Civil Engineering Journal
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Sensitivity and Optimization Analysis of Torsional Behavior in Multicellular Thin-Walled Tubes
No full textMulticellular thin-walled tubes are widely used due to their lightweight, economical design, and superior shear and torsional performance. Their design is sometimes governed by the available materials and the required dimensions. The current study uses advanced sensitivity analysis with meta-modeling tools to understand how different geometric and mechanical factors affect the torsional performance of multicellular thin-walled tubes. The geometric factors include the length, thickness, and width of the beams, while the mechanical properties involve the shear modulus. Variance-based sensitivity analysis is used to assess how variations in these factors impact the rate of twist, torsional stiffness, and shear stress. The interconnected relations between input parameters are exploited for optimal design and superior performance. The results revealed that for a three-celled tube, thick horizontal interior elements with thin deep vertical elements and thin exterior elements provide an optimal design when the cross-sectional area is constrained. This finding, combined with varying the geometrical and material properties, results in an optimal design using CFRP composites when constrained by minimizing the total weight and superior torsional performance. The analysis can be extended to include other constraint(s), but changing the design constraints might change the optimal design. Doi: 10.28991/CEJ-2024-010-09-09 Full Text: PD
Shearing Behavior at the Interface of Sand-Structured Surfaces Subjected to Monotonic Axial Loading
No full textEnhancing the interface shear strength is crucial in the capacity and design of several geotechnical structures when subjected to static loading. The efficiency of these structures can be enhanced by utilizing innovative designs that allow the mobilization of higher interface shear resistance with bio-inspired-engineered or structured (rough) surfaces when compared to conventional smooth or random rough surfaces of the same geometry (i.e., soil-foundation contact area). Bio-inspired-engineered surfaces used in this study are developed after surfaces with snakeskin-inspired and engineered rough designs that maximize the interface shear resistance in cohesionless and cohesive soils. The frictional behavior and resistance of the bio-inspired-engineered surfaces were experimentally evaluated utilizing a modified interface direct shear apparatus on three locally available sand specimens. Results from tests on smooth surfaces against three different sands mobilized almost the same resistance and soil contraction. The results indicate a behavior significantly influenced by the shape and arrangement of the surface features, accompanied by larger resistance and volume dilation. A parametric study on the characteristics of the structured elements on three sands revealed the isolated impact of elements arrangement, shape, and roughness on the maximum attainable interface strength. The surface element characteristic ratio is found to control the load-transfer mechanism between sand and bio-inspired-engineered structured surfaces. Doi: 10.28991/CEJ-2024-010-10-06 Full Text: PD
Comparative Study of Different Classification Methods and Winner Takes All Approach
No full textOne of the most popular methods in remote sensing for gathering and evaluating satellite data is the classification of images. Several categories exist for image classification techniques, including supervised and unsupervised classification, pixel-based, object-based, and rule-based approaches. Each type of technique has pros and cons of its own. Choosing the method that produces the best results is one of the issues with image classification. The "best" model for classifying images relies on the particular task and the dataset used. The ideal classification technique is a crucial component in increasing classification accuracy. The strengths and drawbacks of various models vary, so selecting one that is appropriate for the job is critical. The main objective of this research is to analyze and compare the results of each classifier used, including ISODATA, K-mean, Maximum likelihood, Minimum distance, Support vector machine, and Neural network then integrate these different types of classification using the winners-takes-all classification approach in order to try to improve the results. The classified images were assessed, and both the overall accuracy and kappa coefficient were calculated and gave 79.50%, 73.89%, 77.05%, and 84.98%, 86.53%, 87.18%, and 88.69% for ISODATA, K-means, Minimum distance (MD), Maximum likelihood (MXL), Support vector machine (SVM), Neural network (NNT), and winner takes all (WTA), respectively. From the results, the Winner takes all (WTA) presented a superior in terms of the overall accuracy and kappa coefficient. Doi: 10.28991/CEJ-2024-010-10-016 Full Text: PD
A Comprehensive Approach to Assess Occupant's Satisfaction and Performances of Residential Building
