A dual scaled boundary finite element formulation over arbitrary faceted star convex polyhedra
- Authors: Ooi, Ean Tat , Saputra, Albert , Natarajan, Sundararajan , Ooi, Ean Hin , Song, Chongmin
- Date: 2020
- Type: Text , Journal article
- Relation: Computational Mechanics Vol. 66, no. 1 (2020), p. 27-47
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- Description: A novel technique to formulate arbritrary faceted polyhedral elements in three-dimensions is presented. The formulation is applicable for arbitrary faceted polyhedra, provided that a scaling requirement is satisfied and the polyhedron facets are planar. A triangulation process can be applied to non-planar facets to generate an admissible geometry. The formulation adopts two separate scaled boundary coordinate systems with respect to: (i) a scaling centre located within a polyhedron and; (ii) a scaling centre on a polyhedron’s facets. The polyhedron geometry is scaled with respect to both the scaling centres. Polygonal shape functions are derived using the scaled boundary finite element method on the polyhedron facets. The stiffness matrix of a polyhedron is obtained semi-analytically. Numerical integration is required only for the line elements that discretise the polyhedron boundaries. The new formulation passes the patch test. Application of the new formulation in computational solid mechanics is demonstrated using a few numerical benchmarks. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
A novel error indicator and an adaptive refinement technique using the scaled boundary finite element method
- Authors: Song, Chongmin , Ooi, Ean Tat , Pramod, Aladurthi , Natarajan, Sundararajan
- Date: 2018
- Type: Text , Journal article
- Relation: Engineering Analysis with Boundary Elements Vol. 94, no. (2018), p. 10-24
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- Description: In this paper, an adaptive refinement strategy based on the scaled boundary finite element method on quadtree meshes for linear elasticity problems is discussed. Within this framework, the elements with hanging nodes are treated as polygonal elements and thus does not require special treatment. The adaptive refinement is supplemented with a novel error indicator. The local error is estimated directly from the solution of the scaled boundary governing equations. The salient feature is that it does not require any stress recovery techniques. The efficacy and the robustness of the proposed approach are demonstrated with a few numerical examples.
A quadtree-polygon-based scaled boundary finite element method for crack propagation modeling in functionally graded materials
- Authors: Chen, Xiaojun , Luo, Tao , Ooi, Ean Tat , Ooi, Ean Hin , Song, Chongmin
- Date: 2018
- Type: Text , Journal article
- Relation: Theoretical and Applied Fracture Mechanics Vol. 94, no. (2018), p. 120-133
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- Description: This paper presents a method to improve the computational efficiency of the scaled boundary finite element formulation for functionally graded materials. Both isotropic and orthotropic functionally graded materials are considered. This is achieved using a combination of quadtree and polygon meshes. This hybrid meshing approach is particularly suitable to be used with the SBFEM for functionally graded materials because of the significant amount of calculations required to compute the stiffness matrices of the polygons/cells in the mesh. When a quadtree structure is adopted, most of the variables required for the numerical simulation can be pre-computed and stored in the memory, retrieved and scaled as required during the computations, leading to an efficient method for crack propagation modeling. The scaled boundary finite element formulation enables accurate computation of the stress intensity factors directly from the stress solutions without any special post-processing techniques or local mesh refinement in the vicinity of the crack tip. Numerical benchmarks demonstrate the efficiency of the proposed method as opposed to using a purely polygon-mesh based approach. © 2018 Elsevier Ltd
A scaled boundary finite element formulation over arbitrary faceted star convex polyhedra
- Authors: Natarajan, Sundararajan , Ooi, Ean Tat , Saputra, Albert , Song, Chongmin
- Date: 2017
- Type: Text , Journal article
- Relation: Engineering Analysis with Boundary Elements Vol. 80, no. (2017), p. 218-229
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- Description: In this paper, a displacement based finite element framework for general three-dimensional convex polyhedra is presented. The method is based on a semi-analytical framework, the scaled boundary finite element method. The method relies on the definition of a scaling center from which the entire boundary is visible. The salient feature of the method is that the discretizations are restricted to the surfaces of the polyhedron, thus reducing the dimensionality of the problem by one. Hence, an explicit form of the shape functions inside the polyhedron is not required. Conforming shape functions defined over arbitrary polygon, such as the Wachpress interpolants are used over each surface of the polyhedron. Analytical integration is employed within the polyhedron. The proposed method passes patch test to machine precision. The convergence and the accuracy properties of the method is discussed by solving few benchmark problems in linear elasticity. © 2017 Elsevier Ltd
A scaled boundary finite element formulation with bubble functions for elasto-static analyses of functionally graded materials
- Authors: Ooi, Ean Tat , Song, Chongmin , Natarajan, Sundararajan
- Date: 2017
- Type: Text , Journal article
- Relation: Computational Mechanics Vol. 60, no. 6 (2017), p. 943-967
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- Description: This manuscript presents an extension of the recently-developed high order complete scaled boundary shape functions to model elasto-static problems in functionally graded materials. Both isotropic and orthotropic functionally graded materials are modelled. The high order complete properties of the shape functions are realized through the introduction of bubble-like functions derived from the equilibrium condition of a polygon subjected to body loads. The bubble functions preserve the displacement compatibility between the elements in the mesh. The heterogeneity resulting from the material gradient introduces additional terms in the polygon stiffness matrix that are integrated analytically. Few numerical benchmarks were used to validate the developed formulation. The high order completeness property of the bubble functions result in superior accuracy and convergence rates for generic elasto-static and fracture problems involving functionally graded materials. © 2017, Springer-Verlag GmbH Germany.
