Single side damage simulations and detection in beam-like structures

Beam-like structures are the most common components in real engineering, while single side damage is often encountered. In this study, a numerical analysis of single side damage in a free-free beam is analysed with three different finite element models; namely solid, shell and beam models for demonstrating their performance in simulating real structures. Similar to experiment, damage is introduced into one side of the beam, and natural frequencies are extracted from the simulations and compared with experimental and analytical results. Mode shapes are also analysed with modal assurance criterion. The results from simulations reveal a good performance of the three models in extracting natural frequencies, and solid model performs better than shell while shell model performs better than beam model under intact state. For damaged states, the natural frequencies captured from solid model show more sensitivity to damage severity than shell model and shell model performs similar to the beam model in distinguishing damage. The main contribution of this paper is to perform a comparison between three finite element models and experimental data as well as analytical solutions. The finite element results show a relatively well performance.

Sulfonated Schiff base copper(ii) complexes as efficient and selective catalysts in alcohol oxidation: syntheses and crystal structures

The reaction between 2-aminobenzenesulfonic acid and 2-hydroxy-3-methoxybenzaldehyde produces the acyclic Schiff base 2-[(2-hydroxy-3-methoxyphenyl) methylideneamino] benzenesulfonic acid (H2L center dot 3H(2)O) (1). In situ reactions of this compound with Cu(II) salts and, eventually, in the presence of pyridine (py) or 2,2'-bipyridine (2,2'-bipy) lead to the formation of the mononuclear complexes [CuL(H2O)(2)] (2) and [CuL(2,2'-bipy)]center dot DMF center dot H2O (3) and the diphenoxo-bridged dicopper compounds [CuL(py)](2) (4) and [CuL(EtOH)](2)center dot 2H(2)O (5). In 2-5 the L-2-ligand acts as a tridentate chelating species by means of one of the O-sulfonate atoms, the O-phenoxo and the N-atoms. The remaining coordination sites are then occupied by H2O (in 2), 2,2'-bipyridine (in 3), pyridine (in 4) or EtOH (in 5). Hydrogen bond interactions resulted in R-2(2) (14) and in R-4(4)(12) graph sets leading to dimeric species (in 2 and 3, respectively), 1D chain associations (in 2 and 5) or a 2D network (1). Complexes 2-5 are applied as selective catalysts for the homogeneous peroxidative (with tert-butylhydroperoxide, TBHP) oxidation of primary and secondary alcohols, under solvent-and additive-free conditions and under low power microwave (MW) irradiation. A quantitative yield of acetophenone was obtained by oxidation of 1-phenylethanol with compound 4 [TOFs up to 7.6 x 10(3) h(-1)] after 20 min of MW irradiation, whereas the oxidation of benzyl alcohol to benzaldehyde is less effective (TOF 992 h(-1)). The selectivity of 4 to oxidize the alcohol relative to the ene function is demonstrated when using cinnamyl alcohol as substrate.

Evolution and biogenesis of microtubule-derived structures

Dissertação apresentada para obtenção do grau de Doutor em Biologia Celular pelo Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa

Utilização de métodos ópticos de correlação de imagem para a determinação da tenacidade à fractura de adesivos estruturais

Mestrado em Engenharia Mecânica

Life-cycle performance of structures: combining expert judgment and results of inspection

Life-Cycle Civil Engineering – Biondini & Frangopol

Vibration control with shape-memory alloys in civil engineering structures

Dissertação apresentada à Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Doutor em Engenharia Civil

Robustness of timber structures in seismic areas

Some of the properties sought in seismic design of buildings are also considered fundamental to guarantee structural robustness. Moreover, some key concepts are common to both seismic and robustness design. In fact, both analyses consider events with a very small probability of occurrence, and consequently, a significant level of damage is admissible. As very rare events,in both cases, the actions are extremely hard to quantify. The acceptance of limited damage requires a system based analysis of structures, rather than an element by element methodology, as employed for other load cases. As for robustness analysis, in seismic design the main objective is to guarantee that the structure survives an earthquake, without extensive damage. In the case of seismic design, this is achieved by guaranteeing the dissipation of energy through plastic hinges distributed in the structure. For this to be possible, some key properties must be assured, in particular ductility and redundancy. The same properties could be fundamental in robustness design, as a structure can only sustain significant damage if capable of distributing stresses to parts of the structure unaffected by the triggering event. Timber is often used for primary load‐bearing elements in single storey long‐span structures for public buildings and arenas, where severe consequences can be expected if one or more of the primary load bearing elements fail. The structural system used for these structures consists of main frames, secondary elements and bracing elements. The main frame, composed by columns and beams, can be seen as key elements in the system and should be designed with high safety against failure and under strict quality control. The main frames may sometimes be designed with moment resisting joints between columns and beams. Scenarios, where one or more of these key elements, fail should be considered at least for high consequence buildings. Two alternative strategies may be applied: isolation of collapsing sections and, provision of alternate load paths [1]. The first one is relatively straightforward to provide by deliberately designing the secondary structural system less strong and stiff. Alternatively, the secondary structural system and the bracing system can be design so that loss of capacity in the main frame does not lead to the collapse. A case study has been selected aiming to assess the consequences of these two different strategies, in particular, under seismic loads.