No full textThis paper aims to endeavor to develop a holistic Post Occupancy Evaluation (POE) framework, amalgamating the utilization of building facilities and Building Performance Attributes (BPA) for appraising the performance of Construction and Design Firms (CDFs) alongside building performance indicators such as occupant satisfaction within residential apartment complexes. The study adopts a tripartite research methodology encompassing theoretical exploration, on-site investigations, and analytical examinations. The theoretical component entails an extensive literature survey to integrate 15 identified BPAs seamlessly. Field inquiries involve rating building performance and gauging occupant contentment. The subsequent analytical phase establishes correlations between building performance metrics and occupant satisfaction levels. This systematic approach synergizes user insights with building services, promising a rigorous and systematic building analysis. The outcomes underscore a robust correlation linking building performance attributes to occupant satisfaction, thus affirming the pivotal role of POE as an indispensable tool for appraising building performance. The analysis reveals ten highly correlated parameters, indicating a substantial 67% connection between the Building Performance Rating (BPR) and the Occupant Satisfaction Score (OSS). These influential parameters guide improvements and updates through Post-Occupancy Evaluations (POE). This process is a valuable learning tool for enhancing future organizational projects and improving building performance. The findings emphasize the pertinence of the criteria employed in evaluating building performance, which is relevant for assessing occupant contentment and CDF's effectiveness. Comparing the previous research, this research posits the potential for widespread adoption of POE in augmenting CDFs' performance and lays the groundwork for expanding its utilization. The scholarly exploration introduces novel perspectives and paves the way for a comprehensive integration of POE to enhance CDFs' operational proficiency. Doi: 10.28991/CEJ-2024-010-02-07 Full Text: PD
Bond Strength of Rectangular CFSST Columns after Exposed to Elevated Temperature
No full textThis article investigates the bond- behavior of Rectangular Concrete-filled stainless-steel tubular (RCFSST) columns under post-fire conditions. The main objective of this research was to obtain Ï„-s relationship of RCFSST columns under the combined effects of high temperature and concrete age. A total of sixteen specimens, including four reference specimens, were tested with different parameters, namely: i) temperature (600 °C, 800 °C & 1000 °C) ii) different concrete ages (30 days, 60 days, 90 days & 180 days). Analyzing the Ï„-s curves of the test specimens, chemical adhesion and micro-locking were the principal forces contributing to bond strength at lower concrete ages under post-fire conditions. At a higher concrete age, RCFSST specimens displayed a longer curve after the inflection point, indicating the contribution of macro-locking forces in amplifying the bond-strength. Five distinct curve types were found from the experiments. Type 1 curves with three stages, i) initial linear, ii) non-linear, and ii) final linear stage, had a higher frequency among the other types. For 90-day cured specimens, a decline in bond strength was observed at higher temperatures, but for 180 days cured specimens, a significant rise was seen under post-fire conditions. A new set of Ï„-s relations for RCFSST columns with different concrete ages under post-fire was established. Doi: 10.28991/CEJ-2024-010-03-019 Full Text: PD
Vehicle Safety Application through the Integration of Flood Detection and Safe Overtaking in Vehicular Communication
No full textRoad safety in Malaysia is a major concern due to frequent floods and accidents caused by overtaking. These issues result in significant injuries and losses. In this paper, we introduce a new system called the Safe Driving Tool (SDT). The SDT integrates a Flood Detection System (FDS) and a Vehicle Overtaking System (VOS) using Long-Range (LoRa) communication technology. The FDS continuously monitors water levels in flood-prone areas. It alerts drivers about potential hazards through vehicle-to-infrastructure (V2I) communication. Simultaneously, the VOS enables safe overtaking maneuvers. It does this by exchanging information with nearby vehicles through vehicle-to-vehicle (V2V) communication. Through testing and experimentation, we have shown that the SDT system effectively reduces accident risks and losses associated with floods and overtaking. The system's performance under various conditions confirms the reliability and effectiveness of LoRa communication technology in enhancing vehicular safety. This study represents a significant advancement in road safety. It combines flood detection and overtaking assistance into a single unified system, addressing two major causes of road accidents in Malaysia. The integration of V2I and V2V communication provides a comprehensive solution that improves driver awareness and decision-making. This ultimately leads to safer driving environments and enhanced driver convenience. Doi: 10.28991/CEJ-2024-010-09-015 Full Text: PD
Highlighting Traffic Accidents on Roundabouts Using MRSS-AHP Expert System
No full textThe frequency and severity of traffic accidents are causing growing concern. This study aims to develop a tool to improve the traffic safety level on roundabouts and identify the influence of traffic operations, geometric parameters, weather, and time of day on improving roundabout traffic safety. It is the first study to evaluate the performance of the integrated Median Ranked Set Sample (MRSS) and Analytic Hierarchy Process (AHP) with statistical analysis. A hierarchy tree of accident causes has been developed using data gathered from accident reports and relevant authorities. Then, the selected stakeholders' professionals prioritized the traffic accident causes using a MRSS and AHP. Moreover, traffic microsimulation software VISSIM was also used to extract traffic operation parameters for the analysis. Afterwards, Analysis of Variance (ANOVA) was used to validate the causes of traffic accidents. The results show that geometric design accounts for 36% of accidents at roundabouts, followed by traffic operation (22%). However, conflicting and queuing lengths are responsible for about 20% of traffic accidents. The tools developed, and the causes of accidents determined in this study will help geometric designers and city planners to take the necessary measures to minimize accidents and enhance traffic safety levels in urban areas. Doi: 10.28991/CEJ-2024-010-04-013 Full Text: PD