Acoustic emission source location on large plate-like structures using a local triangular sensor array
- Authors: Aljets, Dirk , Chong, Alex , Wilcox, Steven , Holford, Karen
- Date: 2012
- Type: Text , Journal article
- Relation: Mechanical Systems and Signal Processing Vol. 30, no. (2012), p. 91-102
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- Description: A new acoustic emission (AE) source location method was developed for large plate-like structures, which evaluates the location of the source using a combined time of flight and modal source location algorithm. Three sensors are installed in a triangular array with a sensor to sensor distance of just a few centimeters. The direction from the sensor array to the AE source can be established by analysing the arrival times of the A 0 component of the signal to the three sensors whilst the distance can be evaluated using the separation of S 0 and A 0 mode at each sensor respectively. The close positioning of the sensors allows the array to be installed in a single housing. This simplifies mounting, wiring and calibration procedures for non-destructive testing (NDT) and structural health monitoring (SHM) applications. Furthermore, this array could reduce the number of sensors needed to monitor large structures compared to other methods. An automatic wave mode identification method is also presented. © 2012 Elsevier Ltd.
Automated health condition diagnosis of in situ wood utility poles using an intelligent non-destructive evaluation (NDE) framework
- Authors: Yu, Yang , Subhani, Mahbube , Hoshyar, Azadeh , Li, Jianchun , Li, Huan
- Date: 2020
- Type: Text , Journal article
- Relation: International Journal of Structural Stability and Dynamics Vol. 20, no. 10 (2020), p.
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- Description: Wood utility poles are widely applied in power transmission and telecommunication systems in Australia. Because of a variety of external influence factors, such as fungi, termite and environmental conditions, failure of poles due to the wood degradation with time is of common occurrence with high degree uncertainty. The pole failure may result in serious consequences including both economic and public safety. Therefore, accurately and timely identifying the health condition of the utility poles is of great significance for economic and safe operation of electricity and communication networks. In this paper, a novel non-destructive evaluation (NDE) framework with advanced signal processing and artificial intelligence (AI) techniques is developed to diagnose the condition of utility pole in field. To begin with, the guided waves (GWs) generated within the pole is measured using multi-sensing technique, avoiding difficult interpretation of various wave modes which cannot be detected by only one sensor. Then, empirical mode decomposition (EMD) and principal component analysis (PCA) are employed to extract and select damage-sensitive features from the captured GW signals. Additionally, the up-to-date machine learning (ML) techniques are adopted to diagnose the health condition of the pole based on selected signal patterns. Eventually, the performance of the developed NDE framework is evaluated using the field testing data from 15 new and 24 decommissioned utility poles at the pole yard in Sydney. © 2020 World Scientific Publishing Company.
- Description: This research is supported by Australian Research Council via Linkage Project (LP110200162) and Industrial Transforming Research Hub for Nanoscience Based Construction Materials Manufacturing (IH150100006) as well as Ausgrid. The authors greatly appreciate the ¯nancial and technical supports from the funding bodies.
