Publications
355 results found
Gu J, Macorini L, Izzuddin BA, 2015, Response of masonry cavity cladding subject to blast loading, ISSN: 1759-3433
This paper investigates the response of a typical cladding system with masonry cavity walls subject to blast loading and the transfer of the blast loads to the surrounding frame. A recently developed mesoscale mixed-dimensional partitioned modelling framework is adopted, where a detailed mesoscale description for the masonry panels is utilised to achieve the desired accuracy, and a domain-partitioning scheme is adopted to enhance computational efficiency. Two different simplified idealisations representing the parts of the masonry cavity cladding at mid-span and near-column locations are considered to investigate the specific responses of the different parts of the cladding. As the cladding panels show brittle failure modes at the mid-span locations, the restraints provided by the edge columns allow a more ductile failure mode. These different failure characteristics are verified considering the results of a larger model representing the portion of a masonry cavity wall between two adjacent columns in a realistic framed building.
Rodriguez-Villares A, Minga E, Macorini L, et al., 2015, An automation strategy for mesoscale partitioned analysis of complex masonry structures, ISSN: 1759-3433
Previous research has shown that detailed mesoscale models with nonlinear interfaces can accurately represent the behaviour of unreinforced masonry structures. Nevertheless, this modelling approach is potentially associated with prohibitive computational demands, and consequently an emphasis has been placed almost exclusively on small scale structures. In light of recent developments of effective strategies which reduce the computational cost, this paper presents an automation approach designed to explore the full capacity of such enhancements. A procedure has been developed to perform the automated assembly of generic mesoscale masonry descriptions embedded with advanced domain partitioning features. From a high level of abstraction, this procedure allows the user to define the geometry of an arbitrary masonry structure such as masonry arches, bridges and facades, and to partition the domain by exploiting factorisation conditions. The use of the proposed procedure allows for the practical investigation of complex masonry structures and the comparative study of various partitioning configurations. Examples are presented to demonstrate the potential of the tool, particularly in the investigation of master-slave coupling and hierarchic features.
Rodriguez-Villares A, Minga E, Macorini L, et al., 2015, An automation strategy for mesoscale partitioned analysis of complex masonry structures, ISSN: 1759-3433
Previous research has shown that detailed mesoscale models with nonlinear interfaces can accurately represent the behaviour of unreinforced masonry structures. Nevertheless, this modelling approach is potentially associated with prohibitive computational demands, and consequently an emphasis has been placed almost exclusively on small scale structures. In light of recent developments of effective strategies which reduce the computational cost, this paper presents an automation approach designed to explore the full capacity of such enhancements. A procedure has been developed to perform the automated assembly of generic mesoscale masonry descriptions embedded with advanced domain partitioning features. From a high level of abstraction, this procedure allows the user to define the geometry of an arbitrary masonry structure such as masonry arches, bridges and facades, and to partition the domain by exploiting factorisation conditions. The use of the proposed procedure allows for the practical investigation of complex masonry structures and the comparative study of various partitioning configurations. Examples are presented to demonstrate the potential of the tool, particularly in the investigation of master-slave coupling and hierarchic features.
Bilbao AB, Izzuddin BA, Vollum RL, 2015, Enhanced nonlinear analysis of three-dimensional concrete structures using damage plasticity modelling, ISSN: 1759-3433
This paper presents an improved numerical procedure for the nonlinear analysis of three-dimensional continuum concrete structures employing damage-plasticity constitutive modelling. Previous convergence difficulties when performing single-step return mappings for larger strain increments necessitated resorting to sub-stepping methods, at the cost of a greater computational expense when calculating the consistent algorithmic tangent stiffness. Quadratic convergence rate at the global level while maintaining the single-step return scheme for the constitutive model is achieved here with a potential reduction in the number of simultaneous equations and with the utilisation of a basic line search technique for particular cases. Initial singularity of the Jacobian matrix is thereby avoided, ensuring a reduction in the convergence measure towards the converged solution. The improved robustness of the enhanced algorithm is confirmed, and its performance at larger scale is demonstrated through two benchmark application examples.
