Faisal Mukhtar | King Fahd University of Petroleum and Minerals (original) (raw)

Papers by Faisal Mukhtar

Journal of Composites for Construction

$Research paper thumbnail of Coupled multiphysics 3-D generalized finite element method simulations of hydraulic fracture propagation experiments$

Engineering Fracture Mechanics

$Research paper thumbnail of Propagation mechanisms and parametric influence in multiple interacting hydraulic fractures: A 3‐D G/XFEM hydro‐mechanical modeling$

International Journal for Numerical and Analytical Methods in Geomechanics

Advances in Structural Engineering

Lightweight concrete (LC) is a viable alternative for conventional normal weight concrete (NC). I... more Lightweight concrete (LC) is a viable alternative for conventional normal weight concrete (NC). It has a reduced weight and similar properties. However, shear provisions design codes are way behind for the case of the LC compared to the NC. This study evaluates the shear design of NC and LC specimens. First, an extensive experimental database of these specimens under shear was compiled. Then, selected shear provisions of design codes were outlined and applied for strength calculations. The calculated strengths were evaluated considering the experimentally measured ones to assess these design codes' overall accuracy and consistency. In addition, the effect of selected parameters (depth, concrete strength, flexure reinforcement ratio, shear span to depth ratio, and nominal maximum aggregate size) on the safety of the design was assessed. The third draft of the Eurocode was the most accurate and consistent for the shear design of LC and NC specimens. Finally, the Eurocode shear pro...

Journal of Composites for Construction, 2022

The performance of concrete structures strengthened with Carbon fibre-reinforced polymer (FRP) sy... more The performance of concrete structures strengthened with Carbon fibre-reinforced polymer (FRP) systems can depend heavily on the bond strength of the interface between the concrete and the reinforced polymer. Even though experimental testing can be used to derive suitable constitutive models, their interpretation and analysis is often limited by the reliability of available numerical/analytical models. The debonding in shear tests can be controlled by the highly non-linear interaction of the bonded interface with the micro-cracks developing within the substrate. This process cannot be efficiently predicted by simplifying assumptions, which is why robust models accounting for those features while relying only on material parameters that can be easily measured and interpreted need to be developed. This paper introduces a framework for developing those models based on the discrete representation of fracture that can be easily deployed into existing finite element codes. The substrate bond failure in addition to the interface bond failure (and any combination of both) are automatically accounted for and the cracks are not pre-specified to the underlying finite element mesh, which means that results are mesh insensitive and discretisation-independent. The validation of the proposed framework is done with modified double shear bond tests between Carbon FRP and concrete. An in-depth analysis is carried out to assess the influence of bond length and CFRP reinforcement area on the debonding behaviour and ductility of the connection.

Case Studies in Construction Materials, 2022

In current state of the World, the pollution is increasing very fast. One of its major reason is ... more In current state of the World, the pollution is increasing very fast. One of its major reason is the production of huge quantity of cement which causes outflow of CO2 into the environment and land dumping of construction and demolition waste which leads to the land pollution. In order to address this major issue, it is important to decrease the utilization of cement by substituting the cement with by product such as slag and using recycled aggregates as a replacement of natural aggregates. This research aimed to utilize evaluate the performance of sustainable high-performance concrete reinforced with steel fibers which is produced with recycled aggregate. Crushed stone aggregates are supplanted with recycled aggregates extracted from source concrete that had compression strength of 45 MPa and 85 MPa at proportions of 50% and 100%. Steel fibers are used at 2% to produce high-performance concrete, and in a few of the mixtures, the cement was substituted with granulated blast furnace slag. In addition to mechanical performance, the durability properties, i.e., electrical resistivity, drying shrinkage, and water absorption, of concrete blends were examined. The test outcomes show that high-performance concrete with the required characteristics can be developed utilizing recycled aggregates extracted from source concrete of high strength. The inclusion of double hooked end steel fibers considerably improves the mechanical characteristics of RAC. Concrete formed with high-quality recycled concrete aggregates and mixes comprising granulated blast furnace slag (GBFS) and double hooked end (DHE) steel fibers shows decreased drying shrinkage and water absorption in comparison to normal concrete. The outcomes of the present study assist in making of suitable high-performance concrete which is sustainable and budget friendly.

