Laminated composites have important applications in modern aeronautical structures due to their extraordinary mechanical and environmental behaviour. Nevertheless, aircraft composite structures are highly vulnerable to impact damage, either by low-velocity sources during maintenance or high-velocity sources during in-flight events. Even barely visible impact damage induced by low-velocity loading, substantially reduces the residual mechanical performance and the safe-service life of the composites structures. Despite the extensive research already carried out, impact damage of laminated composite structures is still not well understood and it is an area of on-going research. Numerical modelling is considered as the most efficient tool as compared to the expensive and time-consuming experimental testing. In this paper, a finite element model based on explicit dynamics formulations is adopted. Hashin criterion is applied to predict the intra-laminar damage initiation and evolution. The numerical analysis is performed using the ABAQUS ® programme. The employed modelling approach is validated using numerical results found in the literature and the presented results show an acceptable correlation to the available literature data. It is demonstrated that the presented model is able to capture force-time response as well as damage evolution map for a range of impact energies.
This paper aims to quantify the evolution of damage in masonry walls under induced seismicity. A damage index equation, which is a function of the evolution of shear slippage and opening of the mortar joints, as well as of the drift ratio of masonry walls, was proposed herein. Initially, a dataset of experimental tests from in-plane quasi-static and cyclic tests on masonry walls was considered. The experimentally obtained crack patterns were investigated and their correlation with damage propagation was studied. Using a software based on the Distinct Element Method, a numerical model was developed and validated against full-scale experimental tests obtained from the literature. Wall panels representing common typologies of house façades of unreinforced masonry buildings in Northern Europe i.e. near the Groningen gas field in the Netherlands, were numerically investigated. The accumulated damage within the seismic response of the masonry walls was investigated by means of representative harmonic load excitations and an incremental dynamic analysis based on induced seismicity records from Groningen region. The ability of this index to capture different damage situations is demonstrated. The proposed methodology could also be applied to quantify damage and accumulation in masonry during strong earthquakes and aftershocks too.
Seismic risk assessment of two real RC multi-story buildings, located on similar soil profile in Kocaeli, is conducted in respect to code-based linear and nonlinear approaches, as well as to P25-v2 Method, a recently suggested method for risk evaluation and preliminary assessment of existing buildings against life-loss. Twenty-five different parameters and seven different collapse criteria are taken into consideration in the suggested P25-v2 Method, including soil and topographic conditions, earthquake demand, various structural irregularities, material and geometrical properties, and location of the buildings. After summarizing the different methodologies and describing the case study buildings, 3D linear-elastic and static nonlinear analyses are performed in parallel to the application of the P25 Method-v2. One of the two case study buildings totally collapsed during 1999 Kocaeli Earthquake, while the other survived with negligible damage, noting that both had legal construction and occupation permissions. SAP2000 and SeismoStruct software packages have been utilised for the analysis procedure to find out the damage states of the structural members at critical stories and to determine the performance levels of the case study buildings. The code-based performance levels and the final performance scores obtained by the preliminary assessment technique are compared in order to underline the existence of the correlation between the detailed procedure and the suggested preliminary assessment technique with the real damage state. Consequently, structural inadequacies, weak points of the buildings and failure reasons are also discussed in this paper.
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DISTENDER will provide integrated strategies by building a methodological framework that guide the integration of climate change(CC) adaptation and mitigation strategies through participatory approaches in ways that respond to the impacts and risks of climatechange (CC), supported by quantitative and qualitative analysis that facilitates the understanding of interactions, synergies and tradeoffs.Holistic approaches to mitigation and adaptation must be tailored to the context-specific situation and this requires a flexibleand participatory planning process to ensure legitimate and salient action, carried out by all important stakeholders. DISTENDER willdevelop a set of multi-driver qualitative and quantitative socio-economic-climate scenarios through a facilitated participatory processthat integrates bottom-up knowledge and locally-relevant drivers with top-down information from the global European SharedSocioeconomic Pathways (SSPs) and downscaled Representative Concentration Pathways (RCPs) from IPCC. A cross-sectorial andmulti-scale impact assessment modelling toolkit will be developed to analyse the complex interactions over multiple sectors,including an economic evaluation framework. The economic impact of the different efforts will be analyse, including damage claimsettlement and how do sectoral activity patterns change under various scenarios considering indirect and cascading effects. It is aninnovative project combining three key concepts: cross-scale, integration/harmonization and robustness checking. DISTENDER willfollow a pragmatic approach applying methodologies and toolkits across a range of European case studies (six core case studies andfive followers) that reflect a cross-section of the challenges posed by CC adaptation and mitigation. The knowledge generated byDISTENDER will be offered by a Decision Support System (DSS) which will include guidelines, manuals, easy-to-use tools andexperiences from the application of the cases studies.
The Krewerder way where residents are in control combined with accelerated assessment concerning earthquake damage seems to be a better way of tackling the reinforcement operation than the usual procedure (see project 'Experiment Krewerd') However, it is necessary to follow the experiment longer to be able to draw firm conclusions and to investigate how resilience develops over time on the level of individual residents and the community as a whole. This research projects targets this.Conclusions set in a report on how resilience develops over time on the level of individual residents and the community as a whole.The Krewerder way where residents are in control combined with accelerated assessment concerning earthquake damage seems to be a better way of tackling the reinforcement operation than the usual procedure (see project 'Experiment Krewerd') However, it is necessary to follow the experiment longer to be able to draw firm conclusions and to investigate how resilience develops over time on the level of individual residents and the community as a whole. This research projects targets this.
Post-earthquake structural damage shows that wall collapse is one of the most common failure mechanisms in unreinforced masonry buildings. It is expected to be a critical issue also in Groningen, located in the northern part of the Netherlands, where human-induced seismicity has become an uprising problem in recent years. The majority of the existing buildings in that area are composed of unreinforced masonry; they were not designed to withstand earthquakes since the area has never been affected by tectonic earthquakes. They are characterised by vulnerable structural elements such as slender walls, large openings and cavity walls. Hence, the assessment of unreinforced masonry buildings in the Groningen province has become of high relevance. The abovementioned issue motivates engineering companies in the region to research seismic assessments of the existing structures. One of the biggest challenges is to be able to monitor structures during events in order to provide a quick post-earthquake assessment hence to obtain progressive damage on structures. The research published in the literature shows that crack detection can be a very powerful tool as an assessment technique. In order to ensure an adequate measurement, state-of-art technologies can be used for crack detection, such as special sensors or deep learning techniques for pixel-level crack segmentation on masonry surfaces. In this project, a new experiment will be run on an in-plane test setup to systematically propagate cracks to be able to detect cracks by new crack detection tools, namely digital crack sensor and vision-based crack detection. The validated product of the experiment will be tested on the monument of Fraeylemaborg.
