Journal of Civil Engineering Researchers
“Journal of Civil Engineering Researchers” is an independent publisher, consistently working towards being an internationally- recognized publishing company, specializing in high-quality electronic publications. Our Online submission, electronic peer review, and production make the process of publishing your article simple and efficient. Our team of editors makes the right decisions based on the quality of a manuscript and its adherence to the norms of the field. Read more Google Scholar, ISC, and ... Indexe the full text of scholarly literature published by the Journal of Civil Engineering Researchers. Online ISSN: 2538-516X
In collaboration with Golestan University and Assoc. Prof. Dr. Morteza Jamshidi
Study the Effect of Soil-Structure Interaction on Natural Period of Conventional Buildings Using Wolf’s Cone Model
Soil-structure interaction is often a difficult problem to study. This article uses Wolf’s Cone Model and its application in the substructure method to investigate the effect of soil-structure interaction on natural period of conventional buildings. In accordance with Iran’s Construction Code 2800, five soil types were considered. The studied structures were 4, 7, and 10 storey buildings. The following results were obtained: 1) The interaction between soil and structure was much more pronounced in finer soils, 2) The relative change in period was greater in shorter buildings, 3) The soil-structure interaction decreased as the ratio of “foundation dimension to soil thickness layer” increased.
Copyright (c) 2026 Journal of Civil Engineering Researchers https://creativecommons.org/licenses/by/4.0
Engineering Geopolymers for Sustainable Construction: From Synthesis to Performance
Because of the large amount of CO₂ emissions associated with its production, ordinary Portland cement (OPC) is gradually replaced by more eco-friendly binders, among which geopolymers are the most promising. This review highlights the most important features of geopolymer cements, the production of which uses aluminosilicate precursors, mainly metakaolin, fly ash, blast furnace slag, and various agricultural wastes, cured at a temperature below 100°C. The review discusses the chemical composition, nanostructure, mechanical performance, and durability of geopolymers, as well as their CO₂ footprint, comparing them to OPC. It was found that geopolymers have a unique amorphous aluminosilicate binder formed by cross-linked SiO₄ and AlO₄ tetrahedra, whereas the OPC binder consists of calcium-silicate-hydrate gel. The formation of a geopolymer’s nanostructure allows achieving compressive strengths of 20 MPa after 4 h and 100 MPa after 28 days. Geopolymers are resistant to acid attack, alkali-silica reaction, high temperatures, and permeability. Moreover, the carbon footprint of fly ash- and slag-based geopolymer concrete can be as low as 70% lower than that of OPC concrete. Nevertheless, due to the need for further research into their behavior in natural conditions, geopolymers currently cannot be recommended as a binder for large-scale construction projects.
Numerical Investigation of the Effect of Mass Irregularity on Progressive Collapse of RC Buildings
Mass irregularity, which amplifies stress concentrations and torsional demands, substantially increases the risk of progressive collapse in reinforced concrete structures. Improper design and non-uniform mass distribution are key contributors to such failures, highlighting the need for optimized design and targeted strengthening measures. This study investigates the effects of column removal on a two-story RC moment-resisting frame using ABAQUS. A one-third-scale frame was numerically modeled under both regular and irregular quasi-static loading, considering the removal of a corner and a side column. The model was validated against experimental results, and structural performance was assessed in terms of load-bearing capacity, stiffness degradation, and energy absorption. Results show that adjacent columns experience higher stress than the removed column due to rapid load redistribution through surrounding beams and columns. The progressive collapse sensitivity index under vertical and lateral loads reached 76.2% and 78.5% for corner-column removal under irregular loading, compared to 71.6% and 72.2% for side-column removal. These findings indicate heightened vulnerability to progressive collapse for corner-column loss and irregular mass distribution, emphasizing the importance of uniform mass distribution and robust structural design to mitigate progressive failure.
Evaluation of High Capacity Helical Piles in Silty Clay
A new foundation system employing in situ grouting of helical screw piles has recently been developed. The paper discusses design considerations, installation procedures and results of full scale field load tests. This study assessed axial static loading tests on single, double and triple helix helical piles under grouted and un-grouted conditions. The field study was conducted to investigate the behavior of helical piles in silty clay soil. Also, the ultimate load capacity (Qu) for each pile test was predicted using six different interpretation methods. Also, the effect of post-grouting on the strength of these piles was assessed and the results of the piles load tests were interpreted using 6 methods presented in literature to predict the ultimate load capacity (Qu) for each pile. Results showed that the grouted helical piles are excellent foundation systems for the resistance of uplift, as well as, compressive loads and resistance against corrosion and less harmful to the environment than other types of piles especially in urban areas.
