2031 research outputs found
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Stiffness Degradation Effects on Seismic Behavior of RC Frame Structures
No full textThis study investigates the influence of stiffness degradation on the seismic performance of reinforced concrete (RC) frame structures, focusing on global response parameters including roof lateral displacement ratio (Δ/H), fundamental period (T1), and internal force redistribution. Nonlinear finite element analyses were conducted in SAP2000 for three representative RC frames (3-, 10-, and 20-story), considering beam-only, column-only, and combined stiffness degradation scenarios. The analytical framework integrates theoretical derivations of effective stiffness models with response-spectrum-based simulations, following the provisions of Vietnamese code (TCVN 9386:2012) and American code (ACI 318-25), as well as the formulations proposed by Paulay & Priestley, Elwood & Eberhard, and Tran & Li. The results reveal a clear height-dependent and nonlinear relationship between stiffness degradation and seismic response. In low-rise frames, beam stiffness reduction primarily governs lateral deformation, whereas column stiffness degradation dominates the dynamic behavior and internal force concentration in medium- and high-rise systems. When the effective stiffness ratio falls below EId/EIg = 0.5, roof drift and fundamental period increase sharply, and internal forces at the column base (M and Q) are amplified, leading to excessive deformation and potential instability. Among the models examined, the Tran & Li formulation provided the highest accuracy and stability when validated against experimental data. The findings emphasize that column stiffness should not be reduced below 50% of the gross section stiffness in high-rise frames to maintain acceptable vibration periods and control lateral drift. The novelty of this work lies in quantifying the nonlinear, height-dependent influence of stiffness degradation across multiple structural parameters, bridging the gap between component-level deterioration and system-level seismic performance. The results provide height-sensitive insights for improving nonlinear seismic analysis and performance-based design of RC frame buildings
Thermo-Economic Optimization and Life Cycle Analysis of Bio-Limestone Bricks Enriched with Eggshells for Buildings
No full textTunisia is confronted with dual challenges in its energy transition and the management of organic waste, where eggshells constitute a significant yet underutilized resource, with an annual production approximating 50,000 tons. This study presents an integrated thermo-economic and environmental assessment of bio-limestone bricks incorporating eggshell waste, addressing critical gaps in sustainable construction research. The primary objectives are to present the thermophysical properties of these innovative bricks, evaluate their energy performance at the building scale through dynamic simulation, and quantify their economic viability and environmental benefits. Using dynamic thermal simulation with TRNSYS software validated by analytical solutions for a building in a Mediterranean climate. The methodology combines energy modeling with detailed economic analysis and life cycle assessment to provide a holistic evaluation framework. Key findings reveal that bricks with 20% eggshell content reduce cooling loads by 50.9% (2648 W vs. 5400 W for conventional bricks), achieve annual energy savings of 81.5 TND with a favorable 1.23-year payback period, and reduce CO₂ emissions by 51%. The originality of this work lies in a complete energy and economic simulation and a simplified environmental assessment for building materials enriched with eggshells, providing both waste recovery strategies and energy efficiency of buildings in hot climates
Effect of Silica Modulus on Concrete Maturity at Different Curing Temperatures
No full textThe variation in early-age strength development of concrete mixes containing locally produced OPC, cured at different temperatures throughout the seasons, has motivated many researchers to investigate this issue. This study analyzed how differences in the constituents of locally sourced OPC, particularly the silica modulus, affect strength development and its impact on concrete maturity at various temperatures. Concrete maturity was calculated using strength development over time to determine an equivalent age required to achieve a specific strength at a standard temperature. The equivalent age is a vital factor for determining the appropriate time to remove formwork at construction sites or to open roads to traffic. The study experimentally evaluated three different proportions of OPC constituents, producing three silica modulus (S.M.) values of 2.4, 2.7, and 3.0. It compared the effect of S.M. variation for two cement contents by assessing two groups of concrete with compressive strengths of 20 N/mm² and 35 N/mm², cured at temperatures of 7, 20, and 35 °C. The results revealed that strength increased with increasing curing temperature at all ages, while the rate of strength development decreased as S.M. increased for both strength levels. In contrast, the activation energy of concrete increased with increasing S.M., with the greatest increase observed in concrete with the higher cement content (35 N/mm²). The maturity function results, expressed in terms of equivalent age for concrete cured at non-standard temperatures (7 and 35 °C), showed that equivalent age was influenced by variations in the OPC S.M., with the effect being more pronounced at S.M. = 2.4 compared with S.M. values of 2.7 and 3.0
Numerical Analysis of Lateral and Vertical Deformation of the Embedded Length of Monopile in a Sandy Soil
