Imperial College London

ProfessorAhmedElghazouli

Faculty of EngineeringDepartment of Civil and Environmental Engineering

Professor of Structural Engineering - Section Head
 
 
 
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Contact

 

+44 (0)20 7594 6021a.elghazouli

 
 
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Assistant

 

Ms Ruth Bello +44 (0)20 7594 6040

 
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Location

 

440Skempton BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

353 results found

Mujdeci A, Guo YT, Bompa DV, Elghazouli AYet al., 2022, Axial and bending behaviour of steel tubes infilled with rubberised concrete, Thin-Walled Structures, Vol: 181, Pages: 1-18, ISSN: 0263-8231

This paper presents an experimental and numerical study into the behaviour of rubberised concrete-filled steel tubes (RuCFST), incorporating concrete with relatively high rubber replacements of up to 60% of mineral aggregates by volume. Axial compression, eccentric compression, and three-point bending tests on circular specimens are carried out and the results are used to validate the nonlinear procedures adopted in continuum finite element (FE) models of RuCFST members. A constitutive material model specific for confined rubberised concrete and associated modelling techniques, developed from existing procedures for concrete-filled steel tubes (CFST), is proposed for RuCFST members. The modelling techniques involve different damage definitions including low strength concrete with high rubber replacements in compression and bending. It is shown that the proposed modelling procedures can predict reliably the structural behaviour of circular RuCFST members under combined axial-bending conditions. The numerical procedures are then employed in undertaking a detailed parametric assessment for RuCFST cross-sections. The results are used to appraise current design procedures and to propose modifications that provide improved capacity predictions for a wide range of properties and loading conditions.

Journal article

Elghazouli AY, Mujdeci A, Bompa DV, Guo YTet al., 2022, Experimental cyclic response of rubberised concrete-filled steel tubes, Journal of Constructional Steel Research, Vol: 199, Pages: 1-17, ISSN: 0143-974X

This paper examines the behaviour of circular steel tubes infilled with concrete incorporating recycled rubber particles. The rubberised concrete-filled steel tubes are tested under lateral cyclic deformations with and without co-existing axial loading. A detailed account of the cyclic tests on twelve specimens is provided together with complementary material and section tests. The rubber replacement ratio is varied up to a relatively high value of 60%, under axial loads reaching up to 30% of the nominal capacity. Hollow steel members are also tested for comparison purposes. The experimental results are discussed in detail with respect to the member stiffness, capacity, ductility, energy dissipation and failure mechanisms. Although high rubber ratios lead to a considerable loss in concrete strength, the test results show that the corresponding reduction in member capacity is much less significant due to the contribution of the steel tube and the comparatively high confinement effects mobilised within the rubberised concrete. In comparison with the members incorporating normal concrete, the rubberised concrete members are found to exhibit up to about 10% and 17% increase in ductility and energy dissipation, respectively, depending on the rubber content. Analytical treatments are then used to suggest simplified relationships for predicting the stiffness, moment-axial strength interaction, plastic hinge length and local ductility criteria. Overall, the test results demonstrate the favourable inelastic cyclic performance of circular steel tubes infilled with rubberised concrete and provide valuable experimental data. The proposed expressions for key response parameters also offer the basis for developing practical assessment and design methods.

Journal article

Elzeadani M, Bompa DV, Elghazouli AY, 2022, Experimental assessment and constitutive modelling of rubberised One-Part Alkali-Activated concrete, Construction and Building Materials, Vol: 353, Pages: 1-27, ISSN: 0950-0618