Earthquakes and robustness for timber structures

Workshop of COST Actions TU0601 and E55 September 21-22 2009, Ljubljana, Slovenia

Robustness of corroded reinforced concrete structures. A structural performance approach

Structure and Infrastructure Engineering, 1-17

Efeitos imediatos da técnica de desrotação do atlas de Rocabado e do SNAG C1/2 de Mulligan na amplitude do teste de flexão-rotação em indíviduos com cefaleia cervicogénica : um ensaio clínico aleatório

RESUMO: A cefaleia cervicogénica é uma forma comum de dor de cabeça, que tem sido associada à existência de uma disfunção das estruturas da coluna cervical superior. Estudos recentes mostram uma grande incidência dessa disfunção a nível de C1-C2, avaliada pelo teste de flexão-rotação. Vários terapeutas manuais, como Brian Mulligan e Mariano Rocabado, têm sido sugerido técnicas de tratamento para este tipo de disfunção. Contudo, a evidência acerca da efectividade dessas técnicas é escassa. Desenho do estudo: Foi efectuado um ensaio clínico aleatório, duplamente cego, composto por três fases: pré-intervenção, intervenção e pós-intervenção. Objectivos: Avaliar e comparar os efeitos imediatos de duas técnicas de Terapia Manual Ortopédica (SNAG C1/2 de Mulligan e técnica de desrotação do atlas de Rocabado), na amplitude de movimento de rotação do segmento vertebral C1-C2, em indivíduos com história de cefaleia cervicogénica e com limitação no teste de flexão-rotação. As técnicas de tratamento foram usadas de forma isolada, em comparação a um grupo placebo. Métodos: Uma amostra de 60 indivíduos, com cefaleia cervicogénica e limitação do teste de flexão-rotação, foram aleatoriamente distribuídos por três grupos: SNAG C1/2 de Mulligan, técnica de desrotação do atlas de Rocabado e grupo placebo. O outcome primário foi a amplitude de movimento obtida no teste de flexão-rotação, que foi medido antes e imediatamente após a intervenção. Resultados: Imediatamente após a intervenção, a amplitude verificada no teste de flexão-rotação aumentou 21.8º (DP, 4.68) no grupo submetido ao SNAG C1/2 de Mulligan, 15º (DP, 5.07) no grupo em que foi aplicada a técnica de desrotação do atlas de Rocabado e 0.65º (DP, 0.67) no grupo placebo. Uma ANOVA modelo misto, 2 por 3, revelou efeito principal significativo do tempo (p<.001) e grupo (p<.001), assim como uma interacção significativa entre grupo e tempo (p<.001), relativamente à variável amplitude do teste de flexão-rotação. Estes resultados indicam que as diferenças verificadas entre os grupos eram dependentes do momento de avaliação. Uma comparação múltipla post hoc revelou que quer as técnicas de Mulligan, quer de Rocabado, produziram efeitos significativamente maiores que a intervenção placebo na amplitude de movimento do teste de flexão-rotação (p<.001 e p=.001, respectivamente). No entanto,não se verificou uma diferença significativa no que diz respeito à efectividade de ambas as técnicas de Terapia Manual Ortopédica aplicadas (p=.42). Conclusão: Esta investigação sugere que as duas técnicas de Terapia Manual Ortopédica avaliadas produziram efeito clínica e estatisticamente significativo na amplitude do teste de flexão-rotação. No entanto, não se verificaram diferenças entre as duas técnicas, no que diz respeito ao seu efeito no ganho de amplitude de movimento. Os resultados obtidos fornecem evidência preliminar sobre a efectividade de ambas as intervenções no tratamento da redução de amplitude de movimento em indivíduos com história de cefaleia cervicogénica.-------------------------------ABSTRACT:Background: Cervicogenic headache is a common form of headache arising from dysfunction in structures of the upper cervical spine. Recent studies have shown a high incidence of C1/2 dysfunction, evaluated by the flexion-rotation test (FRT). Several manual therapists have suggested different approaches to manage that dysfunction, such as Brian Mulligan and Mariano Rocabado. However, the evidence of the effectiveness of those manual techniques is anedoctal. Design: Randomized double blinded controlled trial with three phases: pre-intervention, intervention and post-intervention. Objectives: To determine and compare the immediate effects of two manual therapy techniques (Mulligan’s SNAG C1/2 and Rocabado’s atlas’ derotation technique) in the range of motion of C1-C2 vertebral segments, in cervicogenic headache patients and with limitation on the flexion-rotatoin test. The treatment techniques were used as single treatments against a placebo group. Methods: A sample of 60 subjects with cervicogenic headache and FRT limitation were randomly allocated into one of three groups: Mulligan’s C1/2 SNAG, Rocabado’s atlas derotation technique or placebo group. The primary outcome was the flexion rotation test range, which was measured before and immediately after the intervention. Results: Immediately after the application of the interventions, FRT range increased by 21.8º (SD, 4.68) for the Mulligan’s C1-2 SNAG group, 15º (SD, 5.07) for the Rocabado’s atlas derotation technique and 0.65º (SD, 0.67) for the placebo group. A 2-by-3 mixedmodel ANOVA a significant main effect of time (p<.001) and group (p<.001), as well as a significant interaction between group and time (p<.001) for the variable FRT range. These results indicate that group differences were dependent on time. A pairwise post hoc comparison revelad that both the Mulligan and Rocabado techniques produced significantly more effect on FRT range of motion than the placebo intervention (p<.001 and p=.001, respectively). However, there was not a significant difference between the effectiveness of the two manual therapy techniques (p=.42).Conclusion: This investigation’s findings suggest that both Mulligan’s C1/2 SNAG and Rocabado’s atlas derotation techniques produced a clinically and statistically significant effect on FRT range, but there were no changes between the two techniques in their effectiveness. These results provide preliminary evidence for the efficacy of both manual therapy techniques in the management of individuals with cervicogenic headache and FRT limitation.

