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

243 results found

Sirumbal-Zapata LF, Malaga Chuquitaype C, Elghazouli AY, 2018, A three-dimensional plasticity-damage constitutive model for timber unde cyclic loads, Computers and Structures, Vol: 195, Pages: 47-63, ISSN: 0045-7949

The performance of timber structures is governed by the nonlinear response at their connections, where high deformation levels and stress concentrations are developed, particularly when subjected to load reversals. To date, no constitutive model for wood under cyclic load exists which is able to incorporate its most important failure modes while considering plastic deformations and cyclic stiffness and strength degradation simultaneously. This paper presents the formulation and implementation of a plasticity- damage model with these characteristics within a continuum mechanics approach. The theoretical framework of both plasticity and damage models is described, and a detailed derivation of the constitutive equations required for their computational implementation and coupling as well as the return mapping and iterative algorithms for their integra- tion are presented. The damage evolution process is handled by two independent scalar variables for tension and compression. A general orthotropic plasticity yield surface with isotropic hardening is employed to incorporate timber plastic flow in compression. A closed-form expression for the plasticity-damage consistent tangent operator is derived. It is demonstrated that the proposed constitutive model captures all the key character- istics required for an accurate modelling of timber under large deformation levels until failure.

JOURNAL ARTICLE

Sirumbal-Zapata LF, Málaga-Chuquitaype C, Elghazouli AY, 2018, A three-dimensional plasticity-damage constitutive model for timber under cyclic loads, Computers and Structures, Vol: 195, Pages: 47-63, ISSN: 0045-7949

© 2017 Elsevier Ltd The performance of timber structures is governed by the nonlinear response at their connections, where high deformation levels and stress concentrations are developed, particularly when subjected to load reversals. To date, no constitutive model for wood under cyclic load exists which is able to incorporate its most important failure modes while considering plastic deformations and cyclic stiffness and strength degradation simultaneously. This paper presents the formulation and implementation of a plasticity-damage model with these characteristics within a continuum mechanics approach. The theoretical framework of both plasticity and damage models is described, and a detailed derivation of the constitutive equations required for their computational implementation and coupling as well as the return mapping and iterative algorithms for their integration are presented. The damage evolution process is handled by two independent scalar variables for tension and compression. A general orthotropic plasticity yield surface with isotropic hardening is employed to incorporate timber plastic flow in compression. A closed-form expression for the plasticity-damage consistent tangent operator is derived. It is demonstrated that the proposed constitutive model captures all the key characteristics required for an accurate modelling of timber under large deformation levels until failure.

JOURNAL ARTICLE

Bompa DV, Elghazouli AY, 2017, Punching shear strength of RC flat slabs provided with shear-heads at interior connections to steel columns, Pages: 823-831

© Springer International Publishing AG 2018. This paper investigates the structural performance of cruciform shear-head systems fully integrated in RC flat slabs at interior connections to steel columns. The test results from a series of six large scale members of which two were provided with headed shear studs, offer a direct evaluation of the full load-deformation behaviour of the specimens as well as the ultimate punching shear strength attained prior to failure at the critical slab perimeter outside the shear-head region. Particular focus is given to the influence of the shear-head and headed shear stud reinforcement to the member kinematics and failure characteristics. The experimental findings coupled with shear field analyses enable the development of analytical models that depict the rotational response and flexural strength as a function of the shear-head characteristics, and support the definition of a shear-head dependent control perimeter required for punching shear strength assessments. Additionally, analytical design expressions that adopt the fundamentals of Model Code 2010, which account for the characteristics of the shear-head system, are proposed and their results capture in a more realistic manner the shear-head influence on the punching shear strength of RC flat slabs in such hybrid configurations in comparison with strength predictions from current conventional RC design methods.

CONFERENCE PAPER

Bompa DV, Elghazouli AY, 2017, Numerical modelling and parametric assessment of hybrid flat slabs with steel shear heads, ENGINEERING STRUCTURES, Vol: 142, Pages: 67-83, ISSN: 0141-0296

JOURNAL ARTICLE

Bompa DV, Elghazouli AY, 2017, Bond-slip response of deformed bars in rubberised concrete, Construction and Building Materials, Vol: 154, Pages: 884-898, ISSN: 0950-0618

JOURNAL ARTICLE

Bompa DV, Elghazouli AY, 2017, Ultimate Behaviour and Design of Hybrid Flat Slabs with Steel Shear Heads, Eurosteel2017

