Publications

Export 67 results:
Sort by: [ Author  (Desc)] Title Type Year
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 
O
Oliveira, Tiago, Pedro Matias, and Corneliu Cismasiu. "Análise Experimental e Numérica de Painéis de Vidro Laminado Sujeitos à Ação de Explosões." 4.o ENCONTRO DE I&D EM CIÊNCIAS MILITARES – ECM 2022. Sintra: Academia da Força Aérea, 2022.
M
Mihali, Alin, Hugo B. Rebelo, and Corneliu Cismasiu. "Explosion consequences assessment in buildings with complex geometries." 19th International Symposium on Interaction of the Effects of Munitions with Structures. Bonn, Germany 2024.
J
Joaquim, Ana, Corneliu Cismasiu, Filipe Santos, and Elsa Caetano. "Estimation of the tensile force in the stay-cables of Salgueiro Maia Bridge using ambient vibration tests." ISDAC2017 - International Symposium on the Dynamics and Aerodynamics of Cables. Porto: FEUP, 2017. artigo_isdac_v5_ec.pdf
G
Gomes, G., H. Rebelo, V. Lúcio, C. Cismasiu, and J. Mingote. "Experimental Research and Development on Blast Resistant Structures." Advances on Testing and Experimentation in Civil Engineering, Springer Tracts in Civil Engineering. Switzerland: Springer Nature, 2023. 1-20.
Gomes, G. J., V. J. G. Lúcio, and C. Cismasiu. "Development of a high-performance blast energy-absorbing system for building structures." AuxDefense2022 - 3rd World Conference on Advanced Materials for Defense. Guimarães, Portugal 2022.
Gomes, G., V. Lúcio, C. Cismasiu, and H. Rebelo. "Blast Assessment – A Methodology." ISMS 2018 10th Anniversary Conference: Military Sciences and Future Security Challenges. War Studies University, Warsaw 2018. gomes.pdf
de Gomes, Gabriel Jesus, Valter José Guia da Lúcio, Corneliu Cismasiu, and José Luis Mingote. "Experimental Validation and Numerical Analysis of a High-Performance Blast Energy-Absorbing System for Building Structures." Buildings. 13.601 (2023): 1-20.
de Gomes, Gabriel Jesus, Valter José Guia da Lúcio, and Corneliu Cismasiu. "Development of a high-performance blast energy-absorbing system for building structures." International Journal of Protective Structures. 15.3 (2024): 484-508. AbstractWebsite

Shock absorbers have been widely used in the automotive and aeronautical industries for many years. Inspired on these devices, the paper presents an analytical and numerical assessment of a high performance protective system for building structures against blast loads, which is composed of a shielding element connected to the main structure, at the floor levels, through ductile Energy Absorbing Connectors (EACs). The EACs exploit the external tube inversion mechanism to absorb a significant part of the imparted kinetic energy from the blast wave. While the system prototype has been developed in laboratory, it was characterized and tested in a full-scale blast testing campaign. A validated finite element model was used next to analyze its performance in a more demanding design scenario. The introduction of EACs notably reduces the peak horizontal loads and the kinetic energy transferred to the protected structure, being expected a significant reduction of the stresses in the supporting vertical elements, in addition to the protection of structural and non-structural members. These results encourage further studies of the presented protective system that can be potentially employed for a large variety of blast threat scenarios, especially when increasing the stand-off is not a possible/viable option and sensitive facilities have to be protected.

Gomes, G. J., Válter Lúcio, and Corneliu Cismasiu. "Full Scale Blast testing of a High-Performance Energy-Absorbing System." PROTEDES2022. Região Sul da Ordem dos Engenheiros, Lisboa 2022.
G, Gomes, Lúcio V, Cismasiu C, and Rebelo H. B. "Blast Assessment - uma metodologia de avaliação." Construção Magazine.86 (2018): 18-23.
F
Freitas, J. A. T., and C. Cismaşiu. "Adaptive p-refinement of hybrid-{T}refftz finite element solutions." Finite Elements in Analysis and Design. 39 (2003): 1095-1121. Abstract

