This study investigates the combined effects of metakaolin (MK), crumb rubber (CR), and polypropylene (PP) fibers on the mechanical and durability-related properties of hardened Roller-compacted concrete (RCC). MK was used as a partial cement replacement at levels ranging from 0% to 20% by weight of cement, while PP fibers were incorporated at volume fractions of 0% to 0.2%, and CR was introduced at replacement ratios up to 1% by weight of aggregate. The performance of the mixtures was evaluated through compressive strength, splitting tensile strength, flexural strength, and water absorption tests. The results indicate that the incorporation of MK significantly enhances mechanical performance up to an optimal replacement level of 15%, beyond which strength gains diminish. PP fiber reinforcement notably improves tensile and flexural behavior, with the optimal fiber content identified as 0.1% by volume. Higher fiber dosages resulted in reduced compressive strength due to fiber agglomeration effects. The synergistic use of MK and PP fibers partially mitigates the adverse effects of CR, resulting in improved mechanical performance and acceptable durability characteristics for RCC applications.
This study analyzed how the sandstone's mineralogy and physical properties affect dynamic Young's modulus (Ed). To model these effects, back propagation multilayer perceptron (BPMLP), K-nearest neighbor (KNN), classification and regression tree (CART), simple and multivariate linear regression (MVLR) were employed. After microscopic analysis, compressional and shear wave velocities, water absorption, porosity, and density were measured on the samples. Results showed the calc-litharenite sandstones exhibited a lower Ed compared to the feldspathic litharenite types. Quartz showed a stronger influence on Ed compared to the porosity and water absorption. A strong correlation between Es and Ed was proposed. The dynamic modulus was found to exceed the static Young's modulus (Es) with a calculated ratio of 2.56 (Ed /Es=2.56). Based on the RMSE, Nash-Sutcliffe index, A20 index, and determination coefficient, the methods were appraised. Within the mineralogical types, quartz had the highest correlation with Ed. Mica, opaque, and fragments showed a negative effect on the Ed, while chert and cement showed a positive effect on the Ed. Among the tested models, BPMLP achieved the highest accuracy, with an R of 0.94, RMSE of 0.08, CPM of 1.73GPa, and A20 value of 0.98, along with NSE of 97.04%, confirming the superiority of AI-based approaches over statistical techniques in predicting Ed.
The mesa-like volcanic Kerekbükk hill in the Eastern Cserhát Mountains (N Hungary) hosts numerous small lakes linked to postglacial landslides. Double Lake (Kettős-tó), near the mesa summit, occurs in a geomorphologically atypical position and has therefore been debated as potentially artificial, with uncertain hydrological behavior and function. This study aimed to answer these questions by integrating geodetic and geological field observations with archival historical sources. A detailed geodetic survey was used to build a high-resolution terrain model and reconstruct basin morphology to distinguish natural landforms from anthropogenic modifications. In parallel, we examined 13th–14th-century boundary charters and historical maps (18th century to present) to assess landscape continuity and the persistence of local reference points. Double Lake comprises two basins within a shallow west–east trending glen: the western basin is a natural depression, whereas the eastern basin shows clear human modification, including artificial deepening and a small embankment dam. Resistant andesite bedrock enhances hydrological isolation and restricts incision, allowing water retention despite a minimal catchment. Cartographic representations vary through time, consistent with seasonal water availability and changing survey precision. Field reambulation indicates that a Medieval charter likely documents Double Lake as a stable boundary point since the early 14th century. Overall, Double Lake is a hybrid feature produced by erosion and weathering of the lava cap, and human interaction for local water management, likely for the construction of a dew pond.