Evaluation of the Effect of Rice husk ash on the Mechanical Properties and Gamma Ray Attenuation of Concrete
This study investigated the viability of rice husk ash (RHA) as a sustainable and performance-enhancing partial substitute for cement in concrete. The used RHA, characterized by a novel chemical composition abundant in silicon and aluminum oxides, was incorporated into ordinary concrete at increasing substitution ratios up to 25%. A comprehensive evaluation was conducted to assess the influence of RHA on various properties of the resulting concrete, including physical (setting time, standard consistency, workability), mechanical (compressive and tensile strength), microstructural (XRD, and EDX), and radiation shielding characteristics. The results indicated that RHA marginally increased cement setting time, with a maximum 7.14% increase observed at a 25% replacement level. However, it significantly increased water demand for standard consistency, reaching 35.7% at 25% replacement. The increased water demand correlated with a reduction in workability, with a maximum slump reduction rate of 57.3% at the 25% replacement level. Importantly, the optimal replacement levels for mechanical strength enhancement were at 10% for compressive strength and 15% for tensile strength, achieving improvements of 13.74% and 9.48%, respectively. Additionally, The Monte Carlo simulation code as well as PhyX software were employed for assessing the concrete samples' significant gamma and fast neutron radiation attenuation characteristics. Gamma-ray attenuation tests demonstrated a modest improvement in the gamma-ray shielding capacity of the resulting concrete. The linear attenuation of the prepared sample containing 15% RHA was found to be higher than the other samples, due to its high density. On the contrary, the 25RHA sample is a less valuable sample. The 15RHA sample had the highest value for FCS (0.090 cm-1) indicating its efficacy and capability as a neutron shield.
Seismic Behavior Evaluation of Steel Frames Equipped with Rotational Friction Damper
In performance-based seismic design, controlled dissipation of earthquake energy without damage to primary structural members is of great importance. Rotational friction dampers (RFDs) are considered an effective solution due to their stable hysteretic behavior and high energy dissipation capacity. However, direct simulation of the nonlinear behavior of RFDs is difficult in conventional linear analyses. In this study, an equivalent linear model for the RFD based on the principle of work-energy equivalence is presented, in which the equivalent rotational stiffness and equivalent viscous damping parameters are derived from kinematic relationships and Coulomb friction. The proposed model is implemented in ETABS software as a linear Link element with a rotational degree of freedom.To evaluate its performance, a one-story, one-bay steel frame was analyzed under three different configurations: (1) an intermediate moment frame (IMF), (2) an IMF with a chevron brace, and (3) an IMF with a chevron brace and an RFD. A linearized time-history analysis was conducted using the El Centro earthquake record. Numerical results show that the simple moment frame (M1) has a maximum displacement of 0.60 cm (drift 0.20%) and a beam moment of 3.5 kN·m. Adding the chevron brace (M2) reduces the displacement to 0.001 cm (a reduction of 99.8%) and the beam moment to 1.2 kN·m (a reduction of 65.7%), but the brace axial force reaches 15 kN. Adding the RFD (M3), while maintaining high stiffness (period 0.0785 sec), reduces the brace axial force by 20% (to 12 kN) and the beam moment by 16.7% (to 1.0 kN·m) compared to M2. Furthermore, the RFD reduces the velocity amplitude, increases the oscillation damping ratio, and improves dynamic stability.The proposed equivalent linear model provides a simple and reliable method for simulating RFDs in practical engineering analyses and demonstrates that the rotational friction damper can serve as an effective solution for reducing internal member forces and enhancing dynamic stability in braced frames.
Prediction of Geopolymer concrete compressive and flexural strengths from extended mix parameters using comparative machine learning models
Ordinary Portland cement has high energy and CO₂ footprint, motivating the use of geopolymer concrete as a lower-carbon structural binder. However, geopolymer mix design still relies on slow trial-and-error that does not achieve target compressive and flexural strengths. Prior studies used machine learning to predict geopolymer strength, but mostly with few input variables, compressive-strength-only targets and limited algorithm comparison. Hence, there is no clear evidence on which model best predicts strengths for extended geopolymer mix designs. For this study, a database of 497 geopolymer mixes with fourteen mix and curing variables was compiled from literature, and four supervised models’ artificial neural network (ANN), support vector machine (SVM), Gaussian process regression (GPR) and classification and regression tree (CART) were trained on normalized data with tuned hyper-parameters. Model performance was evaluated using correlation coefficient, root mean square error and mean absolute error for separate compressive and flexural targets. All four models achieved high predictive accuracy on test data, with ANN giving the best compressive-strength performance. For flexural strength, SVM provided the most accurate predictions. Different mechanical responses of geopolymer concrete are best represented by different model structures and that multi-parameter machine-learning frameworks can markedly reduce empirical trial batches. Overall, developed comparative machine-learning framework directly addresses limitations of trial-and-error geopolymer mix design by providing practical tool to predict compressive and flexural strengths from mix parameters and to support performance-based, low-carbon mix design. Future work should expand the database to other mechanical and durability properties and embed tools in decision-support software.
