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A Model for the Reduction of Flood Peak Discharge (ΔQp) Due to the Retarding Basin
Get PDFThis research aims to develop a model for flood peak discharge reduction (ΔQp) through the placement of retarding basins within a watershed system, represented by the area ratio of the controlled watershed (RAk) and the maximum storage capacity of the retarding basin (Vk). The area ratio of the controlled watershed (RAk) is defined as the ratio between the catchment area of the retarding basin and the total watershed area (Ak/A). The methodology involves simulating various retarding basin placements (RAk) and different maximum storage capacities (Vk) for several flood return periods (QT). This study was conducted in the urban agglomeration area of Wonosari, Gunungkidul Regency, Special Region of Yogyakarta, Indonesia. The placement and utilization of retarding basins result in varying levels of flood peak discharge reduction (ΔQp) at the downstream control point (Taman Pancuran), depending on the maximum storage capacity of the retarding basin (Vk) and its placement within the watershed (RAk). The resulting empirical equations for flood peak discharge reduction (ΔQp) using the retarding basin method are as follows: ΔQp = 0.105654 − 0.014593 Vk − 0.029251 RAk + 0.011089 QT for Vk values in the range (V1–V4) = 36.4–208.8 × 10³ m³, and ΔQp = 1.374989 − 0.003702 Vk − 0.338381 RAk + 0.004773 QT for Vk values in the range (V4–V200) = 136.2–7039.1 × 10³ m³. An observed anomaly was identified, where ΔQp became positive at small values of Vk and RAk, indicating an increase in peak discharge (Qp)
Effect of Incorporating Hematite Powder on Torsional Behavior of High Strength Steel Fiber Reinforced Concrete Members
Get PDFThis research aims to investigate the effect of hematite powder on the first cracking and ultimate torsional resistance, crack patterns, and angle of twist of high-strength concrete beams strengthened with steel fibers under pure torsion. The study was carried out in two stages. The first stage consisted of six hollow cross-section beams to determine the best ratio and type of steel fiber that provide the highest torsional resistance. The second stage aimed to find the optimal ratio of hematite powder that can improve the torsional resistance of high-strength steel fiber-reinforced concrete without causing implementation problems. This was achieved by testing six hollow cross-section beams with hematite ratios of 0.5%, 1%, 1.5%, 2.5%, 3.5%, and 5% as cement replacements. The results showed that using hematite powder up to 2.5% as a cement replacement, combined with a 1.5% mix of steel fibers (50% end-hooked and 50% corrugated), increased both the first cracking and ultimate torque, along with a relative increase in the angle of twist. Additionally, it delayed crack development, reduced crack width, and increased the number of cracks at failure
Experimental Study on Electrochemical Corrosion Law of Rebar Under Alternating Magnetic Field
No full textThe alternating magnetic field (MF) environment of coastal substations and magnetic levitation systems generates strong electromagnetic interference, which may affect the corrosion behavior of rebars in concrete structures. To clarify the influence law of rebar corrosion when exposed to an alternating MF, an alternating MF simulation test device was designed and manufactured according to the principle of alternating electromagnetic induction. The macroscopic corrosion morphology and electrochemical corrosion characteristics of rebars under alternating MF of different intensities were investigated by accelerated corrosion tests, electrochemical tests and natural corrosion electrochemical tests. The corrosion behavior mechanism of rebars under alternating MF was revealed. The results show that: 1) The diffusion rate and concentration of corrosion products in the solution are proportional to the magnetic induction strength. The alternating MF accelerates rebar corrosion. 2) The Ecorr of rebar shifts negatively with the magnetic induction strength increases, with a more pronounced shift in the early stage of corrosion than in the later stage. 3) Under the natural corrosion state, the 5 mT MF makes the open circuit potential (OCP) shift 12 mV negatively compared with that without MF. When the potential reaches 8mV, the passivation film begins to be destroyed. 4) The R1 of rebar is inversely proportional to the magnetic induction strength
Advanced Retrofitting Solutions for RC Slabs: CFRP, ECC, and Steel Plate Comparison
