246 results found
Sirumbal-Zapata LF, Malaga-Chuquitaype C, Elghazouli AY, 2018, A three-dimensional plasticity-damage constitutive model for timber under cyclic loads, COMPUTERS & STRUCTURES, Vol: 195, Pages: 47-63, ISSN: 0045-7949
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.
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.
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
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
This paper is concerned with examining the complete bond-slip behaviour between deformed reinforcement bars and concrete incorporating rubber particles from recycled tyres as a partial replacement for mineral aggregates. An experimental study consisting of fifty-four pull-out tests on cylindrical rubberised and normal concrete specimens, in conjunction with two reinforcement sizes with short embedment lengths, is described. In addition to a detailed assessment of the full bond-slip relationship, the test results offer a direct interpretation of bond behaviour under practical levels of confinement and its influence on the failure modes. Particular emphasis is given to the characteristic bond behaviour of rubberised concrete in terms of maximum bond strength and splitting strength as well bond stiffness and slip parameters. The detailed test measurements and observations provided in this study enable the definition of key bond parameters depicting the interfacial behaviour between rubberised concrete and deformed bars. The findings also permit the development of modified approaches for reliable representation of the failure modes and bond capacities for the concrete materials considered in this investigation.
Bompa DV, Elghazouli AY, 2017, Ultimate Behaviour and Design of Hybrid Flat Slabs with Steel Shear Heads, Eurosteel2017
Bompa DV, Elghazouli AY, 2017, Ductility considerations for mechanical reinforcement couplers, Structures, Vol: 12, Pages: 115-119
© 2017 Institution of Structural Engineers Mechanical reinforcement couplers can offer considerable constructional and economic advantages in comparison with conventional methods of lap splicing, particularly when the requirements for seismic detailing exacerbates reinforcement congestion problems. However, the lack of specific codified guidance on ductility considerations hinders the application of mechanical couplers under inelastic conditions. To this end, this brief paper provides an overview of various reinforcement coupling systems, as well as a comparative assessment of their ‘in-air’ and ‘in-concrete’ performance, based on results extracted from a collated database. The main behavioural characteristics of different coupler forms are discussed, and their key performance parameters are compared. In addition to strength and ductility, the influence of the coupler size and arrangement on the ductility of structural members is discussed. The comparative assessments presented offer some guidance for the selection and application of mechanical reinforcement couplers in inelastic regions, and highlights areas in which further detailed investigations are required.
Bompa DV, Elghazouli AY, Xu B, et al., 2017, Experimental assessment and constitutive modelling of rubberised concrete materials, CONSTRUCTION AND BUILDING MATERIALS, Vol: 137, Pages: 246-260, ISSN: 0950-0618
Bravo-Haro M, Tsitos A, Elghazouli AY, 2017, Influence of Deterioration Modelling on Local Deformation Demands in Steel Moment Frames, Eurosteel2017
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
Cedron F, Elghazouli AY, 2017, Seismic Behaviour of Single Layer Cylindrical Lattice Steel Shells, Eurosteel2017
Elghazouli AY, 2017, Seismic design of building structures to Eurocode 8, CSCEHKB Conference, Pages: 62-69
Elghazouli AY, 2017, Seismic Performance of Structural Members Incorporating Recycled Rubber Materials, XVII ANIDIS Conference on Earthquake Engineering, Pages: KL25-KL33
Elghazouli AY, Bompa DV, Xu B, et 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.
Elghazouli AY, Castro JM, 2017, Design of Steel Structures, Seismic Design of Buildings to Eurocode 8, Editors: Elghazouli, Pages: 157-192, ISBN: 9781498751599
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
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
Malaga Chuquitaype C, Elghazouli AY, 2017, Design of Timber Structures, Seismic Design Of Buildings To Eurocode 8, Editors: Elghazouli, Pages: 213-234
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.
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
Moharram MI, Bompa DV, Elghazouli AY, 2017, Inelastic Assessment of Hybrid Reinforced Concrete Assemblages, fib Symposium 2017, Pages: 1336-1343
Moharram MI, Bompa DV, Elghazouli AY, 2017, Performance and Design of Shear Keys in Hybrid RC Beam and Steel Column Systems, Eurosteel2017
Salawdeh S, English J, Goggins J, et 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
Diagonal bracing members and their connections to beams and columns are the key lateral resisting components in concentrically braced frames (CBFs). Although gusset plate connections are widely used to connect bracing and frame members in such systems, their design often involves significant simplifications and idealisations due to the complexity of their behaviour under seismic loading. A conventional approach, which utilises a standard linear clearance zone that permits out-of-plane brace deformation, is typically used in the design of gusset plates. This approach can result in overly large connections with cumbersome details. The desire to achieve an improved balance between the gusset over-strength, on the one hand, and a favourable overall frame performance coupled with practical connection detailing, on the other, has prompted proposals for an improved design approach. However, before new recommendations on the design of gusset plate connections can be provided for use in codified guidance, there is a need to assess the performance of such detailing alternatives under realistic earthquake loading conditions. Accordingly, in this study, the performance of different brace connection configurations and gusset plate designs are examined using shake table testing. The paper describes twelve single-storey full scale shake table tests, which were performed on the AZALEE seismic testing facility at CEA Saclay. In seven of these tests, the gusset plates at the end of the brace members were connected to both beam and column flanges, while in the other five tests these were connected to the beam flange only. Conventional gusset plate design with a standard linear clearance was used for six tests, whereas a more balanced design with a nonlinear elliptical clearance detail was used for the others. The experimental set-up, specimen details, and loading procedures are presented, together with a detailed account of the results and observations. The main findings and their imp
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
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.
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
Xu B, Bompa DV, Elghazouli AY, et al., 2017, Behaviour of rubberised concrete members in asymmetric shear tests, Construction and Building Materials, Vol: 159, Pages: 361-375, ISSN: 0950-0618
This paper deals with the experimental behaviour of rubberised concrete members subjected to asymmetric four-point shear loading. A detailed account of tests on 15 prismatic members using conventional concrete as well as rubberised concrete, with relatively high replacement ratios of both fine and coarse mineral aggregates with rubber particles, is given. The results enable direct assessment of strength and complete deformation characteristics including the post-peak response for ultimate behaviour governed both by shear and mixed-mode tensile-shear. After describing the material properties, mix designs and member details, the main observations from detailed measurements of the crack kinematics through a digital image correlation monitoring system, with focus on members developing shear-governed response, are reported. Complementary numerical studies are undertaken using nonlinear finite element procedures which are validated against tests developing shear-governed failures. In order to provide further insight into the key response characteristics, particularly those related to ultimate strength, a number of numerical sensitivity studies employing various constitutive parameters are also carried out. Moreover, comparative assessments in terms of shear resistance, toughness and force transfer across the cracked interfaces are performed and discussed. The detailed test measurements, coupled with the results obtained from the numerical simulations, permit the definition of expressions for representing the shear resistance as a function of the rubber content and concrete compressive strength.
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
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
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
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