This study deals with the development and assessment of rubberised one-part alkali-activated concrete. An experimental programme, focusing on optimising the material proportions for high flowability and compressive strength, is firstly described. This includes varying the proportions of aluminosilicate precursors, binder-to-aggregate ratio, activator dosage, and admixture quantity to find an optimum mix design with stable strength development up to 90 days. Crumb rubber particles are then added to replace up to 60 % by volume of the natural mineral aggregates. The effect of rubber addition on the mechanical properties is quantified and analytical expressions for the compressive strength, elastic modulus, splitting tensile strength, and flexural strength are presented. A database consisting of 241 conventional rubberised concrete as well as 57 rubberised alkali-activated mixes, available in the literature, is then assembled and used for direct comparison of the characteristics of different rubberised concrete materials. It is shown that the degradation in compressive strength for one-part rubberised alkali-activated concrete with high rubber replacement ratios falls within similar ranges as conventional and two-part alkali-activated rubberised concrete. However, the results show that the elastic modulus of one-part rubberised alkali-activated concrete is significantly lower than that of rubberised concrete mixes with the same compressive strength. Moreover, while the lateral crushing strain of one-part rubberised alkali-activated concrete increases with higher rubber replacement ratios, the axial crushing strain reduces slightly. It is also shown that the post-peak stress–strain response exhibits greater softening with higher rubber ratios. Based on the findings of the study, constitutive models for representing the compressive stress–strain response and flexural stress-crack width response are proposed. The presented expressions provide insights into the

Journal article

Guo YT, Bompa DV, Elghazouli AY, 2022, Nonlinear numerical assessments for the in-plane response of historic masonry walls, Engineering Structures, Vol: 268, Pages: 1-20, ISSN: 0141-0296

This study examines the in-plane cyclic response of historic masonry elements using a micro modelling approach that incorporates damage-plasticity and surface-based cohesive-contact interface approaches. The nonlinear procedures adopted are validated against tests on dry and wet panels in diagonal compression and large walls under reverse shear-compression loading. Considering the inherent material variability, the numerical results are shown to correlate well with the test results in terms of stiffness, strength, ductility, overall hysteretic response, and cyclic degradation. Based on the validated models, followed by exploratory sensitivity studies, detailed parametric assessments are carried out. The parameter ranges are selected to cover historical masonry materials, consisting of bricks and mortar, and address both dry and wet conditions. Four typical failure modes, namely, flexural strut crushing, diagonal cracking, flexural toe crushing, and mixed sliding, in an order of increasing ductility, are quantified and discussed. It is shown that wet masonry walls have an average reduction of 16% in terms of stiffness and capacity compared with the dry counterparts. Although the failure modes in dry and wet wall pairs are similar, some cases are identified in which the weaker moisture-affected joint strength results in a shift to a more brittle mode. It is also shown that the ductility of the flexural strut crushing mode, which often governs the failure of historical masonry due to its low strength, is considerably overestimated in existing guidelines. Based on the results of the parametric investigations, analytical models for predicting the inelastic response are evaluated, and suggestions for modifications are proposed.

Journal article

Elzeadani M, Bompa DV, Elghazouli AY, 2022, One part alkali activated materials: A state-of-the-art review, Journal of Building Engineering, Vol: 57, Pages: 104871-104871, ISSN: 2352-7102

This article assesses the state-of-the-art for research on one-part alkali-activated materials, with particular emphasis on recent work dealing with the constituent materials, preparation methods, fresh properties, mechanical properties, and durability characteristics. The review, which covers over 170 studies, first discusses the different precursors, solid activators, admixtures, and aggregates used within such materials. Preparation techniques of one-part alkali-activated materials are then addressed, including pre-mixing treatment, mixing and curing, and 3D-printing. Reaction mechanisms and resulting binding phases are also outlined, followed by a detailed discussion on the fresh, mechanical and durability characteristics. The sensitivity of the compressive strength to different precursors and solid activators with varying chemical compositions, is examined, and predictive strength equations are proposed for common mixes. A brief comparison between the fresh, mechanical and durability characteristics of one-part and two-part AAMs is outlined, followed by a discussion on design standards as well as health and environmental aspects. The review concludes with suggestions for future research for key applications, with due consideration to the projected availability of precursors and the sustainability of solid activators. It is shown that despite the significant recent developments on one-part alkali-activated materials, further progress necessitates future research with a focus on optimising mixes made from precursors other than fly ash and blast furnace slag, as well as detailed investigations on structural members and components.