CONFERENCE PAPER

Bompa DV, Elghazouli AY, 2017, Ductility Considerations for Mechanical Reinforcement Couplers, Structures, Vol: 12, Pages: 115-119, ISSN: 2352-0124

JOURNAL ARTICLE

Bompa DV, Elghazouli AY, Xu B, Stafford PJ, Ruiz-Teran AMet al., 2017, Experimental assessment and constitutive modelling of rubberised concrete materials, CONSTRUCTION AND BUILDING MATERIALS, Vol: 137, Pages: 246-260, ISSN: 0950-0618

JOURNAL ARTICLE

Bravo-Haro M, Tsitos A, Elghazouli AY, 2017, Influence of Deterioration Modelling on Local Deformation Demands in Steel Moment Frames, Eurosteel2017

CONFERENCE PAPER

Bravo-Haro MA, Tsitos A, Elghazouli AY, 2017, Influence of cyclic degradation on inelastic seismic demands in steel moment frames, 16th World Conference on Earthquake Engineering, Pages: paper No 1033-paper No 1033

CONFERENCE PAPER

Cedron F, Elghazouli AY, 2017, Seismic Behaviour of Single Layer Cylindrical Lattice Steel Shells, Eurosteel2017

CONFERENCE PAPER

Elghazouli AY, 2017, Seismic design of building structures to Eurocode 8, CSCEHKB Conference, Pages: 62-69

CONFERENCE PAPER

Elghazouli AY, Bompa DV, Xu B, Stafford PJ, Ruiz-Teran AMet al., 2017, Inelastic behaviour of RC members incorporating high deformability concrete, Pages: 2399-2406

©Springer International Publishing AG 2018. This paper examines the inelastic behaviour of dissipative zones in structural members incorporating high deformability concrete materials in which mineral aggregates are partly replaced by rubber particles. An experimental study on three large-scale circular reinforced concrete column specimens, subjected to lateral cyclic displacements and co-existing axial loads, is described. The testing arrangement, specimen details, and main observations, are presented and discussed. The test results enable a direct assessment of the strength and ductility characteristics of the specimens. In particular, the study permits an evaluation of the comparative performance of structural members with and without rubber replacement, as well as the influence of external confinement. The results show that, in comparison with conventional reinforced concrete members, structural elements incorporating a significant proportion of aggregate replacement by rubber particles can offer a good balance between bending capacity and ductility, particularly for modest levels of co-existing axial loads. For column members required to sustain substantial gravity loads, favourable performance can be achieved in rubberised concrete members by means of strength enhancement through external confinement such as fibre reinforced sheets. Based on the experimental findings, the main material and response parameters are discussed and their influence on the overall structural behaviour are highlighted.

CONFERENCE PAPER

Elghazouli AY, Castro JM, 2017, Design of Steel Structures, Seismic Design of Buildings to Eurocode 8, Editors: Elghazouli, Pages: 157-192, ISBN: 9781498751599

BOOK CHAPTER

Elghazouli AY, Castro JM, 2017, Design of Composite Steel/Concrete Structures, Seismic Design of Buildings to Eurocode 8, Editors: Elghazouli, Pages: 193-212, ISBN: 978-1-4987-5159-9

BOOK CHAPTER

Karagiannis V, Malaga-Chuquitaype C, Elghazouli AY, 2017, Behaviour of hybrid timber beam-to-tubular steel column moment connections, ENGINEERING STRUCTURES, Vol: 131, Pages: 243-263, ISSN: 0141-0296

JOURNAL ARTICLE

Malaga Chuquitaype C, Elghazouli AY, 2017, Design of Timber Structures, Seismic Design Of Buildings To Eurocode 8, Editors: Elghazouli, Pages: 213-234

BOOK CHAPTER

Moharram M, Bompa D, Elghazouli A, 2017, Inelastic assessment of hybrid RC beams to steel column configurations using structural steel shear-keys, Pages: 1336-1343

© Springer International Publishing AG 2018. This study describes experimental and numerical investigations into the inelastic behaviour of hybrid reinforced concrete (RC) beams. The RC beams are connected to steel columns by means of fully embedded structural steel profiles. Observations from a series of ten full-scale hybrid Steel/RC specimens are presented. Nonlinear finite element procedures are carried out and validated against the experimental results from the hybrid tests in this paper. The ability of the numerical models to provide faithful prediction, using a consistent set of material modelling parameters, provides a high level of confidence in the reliability of the simulation techniques. Finally, some simplified analytical representations of the failure surfaces are proposed in which potential failure conditions are predicted and classified in reference to a suggested hybrid Mode Index.