Enhancing the Flexural Capacity of Reinforced Concrete Beam by Using Modified Shear Reinforcement
No full textMany researchers have studied how modifying conventional shear reinforcement into spiral and truss systems improves the behavior of RC beams. However, there is a scarcity of studies investigating the influence of spiral reinforcement, and limited research is available on the flexural capacity of beams utilizing truss reinforcement systems. Additionally, recent designs focused only on the rectangular spiral and rectangular truss systems, underscoring the necessity of incorporating a new design of modifications in the stirrup configurations. These gaps must be addressed to identify the most effective design for achieving the desired flexural capacities. As a result, the present study conducts a simulation and experimentation on RC beams utilizing modified stirrups through the Abaqus software to describe the load-deflection relationship, determine the flexural capacity and ductility, and analyze the failure mode and crack patterns. The present study simulated seventeen finite element models, including one control beam as BN and four various designs that used rectangular spiral (BR-S), rectangular truss system (BT-R), and a new modification, namely vertical X-shaped stirrups (BV-X), and X-shaped truss system (BT-X) with four spacings of 150mm, 125mm, 100mm, and 75mm. The findings reveal that the most effective enhancement in RC beam behavior was observed within the BT-R group, particularly with BT-R 100, which demonstrated a remarkable 6.551% increase in flexural capacity compared to BN. Moreover, stirrup spacing and inclination considerably impact the beam's performance, depending on the various modifications of stirrups in RC beams. Furthermore, uniform failure modes have been observed across all models and specimens, including BN, demonstrating that modified stirrups improve RC beam performance. The present study compared and verified the finite element simulation results through an actual experiment from BN and BT-R 150 models and specimens. Doi: 10.28991/CEJ-2024-010-06-02 Full Text: PD
Retrofitting Bolted Flange Plate (BFP) Connections Using Haunches and Extended End-Plates
No full textIn Indonesia, one of the most common forms of connection is the Bolted Flange Plate (BFP) moment connection. Nevertheless, their current setups do not satisfy the strict requirements outlined in AISC 358-22. Therefore, this study uses advanced sub-assemblage numerical modeling simulations using ANSYS software to propose a novel way to integrate a half WF extended end-plate connection and trapezoidal haunch in order to fortify BFP moment connections, which does not meet the requirement required by AISC 358-22. Methodologically, the research entails comprehensive modeling and analysis of the proposed retrofit scheme. Six distinct connection models were scrutinized: the BFP-UR representing the existing connection extracted from a structure in Surabaya; the BFP-R4E and BFP-R4ES models, embodying connection retrofits with a half WF extended end-plate; and the BFP-RTR and BFP-RSTR models, embodying connection retrofits with a trapezoidal haunch. Additionally, the BFP-RTRE model integrates both an extended end plate and a trapezoidal haunch in the retrofit scheme. The analytical findings unveil that the proposed strengthening paradigm manifests heightened and superior rotational moment characteristics relative to the pre-reinforcement configuration, albeit encountering stiffness degradation attributable to buckling effects on the main beam. Notably, the analysis indicates that degradation ensues when rotational displacement exceeds 4%, with only the BFP-RTR and BFP-RSTR models exhibiting degradation at a 3% rotation threshold. Crucially, the connections demonstrate the capability to withstand 80% of the beam's plastic moment under a 4% rotational displacement, thereby aligning with the stringent requisites delineated in AISC 341-22. Doi: 10.28991/CEJ-2024-010-08-03 Full Text: PD
The Buildings' Reliability Calculating Method Using a Simple Seismic Impact Model
No full textNon-canonical spectral representation of seismic activity is employed to assess the reliability of nonlinearly modeled buildings. Seismic impact is modeled using a random process, represented by simple functions with random parameters. We consider random processes with correlation functions expressed as a sum of cosine-exponential terms. Reliability, defined as the probability of failure-free operation, is determined using statistical testing methods. The reliability calculation algorithm is implemented in MATLAB. As an illustrative example, we calculate the reliability of a section of a one-story industrial building frame modeled by a nonlinear system. Failure is defined as exceeding experimentally determined permissible displacement limits. Our calculations involve up to 2000 realizations of the random process. We analyze histograms, empirical distribution functions, and reliability values of maximum fragment movements. We find that using 100 realizations of the random process yields satisfactory accuracy in determining reliability. This reliability calculation method is recommended for rapid reliability estimates across various structure types, including those employing seismic isolation systems. We also observe a correlation between displacement magnitudes calculated under accelerograms and a random process represented in a non-canonical form. Thus, we recommend this method for reliability assessments in multi-story buildings. Doi: 10.28991/CEJ-2024-010-08-019 Full Text: PD