Journal article

Elghazouli A, Bompa DV, Mourad SA, Elyamani Aet al., 2022, Seismic performance of heritage clay brick and lime mortar masonry structures, 17th European Conference on Earthquake Engineering

Conference paper

Elghazouli A, Bompa DV, Mourad SA, Elyamani Aet al., 2022, Seismic performance of heritage clay brick and lime mortar masonry structures, Progress in European Earthquake Engineering and Seismology, Editors: Vacareanu, Ionescu, Publisher: Springer

Book chapter

Elghazouli A, Bompa DV, El-Zeadani M, 2022, Mechanical properties and stress-strain response of rubberised one-part alkali-activated concrete, 14th fib Sympsoium in Civil Engineering, Pages: 265-272, ISSN: 2617-4820

Conference paper

Liapopoulou M, Stafford PJ, Elghazouli A, 2022, Duration effects on the seismic collapse of steel frames, 17th European Conference on Earthquake Engineering, Pages: Paper ID 8642-Paper ID 8642

Conference paper

Guo Y, Bompa DV, Elghazouli A, 2022, Numerical modelling of the cyclic behaviour of clay brick and lime mortar masonry elements, 17th European Conference on Earthquake Engineering, Pages: Paper ID 8472-Paper ID 8472

Conference paper

Bompa DV, Elghazouli A, 2022, Ultimate cyclic response of steel reduced beam section connections, 17th European Conference on Earthquake Engineering, Pages: Paper ID 3438-Paper ID 3438

Conference paper

Martinez-Paneda M, Elghazouli A, 2022, Seismic performance of tall buildings with novel damping approaches, 17th European Conference on Earthquake Engineering, Pages: Paper ID 4311-Paper ID 4311

Conference paper

Bompa D, Bogdan T, Elghazouli A, Nuñez E, Eatherthon M, Leon Ret al., 2022, Nonlinear Numerical Assessment of SteelReduced Beam Section Connections, Proceedings of the 10th International Conference on Behaviour of Steel Structures in Seismic Areas - STESSA 2022, Editors: Mazzolani, Dubina, Stratan, Publisher: Springer, Pages: 252-260

Book chapter

Sahin B, Bravo-Haro MA, Elghazouli AY, 2022, Assessment of cyclic degradation effects in composite steel-concrete members, Journal of Constructional Steel Research, Vol: 192, Pages: 107231-107231, ISSN: 0143-974X

This paper investigates the inelastic behaviour of composite steel concrete beams, with particular emphasis on cyclic deterioration effects. A detailed continuum model is firstly developed to represent the hysteretic response of composite steel beam and concrete slab assemblages, validated against available experimental cyclic results on both steel and composite members. The proposed model is then adopted to perform detailed parametric assessments which are used to gain insights into the key response characteristics related to the inelastic cyclic performance of composite steel/concrete members, including their stiffness, capacity, and ductility. A synthetically generated numerical database is subsequently used to develop relationships governing the plastic rotation and cyclic degradation of dissipative composite beams as a function of the main geometric and material properties, with focus on members designed to European codified procedures. The deterioration effects are shown to be dependent on a number of key factors including, most significantly, the composite beam depth and the steel cross-section slenderness. In addition to the asymmetry in behaviour under sagging and hogging moments, it is shown that composite members typically exhibit 20% more degradation under cyclic loading compared to their bare steel counterparts. Importantly, the proposed cyclic degradation expressions for composite beams also enable the calibration of widely used uniaxial deterioration models which are suitable for implementation in computationally efficient nonlinear inelastic frame analysis for structural systems. These expressions also provide fundamental information required for idealised pushover representations for practical seismic assessment and design purposes.

