using FDM.
Yun-Fei Fu; Bernard Rolfe; Louis N. S. Chiu; Yanan Wang; Xiaodong Huang; Kazem Ghabraie. Design and experimental validation of self-supporting topologies for additive manufacturing. Virtual and Physical Prototyping 2019, 14, 382 -394.
AMA StyleYun-Fei Fu, Bernard Rolfe, Louis N. S. Chiu, Yanan Wang, Xiaodong Huang, Kazem Ghabraie. Design and experimental validation of self-supporting topologies for additive manufacturing. Virtual and Physical Prototyping. 2019; 14 (4):382-394.
Chicago/Turabian StyleYun-Fei Fu; Bernard Rolfe; Louis N. S. Chiu; Yanan Wang; Xiaodong Huang; Kazem Ghabraie. 2019. "Design and experimental validation of self-supporting topologies for additive manufacturing." Virtual and Physical Prototyping 14, no. 4: 382-394.
This paper aims to explore the effects of optimisation parameters (the filter radius, mesh size, and target volume fraction) on the compliance and manufacturability of smooth self-supporting topologies for additive manufacturing (AM); and conduct manufacturability experiments of selected simulation results with the Selective Laser Melting (SLM) technology. In this study, smooth self-supporting topologies are obtained with a combined method of the Solid Isotropic Microstructure with Penalization method (SIMP) with the smooth boundary representation and Langelaar's AM filter. Numerical examples illustrate that a higher filter radius can lead to simpler smooth self-supporting topologies, but curved top corners that violate the critical overhang angle of 45° are inevitably generated. Additionally, the mesh size is found to be not as an important factor as the filter radius in affecting the manufacturability and performance. As a result of the self-supporting constraint, a small volume fraction can easily result in structural discontinuity. The experimental results demonstrate that the self-supporting topologies obtained are all printable in SLM.
Yun-Fei Fu; Bernard Rolfe; Louis N. S. Chiu; Yanan Wang; Xiaodong Huang; Kazem Ghabraie. Parametric studies and manufacturability experiments on smooth self-supporting topologies. Virtual and Physical Prototyping 2019, 15, 22 -34.
AMA StyleYun-Fei Fu, Bernard Rolfe, Louis N. S. Chiu, Yanan Wang, Xiaodong Huang, Kazem Ghabraie. Parametric studies and manufacturability experiments on smooth self-supporting topologies. Virtual and Physical Prototyping. 2019; 15 (1):22-34.
Chicago/Turabian StyleYun-Fei Fu; Bernard Rolfe; Louis N. S. Chiu; Yanan Wang; Xiaodong Huang; Kazem Ghabraie. 2019. "Parametric studies and manufacturability experiments on smooth self-supporting topologies." Virtual and Physical Prototyping 15, no. 1: 22-34.
The use of self-compacting concrete (SCC) reinforced with fibers has great potential in the precast concrete industry as the concrete can be delivered straight into the moulds, without any vibration or compacting effort. Similarly, it has the potential to replace traditional steel reinforcement depending on the design requirements. Novel synthetic fibers have recently become available in the market, but still, limited information is available on the performance of SCC reinforced with such fibers. This paper investigates the use of twisted-bundle macro-synthetic fiber in self-compacting concrete. Three different concrete mixtures with fiber dosage of 4, 6, and 8 kg/m3 were produced in large scale batches, and their performance was compared in terms of slump-flow, compressive strength, split tensile strength, modulus of elasticity, and flexural strength. Moreover, a comprehensive evaluation of the post-cracking residual strength is presented. It was found that the mixture with 4 kg/m3 fiber content has the most satisfactory flowability, whereas 8 kg/m3 mixture achieved the highest residual flexural strength. Based on the observed post-cracking behavior, a simplified stress-crack opening constitutive law is proposed. Since the fiber dosage affects the residual flexural strength, a factor related to fiber content is recommended while determining the ultimate residual flexural strength.
Estela Oliari Garcez; Muhammad Ikramul Kabir; Alastair MacLeod; Mahbube Subhani; Kazem Ghabraie. Self-Compacting Concrete Reinforced with Twisted-Bundle Macro-Synthetic Fiber. Applied Sciences 2019, 9, 2543 .