A framework for robustness assessment in the context of corroded RC structures

Structural robustness is an emergent concept related to the structural response to damage. At the present time, robustness is not well defined and much controversy still remains around this subject. Even if robustness has seen growing interest as a consequence of catastrophic consequences due to extreme events, the fact is that the concept can also be very useful when considered on more probable exposure scenarios such as deterioration, among others. This paper intends to be a contribution to the definition of structural robustness, especially in the analysis of reinforced concrete structures subjected to corrosion. To achieve this, first of all, several proposed robustness definitions and indicators and misunderstood concepts will be analyzed and compared. From this point and regarding a concept that could be applied to most type of structures and dam-age scenarios, a robustness definition is proposed. To illustrate the proposed concept, an example of corroded reinforced concrete structures will be analyzed using nonlinear analysis numerical methods based on a contin-uum strong discontinuities approach and isotropic damage models for concrete. Finally the robustness of the presented example will be assessed.

Protein glycosylation of exosomes from ovarian carcinoma cells: structures and biological roles

Dissertation presented to obtain the Ph.D. degree in Biology

Robustness of corroded reinforced concrete structures

Short Term Scienti c Mission, COST ACTION TU-0601

A reliability-based measure of robustness for concrete structures subjected to corrosion

This work is a contribution to the definition and assessment of structural robustness. Special emphasis is given to reliability of reinforced concrete structures under corrosion of longitudinal reinforcement. On this communication several authors’ proposals in order to define and measure structural robustness are analyzed and discussed. The probabilistic based robustness index is defined, considering the reliability index decreasing for all possible damage levels. Damage is considered as the corrosion level of the longitudinal reinforcement in terms of rebar weight loss. Damage produces changes in both cross sectional area of rebar and bond strength. The proposed methodology is illustrated by means of an application example. In order to consider the impact of reinforcement corrosion on failure probability growth, an advanced methodology based on the strong discontinuities approach and an isotropic continuum damage model for concrete is adopted. The methodology consist on a two-step analysis: on the first step an analysis of the cross section is performed in order to capture phenomena such as expansion of the reinforcement due to the corrosion products accumulation and damage and cracking in the reinforcement surrounding concrete; on the second step a 2D deteriorated structural model is built with the results obtained on the first step of the analysis. The referred methodology combined with a Monte Carlo simulation is then used to compute the failure probability and the reliability index of the structure for different corrosion levels. Finally, structural robustness is assessed using the proposed probabilistic index.