River–aquifer interactions play a significant role during floods, yet they are often simplified or neglected in hydrodynamic models. Horizontal infiltration across the riverbed and vertical infiltration through the floodplain jointly contribute to bank storage, delaying and attenuating flood waves. This study presents a conceptual numerical framework that couples 1D surface hydrodynamics, 2D groundwater flow, and a vertical infiltration module to represent these exchanges during overbank flooding. Applied to a simplified lowland river system, the model captures both lateral and vertical flux components and quantifies their contributions to flood wave attenuation. Our findings indicate that, in a 50-km river reach, vertical infiltration through the floodplain accounts for approximately 90% of total bank storage. Total bank storage can contribute up to 4.3% of flow attenuation and reduce peak river water levels by as much as 24 cm. These results highlight the substantial influence of bank storage on extreme flood events and underscore the importance of representing groundwater pathways in flood modelling. The proposed model provides a practical, process-based framework for representing bank storage through a two-way coupled surface water-groundwater formulation with a few physically based parameter set. By explicitly resolving the governing exchange processes, the model enables improved inclusion of bank storage dynamics in flood modelling, while avoiding both simplified loss-type formulations and the complexity of fully multidimensional coupled SW–GW models.
High-frequency vibratory pile driving in saturated non-cohesive soils can induce excess pore pressure and localized instability, posing liquefaction risks to foundation. In this study, we propose a computational framework to assess the liquefaction potential and its spatial impact range by quantifying the energy dynamics between transmitted vibration energy during pile driving and the soil's liquefaction resistance. Model-scale experiments reveal that excess pore pressure accumulation and stress redistribution occur near the pile, indicating the onset of localized instability under high-frequency excitation. The proposed method incorporates a frequency-dependent soil attenuation coefficient, α(f), to capture the critical role of vibration frequency in energy transmission and liquefaction behavior. The framework iteratively evaluates the liquefaction energy demand (NED) and liquefaction energy capacity (NEC), enabling precise estimation of the liquefaction range. Shear modulus reduction and damping ratio curves derived from typical sandy soils are integrated into the analysis to reflect strain-dependent soil behavior. Case studies validate the method's ability to provide early liquefaction risk assessments, with practical implications for optimizing pile driving operations. Although assumptions such as neglecting pore pressure dissipation may overestimate liquefaction extent in shallow layers, the framework bridges theoretical modeling and engineering practice, offering a frequency-sensitive basis for foundation design in complex ground conditions.
In the practice of flood control reservoir sizing the smooth theoretical stage-storage power function relationship necessary for an analytical solution of the nonlinear storage equation is often replaced by a complex series of piece-wise linear functions. A recursive analytical solution can still be employed provided the straight line sections are segmented into a series of intervals over which the straight lines are approximated to a prescribed accuracy by individual power functions. During the application of the recursive analytical solution one must keep track of the outflow stage in order to employ the relevant parameters of the piecewise power functions.
Over the past decade, cement-based composites incorporating natural fibers have emerged as promising alternatives to conventional building materials due to their environmental benefits. The current trend in sustainable construction highlights the growing interest in bio-composites, particularly mortars reinforced with vegetable fibers, which combine technical efficiency with ecological responsibility. Compared to conventional mortars, these bio-composites reduce environmental impact, improve energy efficiency through their low density, and offer enhanced crack resistance and durability under flexural stresses. Hemp fibers, with their complex internal structure and mechanical resilience, are particularly suited for reinforcing cementitious matrices. This study examines the integration of hemp fibers into cement-based composites, aiming to enhance their mechanical performance for construction use. The fibers underwent alkali treatment with different concentrations of sodium hydroxide (NaOH) and were prepared in various lengths before being blended into the mortar. A design of experiments using Response Surface Methodology (RSM) was employed to evaluate the influence of these variables on compressive and flexural strength, tested after 28 days of curing. The outcomes were analyzed through Analysis of Variance (ANOVA) to identify optimal conditions. Additionally, a predictive model was developed to describe the behavior of the composites under varying treatment parameters. This research offers practical insights into the sustainable development of fiber-reinforced cementitious materials and highlights strategies for optimizing their mechanical performance using natural reinforcements.