Construction and Building Materials, 2021

Abstract This paper studies the bond performance between fiber-reinforced polymer (FRP) and concr... more Abstract This paper studies the bond performance between fiber-reinforced polymer (FRP) and concrete using two variations of the double shear lap test setups. Experimental tests were conducted followed by a series of finite element simulations using cohesive zone model. The experiment utilized an improved double-pull shear setup with the tests conducted on specimens of varying FRP-concrete bond lengths. The numerical simulations were carried out for the improved as well as the traditional setups using two converged meshes with both 2- and 3-D spatial idealizations to study their relative performance. The results are discussed in light of the damage mechanism, load–displacement, strain and stress distribution, bond-slip behavior, and fracture energy. The tested specimens show no effect of bond length variation on the FRP-concrete interfacial strength so long as the bond length exceeds the effective bond length – Only the case of bond length lower than the effective bond length shows otherwise. The study also succeeds in validating the 2- and 3-D numerical simulations using the experiments in both the two cases of spatial idealizations and the two types of test setups in terms of strain and stress distributions, bond-slip curve, and fracture energy. However, while the 3-D models succeed in capturing the failure load accurately, the 2-D models fail to do so. Evidence of similar performance between the improved double shear test and traditional double shear test setups reaffirms the fact that the former could be used to replace the latter.

$Research paper thumbnail of Validation of a 3-D adaptive stable generalized/eXtended finite element method for mixed-mode brittle fracture propagation$

International Journal of Fracture, 2020

In this paper, a Stable Generalized/eXtended Finite Element Method (SGFEM) is combined with mesh ... more In this paper, a Stable Generalized/eXtended Finite Element Method (SGFEM) is combined with mesh adaptivity for the robust and computationally efficient simulation of mixed-mode brittle fracture propagation. Both h-refinement around the fracture front and p-enrichment of the analysis domain are used to control discretization errors. A Linear Elastic Fracture Mechanics (LEFM) model based on Griffith’s criterion is adopted. LEFM scaling relations are used at each fracture propagation step to back calculate SIFs that meet Griffith’s criterion. As a result, no iterations are necessary to find loading scaling parameters or fracture size that meets Griffith’s criterion. The method is validated against several experimental data sets for mode I and mode I+II fracture propagation problems. Very good agreement between SGFEM and experimental results is observed. These include fracture path, Crack Opening Displacement (COD), and load and fracture length versus COD curves. The computational efficiency of the method is also assessed.

Construction and Building Materials, 2021

background: Many NSTEACS patients are medically managed without coronary revascularization. The r... more background: Many NSTEACS patients are medically managed without coronary revascularization. The reasons vary and may impact prognosis. methods: EPICOR Asia (NCT01361386) is a prospective study of hospital survivors post ACS enrolled in 219 hospitals from 8 countries/ regions in Asia (06/2011-05/2012). All medically managed NSTEACS patients in EPICOR Asia were classified into 3 groups: 1) no coronary angiography (CAG-); 2) non-significant coronary artery disease (CAD) on angiogram (CAG+ CAD-); and 3) significant CAD (CAG+ CAD+). We compared baseline differences between groups, and report 1-y mortality rates. Results: Of 6,164 NSTEACS patients, 2,272 (37%) were medically managed only, with 1,339 (59%), 254 (11%) and 679 (30%) patients in the CAG-, CAG+ CAD-, and CAG+ CAD+ groups, respectively. There were marked differences in number of NSTEACS patients medically managed among the 8 countries/regions (13-81%). Between-group differences were seen in baseline characteristics (Table). CAG+ CADpatients were younger with fewer CV risk factors than CAG+ CAD+. CAG-patients were older, more likely with known CV disease, more frequently admitted to hospitals with no cath lab, and had the highest 1-y mortality (6.9% versus 3.3% for EPICOR Asia overall). conclusion: NSTEACS patients who are medically managed are a heterogeneous group with different clinical features and outcomes e.g. mortality risk. The factors underlying different management strategies, and to improve prognosis, need to be identified.

