Civil Engineering Dimension (E-Journal)
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A Comparative Study on Bio-Inspired Algorithms in Layout Optimization of Construction Site Facilities
Get PDFA good arrangement of site layout on a construction project is a fundamental component of the project’s efficiency. Optimization on site layout is necessary in order to reduce the transportation cost of resources or personnel between facilities. Recently, the use of bio-inspired algorithms has received considerable critical attention in solving the engineering optimization problem. These methods have consistently provided better performance than traditional mathematical-based methods to a variety of engineering problems. This study compares the performance of particle swarm optimization (PSO), artificial bee colony (ABC), and symbiotic organisms search (SOS) algorithms in optimizing site layout planning problems. Three real-world case studies of layout optimization problems have been used in this study. The results show that SOS has a better performance in comparison to the other algorithms. Thus, this study provides useful insights to construction practitioners in the industry who are involved in dealing with optimization problem
Wave Trajectory Study on the Coast of Lhoknga, Aceh Besar, Indonesia: A Numerical Model Approach
Get PDFA numerical model of wave trajectory using shoaling and refraction formula was proposed in the coastal waters of Lhoknga, Aceh Besar, Indonesia. The developed model used a two dimensional (2D) numerical methods for wave trajectory with the input of wave height and period; 0.62 m and 8 second for high tide and 0.47 m and 6 second for low tide. This model was tested on site during low tide and high tide conditions for verification. The purpose of this numerical study is to trace the distribution of wave trajectory because of shoaling, wave breaking, and wave refraction. The model determines the wave height and crest pattern of the ray wave trajectory. The simulation result shows the pattern of the wave propagation at Lhoknga beach moves from the northwest to the east and south of the coast. The model also informs that the maximum wave height during high tide condition is 1.72 m and 1.31 m during low tide condition. The result indicates that the coast of Lhoknga has moderate wave conditions caused by a gentle beach bathymetry slope
Displacement and Stress Function-based Linear and Quadratic Triangular Elements for Saint-Venant Torsional Problems
Get PDFTorsional problems commonly arise in frame structural members subjected to unsymmetrical loading. Saint-Venant proposed a semi inverse method to develop the exact theory of torsional bars of general cross sections. However, the solution to the problem using an analytical method for a complicated cross section is cumbersome. This paper presents the adoption of the Saint-Venant theory to develop a simple finite element program based on the displacement and stress function approaches using the standard linear and quadratic triangular elements. The displacement based approach is capable of evaluating torsional rigidity and shear stress distribution of homogeneous and nonhomogeneous; isotropic, orthotropic, and anisotropic materials; in singly and multiply-connected sections. On the other hand, applications of the stress function approach are limited to the case of singly-connected isotropic sections only, due to the complexity on the boundary conditions. The results show that both approaches converge to exact solutions with high degree of accuracy
Metaheuristic-Based Machine Learning System for Prediction of Compressive Strength based on Concrete Mixture Properties and Early-Age Strength Test Results
Get PDFEstimating the accurate concrete strength has become a critical issue in civil engineering. The 28-day concrete cylinder test results depict the concrete's characteristic strength which was prepared and cast as part of the concrete work on the project. Waiting 28 days is important to guarantee the quality control of the procedure, even though it is a slow process. This research develops an advanced machine learning method to forecast the concrete compressive strength using the concrete mix proportion and early-age strength test results. Thirty-eight historical cases in total were used to create the intelligence prediction method. The results obtained indicate the effectiveness of the advanced hybrid machine learning strategy in forecasting the strength of the concrete with a comparatively high degree of accuracy calculated using 4 error indicators. As a result, the suggested study can provide a great advantage for construction project managers in decision-making procedures that depend on early strength results of the tests
Considering the Effect of Motorcyclist Risk Tolerance in Accident Risk Management: A Preliminary Study
Get PDFNegative perceptions about accident are usually associated with speeding behavior. However, risk perception has not been considered in accident risk management. It is accepted as a personality matter, thus the number of accidents per year was used as accident risk tolerance indicator. Consequently, due to insufficient measurable indicators, it would be difficult to prevent the increasing speeding behavior. This paper discusses the improvement of accident risk tolerance indicators, i.e. safety factor and margin of safety, and their possible usage in speed management policies. These indicators were built based on the correlation between the results of interview and braking maneuver test. From this combine approach, using aggregated-individual and expert acceptance models, it was found that risk tolerance arose because motorcyclists accepted both the advantages and disadvantages gained from speeding, obtained through their riding frequency, duration of riding and/or accident involvement experienced. However, inappropriate speed due to miss-perception toward braking capability should be avoided. Inversely, an appropriate speed management should consider their travelling expectatio
