Over the past three decades, the strengthening and repair of existing civil engineering structures using FRP laminates has attracted a great deal of attention. With the advances in polymer science, ...adhesive bonding has become a common joining technology in these applications. Despite numerous studies that address the short-term behaviour of adhesively bonded FRP/steel joints, uncertainty with respect to long-term performance still remains. This knowledge gap is regarded as a critical barrier, hindering the widespread application of FRPs to strengthen and retrofit steel structures. This paper presents the state of the art in terms of the durability of FRP/steel joints used in civil engineering applications. Important influential factors relating to the durability of adhesively bonded joints are reviewed and different damage mechanisms are discussed. Moreover, related investigations of the combined environmental durability of these joints are critically reviewed and the findings are presented. The paper concludes with a discussion to motivate future research topics, while it is emphasised that the generalisation of the available results is questionable.
Summary Geophysics and Geotechnical Engineering commonly use one-dimensional (1D) wave propagation analysis, simplifying complex scenarios by assuming flat and homogeneous soil layers, vertical ...seismic wave propagation, and negligible pore water pressure effects (total stress analysis). These assumptions are commonly used in practice, providing the basis for applications like analyzing site responses to earthquakes and characterizing soil properties through inversion processes. These processes involve various in-situ tests to estimate the subsurface soil’s material profile, providing insights into its behavior during seismic events. This study seeks to address the limitations inherent to 1D analyses by using three-dimensional (3D) physics-based simulations to replicate in-situ tests performed in the Argostoli basin, Greece. Active and passive source surveys are simulated, and their results are used to determine material properties at specific locations, employing standard geophysical methods. Our findings underscore the potential of 3D simulations to explore different scenarios, considering different survey configurations, source types, and array sets.
In the Cigéo project for deep geological of radioactive waste, the project manager has to follow the convergence of tunnel (cells) cross-section built at 490 m depth. This convergence is due to the ...mechanical pressure in the rock layer. Vibrating Wire Extensometers (VWE) are ised to measure the strain at their locations. Our objective is to optimize the location of sensors to estimate the horizontal stress due to strain observations. This issue is solved using an inverse problem, which first requires the creation of a direct model that represents the bahviour of a cross-section. From rock data measured on site, thanks to an underground demonstrator, a numerical model is developed to generate s strain database for different VWE locations with different rock stresses and rigidities. The theoritical orientation of the sensors is orthoradial, but they can have angle and intrinsic errors. Considering various types of uncertainties, an inverse model based on Bayesian approach is developped to calculate the probability distribution of stresses. The last step is to use a genetic algorithm to determine the optimal sensor distribution. The best sensor placements is found to be near the kidneys, i.e. at more or less 45° around 0° and 180°.
Crack propagation can be affected by the holes of the placement of rebars in the reinforced concrete and the resulting changes in the homogeneous structure of concrete. This experimental study aimed ...at investigating the fiber self-compacting concrete failure and crack propagation in concrete specimens with circular central holes and contain 2, 4, and 8 fiber percentages. The crack propagation mechanisms under the uniaxial compressive strength of the concrete were studied by investigating the holes created by rebars buried in the reinforced concrete. Three concrete mix designs with different compressive strengths of 27, 30, and 33 MPa were used for detailed analysis of the fiber concrete behavior by 224 standard 150 mm cubic specimens. The results showed the insignificant impact of small holes with an approximate area of 1.4% of the specimen surface area on the failure structure so that crack propagation in this case was similar to that occurred in the hole-free concrete. The compressive strength of concrete decreased, by increasing the crack prorogation around the holes. The compressive strength of the concrete may be reduced significantly by increasing the hole diameter. Taking into account these factors in the design of the connection core can reduce the compressive strength of concrete by 30% depending on the rebar grid.
Peat soil presents significant challenges for construction due to its inherent weak properties, including high water content, limited permeability, low shear Strength, low specific gravity, and ...acidity. Despite the potential of Mg-rich synthetic gypsum (MRSG) to improve soil properties, research on its use for stabilising severely poor peat soils is limited. This study addresses this gap by investigating the efficacy of MRSG in peat soil stabilisation using a novel multi-layering backfill approach. The methodology includes soil classification of peat soil. And, to understand the mechanical and chemical changes of stabilized peat soil, the unconfined compressive Strength (UCS) testing and microstructural analysis using SEM, EDX, and XRD before and after stabilisation are studied. Peat samples were treated with MRSG through backfilling method in 5, 7, and 9 layers and evaluated the strength increment after curing periods of 7, 28, and 60 days. Results demonstrate that MRSG significantly enhanced the compressive strength, increasing it to 210.33 kPa as early as 7 days for 9 layers of backfill incomparable with the untreated soil strength of 51.87 kPa. The new cementitious product in the soil known as ettringite was observed from SEM analysis and confirmed by the EDX and XRD analysis. By recycling industrial byproducts, this environmentally friendly method encourages sustainability and lessens dependency on raw resources, which is important for infrastructure construction and other projects in areas rich in peat.
This paper takes place in improving the energy performance assessment of cob buildings, by evaluating thevariability of its hygrothermal properties at the material scale, related to the traditional ...construction process. Forso, we proposed and analysed data to handle the variability of the hygrothermal properties. The specimens weremanufactured using a moulding method representative of on-site cob wall manufacturing process, for three plants species (hemp shiv, flax yarn and hay stalk) and three fibre content (0, 1% and 3%). Using non-destructivetests and statistical analysis, the random variability of cob composites hygrothermal properties (density, thermalconductivity, specific heat capacity, water-vapor permeability, moisture buffering value and sorption isotherms)was found as well as the variability distribution. It has been shown that the variability of properties is sensitive tothe nature of plant fibres specie and the fibre content. Using the variability indicators, it has been found on thermal conductivity, a low coefficient of variation of 2.88% for 1%-flax fibred mixture (lower than unfibred material) and a high one for 3%-hemp composites of 10.88%. The variability of sorption isotherms was usually found to be high at lower humidity loads. It has been shown that increase fibre content stabilizes the variability of properties. Moreover, some evolution trends of the variability according to mixes was proposed; two parameters were found: the first, either FCmax highlighting the fibre content for which the maximum of variability was achieved or FCmin for the opposite; the second is FCres highlighting the residual variability, for high fibre content. The distribution of properties were found to be generally centered.
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