Composite Structures, 2021

This study investigates the shear behavior and debonding characteristics of initially ductile RC ... more This study investigates the shear behavior and debonding characteristics of initially ductile RC beams (failing in flexure when unstrengthened) at the verge of transitioning to a more brittle shear failure upon strengthening using external flexural carbon fiber reinforced polymer (CFRP). Despite the absence of shear CFRP strengthening, various degrees of improvement in the shear capacity were achieved depending on the flexural CFRP amount. However, steeper shear cracks that bypass the stirrups in addition to the nonyielding stirrups results in shear capacities that cannot be reliably predicted using the ACI and other similar codes’ provisions. Instead of adopting capacity models that focus on the shear failure alone or the crack-induced debonding as oneway cause-effect (shear crack-debonding) relationship, a more holistic capacity prediction approach (calibrated with finite element anlaysis) that considers the synergistic effect between the shear failure and the CFRP debonding is provided. Since any enhancement in flexure must be checked against shear, the presented capacity prediction approach could be a more handy means to assess the shear strengthening level needed in such cases where the flexural strengthening is insucient to achieve the overall structural upgrade sought. The designed beams – i.e. at the verge of changing failure mode with flexural FRP strengthening – and the test program could serve as a bond assessment philosophy in the sense that this upper bound brittle failure mechanism provides more realistic behavior of the crack-induced debonding performance of FRP-strengthened beams. Analytical load-deflection assessment of the tested specimens is also provided.

International Journal of Mathematical Education in Science and Technology, 2020

Use of three-force member concept for rigid bodies whenever possible, to circumvent the more taxi... more Use of three-force member concept for rigid bodies whenever possible, to circumvent the more taxing use of equilibrium equations has been long-established. However, most students fail to reap its benefits due to a number of reasons, including the fact that its importance is hardly emphasized to them; skills and details needed for the concept are missing in many undergraduate textbooks on Statics. This paper revisits and solidifies the understanding of three-force member in exploiting its potential for solving difficult problems. The paper addresses one of the most frequent students' questions and concerns that the authors have faced in their experience of teaching Statics. This topic is revitalized herein, and its importance emphasized, to obviate the possibility of students' wrong impression about its obsoleteness, by presenting detailed material in a pedagogical manner to serve as an addendum to any textbook for university undergraduate course in Statics. This serves as a good reference for both instructors and students in the course and eliminates their difficulty in accessing a concise document on the topic. Four examples, with increasing complexity, are solved where quicker and easier steps using three-force member concept are compared with the lengthier and relatively more difficult use of equilibrium equations.

Journal of Reinforced Plastics and Composites, 2020

The performance of fiber reinforced polymer externally bonded to concrete is greatly influenced b... more The performance of fiber reinforced polymer externally bonded to concrete is greatly influenced by the environmental conditions to which it is exposed during service. Temperature and humidity are the two common environmental factors that alter the bond behavior of externally bonded fiber reinforced polymer. This paper reviews the experimental and computational approaches used to evaluate the hygrothermal effects—that is, the effect of temperature and humidity—on the durability of the fiber reinforced polymer–concrete bond, as well as on the bond’s performance under loading conditions. Some experimental testing conducted in the laboratory and in situ are critically reviewed and presented. Implemented approaches for improving bond performance under hygrothermal conditions and their modeling techniques are also presented. The paper concludes by discussing the review’s salient issues. The ongoing wide application of externally bonded fiber reinforced polymer creates opportunities for ne...

International Journal of Steel Structures, 2019

Based on thin shell theory, closed form expressions of SCF are obtained for pressurized spherical... more Based on thin shell theory, closed form expressions of SCF are obtained for pressurized spherical vessel-cylindrical nozzle juncture. These expressions, based on the popular Hetenyi's analytical solution, can be used to substitute the more conventional graphical form of presentation. To simulate the phenomenon in a more general sense, non-dimensionalized forms of the solutions are reported as functions of the vessel-nozzle geometrical ratios. Illustrations are made on the application of the symbolic expressions so derived to study the location of maximum stresses on the juncture as well as provide an alternative presentation of the SCF plots that are believed to be more accurate and all-encompassing than the conventional ρ-SCF plots. Verification is made using the exact solution and the finite element analysis.

Composites Part B: Engineering, 2018

Performance assessment of the bond between FRP as externally bonded reinforcement (EBR) and concr... more Performance assessment of the bond between FRP as externally bonded reinforcement (EBR) and concrete requires establishing bond-slip characteristics using appropriate experiments, one of which is the double shear bond test. Different versions of the said test, ranging from its traditional form to improved versions, exist. Yet, the improved versions themselves are not without shortcomings. The aim of this paper is to present a simple and improved double shear test setup, customized to ease its application in FRP-concrete bond tests in addition to satisfying other important functional requirements. Designed and fabricated as a Y-hook-cylinder system to substitute half of the traditional double shear specimen size, the simple feature of traditional approach is retained in the other half. Performance of the developed setup is, first, verified against that of the traditional approach on a number of specimens. Subsequently, the proposed system is used to conduct an exploratory study on the influence of coarse aggregate type on FRP-concrete bond behavior. Two concrete types are produced; one containing fresh aggregate and the other consisting of steel slag aggregate substituting 30% of the maximum fresh aggregate size in the first concrete type. Typical bond-slip models of the two specimen types are developed and compared with several other literature sources. The results, both in terms of the debonding load and bondslip characteristics, show improvement in bond performance when a substrate failure occur in the specimens containing steel slag aggregate.