CFRP repaired welded thin-walled cross-beam connections subject to in-plane fatigue loading
- Authors: Xiao, Zhigang , Zhao, Xiao
- Date: 2012
- Type: Text , Journal article
- Relation: International Journal of Structural Stability and Dynamics Vol. 12, no. 1 (2012 2012), p. 195-211
- Full Text: false
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- Description: Cracked cross-beam connections made of thin-walled rectangular hollow sections (RHS) are repaired with carbon fiber-reinforced polymer (CFRP) sheets. Constant amplitude fatigue experiments are conducted on the repaired specimens. A pilot test is conducted on a T-connection of square hollow sections (SHS) to explore the effective method of applying CFRP. Due to the peeling effect at the corner region of the SHS-to-SHS connection, early debonding happens in the pilot test that only results in a slight extension in fatigue life. In the following experiments of repairing RHS-to-RHS cross-beam connections, circumferential or transverse restraining CFRP patches are applied in the corner region that prevents early debonding successfully and leads to significant increase in fatigue life. Finally, an improvement is made with the addition of steel strengthening plates that increase both the flexural stiffness and fatigue life of the cracked specimens significantly. The proposed retrofitting method may be useful for repairing other similar fatigue-cracked welded tubular connections.
Crack propagation modelling in concrete using the scaled boundary finite element method with hybrid polygon-quadtree meshes
- Authors: Ooi, Ean Tat , Natarajan, Sundararajan , Song, Chongmin , Ooi, Ean Hin
- Date: 2017
- Type: Text , Journal article
- Relation: International Journal of Fracture Vol. 203, no. 1-2 (2017), p. 135-157
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- Description: This manuscript presents an extension of the recently-developed hybrid polygon-quadtree-based scaled boundary finite element method to model crack propagation in concrete. This hybrid approach combines the use of quadtree cells with arbitrary sided polygons for domain discretization. The scaled boundary finite element formulation does not distinguish between quadtree cells and arbitrary sided polygons in the mesh. A single formulation is applicable to all types of cells and polygons in the mesh. This eliminates the need to develop transitional elements to bridge the cells belonging to different levels in the quadtree hierarchy. Further to this, the use of arbitrary sided polygons facilitate the accurate discretization of curved boundaries that may result during crack propagation. The fracture process zone that is characteristic in concrete fracture is modelled using zero-thickness interface elements that are coupled to the scaled boundary finite element method using a shadow domain procedure. The scaled boundary finite element method can accurately model the asymptotic stress field in the vicinity of the crack tip with cohesive tractions. This leads to the accurate computation of the stress intensity factors, which is used to determine the condition for crack propagation and the resulting direction. Crack growth can be efficiently resolved using an efficient remeshing algorithm that employs a combination of quadtree decomposition functions and simple Booleans operations. The flexibility of the scaled boundary finite element method to be formulated on arbitrary sided polygons also result in a flexible remeshing algorithm for modelling crack propagation. The developed method is validated using three laboratory experiments of notched concrete beams subjected to different loading conditions.
Crack propagation modelling in functionally graded materials using scaled boundary polygons
- Authors: Ooi, Ean Tat , Natarajan, Sundararajan , Song, Chongmin , Tin-Loi, Francis
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Fracture Vol. Online first, no. 192 (2015), p. 87-105
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- Description: A recently developed scaled boundary finite element formulation that can model the response of functionally graded materials is further developed to model crack propagation in two-dimensions. This formulation can accurately model the stress singularity at the crack tip in heterogeneous materials. The asymptotic behaviour at the crack tip is analytically represented in the scaled boundary shape functions of a cracked polygon. This enables accurate stress intensity factors to be computed directly from their definitions. Neither local mesh refinement nor asymptotic enrichment functions are required. This novel formulation can be implemented on polygons with an arbitrary number of sides. When modelling crack propagation, the remeshing process is more flexible and leads to only minimal changes to the global mesh structure. Six numerical examples involving crack propagation in functionally graded materials are modelled to demonstrate the salient features of the developed method.
Crack propagation modelling in functionally graded materials using scaled boundary polygons
- Authors: Ooi, Ean Tat , Natarajan, Sundararajan , Song, Chongmin , Tin-Loi, Francis
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Fracture Vol. 192, no. 1 (2015), p. 87-105
- Full Text: false
- Reviewed:
- Description: A recently developed scaled boundary finite element formulation that can model the response of functionally graded materials is further developed to model crack propagation in two-dimensions. This formulation can accurately model the stress singularity at the crack tip in heterogeneous materials. The asymptotic behaviour at the crack tip is analytically represented in the scaled boundary shape functions of a cracked polygon. This enables accurate stress intensity factors to be computed directly from their definitions. Neither local mesh refinement nor asymptotic enrichment functions are required. This novel formulation can be implemented on polygons with an arbitrary number of sides. When modelling crack propagation, the remeshing process is more flexible and leads to only minimal changes to the global mesh structure. Six numerical examples involving crack propagation in functionally graded materials are modelled to demonstrate the salient features of the developed method. © 2015, Springer Science+Business Media Dordrecht.
