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Mendes L.A.M.,Institute Engineering Of Estruturas | Mendes L.A.M.,National Laboratory for Civil Engineering | Castro L.M.S.S.,Institute Engineering Of Estruturas | Castro L.M.S.S.,University of Lisbon
Advances in Engineering Software | Year: 2013

This paper presents a new approach to perform incremental dynamic analyses on reinforced concrete buildings using the so-called hybrid discretizations, taking advantage of parallelized computations and domain decomposition techniques to enhance the capability and performance for the analysis of large-scale problems. The concept of hybrid discretization consists in the combination of different modelling approaches for the three-dimensional structural elements. Where most of the non-linear phenomena are expected to occur, refined meshes and more complex constitutive relations are adopted. Elsewhere, simplified structural models are considered. Special attention is devoted to the definition of adequate techniques to treat the transition zones between different structural models. The efficiency and accuracy of alternative kinematic constraint techniques are studied and assessed. The paper ends with two validation examples that test the accuracy and the computational performance of the proposed methodology. © 2012 Elsevier Ltd. All rights reserved. Source


Mendes L.A.M.,Institute Engineering Of Estruturas | Castro L.M.S.S.,Institute Engineering Of Estruturas | Castro L.M.S.S.,University of Lisbon
Engineering Structures | Year: 2014

This paper presents a new constitutive model for the simulation of reinforcing steel bars used in common reinforced concrete structures and it is designed to be used for general loading cases. The model includes the well-known Guiffrè-Menegotto-Pinto softened branch, although new expressions are proposed for the evolutions of the curvature-related parameter and of the yield surface. The constitutive relation is enhanced with an innovative and simplified proposal for considering ultra-low-cycle fatigue effects. This phenomenon is particularly important for structures that undergo a small number of very large displacement cycles, e.g. when subjected to intense seismic events. It is known that in those situations the steel reinforcements experience a continuum and significant strength decrease that ultimately leads to premature failure induced by fatigue. The model's mathematical description and some relevant implementation issues are described. Its accuracy is assessed by means of a series of validation tests using experimental data available in the bibliography. © 2014 Elsevier Ltd. Source


Mendes L.A.M.,Institute Engineering Of Estruturas | Mendes L.A.M.,National Laboratory for Civil Engineering | Castro L.M.S.S.,Institute Engineering Of Estruturas | Castro L.M.S.S.,University of Lisbon
Computers and Structures | Year: 2013

This paper introduces an original model to simulate the bond failure between concrete and reinforcing steel bars. The model was developed to be used in threedimensional analyses within the framework of the Finite Element Method and for general loading cases. It was designed using a hierarchical approach by combining what is called the base model, which acts as the skeleton of the model and introduces the basic response under monotonic and reversed loading, and four independent and optional sub-models used to enhance the simulation when needed, by considering the cyclic resistance degradation, the peak stress slip evolution, the reload slip evolution and the radial stress effect. The model implementation within the framework of the Finite Element Method is described and its accuracy is assessed using a series of validation tests. At the end, the main conclusions extracted from this work are presented.© 2013 Elsevier Ltd. All rights reserved. Source


Kuipers M.,University of Lisbon | Kuipers M.,Institute Novas Tecnologias | Tome A.,University of Lisbon | Tome A.,Institute Engineering Of Estruturas | And 5 more authors.
Automation in Construction | Year: 2014

Occupancy and movement data is key information in all phases of the life cycle of built environments, because it has direct repercussions on multiple aspects of their performance. Knowledge on how built spaces are really used remains scarce, despite the technological advances currently available. This paper proposes a system that combines the capacities of computer vision based tracking and the identification capacities of radio frequency-based sensing (RFID) to aid the analytical procedures of the study of the functional condition of architectural artifacts. This will enable us to gain a better understanding of the connections established within the spatial conditions. The process allows one to: a) represent, describe and quantify occupancy/co-presence patterns and movement/navigation patterns; b) characterize the types of users (e.g., professor, student, staff) associated to them; and c) establish correlations between the occupancy/movement patterns and the configurational properties of space. © 2014 Elsevier B.V. Source

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