AMA StyleEstela Oliari Garcez, Muhammad Ikramul Kabir, Alastair MacLeod, Mahbube Subhani, Kazem Ghabraie. Self-Compacting Concrete Reinforced with Twisted-Bundle Macro-Synthetic Fiber. Applied Sciences. 2019; 9 (12):2543.
Chicago/Turabian StyleEstela Oliari Garcez; Muhammad Ikramul Kabir; Alastair MacLeod; Mahbube Subhani; Kazem Ghabraie. 2019. "Self-Compacting Concrete Reinforced with Twisted-Bundle Macro-Synthetic Fiber." Applied Sciences 9, no. 12: 2543.
The problem of finding the optimal reinforcement layout for underground openings is considered. The rock material is assumed to sustain only compressive stresses while the reinforcements are in pure tension. It is shown that in this case, the optimal reinforcement layout can be achieved by solving a truss optimisation problem. The theory of truss optimisation is briefly presented. It is shown that the optimal layout of reinforcing bars is independent of the material properties of the reinforcing bars and the ground material.
Kazem Ghabraie. On Optimal Reinforcement Layout for Underground Openings. Advancements in Geotechnical Engineering 2018, 217 -224.
AMA StyleKazem Ghabraie. On Optimal Reinforcement Layout for Underground Openings. Advancements in Geotechnical Engineering. 2018; ():217-224.
Chicago/Turabian StyleKazem Ghabraie. 2018. "On Optimal Reinforcement Layout for Underground Openings." Advancements in Geotechnical Engineering , no. : 217-224.
This paper introduces an innovative composite railway sleeper with an optimal material usage for a narrow-gauge railway track under static loading condition. The composite sleeper is designed using sandwich panels that were bonded and coated with epoxy polymer matrix. The sleeper’s optimized shape was obtained using topology optimization. The vertical deflection and sleeper-ballast contact pressure of the optimized sleeper were analyzed by finite-element simulation and compared with a traditional timber sleeper. Prototype sleepers were then manufactured and their performance was evaluated experimentally. Results showed that the optimal sleeper shape only needs 50% volume of materials required for a standard rectangular timber sleeper. The performance of the optimal sleeper satisfactorily met the Australian standard requirements and was very similar to a timber sleeper indicating the high potential of this sleeper technology to replace the existing timber sleepers. This new sleeper is currently being tested in the Queensland Rail network as part of their sleeper maintenance program.
Wahid Ferdous; Allan Manalo; Gerard Van Erp; Thiru Aravinthan; Kazem Ghabraie. Evaluation of an Innovative Composite Railway Sleeper for a Narrow-Gauge Track under Static Load. Journal of Composites for Construction 2018, 22, 04017050 .
AMA StyleWahid Ferdous, Allan Manalo, Gerard Van Erp, Thiru Aravinthan, Kazem Ghabraie. Evaluation of an Innovative Composite Railway Sleeper for a Narrow-Gauge Track under Static Load. Journal of Composites for Construction. 2018; 22 (2):04017050.
Chicago/Turabian StyleWahid Ferdous; Allan Manalo; Gerard Van Erp; Thiru Aravinthan; Kazem Ghabraie. 2018. "Evaluation of an Innovative Composite Railway Sleeper for a Narrow-Gauge Track under Static Load." Journal of Composites for Construction 22, no. 2: 04017050.
Topology optimisation techniques typically use a very small positive density \(\varepsilon \) to model voids. Despite its simplicity and generally acceptable results, this approach can impose a number of difficulties. The weak material should be weak enough to validate the approximation of void areas, but on the other hand, using a very weak material can result in ill-conditioning of the stiffness matrix. Further and more serious complications can arise, for example in non-linear problems where weak elements cause numerical instabilities in the solution procedure. By studying the mechanical responses of structures when \(\varepsilon \rightarrow 0\), this paper presents a simple approach to use arbitrarily weak material properties in void areas. This approach would effectively allow us to actually remove the void areas from the mesh in a range of problems and avoid the above-mentioned complexities.
Kazem Ghabraie. A Simple Approach to Deal with Zero Densities in Topology Optimisation. Advances in Structural and Multidisciplinary Optimization 2017, 1019 -1026.