Optimal design of a composite trapezoidal channel cross section using sensitivity analysis
This paper presents the optimal shape of a compound trapezoidal cross-section by considering sensitivity analysis of design variable in shape optimization of trapezoidal open channel. the sensitivity analysis of the effect of discharge and channel bottom slope on design variables, constraints and objective function. The objective function is to minimize the cost of excavation and lining and the cost of water lost as seepage and evaporation losses, the design variables are the depth and width of the channel bottom, side slopes and free board, the constraints include uniform flow, maximum and minimum velocity, Froud number and water surface width. Optimization was performed with different values ​​of discharge and channel bottom slope in two stages and with several models. In the first stage, at a constant slope, with increasing discharge, the values ​​of discharge, bed width, free board, flow velocity, flow cross-sectional area and cost increase, but the side slope decreases. in the second stage, at constant discharge values, as the slope of the channel bottom increases, the values ​​of flow depth, bed width, flow cross-section area, and overall channel construction cost decrease. Results of sensitivity analysis show that all of design variables are important.
Evaluation of Mechanical Properties of Activated Alkali Concrete Based on Non-Destructive Ultrasonic Wave Velocity Testing
In this experimental study, a mixed design of ordinary concrete containing Portland cement (OPCC) with a grade of 500 kg/m3 and a design of activated alkali concrete (AAC) based on granulated blast furnace slag (GBFS) were made. In order to investigate the mechanical properties, ultrasonic pulse velocity (UPV) tests were performed on concrete designs at a temperature of 21 ℃ at curing ages of 7, 28 and 90 days. The results indicated that the UPV improved with increasing curing age in OPCC and AAC samples. In this regard, in OPCC, the minimum (4128 m/s) and maximum (6179 m/s) UPV was obtained at curing ages of 7 and 90 days, respectively, which had a superiority of 49.68% at the age of 90 days. In AAC, the minimum (4723 m/s) and maximum (5531 m/s) UPV was achieved at 7 and 90 days of curing, respectively, with a 17.1% advantage at 90 days. At 90 days of curing (as the optimum age), the UPV in AAC decreased by 11.71% compared to OPCC at the same age. The results of the analysis of scanning electron microscope (SEM) images on concrete samples in this study were in complete agreement with the UPV test results.
From Agricultural Waste to Construction Material: The Necessity of Controlled Water Curing for CLR-Concrete
The sugar industry generates substantial agricultural waste, necessitating sustainable recycling pathways. This study explores the valorization of Carbonation Lime Residue (CLR), a waste from sugar beet processing, in concrete as a partial cement replacement. Given the critical impact of curing on performance, this research specifically investigates the effect of curing conditions on CLR-based concrete. Specimens with 0% to 40% CLR were prepared and subjected to two distinct curing regimes: stagnant water and controlled curing with periodic water replacement. Compressive strength was evaluated at 7, 28, 56, and 90 days, while the curing water was monitored for electrical conductivity (EC) and total dissolved solids (TDS). The results revealed that stagnant water curing led to a sharp decline in long-term strength, attributed to the leaching of impurities and a consequent harmful increase in water salinity. Conversely, controlled water curing with periodic refreshing prevented salt accumulation and facilitated a continuous strength gain for all mixes. A 20% cement replacement with CLR was found to be structurally viable under this proper curing method. This study conclusively demonstrates that controlled water curing is not merely beneficial but essential for producing durable green concrete from agricultural waste, effectively transforming it into a valuable construction material.
Seismic Retrofit of Corrosion-Damaged Reinforced Concrete Bridges Using Fiber-Reinforced Polymer Composites: A Comprehensive Review
Reinforced concrete (RC) bridges worldwide are increasingly vulnerable to seismic events and deterioration mechanisms, particularly reinforcement corrosion. This review paper examines the application of Fiber-Reinforced Polymer (FRP) composites as an innovative solution for seismic retrofitting of corrosion-damaged RC bridges. FRP materials offer exceptional properties including high strength-to-weight ratio, excellent corrosion resistance, ease of installation, and minimal geometric modification of structural elements. The paper synthesizes findings from recent experimental and numerical studies on FRP-strengthened RC members, with emphasis on beams, columns, slabs, and bridge pile applications. Key aspects discussed include the corrosion mechanisms affecting steel reinforcement, the electrochemical implications of FRP-steel interaction, and the comparative performance of various FRP types including carbon, glass, and aramid fibers under seismic loading conditions. The review demonstrates that properly designed FRP retrofitting systems can significantly enhance flexural and shear capacity, ductility, and energy dissipation of corrosion-damaged bridge components. However, careful consideration must be given to galvanic coupling effects when carbon FRP is employed in chloride-contaminated concrete environments. This paper contributes to the growing body of knowledge on sustainable infrastructure rehabilitation and provides practical insights for engineers engaged in bridge retrofit projects.
