Browsing by Author "Fernandes, P."
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- Characterisation of Portuguese RC Precast Industrial Building StockPublication . Rodrigues, H.; Sousa, R.; Vitorino, H.; Batalha, N.; Varum, H.; Fernandes, P.; Liu, ZaobaoThe construction of a vulnerability model requires reliable information on the features of the buildings in the study. The purpose of this work is the characterisation of the precast industrial buildings in Portuguese industrial park, based on the survey of 73 design projects of existing buildings. The collected data are based on a previous study on the features that influence the seismic response of this type of buildings. The parameters collected are associated with the global geometry and specific elements characteristics (e.g., column dimensions, reinforcement ratios, and connections details), to the mechanical properties of the materials and other parameters that can give some important information in the characterisation of the buildings (e.g., construction year and localization). In the end, a comparison with other available databases, namely, from Italy and Turkey, is done in order to conclude about the similarity. This information is important to define representative experimental specimens and numerical simulation to conduce seismic risk analysis.
- Partial Safety Factors for Prestressed Concrete Girders Strengthened with CFRP LaminatesPublication . Dias-da-Costa, D.; Neves, L. A. C.; Gomes, S.; Graça-e-Costa, R.; Hadigheh, S. A.; Fernandes, P.This paper provides a framework for the calibration of partial safety factors in prestressed concrete (PC) girders strengthened in flexure with carbon fiber-reinforced polymer (CFRP) laminates. A hybrid approach was proposed to take advantage of comprehensive nonlinear numerical models in reliability analysis using a first-order reliability method (FORM) in conjunction with the response surface method (RSM). The PC girders selected for analyses were taken from real structures designed and built in the 1980s based on old standards that now require strengthening and upgrade due to partial corrosion of the prestressing strands. Using the proposed approach, a sensitivity analysis was performed to identify the most relevant variables and assess the area of CFRP laminates needed to restore capacity up to new design standards. A partial safety factor was proposed for strengthening PC girders using CFRP laminates. Sensitivity analysis showed that traffic loads and model uncertainties are the most important variables for calibration.
- Probabilistic-based characterisation of the mechanical properties of CFRP laminatesPublication . Gomes, S.; Dias-da-Costa, D.; Neves, L.A.C.; Hadigheh, S.A.; Fernandes, P.; Júlio, E.Fibre reinforced polymer (FRP) composites have been increasingly used worldwide in the strengthening of civil engineering structures. As FRP becomes more common in structural strengthening, the development of probability-based limit state design codes will require accurate models for the prediction of the mechanical properties of the FRPs. Existing models, however, are based on small sample sizes and ignore the importance of the tail region for analyses and design. Addressing these limitations, this paper presents a probabilistic-based characterisation of the mechanical properties of carbon FRP (CFRP) laminates using a large batch of tension tests. The analysed specimens were pre-cured laminates of carbon fibres embedded in epoxy matrices, which is the most commonly used laminate for the strengthening concrete beams and slabs. Based on the existing data, probabilistic models and correlations were established for the Young's modulus, ultimate strain and tensile strength. Analyses demonstrate the suitability of the Weibull distribution for the estimation of CFRP properties. Results also show that the statistical characterisation of the mechanical properties should be performed with a focus on the tail region. The proposed distributions constitute a set of validated probabilistic models that can be used for performing reliability analyses of structures strengthened with CFRP laminates.