Crack propagation prediction of CFRP retrofitted steel plates with different degrees of damage using BEM
- Authors: Yu, Qian Qian , Zhao, Xiao , Chen, Tao , Gu, Xianglin , Xiao, Zhigang
- Date: 2014
- Type: Text , Journal article
- Relation: Thin-Walled Structures Vol. 82, no. (2014), p. 145-158
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- Description: Although carbon fibre reinforced polymer (CFRP) materials have proven effective in strengthening steel structures especially when used to improve fatigue behaviour, further study is required to investigate their effectiveness when applied at different stages of crack propagation in steel elements. This paper presents a numerical study on CFRP retrofitted steel plates with different degrees of damage using the boundary element method (BEM). The numerical results compared well with the experimental data, which demonstrated that the BEM is reliable for crack propagation analysis of CFRP laminate retrofitted steel plates. Finally, a parametric analysis was conducted to investigate the influence of bond length, bond width, CFRP stiffness and adhesive shear modulus on stress intensity factor (SIF) values. © 2014 Elsevier Ltd.
DEM modeling of particle breakage in silica sands under one-dimensional compression
- Authors: Shi, Danda , Zheng, Lin , Xue, Jianfeng , Sun, Jing
- Date: 2016
- Type: Text , Journal article
- Relation: Acta Mechanica Solida Sinica Vol. 29, no. 1 (2016), p. 78-94
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- Description: A Discrete Element Method (DEM) model is developed to study the particle breakage effect on the one-dimensional compression behavior of silica sands. The 'maximum tensile stress' breakage criterion considering multiple contacts is adopted to simulate the crushing of circular particles in the DEM. The model is compared with published experimental results. Comparison between the compression curves obtained from the numerical and experimental results shows that the proposed method is very effective in studying the compression behavior of silica sands considering particle breakage. The evolution of compression curves at different stress levels is extensively studied using contact force distribution, variation of contact number and particle size distribution curve with loading. It is found that particle breakage has great impact on compression behavior of sand, particularly after the yield stress is reached and particle breakage starts. The crushing probability of particles is found to be macroscopically affected by stress level and particle size distribution curve, and microscopically related to the evolutions of contact force and coordination number. Once the soil becomes well-graded and the average coordination number is greater than 4 in two-dimension, the crushing probability of parent particles can reduce by up to 5/6. It is found that the average contact force does not always increase with loading, but increases to a peak value then decreases once the soil becomes more well-graded. It is found through the loading rate sensitivity analysis that the compression behavior of sand samples in the DEM is also affected by the loading rate. Higher yield stresses are obtained at higher loading rates. © 2016 The Chinese Society of Theoretical and Applied Mechanics.