Construction and Building Materials, 2018

h i g h l i g h t s There are five major laboratory test methods for FRP-concrete interfacial bon... more h i g h l i g h t s There are five major laboratory test methods for FRP-concrete interfacial bond. Attributes, characteristics and variations of each test method are analysed. Different approaches and means for data acquisition are discussed. There exist avenues for further development of existing test methods. An improved version of double shear test setup is proposed.

Arabian Journal for Science and Engineering, 2016

A detailed study for the stresses around internally pressurized cylindrical vessel-cylindrical no... more A detailed study for the stresses around internally pressurized cylindrical vessel-cylindrical nozzle junctures is carried out using the finite element method. Based on thin shell theory, two simplified expressions (functions of the vessel-nozzle geometrical ratios) of stress concentration factor (SCF) are obtained: one for the main vessel and the other for the nozzle, respectively. The analysis was also used to study the location of maximum stresses at the juncture as well as provide a more accurate presentation of design charts than the ρ-SCF plots. Verification is made using some established models available in the literature.

Journal of Pressure Vessel Technology, 2016

In a related work previously carried out by the authors, finite element analysis of cylindrical v... more In a related work previously carried out by the authors, finite element analysis of cylindrical vessel–cylindrical nozzle juncture based on the use of thin shell theory, due to the fact that the intersecting nozzle sizes are moderate to large, have been presented. Such analysis becomes invalid in cases when the nozzles are small in sizes which may result in nozzles whose configuration violates the validity of shell assumption. As a result, use of solid elements (based on theory of elasticity) in modeling the cylindrical vessels with small-diameter nozzles is presented in the present paper. Discussions of the numerical experiments and the results achieved are, first, given. The results are then compared with the prediction by other models reported in the literature. In order to arrive at the overall design charts that cover all the possible ranges of nozzle-to-vessel diameter ratio, the charts for the vessels with moderate-to-large-diameter nozzles are augmented with those of cylindr...

Applied Mathematics and Computation, 2016

This work proposes the use of a mesh-free technique, derived from the generalized Taylor polynomi... more This work proposes the use of a mesh-free technique, derived from the generalized Taylor polynomials, for the analysis of axisymmetric plates and shells. The primary solution variable(s) is/are assumed to take the form of a truncated Taylor series around a point c, and the unknown coefficients of the expansion are determined using the governing differential equation(s) and boundary conditions. The method is free of shape-parameter calibration needed in some other famous mesh-free techniques such as the RBF, and is quite easy to formulate and program. Successful application of the method to several benchmark problems of axisymmetric plate and shell structures proves its robustness. The results have been verified using the existing rigorous analytical solutions that are in most cases not suited to practical engineering calculations.

Journal of Pressure Vessel Technology, 2016

Parametric study of the thin shell solution of internally pressurized spherical vessel–cylindrica... more Parametric study of the thin shell solution of internally pressurized spherical vessel–cylindrical nozzle juncture is used to develop simplified closed-form formulas of stress concentration factor (SCF) as functions of the key vessel–nozzle geometric parameters known to influence the solution. The SCF values are not based on the vessel stresses alone; nozzle stresses are also analyzed and the corresponding SCF determined. Therefore, for a given vessel–nozzle juncture, the designer will be left with adequate information upon which to decide the controlling SCF. Predictions by the proposed equations are validated using finite element method (FEM). Consequently, design charts are presented based on both the vessel's and nozzle's SCF as predicted by the proposed expressions.

Applied Mathematical Modelling, 2016

Abstract This paper demonstrates the use of a well-known meshless method, radial basis functions ... more Abstract This paper demonstrates the use of a well-known meshless method, radial basis functions (RBF), to solve the torsion of a prismatic bar having a rectangular/square cross-section. First part of the analysis deals with the elastic solution of the problem formulated using the RBF technique. The result is used in verifying the feasibility of the approach and, subsequently, as an initial guess for the iterative procedure utilized in the analysis of the elasto-plastic torsional behavior of the bar. Verification of the results is made using finite difference method (FDM), method of fundamental solutions (MFS) and the exact elastic solution.

