فهرست مطالب

Civil Engineering - Volume:17 Issue:9, 2019
  • Volume:17 Issue:9, 2019
  • تاریخ انتشار: 1398/05/09
  • تعداد عناوین: 12
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  • Evaluating the Effects of Earthquake Wave Propagation on Buried Curved Pipes Using Static Analysis
    Nadia Rahimi, Hamed Arzani, Mussa Mahmoudi * Pages 1353-1361
    Pipelines as lifeline play a key role in water, gas, and oil delivery. One of the effective factors in the design of buried pipes is fault existence on its path. One of the other effective factors in the pipeline design is the propagation of earthquake waves along it. Wave propagation means that the different parts of the pipes are vibrating with different values of accelerations due to earthquake wave propagation. This phenomenon can cause great stress and strain in the pipes. For determining the response of the burial pipelines due to wave propagation, a specific time history analysis is necessary using an earthquake accelerogram, which is highly complicated. The present study was conducted to evaluate the effects of earthquake wave propagation on the seismic response of curved buried pipes using simple method. In this method, it is assumed that during the earthquake, the burial pipe in the soil is deformed the same as its surrounding soil. Therefore, for seismic analysis of the pipe, the displacement record is used instead of acceleration record. The results showed that the earthquake wave propagation affect the seismic performance of buried pipelines considerably. Hence, it can be claimed that a decrease in the wave velocity in the soil would result in an increase in the longitudinal component of strain in the pipeline. Moreover, it was found that the curvature angle of 30° would have the greatest effect on the seismic response of pipelines. Finally, it was demonstrated that the longitudinal component of vibration has a greater effect on pipeline design compared to other components of the vibration.
    Keywords: Buried pipes, Static analysis, Wave propagation, Seismic performance, Curved pipelines
  • Removal of Pollutants from Landfill Leachate Using Physicochemical Technique
    Nur Syazwani Binti A. Rahman, Norashikin Ahmad Kamal * Pages 1373-1381
    Sanitary landfill leachate had been described as the most polluted wastewater. The available technologies to treat leachate landfills are physical/chemical and biological treatment. However, literature shows that filtration technique is preferable, as the selective materials are easily obtained and required minimum cost. The aim of this study is to treat pollutants (BOD, COD, ammoniacal nitrogen, zinc, and copper) in leachate using peat moss as sole adsorbent and co-adsorbent with bentonite. The research was conducted by measuring initial and final concentration of pollutants in leachate. Based on the results, the percentage removal of the BOD, COD, ammoniacal nitrogen, zinc, and copper using peat as single adsorbent 26.2%, 91.97%, 83.4%, 96%, and 90%. While using mixed adsorbents are 31.3%, 94.6%, 89.1%, 90.6%, and 90%. The total volume of leachate was 1200 mL able to pass through sole adsorbent of peat moss within 14 h. In conclusion, leachate can be treated efficiently using peat moss with the addition of bentonite.
    Keywords: Pollutant, Landfill leachate, Peat moss, Bentonite
  • Collapse Assessment for a RC Frame Structure in Bucharest (Romania)
    Florin Pavel *, Andrei Pricopie, George Nica Pages 1373-1381
    The focus of this paper is to evaluate the collapse probability of a planar RC frame structure designed for the seismic conditions of Bucharest (Romania). The assessment is performed using both static and dynamic nonlinear analyses. 1000 pushover curves are sampled for the analysed structure taking into account the uncertainty due to the materials’ strengths and due to the gravitational loading. The nonlinear time–history analyses are conducted on equivalent SDOF structures derived from each sample of pushover curves. Finally, the collapse assessment is assessed through multiple stripe analyses performed using a ground motion dataset of 20 representative horizontal components recorded in Bucharest area during three past major intermediate-depth Vrancea earthquakes. The results show an annual collapse probability of the order 3.0 × 10−3 to 6.0 × 10−5, which represents a value similar with those obtained in order studies in the literature. The nonlinear analyses also show that the epistemic uncertainty due to the modelling uncertainties has a much smaller contribution to the total uncertainty as compared to the record-to-record variability. The most important parameters affecting the collapse fragility appear to be the concrete compressive strength and the Young’s modulus for concrete.
    Keywords: Pushover curve, Multiple-stripe analysis, Vrancea seismic source, Equivalent SDOF, Strength uncertainty, Loading uncertainty
  • Design Gyration Number Determination of 100 mm-Diameter Asphalt Mixtures
    Serkan Tapkın *, Mustafa Keskin Pages 1383-1396
    At present, there is no accepted standard by highway authorities on the compaction procedures of 100 mm-diameter gyratory compactor specimens. In previous studies on gyratory compaction, the method of either coring from 150 mm specimens, or preparing taller specimens than the usual 63.5 mm-long Marshall specimens, has been undertaken. However, the utilisation of 150 mm-moulds produces a significant amount of mechanical disturbance during the coring process of 100 mm-diameter specimens. The note-worthy aspect of this study is that a new standard for preparing gyratory compactor specimens with a diameter of 100 mm and a length of approximately 63.5 mm has been proposed for the first time. In this study, the design gyration number of the asphalt mixture was obtained by carrying out extensive laboratory testing on the specimens prepared, and by changing various testing parameters including the gyration number, angle of gyration, specimen height, and ram pressure. First, tests using 600 kPa ram pressure and a 1.25° gyration angle with varying gyration numbers were carried out. Then, the gyration angle was changed from 1.25° to 1.85° by 0.05° increments. Following that, a completely different pattern of loading level using 240 kPa with a 2° gyration angle was investigated. And finally, changing the gyration angle from 1.60° to 2.40° by 0.20° increments was carried out to provide a wider scope of investigation. As a result, the design gyration number for 100 mm-diameter asphalt mixtures was determined as 40 under medium traffic conditions.