Groundwater Flow Modeling Using Finite Element Method and Intelligent Aquifer Mesh
In groundwater flow modeling, as in any modeling problem, a certain amount of error is inevitable. In groundwater flow and contaminant transport modeling, recharge and discharge wells act as point sources or sinks. How these wells are treated can influence accuracy and reduce uncertainty or increase the amount of error. This study investigates an intelligent aquifer mesh. To illastrate the theory, two hypothetical aquifers with triangular and square elements were examined, in both confined and unconfined conditions. In the intelligent aquifer mesh, after gridding the model domain, pumping or recharge wells are considered as nodes. Consequently, the numbering of nodes and elements are updated accordingly. Groundwater flow modeling is performed on the updated mesh to enhance accuracy. The results of this research indicated that considering the recharge and pumping wells as a node and re-gridding the model area can perform groundwater flow modeling with more accuracy and ultimately the results will be more reliable.
Numerical analysis of the steel fiber reinforced concrete piles and prestressed concrete beam
This paper studies the structural behavior of prestressed concrete beams and steel fiber reinforced concrete piles. A nonlinear finite element formulation based on the principle of virtual work is developed to analyze the response of these prestressed structural elements under applied loads. The model accounts for material nonlinearity, second-order effects, and variable stiffness through an incremental loading procedure. Simpson’s integration scheme is adopted to evaluate the cross-sectional response of each element. The governing equations describing beam behavior are established, and the influence of compressive strength and prestressing force on structural performance is examined. Experimental tests conducted on prestressed concrete beams and steel fiber–reinforced concrete piles are used to validate the proposed approach. A comparison between numerical and experimental results demonstrates the accuracy and reliability of the developed formulation.
Optimal Aggregate Content in Recycled Concrete
The rapid increase in concrete waste has emerged as a significant global environmental challenge. In addition, the depletion of natural resources commonly used in concrete production highlights the necessity of adopting sustainable alternative materials. The incorporation of recycled aggregates in new concrete is considered an effective approach to reducing environmental degradation and preserving natural resources. This study aims to evaluate the influence of replacing natural coarse aggregates with recycled coarse aggregates on the properties of fresh and hardened concrete. For this purpose, three replacement levels—0%, 50%, and 100%—were examined. A slump test was conducted to assess the workability of fresh concrete, while 28-day hardened samples were subjected to compressive strength, direct tensile strength, and indirect tensile (splitting) strength tests. The results indicate that increasing the replacement ratio of recycled aggregates leads to a notable reduction in compressive strength as well as direct and indirect tensile strengths. Furthermore, higher proportions of recycled aggregates significantly decreased the slump value, thereby reducing the workability of fresh concrete. These findings suggest that although the use of recycled aggregates is environmentally advantageous, their incorporation requires careful technical considerations in concrete mix design.
Numerical Development of a Re-centering Damper with High Seismic Performance, Including Friction Wedges and SMA Rods
Re-centering dampers, developed using shape memory alloy (SMA)-based dampers and their superelasticity capability, absorb earthquake energy and provide a re-centering capability for the structure. In this study, the laboratory sample of Zhang's re-centering damper was first validated using ABAQUS software, followed by parametric analysis involving changes in the number and diameter of SMA rods, the friction coefficient of the wedges, and the placement configuration of two dampers, which were numerically investigated. The results indicated that increasing the diameter and number of rods, as well as the friction coefficient, enhances seismic resistance and stiffness but reduces ductility; excessive increase in friction only boosts the stiffness and ductility of the damper's compressive section while reducing seismic resistance. A friction coefficient of approximately 0.12 is recommended, whereas Zhang assumed 0.09. Additionally, the results showed: in parallel configuration, resistance and stiffness are higher but ductility is lower, whereas in series configuration, all three parameters decrease.