Journal of Composites for Construction

$Research paper thumbnail of Coupled multiphysics 3-D generalized finite element method simulations of hydraulic fracture propagation experiments$

Engineering Fracture Mechanics

$Research paper thumbnail of Propagation mechanisms and parametric influence in multiple interacting hydraulic fractures: A 3‐D G/XFEM hydro‐mechanical modeling$

International Journal for Numerical and Analytical Methods in Geomechanics

Advances in Structural Engineering

Journal of Composites for Construction, 2022

Case Studies in Construction Materials, 2022

Construction and Building Materials, 2021

$Research paper thumbnail of Validation of a 3-D adaptive stable generalized/eXtended finite element method for mixed-mode brittle fracture propagation$

International Journal of Fracture, 2020

Construction and Building Materials, 2021

Composite Structures, 2021

International Journal of Mathematical Education in Science and Technology, 2020

Journal of Reinforced Plastics and Composites, 2020

International Journal of Steel Structures, 2019

Composites Part B: Engineering, 2018

Construction and Building Materials, 2018

Arabian Journal for Science and Engineering, 2016

Journal of Pressure Vessel Technology, 2016

Applied Mathematics and Computation, 2016

Journal of Pressure Vessel Technology, 2016

Applied Mathematical Modelling, 2016

25th Australasian Conference on Mechanics of Structures and Materials (ACMSM25), Brisbane, Australia, 2018

This study presents new observations about early-age FRP-concrete bond behaviour under hygrotherm... more This study presents new observations about early-age FRP-concrete bond behaviour under hygrothermal conditions whose details have been omitted in previous works in the area. Several accelerated laboratory conditioned double shear bond tests were conducted on FRP-concrete specimens using two different concrete mixtures for a period of 5 weeks. For the concrete and adhesive materials used, the selected exposure period yields results with little decrease to even increase in the bond capacity contrary to the anticipated immediate bond degradation. In addition to the FRP-concrete double shear bond tests, the work includes two more experiments, one for the epoxy dumbbells and the other for the FRP coupons in order to provide more legitimate basis for the conclusions against the commonly adopted approaches reported in the literature. The study identifies two regimes defining the bond behavior as the exposure period or temperature increases: strength-gain and strength-deterioration regimes. Whether or not moisture and/or temperature deteriorates the FRP-concrete bond, depends on the threshold point delineating the two defined regimes. The threshold point, itself, depends on the epoxy glass transition temperature, concrete material and behaviour as well as deterioration rates of epoxy cohesion and that of its interfaces with the other adherends. Some recommendations on the need for assessment, in form of additional test protocol, to establish the minimum exposure and temperature level needed to capture the approximate instant for initiation of the FRP-concrete bond degradation.

13th World Congress on Computational Mechanics (WCCM XIII), New York City, NY, USA, 2018

As a popular numerical technique, the differential quadrature method (DQM) expresses each derivat... more As a popular numerical technique, the differential quadrature method (DQM) expresses each derivative and/or integral, in the differential or integro-differential equations, as a weighted sum of the solution values at some selected nodes. This allows discrete values of the primary solution variable(s) to be obtained with only few grid points. The method has gained wide acceptance in the area of computational mechanics. Despite its advantages, DQM requires extra efforts for additional quadrature formulations each time any other secondary variable is needed. Moreover, result at few discrete points hinders sufficient visual representation of the overall solution pattern, and results of the non-sampled points may not be obvious in some cases. Also, some terms in nonlinear problems necessitate inconvenient use of intermixed summation indices. In order to increase the flexibility of the method while maintaining its accuracy, this paper proposes the functional differential quadrature method (f-DQM) that yields a symbolic/functional form of the solution valid throughout the domain under consideration. Some of the advantages of the proposed method include (1) ease in post-processing, as any other secondary variable of interest can be obtained by directly operating on the closed-form solution, (2) means for better visual pattern/description of the solution while utilizing quadrature-based formulation to achieve high accuracy with only few nodes, and (3) possibility for direct analytical computation of differentials and/or integrals during the solution process for terms that require inconvenient use of nested quadrature formulations. The convenience and power of symbolic software programs can be harnessed both during the pre and post-processing stages. Problems of bending of a thin plate and linear and nonlinear elastoplastic torsion of a bar are analyzed to illustrate the features of the proposed method.