Chisari C, Macorini L, Amadio C, et al., 2015, An experimental-numerical procedure for the identification of mesoscale material properties for brick-masonry, ISSN: 1759-3433
©Civil-Comp Press, 2015. The response of unreinforced masonry is very complex because of its inherent heterogeneity and nonlinear behaviour, which is governed by the interaction between masonry units and mortar joints. Mesoscale modelling can provide a very good representation of the actual response of masonry structures when using adequate material parameters for the individual components. An attractive strategy has been recently developed by the authors for the calibration of the mesoscale material properties. This is based upon the inverse analysis of the macroscale behaviour of a part of the structure subjected to the pressures exerted by two flatjacks arranged along the mortar bed joints and the perpendicular direction. Thus far this strategy has been applied only to pseudo-experimental data, whereas in this paper it is enhanced considering the experimental results obtained in physical laboratory tests on running bond masonry walls. It is demonstrated that inverse analysis of the measured experimental displacement field allows the estimation of the elastic properties, the cohesion and the friction angle for the interface elements used in the mesoscale description to represent mortar joints.
Micallef M, Yollum R, Izzuddin B, et al., 2015, Crack control in base-restrained reinforced concrete walls, Pages: 143-144, ISSN: 2617-4820
Due to its low tensile strength, concrete invariably cracks if early-age and long-term volumetrie changes are restrained. The aim of this research is to increase the confidence with which engineers can predict and control crack widths in reinforced concrete (RC) walls with either edge or combined edge and end restraint. The research was motivated by complaints from industry that Eurocode 2 (EN 1992) can require considerably more reinforcement for crack control than the previous UK code BS8007. The paper describes a series of tests which were carried out on 3.5 m long base-restrained RC walls to investigate cracking due to early-age thermal contraction and subsequent drying shrinkage. The tests systematically investigated the influences of reinforcement ratio, bar diameter and cover on crack width and spacing. The paper summarises the key experimental findings as well as comparing the measured crack widths and spacings with the predictions of BS8007 and EN 1992. lt also gives an overview of the non-linear finite element analysis which is being used to simulate the tested walls. The broader aim of the numerical modelling is to develop a procedure for predicting crack development with reasonable accuracy to allow the consideration of other boundary conditions than those considered in the tests.
Chisari C, Macorini L, Amadio C, et al., 2015, An experimental-numerical procedure for the identification of mesoscale material properties for brick-masonry, ISSN: 1759-3433
©Civil-Comp Press, 2015.The response of unreinforced masonry is very complex because of its inherent heterogeneity and nonlinear behaviour, which is governed by the interaction between masonry units and mortar joints. Mesoscale modelling can provide a very good representation of the actual response of masonry structures when using adequate material parameters for the individual components. An attractive strategy has been recently developed by the authors for the calibration of the mesoscale material properties. This is based upon the inverse analysis of the macroscale behaviour of a part of the structure subjected to the pressures exerted by two flatjacks arranged along the mortar bed joints and the perpendicular direction. Thus far this strategy has been applied only to pseudo-experimental data, whereas in this paper it is enhanced considering the experimental results obtained in physical laboratory tests on running bond masonry walls. It is demonstrated that inverse analysis of the measured experimental displacement field allows the estimation of the elastic properties, the cohesion and the friction angle for the interface elements used in the mesoscale description to represent mortar joints.
Macorini L, Izzuddin BA, 2014, Nonlinear analysis of unreinforced masonry walls under blast loading using mesoscale partitioned modeling, Journal of Structural Engineering, Vol: 140, Pages: 1-1, ISSN: 0733-9445
This paper presents the application of an advanced modeling strategy for the nonlinear analysis of structures with unreinforced masonry (URM) components under blast loading. This approach enables the investigation of the nonlinear dynamic response of large struc-tures with URM walls, accounting for the mechanical and geometrical characteristics of URM components, the coupling between the in-plane and out-of-plane response as well as the interaction between URM panels and the other parts of the considered structural system. According to the utilized strategy an URM wall is described by a parent structure, which consists of super-elements representing the partitioned subdo-mains, allowing effective parallelization of the nonlinear structural analysis simulation. Each partition is represented by a detailed 3D mes-oscale model, which uses an advanced 2D nonlinear interface element that allows the representation of crack propagation in URM elements. Furthermore, the macroscale model considers only the partition boundaries of the mesoscale descriptions and specific macro-elements are introduced to reduce the number of freedoms leading to further enhance the computational savings. Several examples are presented in the paper to validate the proposed approach and to demonstrate its major computational benefits in simulating the response of structures with URM walls subjected to blast loading.