Get PDFRetrofitting reinforced concrete (RC) slabs is crucial for enhancing their flexural strength, ductility, and durability, particularly in aging or seismically deficient structures. This study aims to evaluate and compare the effectiveness of three retrofitting techniques: steel plate bonding, carbon fiber reinforced polymer (CFRP) sheets, and engineered cementitious composites (ECC) with expanded steel mesh in improving the structural behavior of RC slabs. The research integrates both experimental testing and numerical analysis using ABAQUS finite element modeling to assess load–deflection behavior, failure mechanisms, and strength enhancement. The findings revealed that the use of CFRP sheets and ECC with expanded mesh significantly improved the slabs’ structural performance, increasing ultimate load capacity by up to 58% and ductility by more than 40% compared to the control specimens. Conversely, steel plate retrofitting showed inferior performance due to inadequate interfacial bonding. The numerical results exhibited strong agreement with the experimental data, with an average FEM-to-test ratio of 1.04. The study highlights the superior efficiency of CFRP and ECC techniques in strengthening RC slabs, offering enhanced deformation capacity, energy dissipation, and overall seismic resilience, which contributes to the ongoing development of sustainable and high-performance rehabilitation strategies for concrete structures
Evaluation of Different Rapid Assessment Approaches for Seismic Risk Evaluation of Masonry Structures
No full textMasonry structures hold notable historical and cultural significance but exhibit inadequate seismic performance due to low-strength materials and structural limitations. This paper aims to investigate and prioritize the seismic risk of masonry buildings to support preservation strategies, enhance urban resilience, and contribute to sustainability. To achieve this, different rapid assessment methods were comparatively applied, providing a practical alternative to detailed seismic analysis, which was impractical for large building stocks. This study focused on the masonry structures of Osijek, a city characterized by moderate seismic hazard, where these buildings are vital to the cultural heritage, tourism, and identity of the local community. Risk prioritization was conducted for 105 masonry buildings using data collected through systematic field observations and measurements. Findings indicate that while rapid assessment methods provide valuable insights for identifying vulnerable structures, their sensitivity and applicability vary according to building characteristics and the available data. The comparative analysis emphasizes that some methods are more effective at detecting structural deficiencies, whereas others are more suitable for large-scale screening when resources are limited. The novelty of this study lies in identifying the efficiency and limitations of different rapid assessment approaches, thereby advancing knowledge in seismic risk prioritization and providing guidance for heritage protection and disaster risk reduction
Strength Characteristics and Material Design of Recycled Flexible Pavement Materials
No full textThis study develops a strength-based mix-design framework for rehabilitating flexible pavements using reclaimed asphalt pavement (RAP) blended with crushed rock (CR) and cement. Objectives were to quantify 7-day unconfined compressive strength (UCS) as a function of mixture variables and to provide field-ready proportioning equations. Methods comprised laboratory testing of RAP–CR blends (RAP = 0–100%) with 2–5% cement, Modified Proctor compaction, and 7-day UCS; regression related UCS to a modified parameter (w/c)(1−k·AS), where asphalt content (AS) is obtained from AS = 0.04·RAP. Findings show that increasing RAP lowers dry density (2.31→2.11 g/cm³) and raises optimum moisture (5.03→7.17%). The 7-day prediction is qᵤ,7 = 23.44/[(w/c)(1−0.22·AS)]0.677 (R² = 0.863). A worked example (4-cm asphalt over a 20-cm base; 20-cm milling) gives RAP = 20%, AS = 0.80, recommended w/c = 1.31, and cement = 4.03% at OMC = 5.28% and dry density = 2.276 g/cm³, satisfying 1.72 MPa (17.5 kg/cm²) at 7 days. Novelty/Improvement: the framework consolidates RAP content and binder effects into a single modified w/c parameter, enabling rapid, transparent proportioning for construction control. Broader impacts include reduced demand for virgin aggregate and haul-off of demolition debris, fewer truck movements and landfill burdens, and potential life-cycle cost savings in network-level rehabilitation
Passive Earth Pressure Analysis for Unsaturated Soils on Retaining Walls Incorporating Arching Effect
No full textRetaining structures in geological and geotechnical engineering are often embedded in unsaturated soil strata. Conventional methods for calculating earth pressure in unsaturated soils typically ignore the rotation of principal stresses in the backfill, a phenomenonknown as the soil arching effect. This study presents a novel analytical framework for determining the passive earth pressure in unsaturated soils that explicitly incorporates this arching effect. The proposed model accounts for both principal stress rotation and the hydro-mechanical coupling between matric suction and soil stress under groundwater influence. Based on the shear strength criterion for unsaturated soils, the model assumes a circular-arc trajectory for the rotating major principal stress, and hydrostatic seepage with matric suction distributed linearly with depth. Using a coordinate axis translation technique, quantitative relationships among lateral earth pressure, interlayer shear stress, and vertical stress are established. The force equilibrium equations for a horizontal differential soil element are then solved to derive closed-form expressions for the passive earth pressure distribution and resultant force. Validation against physical model tests and numerical simulations confirms the model’s accuracy and demonstrates its superiority over the extended Rankine theory, which systematically underestimates passive resistance. Parametric studies highlight the influences of groundwater depth, initial matric suction, and soil strength parameters. The proposed framework offers a more realistic and mechanically sound basis for the design of retaining structures in unsaturated soil environments