An adaptive p-refinement procedure for the implementation of the displacement model of the hybrid-{T}refftz finite element formulation is presented. The procedure is designed to select and implement automatically the degrees of freedom in the domain (displacements) and on the boundary (surface forces) of the element to attain a prescribed level of accuracy. This accuracy is measured on the strain energy of the system for a prescribed finite element mesh. Local measures of error can be easily accounted for. The performance of the adaptive procedure suggested is illustrated using two-dimensional potential problems.

de Freitas, J., I. Moldovan, and C. Cismaşiu. "Hybrid-Trefftz displacement element for poroelastic media." Computational Mechanics (2011): 1-15. AbstractWebsite

The elastodynamic response of saturated poroelastic media is modelled approximating independently the solid and seepage displacements in the domain and the force and pressure components on the boundary of the element. The domain and boundary approximation bases are used to enforce on average the dynamic equilibrium and the displacement continuity conditions, respectively. The resulting solving system is Hermitian, except for the damping term, and its coefficients are defined by boundary integral expressions as a Trefftz basis is used to set up the domain approximation. This basis is taken from the solution set of the governing differential equation and models the free-field elastodynamic response of the medium. This option justifies the relatively high levels of performance that are illustrated with the time domain analysis of unbounded domains.

Freitas, J. A. T., and C. Cismaşiu. "Hybrid-{T}refftz displacement element for spectral analysis of bounded and unbounded media." International Journal of Solids and Structures. 40 (2003): 671-699. Abstract

The hybrid-{T}refftz displacement element is applied to the elastodynamic analysis of bounded and unbounded media in the frequency domain. The displacements are approximated in the domain of the element using local solutions of the wave equation, the Neumann conditions are enforced directly and the surface forces are approximated on the Dirichlet and inter-element boundaries of the finite element mesh. Two alternative elements are developed to model unbounded media, namely a finite element with absorbing boundaries and an unbounded element that satisfies explicitly the Sommerfeld condition. The finite element equations are derived from the fundamental relations of elastodynamics written in the frequency domain. The numerical implementation of these equations is discussed and numerical tests are presented to assess the performance of the formulation.

Freitas, J. A. T., and C. Cismaşiu. "Developments with hybrid-{T}refftz stress and displacement elements." Computer Assisted Mechanics and Engineering Sciences. 8 (2001): 289-311. Abstract

The paper reports on the work on hybrid-{T}refftz finite elements developed by the Structural Analysis Research Group, ICIST, Technical University of Lisbon. A dynamic elastoplastic problem is used to describe the technique used to establish the alternative stress and displacement models of the hybrid-{T}refftz finite element formulations. They are derived using independent time, space and finite element bases, so that the resulting solving systems are symmetric, sparse, naturally $p$-adaptive and particularly well suited to parallel processing. The performance of the hybrid-{T}refftz stress and displacement models is illustrated with a number of representative static and dynamic applications of elastic and elastoplastic structural problems.

Freitas, J. A. T., C. Cismasiu, and Z. M. Wang. "Comparative analysis of hybrid-Trefftz stress and displacement elements." Archives of Computational Methods in Engineering. State of the art reviews. 6.1 (1999): 35-39.
Freitas, J. A. T., and C. Cismaşiu. "Numerical implementation of hybrid-{T}refftz displacement elements." Computers & Structures. 73 (1999): 207-225. Abstract

The numerical implementation of the displacement model of the hybrid-{T}refftz finite element formulation is presented. The geometry of the supporting element is not constrained a priori. Unbounded, non-convex and multiply connected elements can be used. The approximation basis is naturally hierarchical and very rich. It is constructed on polynomial solutions of the governing differential equation, and extended to include the particular terms known to model accurately important local effects, namely the singular stress patterns due to cracks or point loads. Numerical and semi-analytical methods are used to compute the finite element matrices and vectors, all of which present boundary integral expressions. Appropriate procedures to store, manipulate and solve symmetric highly sparse systems are used. The characteristics of the finite element solving system in terms of sparsity and conditioning are analysed, as well as its sensitivity to the effects of mesh distortion, incompressibility and rotation of the local reference systems. Benchmark tests are used also to illustrate the performance of the element in the estimation of displacements, stresses and stress intensity factors.