Design and installation of subsea cable, pipeline and umbilical crossing interfaces
- Authors: Reda, Ahmed , Howard, Ian , Forbes, Gareth , Sultan, Ibrahim , McKee, Kristoffer
- Date: 2017
- Type: Text , Journal article
- Relation: Engineering Failure Analysis Vol. 81, no. (2017), p. 193-203
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- Description: Deterioration of subsea cable, pipeline and umbilical crossings often occur due to relative movement between the crossing members. Any crossing design should aim to achieve a sound, fit for purpose solution that will be maintenance free over the crossing life. Due to the increased density of subsea fields, crossing instances need to be increasingly accommodated. Current subsea design codes are not explicit in the criteria for subsea crossings, beyond recommending pipeline separation distances. The work within this paper describes two case studies in the novel use of articulated padding applied to the crossing member, using the crossed pipeline as a support and then using the articulated padding resting on traditional grout-bag supports. The results highlight the ability of the articulated padding to provide the required separation on subsea crossings without the need for extra support design. It is also shown that the articulated padding can be used on grout-bag shoulder supports to allow full subsea crossing separation for crossing lays that will undergo large environmental loading conditions, and hence relative motion. The results presented also provide a basis for the development of future industry standards incorporating articulated padding designs. © 2017 Elsevier Ltd
Development of a unified railway track stability management tool to enhance track safety
- Authors: Ahmad, Shah , Mandal, Nirmal , Chattopadhyay, Gopinath , Powell, John
- Date: 2013
- Type: Text , Journal article
- Relation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit Vol. 227, no. 5 (2013), p. 493-516
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- Description: Track buckling is a serious problem for railways. High longitudinal rail stresses contribute to problems such as track buckling, rail joint failure, rail breakage and failure of turnouts. The direct and indirect costs of track buckling problems are very high. The influences of rail temperature, stress-free temperature (SFT) and lateral misalignment of track on track buckling need comprehensive investigation. In this paper, an experimental design comprising strain gauges, thermocouples and rail stress sensors has been implemented on the Queensland Rail heavy haul 60 kg/m rail network. A new creep measurement technique using internal rail stress has been developed. The changes in rail neutral temperature due to the variation of actual rail temperature and the occurrence of rail creep in straight and curved track is quantified. Modes of differences of SFT in the two rails at a location, and of SFT in straight track and in curved track are discussed. The relationship of SFT to rail temperature is also presented. Daily variation in rail temperature due to ambient air temperature is presented. Field trials showed that SFT can vary by 2-3 °C during the day. Based on this finding and the derivation of an equation for change of SFT, an improvement in utilising rail creep measurements for assessing track condition has resulted. This finding suggests that it is possible to determine the SFT throughout a day rather than just a single SFT value. This paper also presents a simple track stability management tool that is based on two major parameters, namely rail stress and track resistance. Each parameter in the tool has been given three levels of value to determine the required preventive measures. Overall, the tool decides the need for speed restriction during hot weather based on the quantified parameters from the field trials and rail standards. © IMechE 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
Development of effective performance measures for wayside rail curve lubrication in heavy haul lines
- Authors: Uddin, Md Gyas , Chattopadhyay, Gopinath , Rasul, Mohammad
- Date: 2014
- Type: Text , Journal article
- Relation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit Vol. 228, no. 5 (2014), p. 481-495
- Full Text: false
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- Description: Rail curve lubrication using wayside gauge face lubrication systems is widely used by the railway industry. It provides cost-effective solutions to reduce rail/wheel wear, energy consumption, costs and noise. Research efforts on cost-effective friction management solutions for the Australian heavy haul industry have been limited. Therefore, the performance measures necessary for the evaluation of effective gauge face lubrication practice have not been developed. Currently, there are no specific performance measures available for heavy haul rail curve lubrication. Also, the performance of in-rail lubrication seems to be poor in most cases. Appropriate performance measures should be implemented that can accurately demonstrate the actual performance of the lubrication. This paper is focused on the development of effective performance measures based on lubrication theory, maintenance regime, field testings of different wayside lubrication equipment technology and different greases currently used on heavy haul lines. Extensive field tests have been conducted on the Queensland Rail Network's North Coast Line, which is a dedicated coal line. Data were collected and analysed for the development of performance measures and cost-effective lubrication decisions. The presented performance measures and illustrative examples could be used by other types of railway networks for enhancement of rail/wheel asset life, asset availability, reliability and safety along with reduction of costs. © IMechE 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
Dynamic cohesive crack propagation modelling using the scaled boundary finite element method
- Authors: Ooi, Ean Tat , Yang, Zhenjun , Guo, Zaoyang
- Date: 2012
- Type: Text , Journal article
- Relation: Fatigue and Fracture of Engineering Materials and Structures Vol. 35, no. 8 (2012), p. 786-800
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- Description: This study develops a scaled boundary finite element method (SBFEM)-based approach for modelling fast cohesive crack propagation in quasi-brittle materials subjected to transient dynamic loadings. In this approach, the elastic bulk material is modelled by SBFEM subdomains and the cracks by nonlinear cohesive interface finite elements that are automatically inserted by a remeshing procedure. The global equation system is solved using an implicit time integration algorithm. Because all the solutions (displacements, stresses, velocities, accelerations) are semi-analytical in an SBFEM subdomain, this approach offers a few advantages over other methods, such as accurate calculation of dynamic stress intensity factors and T-stress without using fine crack-tip meshes, simpler remeshing, more accurate and efficient mesh mapping, and the need of much fewer degrees of freedom for the same accuracy. The approach is validated by modelling two concrete beams under impact, subjected to mode-I and mixed-mode fracture, respectively. © 2012 Blackwell Publishing Ltd.