No full textA monopile is a large-diameter steel cylinder partially inserted into seabeds; thus, it is one of the major selections of offshore wind and tower foundations. This study aimed to investigate the effect of monopile diameter, thickness, and ratio of soil embedded depth to height of water on the lateral and vertical displacements of the embedded part of the pile. In the study, the monopile was subjected to a lateral displacement equivalent to 10% of the pile diameter at the pile head in order to examine the lateral and vertical deformations of the embedded length of the pile. The three-dimensional finite element software PLAXIS 3D was used to simulate the study. The soil layer used consisted of one layer of medium-dense sandy soil. The study involved investigating the location along the embedded depths that exhibit zero lateral and vertical displacements; that location was found to depend on the monopile diameter, wall thickness, and ratio of embedded depth to water height. The depth of zero lateral displacement was found to increase as pile rigidity and wall thickness increase. The study shows that increasing the L/H ratio on the embedded depth of zero lateral displacement, LHzero, diminishes with increasing monopile diameter for the same wall thickness. Also, the variation of lateral displacement along pile length demonstrates a constant trend behavior regardless of pile thicknesses and diameters, but the depth of zero lateral displacement, LHzero, was varied. Furthermore, the monopile diameter effect on the vertical displacement shows that as the monopile diameter increases, the depth of zero vertical displacement decreases. Also, as L/H decreased, the depth of zero vertical displacement declined
Structural Behavior of Beam-Column Connection Using Post-Installed Steel and GFRP Rebars
No full textThis study investigates the performance of steel and GFRP bars as post-installed reinforcement for retrofitting concrete infrastructure through experimental evaluation of the structural performance of the beam-column connection specimens. Three groups of concrete specimens were tested under flexural loading to investigate the influence of bar diameter, bar material (Steel vs. GFRP), and installation method on failure modes, load-deflection curves, and bond strength. The main failure mode at the connections was concrete breakout; however, specimens reinforced with small-diameter post-installed bars tended to fail by bar pullout. The load capacity increases by 9.64% and 12.5% when the diameter of the post-installed GFRP bar increases from 12 to 16 mm and 20 mm, respectively, and the deflection at the midspan of the beam decreases by 17.9% and 33.6% for 16 and 20 mm bars. Specimens with cast-installed reinforcements showed comparable load capacity to post-installed specimens but exhibited lower displacements. Increasing bar diameter reduced bond strength, and GFRP bars showed lower bond strength than steel bars. Overall, the results highlight the potential of GFRP bars as reliable post-installed reinforcement for strengthening critical concrete connections
Flood Simulation Utilizing HEC-HMS and HEC-RAS
No full textThe substantial amount of rainfall leading to runoff in floodplain regions poses hazards to residents within these areas and surrounding zones; consequently, flood simulation is crucial for precise risk evaluation and the formulation of water utilization strategies. In this research, hydraulic and hydrological models, supported by Geographic Information Systems (GIS), were employed to simulate rainfall-runoff mechanisms in Wasit Governorate, central Iraq. A resolution of 30 m Digital Elevation Model (DEM) was supplied by the USGS, geospatially processed, and then imported into the Hydrologic Modeling System (HEC-HMS) at the Hydrologic Engineering Center. The runoff within the research area was estimated using the SCS-CN approach. In order to find the Curve Numbers (CN), a number of datasets were combined, including those pertaining to land use, land cover (LULC), and soil types. The HEC-HMS system was fed CN values obtained from GIS, which varied between 73.95 and 97.61. During the incident in November 2015, the Hydrologic Engineering Center's River Analysis System (HEC-RAS) was utilized to simulate floods using the runoff data resulting from HEC-HMS. Inundation maps were produced using RAS-Mapper within HEC-RAS, depicting flood depth and velocity through the study area. The flood model underwent calibration through comparison of the simulation results with satellite imagery for November 14, 2015. Using CSI, the hydrological factors Ia, Muskingum K, and X, and impervious % were adjusted using sensitivity analysis to achieve the greatest convergence between the model and satellite image. The result of CSI was 88.56%, (HR) was 96.31%, and (FAR) was 8.33%. The validation has been done for the calibrated parameters, and the results were compared with satellite imagery for April 3, 2019. The high level of concordance allowed for the final inundation map to be approved. The importance of measuring runoff for managing water resources effectively and reducing flood risks is highlighted by this study
Unveiling the Barriers to Value Management Implementation in Building Projects: An Integrated EFA-SEM-ANN Analysis Approaches