Copyright (c) 2025 Journal of Civil Engineering Researchers https://creativecommons.org/licenses/by/4.0
Numerical investigation of a steel frame braced with a central-cylinder cable system using shape memory alloy
Conventional steel braces increase the risk of structural damage during earthquakes due to compressive buckling. In this study, the performance of a steel frame equipped with a memory alloy cable brace with a central cylinder is investigated through numerical modeling in ABAQUS. This system is expected to exhibit superior seismic performance compared to traditional braces due to characteristics such as superelasticity, self-centering, and energy dissipation, and to return to its initial state after an earthquake. It can significantly enhance the seismic performance of steel frames with minimal construction interference and reduced construction time. After model validation, this study evaluates the effects of cable type, memory alloy properties, and cable diameter on the lateral performance of the steel frame with central cylinder cable braces. The results indicate that even using steel cables in this system significantly increases strength, stiffness, and energy absorption compared to a frame without braces, although ductility decreases by 25%. Replacing the steel cable with a memory alloy cable simultaneously improves strength, stiffness, energy absorption, and ductility (by 10%) compared to the steel-cable specimen, compensating for the ductility reduction. Furthermore, enhancing the superelastic properties of the memory alloy increases the load-bearing capacity and absorbed energy, while increasing the memory alloy cable diameter (from 6 to 16 mm) improves all performance indicators, especially stiffness and strength, without significant loss of ductility. Overall, the results demonstrate that using memory alloy cables, along with optimizing their properties and diameter, is an effective approach for simultaneously improving strength, stiffness, ductility, energy dissipation, and seismic behavior of structures.
Production of Green Concrete Using Waste Carbonation Lime Residue from Sugar Factory
This research investigates the possibility of producing green concrete using Carbonation Lime Residue (CLR), a waste by-product from the Naghsh-e Jahan Sugar Factory in Isfahan (Iran). The primary objective is to recycle this industrial waste by utilizing it as a partial replacement for cement in concrete production, aligning with waste management goals, environmental preservation, and economic benefits. Concrete samples were prepared with different percentages of CLR replacement (0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, and 40%) for cement, maintaining a constant water-to-cement ratio of 0.35. These samples were subjected to compressive strength tests (at 7, 28, and 56 days) and tensile strength tests (Brazilian method). The results indicated that both compressive and tensile strengths decrease with an increase in the replacement percentage. This reduction is primarily attributed to the presence of impurities and sugary substances in the CLR, as confirmed by SEM and EDX analyses. However, it was observed that up to a 25% replacement level, the reduction in compressive and tensile strengths was less than respectively 15% and 10%. This level of reduction is considered acceptable given the environmental and economic advantages derived from utilizing this waste material. Therefore, using waste CLR as a cement replacement in concrete up to 25% is deemed a practical and effective solution, particularly for non-structural applications or in regions near sugar factories, contributing to sustainable development and a circular economy.
The Effect of Using Fly Ash with Various Additives on the Microstructure and Compressive Strength of Self-Compacting Concrete (Review Study)
This review article provides a comprehensive investigation into the effects of utilizing fly ash (FA) along with other mineral additives such as metakaolin (MK), silica fume (SF), hydrated lime (HL), and others on the properties of Self-Compacting Concrete (SCC). The primary objective of this study is to analyze and synthesize existing research on the simultaneous influence of various chemical additives and fly ash on the microstructure and compressive strength of self-compacting concrete. Recognized for its ease of implementation and enhanced performance, self-compacting concrete is considered an advanced technology in the concrete industry, and the use of mineral additives, particularly fly ash, can contribute to the improvement of its mechanical properties and durability.The methodology of these studies primarily involves examining the concrete microstructure using Scanning Electron Microscopy (SEM) and evaluating the compressive strength of concrete specimens at different ages. Results indicate that partial replacement of cement with activated fly ash (using sodium hydroxide) can reduce the hydration process while enhancing pozzolanic reactions, leading to improved strength properties. The optimal performance of activated fly ash-based SCC, in terms of strength, was observed at 10% to 15% replacement. SEM images revealed that fly ash particles are spherical, whereas activated fly ash particles are angular and elongated, which contributes to improved concrete matrix density and reduced porosity, thereby increasing compressive strength.Furthermore, studies on concrete containing mineral additives demonstrated that MK provides higher initial strength compared to other additives. This study concludes that the use of fly ash and other mineral additives, particularly in combination with activators or hydrated lime, can effectively enhance the mechanical and microstructural properties of self-compacting concrete, making it a sustainable and efficient option for construction applications. This review also underscores the importance of a profound understanding of the relationship between material composition, microstructure, and mechanical properties for the optimal formulation of SCC.