In seismic design, scaling of ground motion records is critical for the accuracy of structural analysis. According to the Turkish Building Earthquake Code (TBEC 2018), for time history analyses, actual ground motions can be scaled according to the design spectrum. The selection of scale factors by the designer can distort the characteristics of the records and lead to erroneous structural analyses. Especially high scale factors can distort the characteristics of the original record. This study proposes a multi-criteria optimization process for determining scaling factors. The objective function was defined as minimizing the impact on the characteristics of the scaled acceleration records. Harmony Search Algorithm (HSA) and Grey Wolf Algorithm (GWO) were used in the optimization process. Additionally, the scaling process was carried out using the SeismoMatch program. The obtained results were compared in terms of the accelerograms and characteristics of the records. The effects of the optimum scale factors were also examined by conducting time-history analyses on a seven story reinforced concrete structure. According to the optimized results, the peak acceleration value in the accelerograms increased by 1.8 times, while scaling with SeismoMatch resulted in a 7.5 fold increase. Following an optimization process conducted on 11 different ground motion records, it has been demonstrated that the proposed variation-constrained method fully satisfies the TBEC 2018 criteria while exhibiting proficiency in preserving the seismological characteristics and energy content of the acceleration records.
This study demonstrates a performance-based regional structural damage prediction methodology through a case study on the Tuen Mun-Yuen Long Basin in Hong Kong, incorporating 3D topographic, basin, and site amplification effects into fragility mapping. Regionalscale spectral element method simulations, accounting for soil nonlinearity, are conducted to quantify the spatial distribution of spectral acceleration amplifications (SaAmp). The 2%-in-50-years uniform hazard spectrum for Hong Kong was disaggregated to identify dominant magnitude-distance scenarios governing the fragility of short-period structures. An input ground motion was selected to match a short-period conditional mean spectrum, ensuring that the seismic hazard controls structural fragility. Two prototypical lowrise reinforced concrete frame structures were analyzed in ETABS to determine their modal properties and base shear threshold values corresponding to three structural component damage states defined in FEMA P-58-1. Structural fragility was subsequently mapped based on the probability of exceeding these damage states under 2%-in-50-years design spectral demand, spatially amplified using the regional SaAmp datasets. The resulting fragility maps reveal pronounced spatial variability in structural damage potential governed by local geological conditions. The prototypical three-story residential structures located above 20-30 m deep basin deposits exhibited collapse probabilities exceeding 50% due to double resonance between the soil and structure. The prototypical single-story warehouse structures remained resilient, with negligible damage probability. The study demonstrates that accounting for the seismic demands that govern structural fragility, together with spatially-distributed 3D site effects, strongly influences the expected level of structural damage. Neglecting these factors may lead to a substantial underestimation of seismic consequences.
In conventional seismic design, reinforced concrete (RC) frames are typically detailed to form plastic hinges that dissipate seismic energy through inelastic deformation, but this strategy also leads to significant local damage under severe loading. Recent research has focused on low-damage strategies that shift inelastic demand from primary RC members to dissipative components. In this study, a frictional and elastomeric seismic device, originally developed for steel structures, was numerically integrated into an RC beam. Initially, the 3D nonlinear finite element modeling approach was calibrated against the load-deflection response of an experimentally tested RC beam from the literature. Subsequently, the calibrated modeling approach was used to evaluate the cyclic response of device-integrated RC beams. A parametric study was performed to investigate the influence of the friction coefficient, bolt pretension, and embedment configuration of longitudinal steel plates. Numerical results indicate that the device can substantially increase the cumulative energy dissipation capacity of the RC beam. When a single, short embedded longitudinal plate is used to transfer high resisting moments, severe strain localization is observed, leading to premature damage in the surrounding concrete. Using multiple embedded longitudinal plates distributes plastic deformations across a larger concrete volume, preventing the formation of a single dominant strain localization band and allowing the friction mechanism to maintain stable hysteretic behavior at larger drift levels. Although these findings are based on numerical analyses and require experimental verification, they support the concept as a promising solution for low-damage RC applications, provided that embedment detailing is carefully designed.
