فهرست مطالب

Civil Engineering - Volume:17 Issue:10, 2019
  • Volume:17 Issue:10, 2019
  • تاریخ انتشار: 1398/08/21
  • تعداد عناوین: 12
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  • Determination of the Hydrodynamic Load on an Inundated Bridge Deck by Measurements Performed on a Physical Model
    Aleš Dráb*, David Duchan, Miroslav Špano, Michal Pavlíček, Pavel Zubík, Pavla Štěpánková Pages 1491-1502

    The paper describes the options for the determination of the hydrodynamic load on an inundated bridge deck based on experimental measurements performed on a physical model. The motivation for resolving the given issue came from real-world cases where options are limited as regards modifications to the level of the bridge superstructure and the road in the immediate surroundings of the bridge. Under these conditions, the given bridge should be evaluated in greater detail from the aspects of both flood discharge capacity and the potential hydrodynamic load if water flow inundates the bridge structure. The subject of the experimental measurements was the determination of what are known as drag, lift and moment coefficients, which are essential for quantifying individual components of hydrodynamic load. The research focused on a special type of load-bearing bridge structure with minimized structural height designed for railroad tracks. Before the actual measurements took place it was necessary to determine a set of measuring equipment that would be economically acceptable for the purposes of research and engineering practice. The results of our experimental measurements confirmed that the selected specific bridge deck shape has a clear and significant influence on the drag coefficient values obtained. The lowest values were achieved by the bridge deck shape with chamfered edges. The correctness of the achieved results was verified by comparison with published domestic and foreign papers on the given field. The achieved results enable the determination of the hydrodynamic load of the examined types of load-bearing bridge structures during the reconstruction or building of new bridges. Other fundamental uses are expected, e.g., in the verification of numerical hydrodynamic models.

    Keywords: Hydrodynamic load, Bridge deck, Drag force, Lift force, Moment, Physical model
  • Analysis of the Effect of Initial Crack Length on Concrete Members Using Extended Finite Element Method
    Deepti Muley*, Mohamed Kharbeche, Wael K. M. Alhajyaseen, Mohammed Al, Salem Pages 1503-1512

    The extended failure process of the prefabricated one-side notched three-point bending concrete beam was simulated by the extended finite element method. Combined with the double-K fracture criterion, the influence of the initial crack length on the fracture parameters of the three-point curved concrete beam and the influence of the initial crack on the concrete structure were studied. In addition, the dynamic response state and crack propagation process of Koyna concrete gravity dam under seismic conditions are simulated, and the influence of initial crack length on these factors is studied. The results show that the existence and length of the initial crack have a certain impact on the development of cracks in concrete members. Under the action of earthquake, the stiffness of the concrete gravity dam is reduced, and the response period of the horizontal and vertical displacement of the top of the gravity dam is not significantly correlated with the initial crack length. However, the opening range of the crack increases as the initial crack length increases. When the initial crack length is 0 m, 0.5 m and 1 m, the crack opening upstream of the gravity dam is 1.26 cm, 1.61 cm and 1.86 cm respectively; the downstream crack opening is 1.73 cm, 2.35 cm and 2.53 cm.

    Keywords: XFEM, Initial crack length, Concrete, Gravity, dam Earthquake
  • New Fused Steel-Coupling Beam with Optimized Shear Panel Damper
    Davood ZareiAbbas*, Ali TasnimiEmail author Pages 1513-1526

    This paper summarizes the development of a new replaceable horizontally steel arc-cut damper (HACD) designed as a fuse element in steel-coupling beams for earthquake protection of reinforced concrete shear walls with openings. The HACD is fabricated from a steel arc-cut plate and restraining plates positioned by vertical steel stiffeners. The proposed damper is an in situ, weld-free energy dissipater device, which eliminates the on-site installation difficulties. The seismic induced energy is dissipated through shear yielding of the arc-cut plate when the device is subjected to inelastic cyclic deformation. The optimized shape of HACD with adequate ductility and dissipation energy capacity is obtained using finite-element analysis. The result of numerical analysis under pseudo-dynamic displacements indicates its suitable energy dissipation, stable hysteric response, and remarkable ductility through shear yielding of the arc-cut shear plate. The performance of the numerical approach is justified through the analysis of tested dissipative device available in the literature.