Journal article

Moharram M, Bompa D, Xu B, Elghazouli AYet al., 2022, Behaviour and design of hybrid RC beam-to-steel column connections, Engineering Structures, Vol: 250, Pages: 2-18, ISSN: 0141-0296

Journal article

Khalil Z, Elghazouli AY, Martínez-Pañeda E, 2022, A generalised phase field model for fatigue crack growth in elastic-plastic solids with an efficient monolithic solver, Computer Methods in Applied Mechanics and Engineering, Vol: 388, Pages: 1-22, ISSN: 0045-7825

We present a generalised phase field-based formulation for predicting fatigue crack growth in metals. The theoretical framework aims at covering a wide range of material behaviour. Different fatigue degradation functions are considered and their influence is benchmarked against experiments. The phase field constitutive theory accommodates the so-called AT1, AT2 and phase field-cohesive zone (PF-CZM) models. In regards to material deformation, both non-linear kinematic and isotropic hardening are considered, as well as the combination of the two. Moreover, a monolithic solution scheme based on quasi-Newton algorithms is presented and shown to significantly outperform staggered approaches. The potential of the computational framework is demonstrated by investigating several 2D and 3D boundary value problems of particular interest. Constitutive and numerical choices are compared and insight is gained into their differences and similarities. The framework enables predicting fatigue crack growth in arbitrary geometries and for materials exhibiting complex (cyclic) deformation and damage responses. The finite element code developed is made freely available at www.empaneda.com/codes.

Journal article

Bompa DV, Bogdan T, Elghazouli AY, Nuñez E, Eatherthon MR, Leon RTet al., 2022, Nonlinear Numerical Assessment of Steel Reduced Beam Section Connections, Pages: 252-260, ISSN: 2366-2557

Cyclic tests on Reduced Beam Section (RBS) connections made of heavy structural sections provided detailed insight into the structural behaviour, including strength, ductility, and failure modes of such configurations. The experimental results indicated that geometrical and material effects need to be carefully considered when designing welded RBS connections incorporating large steel profiles. To better interpret the experimental results, nonlinear finite element simulations are conducted for the test series, comprising four large-scale specimens with distinct sizes. It is shown that the numerical models can reproduce the overall moment-rotation curves, inelastic distribution, as well as failure modes. The findings point out the need, in relatively large sections with thick flanges, for a deeper RBS cut than currently specified in design guidance. This modification would be required to promote a response governed by extensive yielding at the RBS while reducing the excessive strain demands at the beam-column welds.

Conference paper

Elzeadani M, Bompa D, Elghazouli AY, 2021, Preparation and properties of rubberised geopolymer concrete: A review, Construction and Building Materials, Vol: 313, Pages: 1-20, ISSN: 0950-0618

Interest in geopolymer concrete (GeoPC) and in rubberised concrete (RuC) has grown over the past two decades. The former offers an attractive alternative to ordinary Portland cement (OPC) concrete given its environmental footprint, while the latter provides a sustainable solution to tyre recycling and helps mitigate the depletion of natural aggregates. The benefits of combining the merits of GeoPC and RuC to form rubberised geopolymer concrete (RuG) as a potential sustainable construction material have been recognised in the past few years. As such, this paper presents a detailed review of RuG highlighting its constituent components, preparation and curing aspects, fresh and physical qualities, durability features, and thermal and sound insulation qualities, with a particular focus on mechanical properties. The influence of crumb rubber replacement on key characteristics is critically reviewed, including the effect of binder type, alkaline solution, alkaline solution-to-binder content, and curing conditions. Comparative quantitative assessments and prediction relationships are also presented where relevant. Finally, gaps in the available literature and recommendations for future research are outlined, with a view to supporting further developments in research and future deployment of RuG materials in practice. Whilst previous studies demonstrate the significant potential of RuG and provide essential information on its funda-mental properties, this review reveals that much research is still needed in order to optimise the merits of the material and to provide a full characterisation of its behaviour at both the material and structural levels under various loading conditions.

Journal article

Elghazouli A, Bompa DV, Mourad SA, Elyamani Aet al., 2021, Structural Behaviour of Clay Brick Lime Mortar Masonry Walls Under Lateral Cyclic Loading in Dry and Wet Conditions, Protection of Historical Constructions Proceedings of PROHITECH 2020, Editors: Vayas, Mazzolani, Publisher: Springer, ISBN: 9783030907877

Book chapter

Martinez-Paneda M, Elghazouli A, 2021, Optimal application of fluid viscous dampers in tall buildings incorporating integrated damping systems, The Structural Design of Tall and Special Buildings, Vol: 30, Pages: 1-26, ISSN: 1541-7808