Riverbank hydraulic structures are typically monitored using deterministic thresholds, whereas their reliability is assessed through probabilistic analysis during design. This separation limits the ability of monitoring systems to quantify evolving structural risk under uncertain geotechnical conditions and stochastic excitations. To bridge this gap, this study proposes an integrated probabilistic monitoring framework that couples offline probability density evolution (PDEM) with online surrogate-based distribution correction. An offline baseline database of response probability density surfaces (PDS) is established by incorporating spatially variable geotechnical parameters and stochastic excitation models within a reduced-dimensional representation. This baseline captures the temporal evolution of structural response distributions under representative environmental scenarios. For near-real-time application, a lightweight surrogate model is developed to infer distribution-level correction parameters from monitoring-derived features, enabling rapid reconstruction of updated PDS without repeated dynamic simulations. The framework is validated through a numerical case study of a fl-shaped anti-scour wall slope. The surrogate-reconstructed PDS demonstrates strong agreement with direct probabilistic solutions, with Jensen-Shannon divergence and Earth Mover's Distance generally below 0.1, while reducing computational cost by more than two orders of magnitude. The proposed method enables real-time extraction of distribution-based risk indicators and provides a probability-informed pathway for monitoring and early warning of hydraulic structures subjected to coupled environmental uncertainties.
This paper presents a numerical investigation of the mechanical behaviour and failure modes of a timber beam with a lapped scarf joint connected by wooden dowels. A finite element model was developed in Abaqus to analyse the structural response of the joint under bending loading. The timber material was modelled as an orthotropic material with nonlinear behaviour, incorporating an appropriate failure criterion to capture stiffness degradation and damage initiation in the structural components. In addition, different contact modelling assumptions between the elements of the joint were considered in order to evaluate their influence on the numerical results. The analysis shows that the numerical model is able to reproduce the global structural response of the beam with reasonable accuracy. However, significant differences in stress distribution and predicted failure modes are observed when different contact assumptions are adopted. The results highlight the important role of contact modelling in the numerical simulation of timber connections with wooden dowels and provide further insight for the development of more reliable finite element models for traditional timber joints
This study innovatively investigates the shear behavior of UHPC-NC composite members by systematically varying key parameters- UHPC interface configuration (ribbed form), thickness (30 mm, 40 mm, 50 mm), stirrup ratio, and shear span ratio. Static loading tests were conducted on four Ultra-High Performance Concrete Reinforced (UR) beams and identical-section Reinforced Concrete Beam (RCB) counterparts. Results reveal that UR beams exhibit 150%-200% higher cracking loads, 31%-48% greater ultimate shear capacity, and significantly enhanced stiffness and ductility compared to RCB beams. Crucially, the UHPC-NC configuration transforms the brittle shear failure mode observed in RCB beams into a ductile flexural failure mode. Furthermore, steel fibers within the UHPC synergize with stirrups to progressively resist shear deformation, effectively mitigating the widening of main cracks. A quantitative relationship between UHPC thickness and shear performance was established, providing valuable engineering design guidelines for bridge reinforcement and semi-precast construction applications. These findings demonstrate the substantial benefits of UHPC integration in enhancing the shear resistance and failure characteristics of composite structural members.
This research paper investigates the efficiency of hybrid vibration control systems combining tuned mass dampers (TMDs) and magnetorheological (MR) dampers for the reduction of seismic vibrations in asymmetric ten-story reinforced concrete buildings. An extensive three-dimensional mathematical representation with two-way eccentricities is formulated that takes into consideration realistic torsional coupling effects. Six historic earthquake records with varied seismic features are used as ground motions scaled to a standard peak ground acceleration of 0.35 g. Five different control settings are test 1. uncontrolled baseline, 2. TMD-only system with 3% mass ratio, 3. MR-only system with four dampers in Passive-On mode, 4. hybrid TMD-MR system with passive control, and 5. hybrid TMD-MR system with a new Response-Tracking Semi-Active Control (RT-SAC) algorithm. Findings indicate that the hybrid RT-SAC setup is superior in performance with an average peak roof displacement reduction of 59.2%, maximum inter-story drift reduction of 46.8%, peak floor acceleration reduction of 48.5%, and base shear reduction of 47.8% compared to the uncontrolled setup. One-way ANOVA statistical analysis demonstrates that control strategy has a significant influence on structural responses (p & iexcl; 0.001), with control configuration accounting for 39.8% variance in peak displacement. The hybrid design offers a more consistent distribution of inter-story drift, with the maximum drift reduced to 1.18% (below the 2.23% exceeding code limits). Energy dissipation analysis indicates that the hybrid system dissipates 48.8% more energy than the uncontrolled structure while requiring a sensible amount of control energy of 92.5 kJ.