Chisari C, Macorini L, Amadio C, et al., 2014, RATIONAL SELECTION OF EXPERIMENTAL DATA FOR INVERSE STRUCTURAL PROBLEMS, 11th World Congress on Computational Mechanics (WCCM) / 5th European Conference on Computational Mechanics (ECCM) / 6th European Conference on Computational Fluid Dynamics (ECFD), Publisher: INT CENTER NUMERICAL METHODS ENGINEERING, Pages: 386-397
Farazman S, Izzuddin BA, Cormie D, 2013, Influence of Unreinforced Masonry Infill Panels on the Robustness of Multistory Buildings, JOURNAL OF PERFORMANCE OF CONSTRUCTED FACILITIES, Vol: 27, Pages: 673-682, ISSN: 0887-3828
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- Citations: 18
Hadjioannou M, Donahue S, Williamson EB, et al., 2013, Experimental evaluation of floor slab contribution in mitigating progressive collapse of steel structures, Pages: 615-626, ISSN: 1743-3509
As a result of several high-profile terrorist attacks against buildings in recent years, mitigating progressive structural collapse has been of particular interest to the structural engineering community. Previous research studies have focused on the impact of an individual column failure on the overall stability of a structure. These studies have relied mostly on computational investigations and experimental tests on individual components. Few studies have been done to predict the behavior of floor slabs above a failed column, and the computational tools used have not been validated against experimental results. The research program presented in this paper extends prior work in this area by testing specimens that include all structural components of a typical floor system in a prototypical steel-framed structure. In total, six full-scale tests will be performed, including three interior 2-bay × 2-bay specimens and three exterior 2-bay × 1- bay specimens. In all tests, the mid-span column will be removed statically while the slab is loaded with the recommended extreme event design load. The slab consists of corrugated decking with lightly reinforced concrete on top that is connected to the floor beams through shear studs and is consistent with typicalbuilding practices in the US. The first test is planned for the summer of 2012. The extensive computational analyses that have been done so far indicate the significant contribution the slab has in sustaining overall building stability and mitigating collapse. Initial analysis results show that the contribution of the corrugated decking acting compositely with the concrete slab is significantly greater than that of the floor beam grillage. The significant contribution of the corrugated decking is attributed to the membrane forces that are developed while the deflections increase. Preliminary analyses suggest that the slab in the test structure can sustain the removal of the mid-span column without collapsing
Izzuddin BA, Macorini L, Rinaldin G, 2013, Partitioned Modelling for Nonlinear Dynamic Analysis of Reinforced Concrete Buildings for Earthquake Loading, 14th International Conference on Civil, Structural and Environmental Engineering Computing, Publisher: Civil-Comp Press, ISSN: 1759-3433
This paper proposes a new approach for the seismic assessment of reinforced concrete (RC) building structures subject to earthquake loading, considering detailed nonlinear dynamic analysis. Noting the potentially prohibitive computational demand of conventional nonlinear finite element analysis based on a monolithic treatment, the proposed approach utilises recent development in partitioned modelling for parallel processing employing a novel dual super-element concept. A case study of a realistic RC building subject to seismic ground excitation is presented, where monolithic as well as alternative partitioned models are considered. It is shown that the proposed approach achieves exceptional parallel performance, which can be disproportionately more than the number of used partitions, in addition to other major benefits of scalability and overcoming memory bottlenecks. This confirms the prospects of the proposed approach as an accurate and computationally practical method for the nonlinear dynamic analysis of structures, in general, and the seismic assessment of RC buildings, in particular.
Macorini L, Izzuddin BA, 2013, Enhanced Mesoscale Partitioned Modelling for Un-Reinforced Masonry Structures, 14th International Conference on Civil, Structural and Environmental Engineering Computing, Publisher: Civil-Comp Press, ISSN: 1759-3433
This paper discusses the benefits of recent enhancements introduced into a partitioned mesoscale modelling approach for brick-masonry structures. These include the use of master-slave coupling and hierarchic features which enable the improvement of efficiency, especially in the analysis of large masonry components. In particular, the new enhancements enable a reduction in the number of nodes at the parent structure and the use of multi-level partitions to distribute the computational load uniformly to the different processors used in parallel. Some numerical examples, including a comparative analysis on the elastic response of a large masonry wall and the nonlinear simulation of a realistic heterogeneous system under extreme loading, are presented to show the effectiveness of the proposed modelling strategy.
