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°.
This study aims to introduce a comprehensive methodology for optimizing complete real structural systems for roofs involving trusses, purlins, and bracing systems jointly, taking into account ...realistic loads and constraints dictated by technical codes, thereby offering a more accurate representation of practical scenarios. The objective is to achieve the minimum mass through size, shape, and topology optimization of both the main truss and purlin structural subsystems. To achieve this goal, the Enhanced Particle Swarm Optimization (EPSO) algorithm is implemented. An example of a realistic case, which takes into account multiple actual constraints such as stress, displacement, buckling, and natural frequency limits, is thoroughly evaluated. After that, 144 other interactions among dimensions of the building and loads applied are simulated, and the mass of the system is obtained for each one of them. The results indicated that the graphs generated from the various simulations allow for the determination of the optimized mass for different building dimensions. Consequently, the cost and raw material consumption can be estimated for common applications. Therefore, it is concluded that this work presents a significant contribution to structural designers, as the proposed methodology enables structural optimization quickly and easily for practical engineers.
This paper presents a comprehensive Discrete Element Method (DEM) calibration program designed for optimal calibration of hot mix asphalt (HMA) in full-scale paving applications. The program allows ...for the calibration of various asphalt mixes and allows for studies such as how tamper stroke affects pre-compaction based on the calibrated HMA. The study identifies key pavement properties essential to the paving process, including pre-compaction resistance, flow behavior, and friction behavior between HMA and steel or asphalt surfaces, and details their laboratory-based evaluation methods. A contact model that incorporates realistic plastic deformation, adhesive forces, and multiple load cycles is presented in this research. Novel features include a two-clump particle shape system and a two-grain distribution for the grading curve. These parameters, combined with the contact model, facilitate the observation of particle orientations and segregations, ensuring an economical yet robust full-scale simulation. Validation included testing and calibration of three different asphalt mixes (Asphalt Concrete (AC) 11 DS, Stone Mastic Asphalt (SMA) 11 DS, and AC 16 BS). The results demonstrate the successful calibration of all relevant pavement properties using the prescribed methodology and settings. This study advances the understanding of HMA pavement properties and provides a practical framework for optimal calibration in full-scale paving scenarios.
In building construction, seepage and dampness in walls present serious problems since they can cause structural failures and damage in both residential and commercial contexts. Finding more ...affordable options is necessary as mitigating these problems frequently requires expensive fixes. This study aims to evaluate the effects of solvothermal-treated polyethylene added at concentrations ranging from 0 to 1.0% on the mechanical properties of concrete and sandcrete blocks. In addition to assessing the workability, split tensile strength, and compressive strength of concrete samples at different levels of the polyethylene (PE) inclusion, the study looked into the water absorption capacity, density, and compressive strength of sandcrete blocks. The blocks’ compressive strength and water absorption capacity reduced as the amount of polyethylene additives rose, although there was a slight increase in the density. These changes remain well within the Nigerian Industrial Standards’ specified limits. Hardened concrete shows a drop in density, compressive strength, and split tensile strength with increasing polyethylene content, while fresh concrete's workability decreases as the percentage increases. 0.4% incorporation of the treated polyethylene achieved the target strength of 20 N/mm
2
while Sandcrete blocks with up to 1% of the solvothermal treated polyethylene had compressive strengths more than the 2.5 N/mm
2
minimum required for non-load-bearing walls. About 61% reduction in water absorption was achieved in 48 h by the blocks, presenting a promising and cost-effective solution for seepage-related issues in building construction.
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.
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