This study investigates axial buckling of sandwich composite shells with anti-tetrachiral lattice cores and graphene-reinforced surfaces, analytically deriving mechanical properties for GPL distributions: uniform (UD), V-pattern (FG-V), and X-pattern (FG-X). The fundamental formulas are formed utilizing Reddy higher-order shear deformation theory (HSDT) and minimize the total potential energy principle. The Navier solution tactic is employed to extract the characteristic equation of the system, which is subsequently resolved to calculate the critical buckling load for different geometric and mechanical parameter configurations. The results reveal that volume fraction and distribution of GPLs significantly influence the buckling load, with optimal performance being contingent upon the geometric constraints of the lattice core. By optimizing the lattice core specifications, the highest buckling load can be achieved with minimal GPL volume fraction, enhancing the economic feasibility of nanoparticle usage in such structures. Notably, the FG-V distribution with a 0.05 wt.% GPL demonstrates the most efficient configuration for maximizing the buckling load. The results emphasize the importance of optimizing the geometry of the lattice core to achieve the maximum buckling load. Specifically, for a lattice configuration with Rx/Ry = 1.5, the optimal inclination angle of 10 degrees leads to a 0.8% increase in buckling load compared to other angles. Similarly, for Rx/Ry = 1, the highest buckling load is obtained at an inclination angle of 60 degrees, which is approximately 30% greater than the minimum buckling load observed. These findings highlight the critical role of geometric optimization in maximizing the structural stability and performance of bi-curved sandwich composite shells.
Utility-scale solar farms require reliable design of tens of thousands of driven steel pile foundations, where wind-induced uplift governs. Spatial variability of the shallow subsurface and limited cone penetration test (CPT) coverage mean pile reliability depends on distance from the nearest test - an uncertainty Eurocode 7 does not capture. This paper proposes a probabilistic methodology combining sequential Gaussian simulation (SGS) of CPT data with three capacity methods (LCPC, AFNOR NF P 94-262 and ICP-05) and FOSM/FORM reliability analysis to quantify uplift reliability along linear Chains connecting adjacent CPT locations. The methodology is applied to a solar farm in Pleistocene sandy deposits with 70 CPTs. Two Chains are analyzed: a 309 m Chain through five CPTs in a uniform zone and a 302 m Chain through four CPTs in a variable zone. Pile reliability is governed by two independent contributions. The first is conditioning geometry: the COV of uplift resistance is smallest at CPT locations and grows with distance, forming a wave-like profile with minima of 1.4-2.7% at CPTs and maxima of 3.2-6.1% at midpoints. The second is geological variability: differences in soil strength shift the mean resistance and dominate the reliability index wherever the deposit is non-uniform. Along Chain 1, the FORM reliability index /3 varies only moderately, driven almost entirely by conditioning geometry. Along Chain 2, /3 spans a range over three times wider, reflecting dominant geological heterogeneity. The Chain-based framework provides a site-specific basis for separating these contributions, for optimizing CPT spacing and delineating geological zones.
The behaviour of columns in irregular structures subjected to seismic effects is significantly influenced by torsional moments arising primarily due to asymmetries in the plan. Torsional moments that occur during earthquakes in irregular buildings have a negative impact on the load-bearing capacity and ductility of columns. Therefore, it is crucial to understand how columns behave when subjected to axial loads and torsional effects in order to ensure safe structural design. Seven column specimens were tested under various axial load ratios. The columns represent residential buildings constructed in earthquake zones prior to 2000 in Turkiye, which do not even meet the seismic code requirements of their construction periods in terms of material properties, longitudinal and transverse reinforcement ratios, and restraint details. This experimental study examined torsional moment capacity, cracking and ultimate rotation values, stiffness loss, ductility and energy dissipation parameters. These were then compared with finite element analyses performed using ABAQUS software. The results reveal that axial load-torsion interaction plays a decisive role in the seismic behaviour of columns, exhibiting a nonlinear character. The findings suggest that there is an optimum axial load range, and that exceeding this range significantly reduces torsional ductility. The study suggests that adequate transverse reinforcement, appropriate detailing and an optimum axial load ratio are crucial for the torsional behaviour of reinforced concrete columns.