    Keywords: Numerical, Coupling beam, Shear panel damper, Fused steel, Energy dissipater
  • In Situ Bioremediation of Textile Dye Effluent-Contaminated Soils Using Mixed Microbial Culture
    Denzil DanielP. Jegathambal*, Brett Bevers Pages 1527-1536

    In situ bioremediation is proposed as a low cost and environmental friendly technology for clean-up of land discharge sites of textile industries. Owing to the large range of dye molecules in the environment, a treatment system using mixed microbial culture is proposed. The mixed microbial population possesses higher degree of biodegradation due to synergistic metabolic activities of the microbial community. In the present study, mixed microbial cultures were cultured from four different sources. The dyes used in the experiments were Direct Red 28, Direct Blue 53 and Azur Blue. Batch studies for industrial application were also attempted to treat sludge landfills for chemical coagulation units of dye effluent treatment plants. Finally, a downward flow continuous flow soil reactor was set up to study the robustness of the technology over long duration of operation. Rate of recharge of mixed dye during the trials was 2 mg per hour per kg of soil. Colour removal of 85% (measured at 595 nm) was observed in the first day and 90% in the second day. A steady removal rate of 98% was observed from the 13th day of operation. Fate of the dye molecules was studied using scanning electron microscope (SEM) and Fourier transform infraRed (FTIR) analysis to establish colour removal due to biodegradation.

    Keywords: In situ bioremediation, Biodegradation, Contaminated soil, Textile dyes, Mixed microbial culture, Infrared spectroscopy
  • An Integrated Planning/Pricing Decision Model for Rail Container Transportation
    Xiaoqiang Zhang*, Lin Li Pages 1537-1546

    Pricing and operation planning are two key issues for railway trainer transportation. Most of the researches tried to optimize the pricing or operation planning strategies separately. As in fact, these two factors are related to each other. The isolated research on either of them cannot get the optimal solution. In this paper, a bi-level model is proposed, which integrate the pricing, the operation planning, and competition from road transportation, to maximize the profit of rail operators. The lower level is designed to minimize the customer’s general cost, and the upper level is to maximize the revenue of rail operators. A descent algorithm based on the sensitivity analysis method is designed to solve the bi-level model. A real transportation network with 5 freight stations of China Railway Corporation is applied to evaluate the proposed model. The results show that our method can improve the rail operator’s profit about 14% compared with the fixed pricing policy under the competition freight transportation market.

    Keywords: Rail container transportation, Operation planning, Pricing, Bi-level model
  • Settlement Prediction Using Support Vector Machine (SVM)-Based Compressibility Models: A Case Study
    Scott Kirts, Boo Hyun Nam, Orestis P. PanagopoulosPetros, Xanthopoulos Pages 1559-1570

    The magnitude of soil settlement depends on several variables such as the compression index, Cc, and recompression index, Cr, which are determined by a consolidation test. This laboratory test is time consuming and labor intensive, thus efforts to correlate the compressibility indexes and soil index properties have been made. In this study, soil compressibility prediction models are enhanced by the support vector machine (SVM) algorithm, and the performances of those correlations are tested via field verification in terms of settlement calculation. The field verification portion of the study consists of identifying sites with borings, consolidation tests, and measured settlement from overlying load. Soil layers, within the influence zone of settlement, are tested to obtain soil index parameters. Once a complete soil profile has been established, a series of settlement analyses were performed. Settlement predictions were made based on both predicted and measured Cr for each soil layer. An additional settlement prediction was made using a rule of thumb equating Cc to Cr. The predicted settlements were then compared to the measured settlement taken in close proximity. Upon conclusion, using the Cr and Cc correlations provides comparable settlement predictions compared to measured settlement and the predicted Cr (using a correlation from predicted Cc) exhibits the strongest settlement predictions. The predicted settlements are lower than the measured settlements for both site locations. This leads one to believe that the influence zone of settlement may be deeper than originally considered.