AMA StyleKazem Ghabraie. A Simple Approach to Deal with Zero Densities in Topology Optimisation. Advances in Structural and Multidisciplinary Optimization. 2017; ():1019-1026.
Chicago/Turabian StyleKazem Ghabraie. 2017. "A Simple Approach to Deal with Zero Densities in Topology Optimisation." Advances in Structural and Multidisciplinary Optimization , no. : 1019-1026.
Evaluating the induced subsidence is a critical step in multi-seam longwall mining. Numerical modelling can be a cost-effective approach to this problem. Numerical evaluation of longwall mining-induced subsidence is much more complicated when more than one seam is to be extracted. Only a few research works have dealt with this problem. This paper discusses the essential requirements of a robust numerical modelling approach to simulation of multi-seam longwall mining-induced subsidence. In light of these requirements, the previous works on this topic are critically reviewed. A simple yet robust FEM-based modelling approach is also proposed that is capable of simulating caving process, rock mass deterioration and subsidence around multi-seam excavations. The effectiveness of this approach in comparison with two other conventional FEM approaches is demonstrated through numerical examples of two different multi-seam mining configurations. Results show that the proposed numerical modelling approach is the only robust method, which is capable of simulating multi-seam subsidence in both demonstrated cases. Copyright © 2016 John Wiley & Sons, Ltd.
Behrooz Ghabraie; Kazem Ghabraie; Gang Ren; John V. Smith. Numerical modelling of multistage caving processes: insights from multi-seam longwall mining-induced subsidence. International Journal for Numerical and Analytical Methods in Geomechanics 2016, 41, 959 -975.
AMA StyleBehrooz Ghabraie, Kazem Ghabraie, Gang Ren, John V. Smith. Numerical modelling of multistage caving processes: insights from multi-seam longwall mining-induced subsidence. International Journal for Numerical and Analytical Methods in Geomechanics. 2016; 41 (7):959-975.
Chicago/Turabian StyleBehrooz Ghabraie; Kazem Ghabraie; Gang Ren; John V. Smith. 2016. "Numerical modelling of multistage caving processes: insights from multi-seam longwall mining-induced subsidence." International Journal for Numerical and Analytical Methods in Geomechanics 41, no. 7: 959-975.
Tin Nguyen; Kazem Ghabraie; Thanh Tran-Cong; Behzad Fatahi. Improving Rockbolt Design in Tunnels Using Topology Optimization. International Journal of Geomechanics 2016, 16, 04015023 .
AMA StyleTin Nguyen, Kazem Ghabraie, Thanh Tran-Cong, Behzad Fatahi. Improving Rockbolt Design in Tunnels Using Topology Optimization. International Journal of Geomechanics. 2016; 16 (1):04015023.
Chicago/Turabian StyleTin Nguyen; Kazem Ghabraie; Thanh Tran-Cong; Behzad Fatahi. 2016. "Improving Rockbolt Design in Tunnels Using Topology Optimization." International Journal of Geomechanics 16, no. 1: 04015023.
Hamid Reza Tabatabaiefar; Behzad Fatahi; Kazem Ghabraie; Wan-Huan Zhou. Evaluation of numerical procedures to determine seismic response of structures under influence of soil-structure interaction. Structural Engineering and Mechanics 2015, 56, 27 -47.
AMA StyleHamid Reza Tabatabaiefar, Behzad Fatahi, Kazem Ghabraie, Wan-Huan Zhou. Evaluation of numerical procedures to determine seismic response of structures under influence of soil-structure interaction. Structural Engineering and Mechanics. 2015; 56 (1):27-47.
Chicago/Turabian StyleHamid Reza Tabatabaiefar; Behzad Fatahi; Kazem Ghabraie; Wan-Huan Zhou. 2015. "Evaluation of numerical procedures to determine seismic response of structures under influence of soil-structure interaction." Structural Engineering and Mechanics 56, no. 1: 27-47.