This paper examines the detailed performance of an Integrated-Damping-System (IDS) approach which wasrecently introduced to provide large damping levels by enabling two parts of a building to move independentlythrough a parallel arrangement of springs and fluid viscous dampers. Extensive assessments into thecharacteristics and distribution of constituent dampers are illustrated through the dynamic response of a typical300m central-core building. Besides examining the system performance under typical wind conditions andselected seismic excitations, five damper placement methods are assessed for various linear and nonlinear damperexponents. It is shown that intermediate exponents provide the best overall response. However, when the designtargets a particular damping, deformation or acceleration related performance parameter, specific combinationsof damper exponent and distribution can result in an optimal application. Most importantly, due to the underlyingIDS nature, which acts as an inherent large-mass damper, the findings show that the overall performance is nothighly sensitive to the damper placement and does not necessitate the use of an advanced distribution. Whilstspecific placements can be adopted to refine targeted performance aspects where necessary, simple and practicaluniform or stiffness proportional arrangements can be consistently employed with the IDS to provide a highlyeffective solution.

Journal article

Elghazouli A, Bompa DV, Mourad SA, Elyamani Aet al., 2021, Structural behaviour of clay brick lime mortar masonry walls under lateral cyclic loading in dry and wet conditions, International Conference on Protection of Historical Constructions

Conference paper

Bompa DV, Elghazouli A, 2021, Shear-compression failure envelopes for clay brick lime mortar masonry under wet and dry conditions, International Conference on Protection of Historical Constructions

Conference paper

Demonceau J-F, Golea T, Jaspart J-P, Elghazouli A, Khalil Z, Santiago A, Santos AF, Simoes da Silva L, Kuhlmann U, Skarmoutsos G, Baldassino N, Zandonini R, Bernardi M, Zordan M, Dinu F, Marginean I, Jakab D, Dubina D, Wertz F, Weynand K, Obiala R, Candeias M, Charlier M, Anwaar Oet al., 2021, Design recommendations against progressive collapse in steel and steel-concrete buildings, Publisher: ECCS - European Convention for Constructional Steelwork, ISBN: 978-92-9147-172-0

Book

Bompa DV, Elghazouli A, 2021, Shear-Compression Failure Envelopes for Clay Brick Lime Mortar Masonry Under Wet and Dry Conditions, Protection of Historical Constructions Proceedings of PROHITECH 2020, Editors: Vayas, Mazzolani, Publisher: Springer, ISBN: 9783030907877

Book chapter

Bompa DV, Elghazouli AY, 2021, Mechanical properties of hydraulic lime mortars and fired clay bricks subjected to dry-wet cycles, Construction and Building Materials, Vol: 303, Pages: 1-17, ISSN: 0950-0618

This paper examines the influence of moisture and chlorides on the mechanical properties of natural hydraulic lime mortars, fired clay brick materials and masonry components. Besides assessing three types of mortars incorporating limes with different hydraulicity levels, a cement-only mortar was also investigated for comparison purposes. The test results indicate that all the hydraulic lime mortars had mass accumulation in the range of 11–14% after being subjected to wet-dry cycles in a sodium chloride solution, whilst the mass uptake was in the range of 3–8% for those made of cement. Salt accumulation produced a denser material leading to compressive cube and flexural strength enhancements by factors ranging between 1.6 and 4.7 in comparison to those in ambient-dry conditions, with even higher factors obtained for compressive cylinder strengths and elastic moduli. In contrast, lime mortar subjected to water-only wet-dry cycles showed constant mass or mass loss, due to cracking. Uniaxial compressive strengths of cylindrical brick cores were about 8.5% higher due to wet-dry cycles in chloride solution, and by about 14.9% lower due to wet-dry cycles in water, compared to the ambient-dry case. Complementary compressive tests on masonry cylinders in ambient-dry conditions were also used to assess the adequacy of existing compressive strength assessment expressions. After modifying the expressions by a set of proposed calibration factors, these are employed to undertake a sensitivity study using the mechanical properties of mortars and bricks subjected to wet-dry cycling. The results of the sensitivity study, combined with strength ranges available in the literature, lead to an identification of a suitable range of materials that can be considered for rehabilitation of some forms of historic masonry.