Problematic expansive soils from the Guabirotuba Formation present engineering challenges, some of them are low shear strength and high compressibility. This research addresses these problems by evaluating the mechanical behavior of this soil when stabilized with lime-activated silica fume (SF) and reinforced with polypropylene fibers (PPF). The experimental program evaluated mixtures containing 6-12% SF, 9% lime, and 0.5% PPF through unconfined compressive strength (UCS), splitting tensile strength (STS), and consolidated undrained (CU) triaxial tests, alongside scanning electron microscopy(SEM). The main findings reveal that lime is essential to activate the pozzolanic reaction of SF. The lime-SF blends form a Calcium Silicate Hydrate (C-S-H) matrix, significantly increasing UCS and STS. While the inclusion of PPF slightly reduced peak STS and had a negligible effect on peak UCS, its primary contribution was transforming the failure mode from brittle to ductile by bridging micro-cracks and preventing abrupt failure. Furthermore, triaxial testing demonstrated that fiber reinforcement consistently increases effective cohesion (c') but decreases the effective friction angle (phi'). SEM analysis corroborated these macroscopic findings, illustrating a densified matrix and strong fiber-matrix adhesion. This study demonstrates that the synergistic use of lime, SF, and PPF enhances the mechanical stability and ductility of Guabirotuba soil, which is relevant in geotechnical engineering applications such as pavement layers, embankments, and earth structures where enhanced post-peak behavior and structural integrityare desirable.
Sustainable concrete can be created by replacing cement with ceramic and brick waste in appropriate proportions. Using brick tile powder (BTP) and ceramic tile powder (CTP) as SCMs is cost-efficient because they recycle ceramic industry waste and offer new output disposal methods. In this study, the effect of replacing cement with BTP and CTP in different ratios and finenesses on workability and strength properties of the mixture was investigated. A sustainability analysis was conducted to estimate the environmental impact of using BTP or CTP as a partial substitute for cement. The performance index approach was used to select the suitable replacement level to obtain a multifunctional mortar mix. Findings reveal that partial replacement of cement with BTP or CTP results in more environmentally friendly binders, reducing production costs and carbon emissions without compromising compressive strength. 20% cement replacement demonstrates a balance between cost efficiency, carbon emission reduction, and compressive strength.
Urban regions are under increasing pressure due to the economic, social, and environmental domains with a steady upward trend in the motor vehicle numbers. Consequently, the demand for liquid fuel oil rises, necessitating gasoline station construction both inside and outside cities. Gasoline stations remain more dangerous even with the adoption of contemporary methods for storing petroleum products and stringent construction and operation guidelines. Furthermore, they pose a risk of hazardous fire and explosion to both humans and buildings. A Geographic Information System (GIS) tool has been developed to model the impacts of gasoline station explosions in urban areas. The tool visualizes relevant variables, such as size of the fireball, danger zone of possible self-emitting combustion, impacted zone of the spilled gasoline combustion, zones of human injuries ranging from 1st degree burns to painful sensations on the skin and mucous membranes, and zones of building damage ranging from total destruction to minor damage. Apart from the danger buffer visualization, affected buildings are extracted, and queries are presented to extract the key statistics. The current study applies the developed strategy to gasoline station network in Tashkent, Uzbekistan, as a case study, to assure model applicability. The study produced encouraging results when assessing station explosion scenarios and displaying danger, human injury, and building damage zones. The model has the advantage of assessing a large collection of gasoline stations automatically, saving time and effort for emergency management while analysing large datasets with hundreds of stations and thousands of buildings in real operation.