Dam sites provide an outstanding opportunity to explore dynamic changes in the groundwater flow regime because of the high hydraulic gradient rapidly induced in their surroundings. This paper investigates the temporal changes of the hydraulic conductivities of the rocks and engineered structures via a thorough analysis of hydrological data collected at the Dokam Dam, Iraq, and a numerical model that simulates the Darcian component of the seepage. Analysis of the data indicates increased seepage with time and suggests that the hydraulic conductivity of the rocks increased as the conductivity of the grout curtain decreased. Conductivity changes on the order of 10-8m/s, in a 20-yr period were quantified using the numerical analysis. It is postulated that the changes in hydraulic properties in the vicinity of Dokan Dam are due to suspension of fine materials, interbedded in small fissures in the rocks, and re-settlement of these materials along the curtain. Consequently, the importance of the grout curtain to minimize the downstream seepage, not only as a result of the conductivity contrast with the rocks, but also as a barrier to suspended clay sediments, is demonstrated. The numerical analysis also helped us to estimate the proportion of the disconnected karstic conduit flow to the overall flow
Elad Dafny; Kochar Jamal Tawfeeq; Kazem Ghabraie. Evaluating temporal changes in hydraulic conductivities near karst-terrain dams: Dokan Dam (Kurdistan-Iraq). Journal of Hydrology 2015, 529, 265 -275.
AMA StyleElad Dafny, Kochar Jamal Tawfeeq, Kazem Ghabraie. Evaluating temporal changes in hydraulic conductivities near karst-terrain dams: Dokan Dam (Kurdistan-Iraq). Journal of Hydrology. 2015; 529 ():265-275.
Chicago/Turabian StyleElad Dafny; Kochar Jamal Tawfeeq; Kazem Ghabraie. 2015. "Evaluating temporal changes in hydraulic conductivities near karst-terrain dams: Dokan Dam (Kurdistan-Iraq)." Journal of Hydrology 529, no. : 265-275.
Finding the optimum distribution of material phases in a multi-material structure is a frequent and important problem in structural engineering which involves topology optimization. The Bi-directional Evolutionary Structural Optimization (BESO) method is now a well-known topology optimization method. In this paper an improved soft-kill BESO algorithm is introduced which can handle both single and multiple material distribution problems. A new filtering scheme and a gradual procedure inspired by the continuation approach are used in this algorithm. Capabilities of the proposed method are demonstrated using different examples. It is shown that the proposed method can result in considerable improvements compared to the normal BESO algorithm particularly when solving problems involving very soft material or void phase.
Kazem Ghabraie. An improved soft-kill BESO algorithm for optimal distribution of single or multiple material phases. Structural and Multidisciplinary Optimization 2015, 52, 773 -790.
AMA StyleKazem Ghabraie. An improved soft-kill BESO algorithm for optimal distribution of single or multiple material phases. Structural and Multidisciplinary Optimization. 2015; 52 (4):773-790.
Chicago/Turabian StyleKazem Ghabraie. 2015. "An improved soft-kill BESO algorithm for optimal distribution of single or multiple material phases." Structural and Multidisciplinary Optimization 52, no. 4: 773-790.
Designing a rock bolt reinforcement system for underground excavation involves determining bolt pattern, spacing, and size. In this paper, a topology optimisation technique is presented and employed to simultaneously optimise these design variables. To improve rock bolt design, the proposed technique minimises a displacement based function around the opening after bolt installation. This optimisation technique is independent of the material model and can be easily applied to any material model for rock and bolts. It is also extremely flexible in that it can be applied to any mechanical analysis method. To illustrate the capabilities of this method, numerical examples with non-linear material models and discontinuities in the host rock are presented. It is shown that the complexity of systems optimised using this approach is only restricted by limitations of the method used to analyse mechanical system responses
Tin Nguyen; Kazem Ghabraie; Thanh Tran-Cong. Simultaneous pattern and size optimisation of rock bolts for underground excavations. Computers and Geotechnics 2015, 66, 264 -277.
AMA StyleTin Nguyen, Kazem Ghabraie, Thanh Tran-Cong. Simultaneous pattern and size optimisation of rock bolts for underground excavations. Computers and Geotechnics. 2015; 66 ():264-277.
Chicago/Turabian StyleTin Nguyen; Kazem Ghabraie; Thanh Tran-Cong. 2015. "Simultaneous pattern and size optimisation of rock bolts for underground excavations." Computers and Geotechnics 66, no. : 264-277.