A Comparative Analysis of Ensemble NWP Models for Flood Forecasting
This study presents the first application of gamma quantile mapping to bias-correct ensemble precipitation forecasts from seven global NWP models (ECMWF, NCEP, UKMO, CMA, JMA, ECCC, NCMRWF) in the data-scarce Saliyan Basin, Iran. The integration of these models with advanced bias correction techniques significantly improves flood forecasting accuracy. To address systematic biases in the raw forecasts, gamma quantile mapping was applied, significantly enhancing the reliability of the precipitation inputs. These bias-corrected forecasts were then used as inputs for the GR4J hydrological model to simulate river flow and predict flood events. The study period included a major flood event in March 2019, which was used to evaluate the performance of the ensemble forecasting system. Results demonstrated that bias correction using gamma quantile mapping substantially improved the accuracy of flood forecasts, with the ECMWF and UKMO models showing the highest skill scores. The ensemble approach effectively captured the uncertainty in flood predictions, providing valuable insights for risk assessment and decision-making. This research highlights the importance of bias correction in ensemble forecasting and offers a robust framework for flood prediction in data-scarce regions. The findings have significant implications for improving flood early warning systems and mitigating flood-related damages in similar basins worldwide.
Numerical investigation of the behavior of concrete beams reinforced with FRP polymer stirrups in the form of straps
In reinforced concrete structures that are in corrosive environmental conditions, there is always a discussion of reinforcement corrosion. Therefore, because of the smaller diameter compared to longitudinal rebars and closer to the surface and consequently closer to the corrosive factors, stirrups are more affected by this corrosion. One of the most effective ways to prevent corrosion of stirrups is to use FRP rebars in structures exposed to corrosion. One of the disadvantages of using FRP rebar is that it is brittle, which makes it impossible to bend these rebars in a workshop environment. Therefore, a group of researchers suggested the use of straps made of FRP plates as stirrups and concluded some laboratory studies in this field. Now, the main goal of this study is to numerically investigate the behavior of beams made with this type of stirrups. For this purpose, 13 beams were modeled in Abaqus software and subjected to three-point bending loading. Also, things such as the type of FRP used, the width of the stirrups, the number of layers of the stirrups and the installation location of these stirrups were investigated and studied. The results of this study showed FRP stirrups with a cross-section equal to steel stirrups have a higher load capacity than beams with steel stirrups. Also, in terms of the beam's ductility, the beam with FRP stirrups has less ductility than the beam with steel stirrups. Regarding the effect of the number of FRP stirrup layers, the results showed that in stirrups with fixed width and variable number of layers, increasing the number of FRP stirrup layers will increase the bearing capacity and reduce ductility.
Integrating Weighted Delay Index (WDI) with Dynamic Critical Path Analysis for Enhanced Delay Assessment in Construction Projects
<span lang="EN-GB" style="font-size: 12.0pt; mso-bidi-font-size: 18.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: Arial; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-GB; mso-fareast-language: EN-US; mso-bidi-language: AR-SA; mso-bidi-font-weight: bold;">Project delay remains one of the most persistent challenges in construction management, often leading to significant cost overruns, contractual disputes, and stakeholder dissatisfaction. Traditional scheduling and delay analysis methods—such as Critical Path Method (CPM), Earned Value Management (EVM), and conventional Extension of Time (EOT) techniques—tend to overlook the relative importance of activities and the dynamic nature of project execution. This study introduces the Weighted Delay Index (WDI), a novel metric that integrates activity-specific weights with dynamic critical path analysis to provide a more nuanced evaluation of delay severity. Activity weights are derived through the Analytical Hierarchy Process (AHP), incorporating four key dimensions: time, cost, risk, and technical impact. The methodology is validated through multiple case studies of construction projects, where WDI trends are compared against actual project delays determined via Time Impact Analysis. Results indicate that Project Duration is the dominant predictor of overall delays, while WDI offers significant diagnostic and managerial value by identifying critical activities whose delays disproportionately affect project performance. Workforce Intensity is found to moderate delay outcomes, with higher intensity generally reducing delay severity. The proposed framework provides project managers with an early-warning and prioritization tool, enabling targeted intervention strategies that go beyond aggregated delay measures. The study contributes to both theory and practice by bridging the gap between deterministic scheduling and dynamic, activity-sensitive delay analysis.
