Papers
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Papers
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Freeze-thaw durability of vacuum infused glass fibre composites with unsaturated polyester and vinyl ester matrices
This paper presents an experimental study about the effects of freeze-thaw cycles (FTC) on the mechanical and thermomechanical properties of glass-fibre reinforced polymer composite laminates produced by vacuum infusion using two different polymer resins: unsaturated polyester (UP) and vinyl ester (VE). Following preconditioning in distilled water for 30 days at 20
Year: 2024
Author(s): Hasan, T.; Correia, J. R.; Garrido, M.; Soares, F.; Cabral-Fonseca, S.; Jorge, M.; J. SENA-CRUZ
: Construction and Building Materials
Editor: Elsevier
Volume:
455.
Keywords: durability; freeze-thaw cycles; vacuum infusion; vinyk ester; unsaturated polyester; Glass-fibre reinforced polymer
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Global and local geometrical imperfections of pultruded GFRP profiles based on a modal approach
ABSTRACT - The ultimate capacity of pultruded glass fibre reinforced polymer (pGFRP) profiles depends significantly on geometrical imperfections (GIs), given their sensitivity to buckling phenomena arising from both thin walls and low elastic moduli. However, GIs are not yet comprehensively addressed in design guidance. This paper proposes a new approach to characterize the initial GIs of pGFRP profiles based on a modal approach. Given the lack of comprehensive knowledge in this area, this study presents a highly accurate and robust methodology to measure GIs and dimensional deviations (DDs) in pGFRP profiles using a 3D contact coordinate measurement machine (CMM). The modal approach encompasses the measurement of dimensional parameters and a point cloud transformation that enables the assessment of GIs associated with pure buckling modes of pGFRP profiles. This procedure allows the quantification of three types of global GIs associated to (i) minor-axis (weak axis), (ii) major-axis (strong axis) bending, and (iii) twist. Additionally, the procedure also includes the assessment of local GIs, considering the wall (plate-like) imperfections. The separation of GIs into these four types (shape and amplitude) is of major relevance as its paves the way to the development of analytical design formulas for the strength prediction of pGFRP members. The approach described in this paper also serves two important purposes: (i) the statistical analysis of DDs and GIs of pGFRP members, and (ii) the identification of distinct shapes and amplitudes of GIs that form the basis for reliable design considerations of pGFRP members.
Year: 2024
Number Pages:
18p..
Author(s): Silvestre, N.; Correia, J.; Pinheiro, A.; Ribeiro, A.; Lages Martins, L.; Lazzari, J.
: Construction and Building Materials
Editor: ELSEVIER
Volume:
412 (2024) 134813.
Keywords: Modal decomposition; Geometrical imperfections; Dimensional deviation; 3D contact measurements; Pultruded profiles; Glass fibre reinforced polymer (GFRP)
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Hygroscopicity and Morphology of Bio-Based Boards
The internal structures and the hygroscopicity of bio-based boards consisting of giantreed (Arundo donax L.) and hazelnut shells as bio-aggregates, and a sodium silicate solution asthe adhesive, were investigated. The aim was to evaluate the influence of each material (the bio-aggregates and adhesive) and their distributions in the boards on the final performance. By carrying out X-ray computed tomography, the internal structures and the porosities of the boards were determined, allowing important considerations of their hygroscopicity. The voids
Year: 2024
Number Pages:
22p..
Author(s): Cintura, E.; Lina Nunes; Molari, L.; Bettuzzi, M.; Morigi, M.; Brancaccio, R.; Faria, P.
: Applied Sciences
Editor: MDPI
Volume:
14, 873.
Keywords: Tomography; Sodium silicate; Moisture buffering; Hygroscopicity; Hazelnut shel; Giant reed; Bio-resource; Bio-aggregate; Arundo donax; Agro-industrial waste
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Hygrothermal behaviour of external thermal insulation composite systems (ETICS) to withstand biological colonisation
ETICS are multilayer building solutions applied to the building external walls to provide animproved thermal performance to the building envelope. However, several questions have beenraised concerning the durability of ETICS, namely related to biological colonisation phenomena.Considering the high susceptibility of ETICS to bio-colonisation, the following research questions arise: (i) what is the impact of surface temperature (ST) and surface relative humidity (SRH)fuctuation on mould growth in ETICS facades? (ii) is it possible to predict mould growth onETICS under fuctuating conditions considering favourable and unfavourable growth conditions?This study aims to investigate the infuence of the hygrothermal behaviour of five different ETICS(with thermal mortars and insulation boards) on mould growth. ETICS were exposed for one yearat an urban site in Lisbon, Portugal, facing North, during which the ST and the SRH weremonitored. Concurrently, numerical simulations were performed to evaluate the hygrothermalbehaviour of the ETICS. Three theoretical indices were applied, using numerically and experimmentally obtained values of ST and SRH as input to provide an indication of the risk of mould growth. The results were complemented and validated by assessing the bio-colonisation, water performance and aesthetic properties of the ETICS. Index 1 (percentage of time with SRH
Year: 2024
Number Pages:
25.
Author(s): Parracha, J.; Veiga, M. R.; Flores-Colen, I.; Lina Nunes
: Journal of Building Engineering
Editor: Elsevier Ltd.
Volume:
86 e 108932.