Xavier FB, Macorini L, Izzuddin BA, 2013, Mesoscale Modelling of Masonry Structures Accounting for Brick-Mortar Interaction, 14th International Conference on Civil, Structural and Environmental Engineering Computing, Publisher: Civil-Comp, ISSN: 1759-3433
This paper presents an advanced zero-thickness interface element which can be used in mesoscale models for unreinforced masonry to describe brick-mortar interaction. In particular, an existing interface formulation has been enhanced by modifying local kinematics and coupling typical mode I separation with in-plane normal strains induced by Poisson's effects. This enhancement allows the differential behaviour of brick units and mortar joints to be properly captured, while circumventing the need for detailed representation of individual components. Application of the proposed mesoscale modelling enables triaxial stress states within bricks to be effectively predicted including significant tensile stresses which may lead to the formation of cracks in unreinforced masonry. The performance of the proposed interface element is assessed by the analysis of a set of prisms subjected to uniaxial compression, where brick-mortar interaction has been found to govern the overall behaviour of the composite system.
Chisari C, Macorini L, Amadio C, et al., 2013, Identification of Brick-Masonry Material Properties Through Inverse Analysis and Genetic Algorithms, 14th International Conference on Civil, Structural and Environmental Engineering Computing, Publisher: Civil-Comp Press, ISSN: 1759-3433
Unreinforced brick/block masonry (URM) has been used for centuries as an effective building material. However, the response of URM is very complex because of its inherent heterogeneity and nonlinear behaviour, which is governed by the interaction between units and mortar. Mesoscale modelling, though computationally demanding, can provide a very good representation of the actual structural response when using adequate mechanical parameters for URM component materials. These can be obtained using numerical calibration based on the results of experimental tests. In this paper, inverse analysis techniques utilising genetic algorithms are employed to calibrate material parameters of an advanced nonlinear mesoscale description, which uses zero-thickness interfaces for representing mortar joints. In particular, the elastic material parameters of mortar interfaces are derived from measurements at the macroscale. In order to apply this procedure to in-situ non-destructive tests, a non-conventional flat-jack test setup has been investigated. The potential and limitations of the proposed method are assessed using computer-generated pseudo-experimental data, where modelling errors are ruled out. Sensitivity and random noise analysis are performed to evaluate the influence of the precision of the measurement equipment employed in the tests.
Fang C, Izzuddin BA, Elghazouli AY, et al., 2013, Modeling of semi-rigid beam-to-column steel joints under extreme loading, Frontiers of Structural and Civil Engineering, Vol: 7, Pages: 245-263, ISSN: 2095-2430
Joints play an important role in providing ductility for steel-composite structures subject to extreme loading conditions, such as blast, fire and impact. Due to sound energy dissipation capability and fabrication efficiency, semi-rigid joints have increasingly received attention during the last decade. This paper presents a component approach for modeling semi-rigid beam-to-column joints based on Eurocode3, where the post-elastic response, including component strain hardening and ultimate rotational capacity, is also considered. Failure criteria are defined based on the ultimate deformation capacity of components and bolt-rows. The model enables a direct integration of joint response into global frame models with the consideration of axial deformability, such that the interaction between bending moment and axial force within the joints can be realistically captured. In addition, elevated temperature can be considered in the joint model via the degradation of the component response. Through comparisons with available test data, the joint model is shown to have good accuracy, and the failure criteria are found to be reliable yet conservative. The strain hardening response of components is shown to have significant influence on the ultimate bending capacity of the joints, while neglecting it usually leads to a conservative prediction. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.
Li ZX, Zhuo X, Vu-Quoc L, et al., 2013, A four-node corotational quadrilateral elastoplastic shell element using vectorial rotational variables, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Vol: 95, Pages: 181-211, ISSN: 0029-5981
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- Citations: 16
Jokhio GA, Izzuddin BA, 2013, Parallelisation of nonlinear structural analysis using dual partition super elements, ADVANCES IN ENGINEERING SOFTWARE, Vol: 60-61, Pages: 81-88, ISSN: 0965-9978
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- Citations: 12
Macorini L, Izzuddin BA, 2013, Nonlinear analysis of masonry structures using mesoscale partitioned modelling, Advances in Engineering Software, Vol: 60-61, Pages: 58-69
This paper presents an effective and accurate computational strategy for unreinforced brick masonry structures. Mesoscale descriptions allow a realistic representation of the nonlinear structural behaviour of URM, but can pose prohibitive computational demands for large-scale problems. To overcome this drawback, the computational strategy presented in the paper employs the domain partitioning approach, which is coupled with an accurate mesoscale finite element model. This allows the effective parallelisation of the nonlinear structural analysis simulation, where significant speed-up can be achieved in the nonlinear analysis of large masonry structures. The potential and effectiveness of the proposed computational strategy are shown through numerical examples, where full-scale masonry structures are considered.
