Numerical and experimental characterization of Steel - Wood doweled joints under Quasi-Static loading

The objective of this work is to investigate the quasi-static mechanical behaviour of doweltypetimber joints. Therefore, four dowel arrangements were experimentally tested to assurethe stability of a steel-wood joint. The results revealed different behaviour regarding thedistance between dowels and distance to the free edge of the wood member. An approachbased on cohesive zone modelling was adopted to replicate both the ductile and brittle failureobserved in the experiments

Comportamento ao corte no plano de paredes frontal

The reconstruction of Lisbon Downtown after the 1755 earthquake was based on a novel constructive system based on masonry buildings with an internal three-dimensional timber-framed structure named "gaiola pombalina". This internal structure aimed at improving the global stability of masonry buildings, enhancing their capacity to dissipate energy under seismic loadings. This paper aims at getting experimental insight on the mechanical behaviour of such timber-framed walls subjected to in-plane loading, as only scarce information is available in literature, in order to assess their effective performance to seismic actions. To do this, the experimental results of cyclic tests carried out on traditional timber-framed walls with distinct typologies will be analyzed, in order to evaluate the failure modes, lateral resistance and energy dissipation; moreover, ahysteretic model will be derived for traditional timber-framed walls. Additionally, the possibility of strengthening the traditional connections of the walls by means of GFRP is also addressed.A reconstrução da Baixa de Lisboa após o terramoto de 1755 foi feita com base num novo sistema construtivo de edifícios de alvenaria com uma estrutura tridimensional interna de madeira designada de "gaiola pombalina", Esta estrutura interna visa reforçar a estabilidade global dos edifícios de alvenaria, melhorando a sua capacidade para dissipar energia quando sujeitos a cargas sísmicas. Este trabalho tem como objetivo a análise do comportamento mecânico de paredes de frontal sujeitas à acção combinada de cargas verticais e de cargas laterais cíclicas de modo a simular o comportamento à acção sísmica. O programa experimental consiste num conjunto de ensaios cíclicos realizados em de frontal tradicionais com tipologias distintas, nomeadamente frontais não preenchidos; (2) frontais com preenchimento em alvenaria; (3) paredes de frontal com reforço nas através da aplicação de materiais compósitos de fibras de (GFRP), A analise de resultados dos ensaios experimentais permite a obtenção de parâmetros tais como a rigidez inicial e a sua degradação, e a dissipação de energia ao longo do processo de carregamento cíclico, Adicionalmente, é possível a obtenção das principais características de deformação e modos de rotura das paredes bem como os diagramas de histerese característicos das paredes, através dos quais e possível derivar um modelo de histerese para estas paredes. Refira-se que muito pouca informação existe neste domínio, pelo que o presente trabalho apresenta grande importância e destina-se a contribuir para o estado da arte

In-plane shear behaviour of traditional timber walls

The reconstruction of Lisbon Downtown after the 1755 earthquake was based on a novel constructive system based on masonry buildings with an internal three-dimensional timber-framed structure named “gaiola pombalina”. This internal structure aimed at improving the global stability of masonry buildings, enhancing their capacity to dissipate energy under seismic loadings. This paper aims at getting experimental insight on the mechanical behaviour of such timber–framed walls subjected to in-plane loading, as only scarce information is available in literature, in order to assess their effective performance to seismic actions. To do this, the experimental results of cyclic tests carried out on traditional timber-framed walls with distinct typologies will be analyzed, in order to evaluate the failure modes, lateral resistance and energy dissipation; moreover, a hysteretic model will be derived for traditional timber-framed walls. Additionally, the possibility of strengthening the traditional connections of the walls by means of GFRP is also addressed

Crack Closure Effects on Fatigue Crack Propagation Rates: Application of a Proposed Theoretical Model

Structural design taking into account fatigue damage requires a thorough knowledge of the behaviour of materials. In addition to the monotonic behaviour of the materials, it is also important to assess their cyclic response and fatigue crack propagation behaviour under constant and variable amplitude loading. Materials whenever subjected to fatigue cracking may exhibit mean stress effects as well as crack closure effects. In this paper, a theoretical model based on the same initial assumptions of the analytical models proposed by Hudak and Davidson and Ellyin is proposed to estimate the influence of the crack closure effects. This proposal based further on Walker’s propagation law was applied to the P355NL1 steel using an inverse analysis (back-extrapolation) of experimental fatigue crack propagation results. Based on this proposed model it is possible to estimate the crack opening stress intensity factor, Kop, the relationship between U=ΔKeff/ΔK quantity and the stress intensity factor, the crack length, and the stress ratio. This allows the evaluation of the influence of the crack closure effects for different stress ratio levels, in the fatigue crack propagation rates. Finally, a good agreement is found between the proposed theoretical model and the analytical models presented in the literature

In-plane shear behaviour of traditional timber walls

The reconstruction of Downtown Lisbon after the 1755 earthquake was based on a novel constructive system of masonry buildings with an internal three-dimensional timber-framed structure named ‘‘gaiola pombalina’’. This internal structure aimed at improving the global stability of masonry buildings, enhancing their capacity to dissipate energy under seismic loadings. But this structural system is not only typical of Portugal, but constitutes part of the built heritage of various countries. This paper aims at getting experimental insight on the mechanical behaviour of timber-framed walls subjected to in-plane loading, as only scarce information is available in literature, in order to assess their effective performance to seismic actions. To do this, the experimental results of cyclic tests carried out on traditional timber-framed walls with distinct typologies will be analysed, namely (1) unreinforced timber-framed walls without infill; (2) timber-framed walls without infill with Glass Fibre-Reinforced Polymer sheets (GFRP) placed at the connections; (3) timber-framed walls with brick masonry infill