Robust Ensemble Machine Learning for Flash Flood Susceptibility Mapping Across Semiarid Regions
No full textFlash floods cause severe environmental and socio-economic impacts in arid and semi-arid regions. This study aims to improve the accuracy of flash flood susceptibility mapping in southwestern Morocco’s Assaka watershed by using an ensemble of machine learning models. Four models, Logistic Regression (LR), Multivariate Discriminant Analysis (MDA), Naïve Bayes (NB), and Multilayer Perceptron (MLP), were trained on a flood inventory of over 1.5 million data points and 14 environmental factors (e.g., altitude, slope, land surface temperature, soil moisture index). Each model produced a susceptibility map, and a voting ensemble of the top-performing models (all above 80% accuracy) further improved reliability. The MLP achieved the highest predictive performance, followed closely by LR and MDA. Sensitivity analysis identified altitude, topographic position index, land surface temperature, and soil moisture index as the most influential factors. The ensemble susceptibility map highlights densely populated areas near the city of Guelmim and infrastructure along major rivers as most prone to flash flooding. These findings enable practical mitigation measures such as improved drainage, early warning systems, and better land-use planning in high-risk zones. Integrating multiple models in an ensemble is a novel approach that reduces uncertainty and provides a more robust tool for flash flood risk prediction
BIM-Based Integrated Model for Project Cost Estimation: A Case Study for Concrete Elements
Get PDFConstruction projects often struggle to align design models, cost estimates, and scheduling processes. To address this challenge, this study presents an integrated 5D BIM model that automates cost and schedule estimation by linking 3D BIM components to a structured database of historical productivity and activity data. A unique coding system connects each BIM object to its corresponding construction tasks, enabling automatic generation of resource-loaded schedules with associated durations, costs, and crews based on the selected construction method. The workflow integrates Autodesk Revit, Navisworks, a relational (SQL) database, and Primavera P6 to achieve seamless interoperability across design, estimating, and scheduling tools. The model is validated through a case study of a six-story reinforced concrete building. Findings show that the approach significantly improves estimation, accuracy, and efficiency. Predicted costs closely match actual values, thereby reducing dispersion among estimates. The automated process minimizes manual data handling while keeping cost and schedule outputs synchronized. Novel contributions include the incorporation of detailed historical productivity data, construction method alternatives, and structured cost/activity records into a unified framework, representing a methodological advance in 5D BIM that bridges the design, estimating, and scheduling domains for more reliable and automated project planning
Behavior of Deep Beams with Different Proportions of Recycled Plastic Type HDPE Instead of Coarse Aggregate
Get PDFOne of the most appealing strategies in the ongoing effort to lessen humans' impact on the environment is using waste plastic as coarse particles in concrete. This innovative approach addresses the pressing issue of mounting plastic waste and aims to diminish the adverse effects of traditional building materials, such as natural aggregates, on the environment. Plastic waste as coarse aggregates exemplifies a professional dedication to creating a resilient infrastructure that mitigates environmental harm and contributes to a greener future for future generations. Eight deep beams were cast with sustainable concrete that was made from two mixtures: one in normal strength (C30) and the other in high-strength concrete (HSC) (1% Hyperplast PC200 of cement) that included HDPE plastic, which was taken from fruit boxes that had been crushed and used in 10, 20, and 30 percentage volumetric proportions as a substitute for coarse aggregate. The two still intact have no HDPE replacement and serve as each deep beam's reference deep beam. Shear failure and ductility in the second group were slightly lower than 2% compared to the reference beam for B30. It can be argued that while the replacement has positive environmental impacts, the 23.5% loss in strength is unwanted, while the 2% decline in ductility is acceptable. While maintaining a competent structural flexural behavior, the first group demonstrated an increase in shear failure by the replacement rate (20%, 30%), and the 10% replacement rate dropped by a tiny percentage (1.25%) in comparison to the reference specimen