No full textValue Management (VM) is a structured method for enhancing the effectiveness of building projects, yet adoption in Jordan remains limited. The study identifies the principal barriers to VM adoption in Jordan’s building sector and ranks them to inform policy and practice. A survey of 101 industry stakeholders captured 19 Likert-type indicators. Exploratory factor analysis (EFA) reduced the indicators to coherent barrier clusters; partial least squares structural equation modeling (PLS-SEM) then validated a reflective measurement model and tested links with VM adoption. An artificial neural network (ANN) with k-fold cross-validation quantified predictor importance and assessed out-of-sample error. EFA produced three clusters—standardization and organizational practices, workshop design and participation, and culture and industry environment—explaining approximately 73% of total variance. PLS-SEM supported reliability and convergent/ discriminant validity and indicated that workshop-related and standardization barriers exert the strongest adverse effects on VM adoption. ANN results corroborated these patterns and highlighted workshop dynamics as the most influential predictor. This work presents the first integrated EFA–SEM–ANN analysis of VM adoption barriers in Jordan. The multi-method evidence yields actionable priorities: institutionalize standardized VM procedures, strengthen VM workshop design and participation, and address organizational culture to accelerate VM uptake
Assessment of Red Sea Shoreline Dynamics Through Satellite Imagery and GIS Analysis
No full textMonitoring and analyzing coastal dynamics is essential due to continuous shoreline changes driven by natural processes and human activities with significant environmental and economic impacts. This study aims to quantitatively assess shoreline change along the Red Sea coast using integrated remote sensing and Geographic Information Systems (GIS) techniques. Multi-temporal satellite imagery from 1980 to 2025 was processed to extract shoreline positions, and shoreline change rates were calculated using the EPR method to determine patterns of erosion and accretion. The study area extends along the northwestern part of Saudi Arabia within the Tabuk region, covering Wadi al Ayn, NEOM Port, and the villages of Al Muwaylih, As Sawrah, Sharma, Al Khuraybah, and Qiyal. The results reveal that erosion rates exceed accretion rates across most shoreline segments during the study period. The average EPR of accretion reached 1.13 m/yr, while erosion recorded a higher magnitude with an average rate of −1.99 m/yr. Spatial analysis showed a total accretion area of 1.634 km² compared to a substantially larger erosion area of 19.624 km². This study lies in providing a comprehensive, long-term spatiotemporal assessment of shoreline dynamics using consistent satellite-based measurements, contributing updated baseline data for coastal management and sustainable development planning in the Red Sea region
From Corrosion to Collapse: Spatiotemporal Evolution of Local Stability in Anchored Anti-Dip Slopes
No full textThe long-term stability of anchored anti-dip slopes in hydropower and mining projects is threatened by corrosion-induced degradation of rock bolt systems. Existing deterministic models relying on global safety factors fail to capture localized failure mechanisms and inherent geotechnical uncertainties. This study aims to develop a probabilistic framework for assessing the spatiotemporal stability evolution of such slopes under progressive bolt corrosion. A novel Factor of Local Safety (FoLS) is introduced to quantify stability at individual rock column levels, enabling spatially explicit assessment. This metric is integrated with a time-variant mechanical model for bolt capacity loss and Monte Carlo simulation for uncertainty propagation. Applied to a representative slope, the framework reveals complex degradation patterns: failure initiates in the extremely active toppling zone, progresses to the moderately active zone, and ultimately extends to the passive and shear sliding zones. Sensitivity analyses highlight the critical influence of bolt inclination, yield strength, bolt-rock bond strength, and grout water-cement ratio. Comparative anchorage scenarios demonstrate the superior long-term effectiveness of lower-bench reinforcement. The study provides a novel, spatially differentiated approach for the design, maintenance, and risk management of anchored anti-dip slopes, emphasizing the necessity of dynamic stability monitoring over time
Theoretical Enhancement of Point Resistance in Sandy Soils Using Bio-Inspired Cranial Asperity Ratios
No full textThis study aims to enhance the bearing capacity of pile foundations in sandy soils through a bio-inspired approach by modifying Meyerhof’s empirical equation using a cranial correction factor. The adjustment considers the geometric influence of the asperity length–height ratio (L/H 20, 26.67, and 33.33) applied to different pile diameters. The analysis was carried out theoretically by calculating point resistance (Qp) using the modified equation, followed by validation through ANOVA and the nonparametric Mann–Whitney test. The results indicate that an L/H ratio of 20 provides the most significant improvement in Qp, ranging from 11.7% to 465.8% compared to the conventional Meyerhof model, particularly at lower D/B ratios where stress concentration can be optimally mobilized. Larger ratios such as 26.67 and 33.33 also improve capacity, though less effectively than L/H 20, yet still outperform unmodified foundations. The correction factors obtained, ranging from Cᵣ 1.07 to 5.66, demonstrate the substantial contribution of geometric modification to load transfer efficiency. The novelty of this research lies in integrating anisotropic interface properties into the classical Meyerhof model, thereby bridging the gap between isotropic predictions and anisotropic experimental evidence. Accordingly, the developed theoretical framework not only strengthens the basis for calculating pile bearing capacity but also opens new avenues for bio-inspired foundation design that is more efficient and sustainable