Simplified Unified Model for Flexural Capacity of Ductile HPC Beams with A Low Reinforcement Ratio
There is no specific model to predict the flexural capacity of ultra-high-performance concrete (UHPC) beams with a low reinforcement ratio. Accordingly, a comprehensive experimental database containing 162 datasets was gathered from literature to propose an explicit analytical model containing various critical features, including fiber volume fraction, fiber aspect ratio, fiber strength, water-to-binder () ratio of mixture, and reinforcement ratio. Additionally, a supplementary experimental study involving a large-scale UHPC beam with a very low reinforcement ratio (almost negligible) was conducted to verify the model's performance. The findings revealed that the proposed bending model achieved an IAE of 10.8% and a COV of 1.04, indicating its high accuracy in comparison to a comprehensive experimental dataset comprising 162 large-scale beam tests. Furthermore, the comparison between the experimental results of the tested beam and the proposed model showed a deviation of 4.5%, which supports the effectiveness of the flexural capacity formulation. A parametric statistical analysis was conducted using Minitab software to evaluate the influence of key parameters affecting the roles of fiber and matrix.
Mechanical Performance and Freeze–Thaw Durability of Expansive Clay Stabilized with Graphene Oxide and Fly Ash: A Laboratory Study
Expansive clay soils are characterized by their high water affinity and significant volume changes, which frequently result in structural issues such as swelling, settlement, and cracking, particularly under freeze–thaw (F–T) conditions. This study investigates a dual-stabilization method using fly ash (FA: 5–15%) and graphene oxide (GO: 0.05–0.15%) to enhance the mechanical strength and durability of such soils. After 28 days of curing, samples underwent 3, 6, and 9 F–T cycles, followed by unconfined compressive strength (UCS) testing. Results show that the GO–FA combination significantly improved soil performance, with the optimal mix (10% FA + 0.1% GO) achieving a 76% increase in UCS at zero cycles and reducing strength loss after nine cycles by over 45% compared to untreated soil. These outcomes demonstrate the promise of GO–FA stabilization as a sustainable and effective solution for expansive soils in cold-region geotechnical engineering.
Investigation on Seismic Behavior of Steel Frames with semi-active Rotational Friction Dampers
In this study, the performance and efficiency have been investigated of friction damper in semi-active control mode in structural responses under the influence of Chichi, Kobe, Tabas and Gazli earthquakes in the near field. Semi-active friction dampers made up of two plates that are slipping over. The contact force between the pages is changed according to the order of the control algorithm and the force on the structure is adjusted at any time during the earthquake. The LQR control algorithm and the shear control rule have been used to determine the contact force at any given moment. A structural ten-story steel X shape bracing system in both directions under dynamic analysis for numerical studies selected and subjected to vibration 4 earthquake specifications and content of different frequency in software Etabs to obtain matrices of mass and stiffness and Matlab to evaluate the different states of being The damper has been investigated. Structural responses in all classes is determined and compared. The results indicate that the use of a friction damper leads to a reduction of displacement, In the mode of using the damper in a semi-active control mode, it is better than active or inactive mode. The damper layout is also examined in four modes, which shows that the use of the damper around the structural plan is better. For example, the base shear when the damper is in around the plan, In active and inactive control mode, it has increased by 41.4% and 84.86% relative to the semi-active control status
Damage Identification in Beams and Plates Using Wavelet Theory and Firefly Optimization Algorithm
Identifying the location and severity of structural damage represents one of the most critical challenges in civil engineering. The ability to identify damage in its earliest stages cannot be overstated in terms of importance. Among the most powerful tools available for damage detection and generally structural health monitoring can name signal data processing. This study uses a two-step procedure based on wavelet theory and an optimization method to identify the location and severety of damage in beams and plates. The damage simulates through the introduction of cracks at targeted locations. Acceleration responses obtained from a dynamic analysis using finite element method undergo wavelet transformation, enabling detailed analysis of the dynamic response signals. Through filtering processes, the structural response signal details are extracted. Disturbances appearing in the signal detail plots indicate the presence of damage, leading to the development of a quantitative index for determining probable damage locations. The second phase is used to properly determine the location and magnitude of the damage using firefly optimization algorithm. To assess the effectiveness of the proposed method, five numerical examples including three beams with varying characteristics and 16, 27, and 20 elements, respectively, and two plates with different support conditions—one with two-edge fixed supports and another with four-edge fixed supports are considered. Different damage scenarios are considered for structures. The findings indicate that the proposed method shows outstanding results in terms of identifying the location and severity of damage using acceleration responses with considering noise interferences.
Optimal Placement of Viscoelastic Layers in Sandwich Beams for Maximum Vibration Attenuation and Minimum Creep Deflections
Until now, various mathematical models have been proposed to characterize the behavior of viscoelastic materials and facilitate their implementation in finite element software. However, it remains unclear which configuration of the viscoelastic layer along the thickness and length of the beam yields the lowest creep deflection and highest damping effect under applied forces. To fill this literature gap, efforts are undertaken in this study to identify the optimal placement of the viscoelastic layers in the sandwich beam. To reach this aim, the creep and dynamic behaviors of sandwich beams with different boundary conditions and various configurations of the viscoelastic layer along the thickness and length were investigated using a finite element model. The obtained results indicate that the damping capability and creep deformations of the sandwich beam are strongly affected by the position of the viscoelastic layers.