Keywords: Numerical simulation; Onsite monitoring; Mould growth; Moisture; Temperature; Thermal insulation materials
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Identifying contributing factors and locations of pedestrian severe crashes using hazard-based duration model
Pedestrian safety remains a significant concern, with the growing number of severe pedestrian crashes resulting in substantial human and economic costs. Previous research into pedestrian crashes has extensively analyzed the influences of weather, lighting, and pedestrian demographics. However, these studies often overlook the critical spatial variables that contribute to pedestrian crashes. Our study aims to explore these overlooked spatial variables by examining the distance pedestrians travel before encountering a severe crash. This approach provides a supplementary perspective in safety analysis, emphasizing the importance of pedestrian movement patterns. The model considers various factors that may influence pedestrian traveled distance before being involved in a severe crash, such as weather conditions, lighting conditions, and pedestrian demographics. Ohio
Year: 2024
Number Pages:
107500.
Author(s): Kakhani, A.; Jalayer, M.; Kidando, E.; Roque, C. A.; Patel, D.
: Accident Analysis & Prevention
Editor: Elsevier
Volume:
198.
Keywords: Crash Severity; Cox Model; Traveled Distance; Pedestrian Crash; Hazard-Based Duration Model
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Improving Surfability Assessment along a Submerged Detached Breakwater at Praia da Vagueira, Portugal
A case study aiming to improve surfing conditions over a submerged detached breakwater, intended to be placed in front of Praia da Vagueira (Aveiro, Portugal), was concluded in April 2022. The final results are revisited and refined by incorporating an alternative wave breaking line detection method, using the resulting eddy viscosity parameter from the COULWAVE numerical model. Preliminary results demonstrate good agreement with experiments and indicate the potential for a more detailed analysis, but further investigation is required.
Year: 2024
Author(s): Tavares, P.; Mendonça, A.C.; Fortes, C. J. E. M.; Bicudo, P.
Editor: IARH EUROPE CONGRESS
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Integrating Uncertainty in Performance Assessment of Water Distribution Networks by Scenario Building
This paper presents and demonstrates a novel scenario-building methodology that integrates contextual and future time uncertainty into the performance assessment of water distribution networks (WDNs). A three-step approach is proposed: (i) System context analysis, identifying the main key factors that impact the WDN performance; (ii) Scenario definition, identifying the implicated WDN variables, describing its possible evolution, and conjugating them to further establish the reference scenario and the two most relevant and opposite ones; and (iii) Scenario modelling, simulating the WDN behaviour for those scenarios. The obtained spatial and temporal hydraulic results are further used to calculate performance metrics. The methodology is applied to a real WDN to assess resilience performance considering infrastructure asset robustness (real water loss performance indicator), service reliability (minimum pressure index), and service flexibility (network resilience index). A new formulation to assess the metric evolution over time is proposed, deducting the further-away performance results by using an uncertainty weight. The results demonstrate that the increase in metric amplitude for the opposite scenarios over time highlights future uncertainty, reflecting context uncertainty, and the comparison of metric spatial distribution (i.e., at the pipe/node levels) highlights critical areas with higher associated uncertainty.
Year: 2024
Number Pages:
18p..
Author(s): Carneiro, J.; Loureiro, D.; Cabral , M.; Covas, D.
: Water
Editor: MDPI
Volume:
Volume 16, Issue 7.
Keywords: Resilience metrics; Scenario modelling; Scenario planning; Aleatory uncertainty; Drinking water networks
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Life Cycle Carbon Assessment of Mortars with Carbonated and Non-Carbonated Recycled Aggregates
Global warming is one of the most important issues that the world is currently facing.The cement industry accounts for around 7% of total global CO2 emissions. According to the 13th United Nations Sustainable Development Goals, cement plants must become carbon neutral by 2050. This neutrality may be achieved by a reduction in CO2 emissions complemented with carbon capture, utilization and storage (CCUS) technologies. In accordance with these sustainable goals,several approaches have been studied. This paper investigates life cycle carbon of mortars produced with carbonated recycled aggregates. In previous works, the carbon dioxide capture capacity of construction and demolition waste (CDW) was analysed, and mortars with CDW recycled aggregates submitted to high levels of CO2 were evaluated in terms of their mechanical performance. This paper focus on the life cycle carbon impact assessment (LCCA) of industrial mortar formulations in a cradle-to-gate boundary. This assessment is carried out through a global warming potential environment impact assessment, since it represents the amount of CO2 equivalent that is sent to the atmosphere and contributes to the
Year: 2024
Author(s): Farinha, C.; Pederneiras, C.; Infante Gomes, R.; Bastos, D.; Veiga, M. R.
: Applied Science
Editor: MDPI
Volume:
14.
Keywords: global warming potential; life cycle carbon assessment; carbon capture and storage; cement; recycled aggregates; construction and demolition waste
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Metrological quality of the excitation force in forced vibration test of concrete dams
Abstract. This paper describes the study of the metrological quality of the excitation force in the context of force vibration test of concrete dams. For this purpose, a measurement uncertainty evaluation was performed, based on available probabilistic information about the input quantities
Year: 2024
Author(s): Lages Martins, L.; Gomes, J. P.; Ribeiro, A.
: Journal of Physics
Editor: IOP Publishing
Volume:
vol. 2647.
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Monitoring internal swelling reactions in concrete dams
Alkali-silica reaction (ASR) and delayed ettringite formation (DEF) are the most common internal swelling reactions (ISR) in concrete dams. The swelling effects and concrete deterioration caused by ISR can be observed in several forms at the structural level, including relative movements between blocks, displacements and deformations, cracking, surface discoloration around the cracks, scaling or spalling as well as surface
Year: 2024
Number Pages:
749-756pp..
Author(s): Conde Silva, J.; Serra, C.
: Procedia Structural Integrity
Editor: Elsevier
Volume:
Volume 64.
Keywords: Expansion estimation; Monitoring instruments; Concrete dams; DEF; ASR
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