Jahromi HZ, Vlassis AG, Izzuddin BA, 2013, Modelling approaches for robustness assessment of multi-storey steel-composite buildings, ENGINEERING STRUCTURES, Vol: 51, Pages: 278-294, ISSN: 0141-0296
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- Citations: 37
Abidin ARZ, Izzuddin BA, 2013, Meshless local buckling analysis of steel beams with irregular web openings, ENGINEERING STRUCTURES, Vol: 50, Pages: 197-206, ISSN: 0141-0296
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- Citations: 24
Khan A, Smith DL, Izzuddin BA, 2013, Investigation of rigid-plastic beams subjected to impact using linear complementarity, ENGINEERING STRUCTURES, Vol: 50, Pages: 137-148, ISSN: 0141-0296
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- Citations: 9
Jahromi HZ, Izzuddin BA, 2013, Energy conserving algorithms for dynamic contact analysis using Newmark methods, COMPUTERS & STRUCTURES, Vol: 118, Pages: 74-89, ISSN: 0045-7949
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- Citations: 10
Abela JM, Potts DM, Vollum RL, et al., 2013, Geotechnical analysis of blinding struts in cut-and-cover excavations, COMPUTERS AND GEOTECHNICS, Vol: 48, Pages: 179-191, ISSN: 0266-352X
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- Citations: 3
Xavier FB, Macorini L, Izzuddin BA, 2013, Enhanced robustness of multi-storey buildings with unreinforced masonry infill, Pages: 265-275
Previous work at Imperial College London by Izzuddin and co-workers led to the development of a multi-level framework for the assessment of building robustness under sudden column loss scenarios, and highlighted the significant potential contribution of unreinforced masonry infill panels towards arresting progressive collapse for such scenarios. The latter work considered the contribution of infill panels using equivalent struts, which are inherently approximate particularly in relation to the modelling of openings and general interaction with the surrounding frame. Recent work by the authors has focussed on the development of a mesoscale modelling approach for unreinforced brick masonry, which has been incorporated within a partitioned modelling framework to provide an accurate and efficient approach for predicting the response of masonry components under extreme loading. This paper employs the detailed mesoscale modelling approach for brick masonry infill panels, with and without openings, making comparisons against the simplified equivalent strut models. The outcomes from the detailed mesoscale models are incorporated within the multilevel robustness assessment framework to provide a more accurate evaluation of the contribution of masonry infill panels to the structural robustness of steel composite buildings under sudden column loss. It is confirmed that this contribution is significantly large to merit the consideration of infill panels in robustness design and assessment practice, subject to quality control during the construction process.
Fang C, Izzuddin BA, Elghazouli AY, et al., 2013, Robustness of multi-storey car parks under localised fire—Towardspractical design recommendations, Journal of Constructional Steel Research, Vol: 90, Pages: 193-208
Maunder EAW, Izzuddin BA, 2013, A hybrid equilibrium element for folded plate and shell structures, International Journal for Numerical Methods in Engineering, Vol: 95, Pages: 451-477, ISSN: 0029-5981
Fang C, Izzuddin BA, Elghazouli AY, et al., 2013, Simplified energy-based robustness assessment for steel-composite car parks under vehicle fire, Engineering Structures, Vol: 49, Pages: 719-732, ISSN: 0141-0296
Moghadam SJ, Izzuddin BA, 2013, AN ANALYTICAL MODEL FOR ELASTO-PLASTIC BUCKLING OF COLUMNS, 12th International Conference on Computational Plasticity (COMPLAS), Publisher: INT CENTER NUMERICAL METHODS ENGINEERING, Pages: 598-607
Kuhlmann U, Roelle L, Izzuddin BA, et al., 2012, Resistance and Response of Steel and Steel-Concrete Composite Structures in Progressive Collapse Assessment, STRUCTURAL ENGINEERING INTERNATIONAL, Vol: 22, Pages: 86-92, ISSN: 1016-8664
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- Citations: 7
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