    Keywords: Consolidation, Soil compressibility, Support vector machine, Field verification, Settlement
  • Experimental Investigation of Bond Stress and Creep Displacements of GFRP Soil Nails Simulated in a Soil Box
    Behrooz Hamedmirjafari, Jafar Bolouri Bazaz, Saeed Abrishami Pages 1559-1570

    Fiber-reinforced polymer bars, as an alternative for steel bars, are widely used to overcome the corrosion problem especially under severe environmental conditions. In the present research, the soil nail system was physically modeled in the laboratory. Since bond stress and creep displacements of the GFRP nails are not well understood yet, the nail–grout and grout–soil interfaces were experimentally investigated simultaneously in a soil box. In the first step, the bond stress of the GFRP soil nails was studied through pullout tests. Subsequently, experimental creep tests were carried out under sustained loads which were equal to a fraction of ultimate pullout load. Furthermore, the effect of soil density and surcharge pressure on bond stress of both interfaces was evaluated. In addition, the ultimate bond strength of the nail–grout interface was measured by physical tests, and the grout could not move. Finally, the dependency of creep displacements on different load ratios and variable surcharge pressures was explored. The results clearly showed that the ultimate pullout load of the steel nail–grout interface with no surrounding soil was more than that of GFRP. The grout–soil bond stress was affected by the variation of soil density more than nail–grout and an almost linear relationship between soil unit weight and bond stress was observed at both the interfaces. Nevertheless, the increment rate of bond stress decreased with the growth in surcharge pressure at both interfaces. Moreover, creep tests displayed an interdependency of creep displacements at the interfaces and rate of reduction of creep displacements with the decrease in the surcharge pressure increment.

    Keywords: Bond stress, Creep tests, Glass fiber-reinforced polymer (GFRP), Load ratio, Soil density, Surcharge pressure
  • The Resistance of Blast Furnace Slag- and Ferrochrome Slag-Based Geopolymer Concrete Against Acid Attack
    Ahmet ÖzcanMehmet*, Burhan Karakoç Pages 1571-1583

    In this study, blast furnace slag- (BFS) and Elazığ ferrochrome slag (EFS)-based geopolymer concretes were produced. Samples were immersed in 5% phosphoric acid (H3PO4), hydrochloric acid (HCl), hydrofluoric acid (HF) and sulfuric acid (H2SO4) solutions for 12 weeks. The compressive strengths, ultrasonic pulse velocities, weight and length changes of the samples were determined in this process. At the same time, visual inspections of the samples were investigated. Scanning electron microscopy (SEM) analysis was performed for the microstructure analysis of the samples removed from the solutions. 5% H2SO4 solution had the most negative effect on the samples. As the EFS ratio in the geopolymer concrete mixture increased, the loss rate in the strength of the samples exposed to acid solutions decreased. H3PO4 solution caused less weight loss in samples than other acid solutions. It was seen that the samples immersed in H3PO4 and HCl solutions shrank and that the samples immersed in HF and H2SO4 solutions expanded. Softening, cracking and corruption occurred on the surfaces of the samples exposed to the acid solutions for 12 weeks. With increasing EFS ratio in the mixture, the deterioration of the samples’ surfaces exposed to acid solutions decreased. Ettringite formations were seen in the SEM images of geopolymer concretes immersed in 5% H2SO4 solution.

    Keywords: Blast furnace slag, Elazığ Ferrochrome slag, Geopolymer concrete, Durability, Chemical effect, Acid attack
  • Numerical and Experimental Investigations of Different Cross-Sectional Configuration of Plain Concrete and CFST Short Columns Under Axial Compression
    Palash Dey*, R. K. Gupta, A. I. Laskar Pages 1585-1601

    In the present study, the finite-element (FE) and experimental analysis were carried out to understand the behaviour of the different cross-sectional configuration of plain concrete and concrete filled steel tube (CFST) short columns. A numerical model for the simulation of columns subjected to axial compression has been established using the commercial software package ABAQUS. The ultimate load carrying capacities of the different configuration of short columns are calculated using ACI-318 code. The results estimated according to the design code are found in good agreement with the FE and measured results. It has been noticed that the ductility of the CFST column is significantly high compared to the concrete alone. The outcome of the study reveals that the circular column profiles are good geometry to be considered, since they have outstanding performance concerning of energy absorption in axial loading condition. Furthermore, it has been noticed that the numerical model shows the satisfactory performance in predicting the failure modes. At the end of the study, it is recommended that the utilization of various grade of concrete layer combination of CFST columns shows a better choice from the economic point of view.