Fonseca, Amândio, Corneliu Cismasiu, and Ildi Cismasiu. "Avaliação da vulnerabilidade sísmica de um edifício pombalino através de análise dinâmica incremental." Jornadas Portuguesas de Engenharia de Estruturas (JPEE). Lisboa: LNEC, APEE, GPBE, SPES, 2022. art_jpee2022_266_afccic_v8.pdf
C
Cismasiu, Corneliu, and Filipe Amarante P. dos Santos. "Numerical simulation of superelastic shape memory alloys subjected to dynamic loads." Smart Materials and Structures. 17 (2008): 025036 (12pp). AbstractWebsite

Superelasticity, a unique property of shape memory alloys (SMAs), allows the material to recover after withstanding large deformations. This recovery takes place without any residual strains, while dissipating a considerable amount of energy. This property makes SMAs particularly suitable for applications in vibration control devices. Numerical models, calibrated with experimental laboratory tests from the literature, are used to investigate the dynamic response of three vibration control devices, built up of austenitic superelastic wires. The energy dissipation and re-centering capabilities, important features of these devices, are clearly illustrated by the numerical tests. Their sensitivity to ambient temperature and strain rate is also addressed. Finally, one of these devices is tested as a seismic passive vibration control system in a simplified numerical model of a railway viaduct, subjected to different ground accelerations.

Cismaşiu, C. The hybrid-{T}refftz Displacement Element for Static and Dynamic Structural Analysis Problems. Lisboa, Portugal: Instituto Superior Técnico, 2000. Abstract

The displacement model of the hybrid-{T}refftz finite element formulation is applied to the solution of geometrically and physically linear static and dynamic problems. As the approximation bases solve locally the governing system of differential equations, the errors in the approximation affect only the implementation of the boundary conditions. Potential and elastostatic problems are used to illustrate the enforcement of the boundary conditions and the convergence of the solutions in energy, stresses and displacements, under both p- and h-refinement sequences and their insensitivity to mesh distortion, incompressibility and positioning of the coordinate system of the approximation basis. Also illustrated is the use of elements with arbitrary geometry and the efficiency that can be reached by including in the bases the solutions associated with dominant local effects, in particular those associated with singular stress fields. An adaptive p-refinement algorithm that exploits the naturally hierarchical nature of the approximation bases is presented and assessed. The formulation is generalised for elastodynamic analysis in the frequency domain of both bounded and unbounded domains, which are modelled either with absorbing boundary conditions or with semi-infinite elements that satisfy the Sommerfeld condition. The performance of the formulation is illustrated with tests on the convergence of the solutions in energy, stresses and displacements and on their insensitivity to mesh distortion, wave length and position of the absorbing boundary, for a wide spectrum of forcing frequencies and under both p- and h-refinement sequences.

Cismaşiu, C., A. Narciso, and F. Amarante dos Santos. "Experimental Dynamic Characterization and Finite Element Updating of a Footbridge Structure." Journal of Performance of Constructed Facilities.10.1061/(ASCE)CF.1943-5509.0000615 (2014).Website
Cismaşiu, Corneliu, Filipe Amarante Dos P. Santos, Rui Da Silva A. Perdigão, Vasco M. S. Bernardo, Paulo X. Candeias, Alexandra R. Carvalho, and Luís M. C. Guerreiro. "Seismic Vulnerability Assessment of a RC Pedestrian Crossing." JOURNAL OF EARTHQUAKE ENGINEERING. X.X (2018): 1-19.
Cismasiu, Corneliu, and Filipe Amarante Dos P. Santos. "Shape Memory Alloys." Ed. Book Corneliu edited by: Cismasiu. ISBN: 978-953-307-106-0. Croatia: Scyio, Publishing, 2010. 127-154. Abstract
n/a
Cismasiu, C., and Amarante F. P. dos Santos. "Towards a semi-active vibration control solution based on superelastic shape memory alloys." 15th WCEE. Lisbon, Portugal 2012. 2012_wcee_0379.pdf
Cismaşiu, Corneliu, Pedro B. S. Silva, José V. Lemos, and Ildi Cismaşiu. "Seismic Vulnerability Assessment of a Stone Arch Using Discrete Elements." International Journal of Architectural Heritage (2021): 1-15. AbstractWebsite
n/a