CONFERENCE PAPER

Moharram MI, Bompa DV, Elghazouli AY, 2017, Experimental and numerical assessment of mixed RC beam and steel column systems, JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH, Vol: 131, Pages: 51-67, ISSN: 0143-974X

JOURNAL ARTICLE

Moharram MI, Bompa DV, Elghazouli AY, 2017, Inelastic Assessment of Hybrid Reinforced Concrete Assemblages, fib Symposium 2017, Pages: 1336-1343

CONFERENCE PAPER

Moharram MI, Bompa DV, Elghazouli AY, 2017, Performance and Design of Shear Keys in Hybrid RC Beam and Steel Column Systems, Eurosteel2017

CONFERENCE PAPER

Salawdeh S, English J, Goggins J, Elghazouli AY, Hunt A, Broderick BMet al., 2017, Shake table assessment of gusset plate connection behaviour in concentrically braced frames, Journal of Constructional Steel Research, Vol: 138, Pages: 432-448, ISSN: 0143-974X

JOURNAL ARTICLE

Sirumbal Zapata LF, Malaga Chuquitaype C, Elghazouli AY, 2017, Coupled plasticity-damage material constitutive model for timber subjected to cyclic loading, 16th World Conference on Earthquake Engineering, Pages: Paper No 1122-Paper No 1122

CONFERENCE PAPER

Tsitos A, Bravo-Haro MA, Elghazouli AY, 2017, Influence of deterioration modelling on the seismic response of steel moment frames designed to Eurocode 8, Earthquake Engineering and Structural Dynamics, ISSN: 0098-8847

© 2017 John Wiley & Sons, Ltd. This paper assesses the influence of cyclic and in-cycle degradation on seismic drift demands in moment-resisting steel frames (MRF) designed to Eurocode 8. The structural characteristics, ground motion frequency content, and level of inelasticity are the primary parameters considered. A set of single-degree-of-freedom (SDOF) systems, subjected to varying levels of inelastic demands, is initially investigated followed by an extensive study on multi-storey frames. The latter comprises a large number of incremental dynamic analyses (IDA) on 12 frames modelled with or without consideration of degradation effects. A suite of 56 far-field ground motion records, appropriately scaled to simulate 4 levels of inelastic demand, is employed for the IDA. Characteristic results from a detailed parametric investigation show that maximum response in terms of global and inter-storey drifts is notably affected by degradation phenomena, in addition to the earthquake frequency content and the scaled inelastic demands. Consistently, both SDOF and frame systems with fundamental periods shorter than the mean period of ground motion can experience higher lateral strength demands and seismic drifts than those of non-degrading counterparts in the same period range. Also, degrading multi-storey frames can exhibit distinctly different plastic mechanisms with concentration of drifts at lower levels. Importantly, degrading systems might reach a "near-collapse" limit state at ductility demand levels comparable to or lower than the assumed design behaviour factor, a result with direct consequences on optimised design situations where over-strength would be minimal. Finally, the implications of the findings with respect to design-level limit states are discussed.

JOURNAL ARTICLE

Tsitos A, Elghazouli AY, 2017, Evaluation of loading protocols for assessing local seismic demands in steel buildings designed to EC8, 16th World Conference on Earthquake Engineering, Pages: Paper No 1559-Paper No 1559

CONFERENCE PAPER

Bompa DV, Elghazouli AY, 2016, Structural performance of RC flat slabs connected to steel columns with shear heads, ENGINEERING STRUCTURES, Vol: 117, Pages: 161-183, ISSN: 0141-0296

JOURNAL ARTICLE

Bompa DV, Elghazouli AY, 2016, Failure Assessment of Combined Hybrid Flat Slab and Steel Column Systems, PSSC'16, 11th Pacific Structural Steel Conference, Pages: 841-848

CONFERENCE PAPER

Chen A, Louca LA, Elghazouli AY, 2016, Behaviour of cylindrical steel drums under blast loading conditions, INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, Vol: 88, Pages: 39-53, ISSN: 0734-743X

JOURNAL ARTICLE

Elghazouli AY, 2016, Seismic Performance and Design of Concentrically Braced Steel Frames, PSSC'16, 11th Pacific Structural Steel Conference, Pages: 68-75

CONFERENCE PAPER

Karagiannis V, Malaga-Chuquitaype C, Elghazouli AY, 2016, Modified foundation modelling of dowel embedment in glulam connections, CONSTRUCTION AND BUILDING MATERIALS, Vol: 102, Pages: 1168-1179, ISSN: 0950-0618

JOURNAL ARTICLE

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