Journal article

Song S-Y, Guo Y-T, Fan J-S, Elghazouli AYet al., 2021, Shear contribution of flange dowel action in steel-concrete-steel composite structures, THIN-WALLED STRUCTURES, Vol: 169, ISSN: 0263-8231

Journal article

Xu B, Li H, Bompa DV, Elghazouli AY, Chen Jet al., 2021, Performance of polymer cementitious coatings for high-voltage electrical infrastructure, Infrastructures, Vol: 6, Pages: 1-20, ISSN: 2412-3811

This paper investigates the electrical, thermal and mechanical properties as well as the environmental performance of polymer cementitious composites (PCCs) as sustainable coating materials for underground power cables and as high-voltage insulators. Particular focus is placed on the optimised mix design and the effect of the manufacturing method on the performance of PCCs, incorporating liquid styrene and acrylic (SA) monomers, wollastonite and muscovite. Microstructural investigations, together with results from strength tests, indicate that the manufacturing method is a key performance parameter. Experimental results show that PCC mixes containing 25% SA emulsion, 12.5% wollastonite and no muscovite provide the most favourable dielectric properties from the mixes investigated. The PCC material has a dielectric strength up to 16.5 kV/mm and a dielectric loss factor lower than 0.12. Additional experiments also show that PCC has good thermal stability and thermal conductivity. The mechanical strength tests indicate that PCC specimens possess reliable strengths which are applicable in structural design. Environmental assessments also show that PCCs possess significantly lower embodied energy and embodied carbon than conventional plastic insulating materials.

Journal article

Goggins J, Jiang Y, Broderick B, Salawdeh S, O’Reilly G, Elghazouli A, Alwahsh H, Bogdanovic A, Rakicevic Z, Gjorgjiev I, Poposka A, Petreski B, Markovski Iet al., 2021, Shake Table Testing of Self Centring Concentrically Braced Frames, Eurosteel 2021

Conference paper

Mujdeci A, Bompa DV, Elghazouli A, 2021, Structural performance of composite steel rubberisedconcrete members under combined loading conditions, Eurosteel 2021

Conference paper

Elghazouli AY, Bompa DV, Mourad SA, Elyamani Aet al., 2021, In-plane lateral cyclic behaviour of lime-mortar and clay-brick masonry walls in dry and wet conditions, Bulletin of Earthquake Engineering, Vol: 19, Pages: 5525-5563, ISSN: 1570-761X

This paper presents an experimental investigation into the structural and material response of ambient-dry and wet clay-brick/lime-mortar masonry elements. In addition to cyclic tests on four large-scale masonry walls subjected to lateral in-plane displacement and co-existing compressive gravity load, the study also includes complementary tests on square masonry panels under diagonal compression and cylindrical masonry cores in compression. After describing the specimen details, wetting method and testing arrangements, the main results and observations are provided and discussed. The results obtained from full-field digital image correlation measurements enable a detailed assessment of the material shear-compression strength envelope, and permit a direct comparison with the strength characteristics of structural walls. The full load-deformation behaviour of the large-scale walls is also evaluated, including their ductility and failure modes, and compared with the predictions of available assessment models. It is shown that moisture has a notable effect on the main material properties, including the shear and compression strengths, brick–mortar interaction parameters, and the elastic and shear moduli. The extent of the moisture effects is a function of the governing behaviour and material characteristics as well as the interaction between shear and precompression stresses, and can lead to a loss of more than a third of the stiffness and strength. For the large scale wall specimens subjected to lateral loading and co-existing compression, the wet-to-dry reduction was found to be up to 20% and 11% in terms of stiffness and lateral strength, respectively, whilst the ductility ratio diminished by up to 12%. Overall, provided that the key moisture-dependent material properties are appropriately evaluated, it is shown that analytical assessment methods can be reliably adapted for predicting the response, in terms of the lateral stiffness, strength and overall load-de

Journal article

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