One Dimensional Site Response Analysis of Liquefaction Potential along Coastal Area of Bengkulu City, Indonesia
Get PDFThis paper presents one dimensional non-linear site response analysis of liquefaction potential caused by the 2000 and the 2007 earthquakes in coastal area of Bengkulu City, Bengkulu, Indonesia. Site investigations, including Standard Penetration Test (SPT) and shear wave velocity (VS) measurement, were conducted in three locations along the coastal area of Bengkulu City. Further, the site investigation data were used in simulation of one-dimensional non-linear site response analysis by applying the synthetic ground motions at bedrock. The results show that liquefaction could happen at 0 to 1.5 m deep. This was indicated by the excess pore water pressure ratio (ru) which exceeded one. At depth between 1.5 m and 20 m, the excess pore water pressure almost reached the initial effective stress decreasing the effective confinement pressure close to zero. The results also indicated that liquefaction is possible to occur in this depth range if a stronger earthquake occurs
A Numerical Investigation on the Structural Behavior of Deficient Steel Frames Strengthened using CFRP Composite
Get PDFCarbon fiber reinforced polymers (CFRP) is one of the materials that is used to strengthen steel structures. Most studies on CFRP strengthening steel on structures have been done on beams and steel columns. No independent study has studied the effect of CFRP strengthening on the structural behavior of steel frames having initial deficiency.The deficiency in steel structures may be created due to the errors caused by construction and others.This study aims to carry out a numerical study on the efficiency of CFRP sheet on strengthening square hollow section (SHS) steel frames having initial deficiency. Seven specimens, five of which were strengthened using CFRP sheets, were analyzed. ANSYS software was used to analyze the SHS steel frames. The results showed that the coverage length, the width, and the number of CFRP layers have a significant effect on increasing and recovering the ultimate load capacity of the SHS steel frames having initial deficiency
Seismic Performance of Existing Building Retrofitted with VSL-Gensui Damper
Get PDFBuildings designed using older code should be checked against the higher demand required by newer code. In this study, performance of Building T of Petra Christian University, Surabaya, Indonesia, which was designed with older Indonesian Seismic Code (PPTGIUG 1983) is investigated. The effectiveness of VSL-Gensui Damper application is also investigated as an effort to enhance the performance of the building. Nonlinear time history analysis was conducted to analyze the building. Spectrum consistent ground acceleration generated from El Centro 18 May 1940 North-South component in accordance to current seismic code was used for analysis. The result shows that the existing building cannot resist the demand specified by current code (SNI 1726:2012) as some frame element failures are detected. The performance is greatly enhanced after installation of VSL-Gensui Dampers. Roof story drift and displacement decreased as much as 9% and 14%, respectively as compared to existing building, and structural element failures were no longer observed
Development of the DKMQ Element for Analysis of Composite Laminated Folded Plate Structures
Get PDFThe discrete-Kirchhoff Mindlin quadrilateral (DKMQ) element has recently been developed for analysis of composite laminated plates. This paper presents further development of the DKMQ for analysis of composite laminated folded plates. In this development, a local coordinate system is set up for each element at its centroid. The DKMQ stiffness matrix is superimposed with that of the standard four-node plane stress quadrilateral element to obtain a 24-by-24 folded plate stiffness matrix in the local coordinate system. To avoid singularity of the stiffness matrix, a small stiffness coefficient is added in the entries corresponding to the drilling degrees of freedom. The local stiffness matrix and force vector are then transformed to the global ones and assembled. The accuracy and convergence of the folded plate element are assessed using a number of numerical examples. The results show that the element is accurate and converge well to the reference solutions
Combining Off-the-Job Productivity Regression Model with EPA’s NONROAD Model in Estimating CO2 Emissions from Bulldozer
Get PDFHeavy duty diesel (HDD) construction equipment which includes bulldozer is important in infrastructure development. This equipment consumes large amount of diesel fuel and emits high level of carbon dioxide (CO2). The total emissions are dependent upon the fuel use, and the fuel use is dependent upon the productivity of the equipment. This paper proposes a methodology and tool for estimating CO2 emissions from bulldozer based on the productivity rate. The methodology is formulated by using the result of multiple linear regressions (MLR) of CAT’s data for obtaining the productivity model and combined with the EPA’s NONROAD model. The emission factors from NONROAD model were used to quantify the CO2 emissions. To display the function of the model, a case study and sensitivity analysis for a bulldozer’s activity is also presented. MLR results indicate that the productivity model generated from CAT’s data can be used as the basis for quantifying the total CO2 emissions for an earthwork activity