    Keywords: Concrete filled steel tube, Short column, Axial compression, Energy absorption capacity, Failure mode
  • Characterization of Near-Fault Effects on Potential Cumulative Damage of Reinforced Concrete Bridge Piers
    Vui Van Cao* Pages 1603-1618

    The objective of this study is to characterize the potential damage of near-fault ground motions on reinforced concrete bridge piers, providing information for engineering practice. To achieve this objective, 200 real near-fault pulse-type records and a bridge pier were selected. The same number of real far-fault ground motions was also selected for comparison. Inelastic time history and damage analyses were performed for the pier subjected to the selected near-fault and far-fault ground motions. The obtained results showed that more than 91% near-fault motions caused the pier to collapse while the pier survived under almost all far-fault motions. The responses of the pier under near-fault motions were characterized by one or few large hysteretic cycles. The damage indices of the pier subjected to near-fault ground motions increased rapidly when the pier underwent pulses of near-fault motions, and the pier damage was mainly caused by pulses. Collapse of the pier subjected to near-fault motions occurred at the pulse time. The duration to collapse, which was defined as the duration from light damage to collapse, of the pier under near-fault motions was extremely short (approximately 2.3–2.5 s). These special and negative structural damage characteristics of near-fault ground motions should be considered in designing and mitigating seismic hazards for structures located in near-fault regions.

    Keywords: Near-fault earthquake, Seismic load, Damage characteristic, Reinforced concrete, Bridge pier
  • Performance Evaluation of Paroxetine Adsorption Using Various Types of Activated Carbon
    Safwat M. Safwat* Pages 1619-1629

    This study was performed to investigate the ability of three different types of activated carbon to remove paroxetine from wastewater through adsorption. These types were extruded activated carbon (EAC), granular-activated carbon (GAC), and powdered-activated carbon (PAC). The three adsorbents were investigated using atomic force microscope, X-ray diffraction, and scanning electron microscopy. The results showed that the adsorption was dependent on the pH, and the removal efficiency of paroxetine increased with a decrease in pH value. The maximum removal efficiencies were 34, 40, and 86.5% for EAC, GAC, and PAC, respectively, at a pH of 4.5. Kinetic studies showed that the adsorption of paroxetine onto the three adsorbents can be expressed by pseudo-second-order kinetics. The intra-particle adsorption model showed that the adsorption mechanism of paroxetine using these adsorbents was controlled by a multistep mechanism. The Boyd kinetic model indicated that the liquid film diffusion may be involved in controlling the adsorption of paroxetine on the three adsorbents. Equilibrium studies showed that the adsorption isotherms could be expressed by the Freundlich, Temkin, and Dubinin–Radushkevich isotherms for EAC, GAC, and PAC, respectively. The change in morphologies of adsorbents confirmed the occurrence of adsorption.

    Keywords: Activated carbon, Kinetics, Isotherm, Paroxetine, Wastewater
  • Sustainability Practices for the Suhua Highway Improvement Project in Taiwan
    How, Jei Shau, Tai, Yi Liu, Po, Han Chen*, Nelson N. S. Chou Pages 1631-1641

    Sustainability of infrastructure has recently been recognized as an important issue for civil engineering projects, not only in the design phase, but also in the construction phase. In this paper, we discuss the sustainability measures taken for the Suhua Highway Improvement Project. This highway is located in eastern Taiwan, running in a north–south direction and connecting Suao (north end) and Hualien (south end). Project design started in 2008 and associated construction work commenced in 2013 and is expected to be finished in early 2020. It includes eight tunnels (24.5 km), thirteen bridges (8.5 km), and embankments (5.8 km), with a total length of 38.8 km. Some key areas of sustainability, including ecology, landscape, carbon reduction, and cultural preservation, have been taken into consideration in the design and construction phases. In this paper, we will discuss and present detailed study results along with the project construction status. This project is the first highway project in Taiwan that tracks the carbon footprint inventory for each detailed activity. Adjusting the concrete mixture through replacing part of cement with coal fly ash and ground-granulated blast-furnace slag helped reduce roughly 34–43% carbon emission. In addition, comprehensive study on ecological conservation has resulted in some remarkable achievements. The highway design also incorporates local characteristics into the bridge architecture, making it a pleasant addition to the landscape. The sustainability practices and measures taken for the Suhua Highway Improvement project could be very helpful for sustainable environment at local and global levels.

    Keywords: Suhua highway improvement, Sustainability, Carbon footprint inventory, Ecological conservation, Landscape, Cultural preservation