Dynamic fracture simulations using the scaled boundary finite element method on hybrid polygon-quadtree meshes
- Authors: Ooi, Ean Tat , Natarajan, Sundararajan , Song, Chongmin , Ooi, Ean Hin
- Date: 2016
- Type: Text , Journal article
- Relation: International Journal of Impact Engineering Vol. 90, no. (2016), p. 154-164
- Full Text: false
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- Description: In this paper, we present an efficient computational procedure to model dynamic fracture within the framework of the scaled boundary finite element method (SBFEM). A quadtree data structure is used to discretise the domain, and 2:1 ratio between the cells is maintained. This limits the number of patterns in the quadtree decomposition and allows for efficient computation of the system matrices. The regions close to the boundary are discretised with arbitrary sided polygons so as to facilitate accurate modelling of the curved boundaries. The stiffness and the mass matrix over all the cells are computed by the SBFEM. Moreover, the semi-analytical nature of the SBFEM enables accurate modelling of the asymptotic stress fields in the vicinity of the crack tip. An efficient remeshing algorithm that combines the quadtree decomposition with simple Boolean operations is proposed to model the crack propagation. The remeshing is restricted only to a small region in the vicinity of the crack tip. The efficiency and the convergence properties of the proposed framework are demonstrated with a few benchmark problems. © 2015 Elsevier Ltd. All rights reserved.
Evaluation of numerical procedures to determine seismic response of structures under influence of soil-structure interaction
- Authors: Tabatabaiefar, Hamid , Fatahi, Behzad , Ghabraie, Kazem , Zhou, Wanhuan
- Date: 2015
- Type: Text , Journal article
- Relation: Structural Engineering and Mechanics Vol. 56, no. 1 (2015), p. 27-47
- Full Text: false
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- Description: In this study, the accuracy and reliability of fully nonlinear method against equivalent linear method for dynamic analysis of soil-structure interaction is investigated comparing the predicted results of both numerical procedures with the results of experimental shaking table tests. An enhanced numerical soil-structure model has been developed which treats the behaviour of the soil and the structure with equal rigour. The soil-structural model comprises a 15 storey structural model resting on a soft soil inside a laminar soil container. The structural model was analysed under three different conditions: (i) fixed base model performing conventional time history dynamic analysis, (ii) flexible base model (considering full soil-structure interaction) conducting equivalent linear dynamic analysis, and (iii) flexible base model performing fully nonlinear dynamic analysis. The results of the above mentioned three cases in terms of lateral storey deflections and inter-storey drifts are determined and compared with the experimental results of shaking table tests. Comparing the experimental results with the numerical analysis predictions, it is noted that equivalent linear method of dynamic analysis underestimates the inelastic seismic response of mid-rise moment resisting building frames resting on soft soils in comparison to the fully nonlinear dynamic analysis method. Thus, inelastic design procedure, using equivalent linear method, cannot adequately guarantee the structural safety for mid-rise building frames resting on soft soils. However, results obtained from the fully nonlinear method of analysis fit the experimental results reasonably well. Therefore, this method is recommended to be used by practicing engineers. Copyright © 2015 Techno-Press, Ltd.
Evaluation of slug flow-induced flexural loading in pipelines using a surrogate model
- Authors: Sultan, Ibrahim , Reda, Ahmed , Forbes, Gareth
- Date: 2013
- Type: Text , Journal article
- Relation: Journal of Offshore Mechanics and Arctic Engineering Vol. 135, no. 3 (2013), p. 8
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- Description: Slug flow induces vibration in pipelines, which may, in some cases, result in fatigue failure. This can result from dynamic stresses, induced by the deflection and bending moment in the pipe span, growing to levels above the endurance limits of the pipeline material. As such, it is of paramount importance to understand and quantify the size of the pipeline response to slug flow under given speed and damping conditions. This paper utilizes the results of an optimization procedure to devise a surrogate closed-form model, which can be employed to calculate the maximum values of the pipeline loadings at given values of speed and damping parameters. The surrogate model is intended to replace the computationally costly numerical procedure needed for the analysis. The maximum values of the lateral deflection and bending moment, along with their locations, have been calculated using the optimization method of stochastic perturbation and successive approximations ( SPSA). The accuracy of the proposed surrogate model will be validated numerically, and the model will be subsequently used in a numerical example to demonstrate its applicability in industrial situations. An accompanying spreadsheet with this worked example is also given.
- Description: C1