Optimizing Date Seed Utilization in Green Concrete: A Methodological Evaluation
Concrete is one of the most widely used construction materials globally; however, its production contributes significantly to carbon dioxide emissions. In the Middle East, annual date production is substantial, and date seeds, as a byproduct, are typically discarded. This study investigates three methods for incorporating date seeds into concrete: (1) Cement replacement: Using powdered date seeds (PDS) as a partial substitute for cement at 5%, 10%, 15%, and 20% levels; (2) Aggregate replacement: Replacing coarse aggregates with crushed date seeds (CDS) at 10%, 20%, and 30% ratios and (3) Hybrid approach: Combining PDS (0%, 5%, 10%, and 20%) with fly ash (fixed at 20%). Mechanical tests revealed that replacing cement with up to 10% PDS had no significant impact on compressive strength, whereas higher replacement levels reduced strength. Similarly, increasing the aggregate replacement percentage led to a decline in concrete strength. In contrast, the hybrid approach—combining PDS with 20% fly ash—enhanced compressive strength. Based on these findings, the third method emerged as the most effective for improving both the strength and sustainability of concrete. The optimized hybrid mixture was selected for further comprehensive evaluation, including tests for tensile strength, flexural strength, water absorption (porosity), sulfate resistance, and freeze-thaw durability. These assessments aimed to verify not only the mechanical properties but also the long-term durability of the modified concrete under diverse environmental conditions.
2D Equivalent Linear Seismic Site Response Analysis in SBFEM
Understanding the dynamic behavior of soil layers under seismic loading is pivotal for accurate seismic design and risk assessment. This study conducts a two-dimensional equivalent linear site response analysis using the Scaled Boundary Finite Element Method with Rayleigh damping to enhanced modeling accuracy. SBFEM combines the advantages of finite and boundary element methods, offering high efficiency in simulating wave propagation and stress concentrations in semi-infinite domains. A MATLAB implementation of the method was validated against previous studies, confirming consistent accuracy across various soil profiles and seismic scenarios. The method demonstrates convergence, accuracy, and stability, requiring fewer elements due to boundary-only discretization. This reduces both computational cost and time while accurately modeling the infinite domain condition. The findings highlight the method’s effectiveness for site response analysis under diverse seismic inputs and layered soil configurations, combining the equivalent linear method with SBFEM as a robust and practical tool for dynamic geotechnical applications.
3D free vibration analysis of nanocomposite beams carbon nanotube reinforced FGM using DQ method
Beams are always noteworthy as an engineering structure due to their wide application in industry such as bridges, railway tracks, floors and ceilings of buildings and many other cases. Therefore, considering the wide application of these materials in industry, the analysis of this category of structures becomes important in the overall design process of these parts in a structure. With the increasing use of beams in industry and the need to increase their efficiency and ensure their proper functioning, the use of new materials such as functionally graded materials[1]has increased. The use of composite materials, shape memory alloys, piezoelectric materials, etc. and the expansion of the scope of use of these materials has led to increased efforts by researchers to achieve the construction and design of structures and parts with better efficiency and quality. On the other hand, conducting experimental analyses on these materials is associated with problems such as size, price, complexity of the laboratory model, etc., hence the presentation of general theoretical models­. More suitable for ‌In this research, the vibration analysis of a nanobeam is considered. Unidirectional FGM (functional properties along the beam thickness) with carbon nanotubes and a layer‌ Metal and ceramic supports on various types of supports ‌Sometimes. ‌The solutions, including simple, complex, etc., were discussed. The solution method in question was the mixing method, and in line with the thickness of the numerical method, the differential function. It has been DQ based on this, relationships have been extracted regarding how to increase the natural frequency and the lowest natural frequency, as well as the length-to-thickness ratio, natural frequency changes, and dimensionless natural frequency changes in the beam.
Retaining Structures in Slope Stabilization: A Comparative Analysis on Safety and Cost Effectiveness
This study evaluates slope stabilization methods using gravity stone walls, reinforced concrete cantilever walls, and pile shoring systems. Stability and economic performance of these systems were compared through analyses conducted with Plaxis 2D and İstCAD software on a model slope subjected to increasing excavation depths. Results show that gravity stone walls are more economical up to 5 m, while cantilever walls are preferable between 5–9 m. Beyond 9 m, both methods become inadequate, and pile shoring systems provide the most effective solution. Each method's advantages and limitations were assessed based on field applicability, cost, and stability.