20th International Conference on Composite Structures, Paris, France, 2017

Corrosion in steel reinforcements due to Chloride presents one of the most serious durability con... more Corrosion in steel reinforcements due to Chloride presents one of the most serious durability concerns in reinforced concrete structures. Its control is generally influenced by factors such as the concrete and steel quality; whether or not admixtures, inhibitors, steel coatings, etc, are used. Since the Chloride transport in this material is governed by diffusion, its Chloride diffusivity becomes the key parameter useful for predicting the propagation and, ultimately, dictates the corrosion initiation and other important parameters. Although the diffusivity is sometimes assumed constant which eases simulating the problem, but different concrete materials produced nowadays, with different properties for the purpose of achieving unique durability and strength requirements results in some non-constant non-linear diffusion coefficients. Consequently, the governing equation itself becomes nonlinear and more involved in terms of solution efforts and strategies. With its many appealing features, the adoption of radial basis function (RBF) method as one of the many meshless methods to solve time-dependent problem proves successful. However, since the conventional RBF discretization (time-space RBF in this case) yields solution in symbolic form, it turns out that the time axis (taken to be orthogonal to the space axes) of the solution domain results in extra burden in the analysis as well as high computational demand in solving nonlinear problems. Hence, the present study aims at circumventing such obstacles for nonlinear Chloride diffusion in concrete. Application of a variant of the time-space RBF, the explicit RBF, for the time dependent phenomena is presented. The work provides more ease and flexibility to use RBF in dealing with nonlinear diffusivity in concrete and other diffusion problems. This is achieved by, first, avoiding individual sub-domain discretization as is the case with time-space RBF. Second, the time derivative of the partial differential operator is approximated by a simple forward difference scheme resulting into a recursive formulation. As a result, contrary to the conventional time-space RBF method, need for finding the unknown coefficients is eliminated in the explicit RBF method. In addition, no system of linear or nonlinear algebraic equations needs to be solved simultaneously. Accuracy of the proposed method is verified using the finite element method.

25th UKACM Conference on Computational Mechanics, University of Birmingham, Birmingham, UK, 2017

The paper presents enriched RBF (e-RBF), enriched MFS (e-MFS) and coupled enriched RBF-MFS for an... more The paper presents enriched RBF (e-RBF), enriched MFS (e-MFS) and coupled enriched RBF-MFS for anti-plane shear (mode III) crack analysis. The enrichments helps in capturing the singularity behaviour at the crack-tip while the coupling strategy helps in minimizing the discretization density which in turn reduces computational cost with better accuracy.

Canadian Society for Civil Engineering Annual Conference (CSCE 2016), London, Ontario, Canada, 2016

A seepage problem beneath an impermeable dam is analyzed, and the flow head and flownets distribu... more A seepage problem beneath an impermeable dam is analyzed, and the flow head and flownets distribution determined using boundary element method (BEM) which requires boundary-only discretization. Since BEM is only applicable to homogeneous problems, the idea of domain decomposition is used to solve the non-homogeneous orthotropic cases. Verification has been achieved using finite element method (FEM) that requires both domain and boundary discretization. The obvious advantage of BEM over FEM is the fact that results of high accuracy with lesser computational time and effort can be obtained. Results achieved indicate an excellent agreement between the BEM-based and FEM approaches.

The Fifth North American Conference on the Design and Use of Self-Consolidating Concrete, Chicago, USA, 2013

Flowability, passing ability and stability are important properties to be considered while design... more Flowability, passing ability and stability are important properties to be considered while designing a robust self-compacting concrete (SCC). The simulation of SCC provides a useful tool for ensuring a robust SCC mix for construction and formwork design. Hence, this paper presents the results of a 2D computational fluid dynamics (CFD) simulation carried out on the slump flow and L-box tests to evaluate the flowability and passing ability of an SCC made with limestone powder (LSP). The Herschel-Bulkley viscosity model is used for modeling the behavior of the fresh concrete. The result obtained shows a good correlation between the numerical simulation and the experimental results.
Another phenomenon studied in the paper is the formwork pressure due to SCC. Application of a new finite element model developed by the authors is proposed here for studying the evolution of lateral pressure in self-compacting concrete, incorporating factors such as the casting rate and the evolution of rheological properties of SCC. The proposed finite element simulation of SCC formwork pressure shows a good correlation with available experimental results from the literature.

9th International Concrete Conference (9CONCRETE-2013), Manama, Bahrain, 2013

Numerical simulation for flow of SCC using computational fluid dynamics (CFD) is a valuable tool,... more Numerical simulation for flow of SCC using computational fluid dynamics (CFD) is a valuable tool, which can be used to predict SCC workability and to tailor its rheological properties to meet the specific mix design specifications. The simulation of flow of SCC can be used to obtain an optimum rheology of the mix in order to ensure its flowability and resistance to segregation during placement without having to conduct a large number of trial mixes.
This paper appends the results obtained based on numerical simulation with experimental data obtained from a companion KFUPM project in which the rheological properties of selected SCC mixes admixed with fly ash were documented. These include the static and dynamic yield stresses and the viscosity. The commercial CFD software ANSYS/FLUENT using Finite Element Modeling was used to perform 2-D simulation of slump flow and L-box tests. A good correlation between the numerical simulation and the experimental results is obtained.

International Conference on Advanced Concrete Technology & Its Applications (ACTA-2012), NUST, Islamabad, Pakistan, 2012

International Congress on Durability of Concrete, Trondheim, Norway, 2012

Concrete Durability is associated with many controlling factors such as the quality of concrete u... more Concrete Durability is associated with many controlling factors such as the quality of concrete used, quality of workmanship, and the operational maintenance. However there are some other factors which are beyond control, including environmental impact such as that imparted by the ingress of chloride into concrete which promote premature deterioration and lessen the useful service life of the structures.
Although environmental issues appear to be beyond our control especially for those building and structures adjacent to the shore and in the vicinity of marine environment, yet one can make it hard for the chloride to penetrate reinforce concrete structures by controlling the quality of concrete in terms of proper placement and curing as well as maintaining adequate cover. Prediction of the useful life of a structure depends on the adopted diffusivity used to model the transient problem of chloride migration into the structures. In literatures, however such modeling is based on ideal and non-damaged diffusivity which is rare to be realistic as even under service loading part of the structures are subjected to damage in the tension zone especially for flexural members.
It is the purpose of this paper to make comparative assessment of the useful life by considering damaged and undamaged diffusivity. Three cases will be contrasted that of undamaged, uniform damage and linear damage depicting damage in flexural member.
A COMSOL package software is used to model the chloride ingress using fink's law with nonlinear diffusivity after incorporating damage. It has been found that the useful life reduced by more than half as compared to the ideal case of using undamaged diffusivity. This calls for different specification of good quality concrete to account for the induced damaged and to prolong the life of the structures as intended.

Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing, Chania, Crete, Greece, 2011

This paper presents a study carried on the effect of damage imparted by the service loading on ch... more This paper presents a study carried on the effect of damage imparted by the service loading on chloride diffusion in concrete. To appreciate the practical engineering application of the phenomenon, a beam of specified span under the influence of both dead and live loads was, first, designed. The effect of the damage was evaluated using a simplified damage model which maps the stress distribution in the beam’s
cross-section to a dimensionless damage parameter. As a result of the low concrete tensile strength as compared to its compressive strength, only the tensile stress distribution within the tensile zone was considered for the damage prediction. Also, as a result of the non-homogeneous nature of reinforced concrete section the transformed moment of inertia of the designed concrete section was used to arrive at
the stress distribution. Validation of the approach was made with existing results from literature.

Annual Conference - Canadian Society for Civil Engineering, Ottawa, Canada, 2011

A robust self compacting concrete (SCC) is characterized by its flowability, passing ability and ... more A robust self compacting concrete (SCC) is characterized by its flowability, passing ability and stability. Numerical simulation of SCC is a valuable tool, which can be used as a means to model and predict concrete workability and to tailor its rheological properties. The simulation of SCC flow could be used for obtaining optimum rheology of the mix to ensure its mobility and segregation resistance during placement. This paper presents the results of numerical simulation of SCC flow using a 2-D computational fluid dynamics (CFD) framework. The commercial CFD software ANSYS/FLUENT was used to perform 2-D simulation of slump flow and L-box tests. The Herschel-Bulkley viscosity model is used for modeling the behavior of fresh concrete. SCC mixes with silica fume as mineral additives was simulated. A good correlation between the numerical simulation and the experimental results is obtained.