    Keywords: Gyratory compaction, 100 mm-diameter specimens, Angle of gyration, Ram pressure, Design gyration number, Medium traffic conditions
  • An Optimal Operation Planning Model for High-Speed Rail Transportation
    Xiaoqiang Zhang *, Lin Li, Muhammad Afzal Pages 1397-1407
    A reasonable train operation plan for railway passenger transportation should jointly optimize the service quality and rail operator’s revenue. This paper synthesizes revenue management and train operation planning to develop an integrated model to maximize the operator’s revenue and minimize passenger’s general cost, which is applied to optimize the rail train frequencies, stopping patterns and seats’ allocation dynamically. An integer program is designed to describe this problem, which is solved by the CVX toolbox. The Chengdu–Chongqing high-speed rail line is applied to demonstrate the effectiveness of the proposed methodology. The optimal frequencies are 95 trains per day, comparing the actual frequencies of 69 trains per day. The total profit increased by 24%, and the passengers’ waiting time reduced greatly. It can be seen that the proposed model is effective for the optimization of the rail planning, which significantly increases the total revenue and reduces the passengers’ waiting time.
    Keywords: Operation planning, Train stop pattern, Pricing, High-speed rail, Revenue management
  • Causal Factors of Driver’s Speeding Behaviour, a Case Study in Oman: Role of Norms, Personality, and Exposure Aspects
    Muhammad Ashraf Javid *, Arwa Faris Ahmad Al, Roushdi Pages 1409-1419
    The objective of this paper is to examine the driver’s characteristics in relation to speeding behaviour and traffic safety issues with the help of a self-reported questionnaire survey. A comprehensive questionnaire was designed considering the attitudes and norms of the local drivers and theoretical background of Norm-Activation Model (NAM) theory. The total collected samples were 301 and data were analyzed using factor analysis and structural equation modelling technique. Excessive speed remains one of the causal factors associated with serious accidents in Oman. Results revealed that individual personality traits, driving culture and traffic exposure, and different situational constraints have significant relationships with the speeding behaviour of drivers. Male and young drivers have more trend of speeding in comparison to other drivers. The study results confirmed that variables of NAM theory have a significant and positive relationship with driver’s speeding behaviour. These findings can be used to develop specific policies aimed at improving the traffic safety on roads. The main priority of public safety policy should be to plan awareness and behavioural change programs for the drivers in Oman about the risks associated with speeding behaviour.
    Keywords: Speeding behaviour, Norms, Personality, Attitudes, Traffic safety
  • A Field Investigation on the Effects of Using USPs in Transition Zone From Ballasted Track to Bridges
    Jaber Mottahed, Jabbar Ali Zakeri *, Saeed Mohammadzadeh Pages 1421-1431
    Transition zone is one of the vulnerable sections in railway tracks. This study was conducted to assess the effects of using under sleeper pads (USPs) in the transition zone from ordinary ballasted track to railway bridges. For this purpose, a railway bridge with two spans (with the length of 7 m) and an overall length of 15.5 m was selected, followed by designing and conducting field tests in three states: (1) without USP, (2) with USP only on bridge section, and (3) with USP on bridge section and transition zone. The vibrational behavior of the bridge and track components was monitored during train passage by the installation of accelerometers on the bridge, rail, sleeper, and installation of linear variable displacement transducer beneath the bridge deck. The results showed that the maximum effects of using USPs in the transition zone were in the first span so that the average value of accelerations in all speeds decreased in the first span. The acceleration of the rails in the third experiment was 4% lower than the second one and 35% lower than the first one. This reduction for sleepers was 9% and 24%, respectively, and for the bridge deck, it was 48% and 66%, respectively.
    Keywords: Transition zone, Under sleeper pad, Railway bridge, Bridge vertical vibration, Field test
  • An Experimental Study on Mechanical Properties and Cracking Behaviors of AFRC Used as Functional Material in Hybrid Beams
    Rajendra Prasad Bohara, Ganchai Tanapornraweekit *, Somnuk Tangtermsirikul Pages 1433-1444
    In this paper, the effects of a constant fiber volume fraction (1%) of four types of aramid fibers (AFs) and one type of steel fiber (SF) on mechanical properties, load capacity, and cracking behavior of concrete were investigated. To use fiber-reinforced concrete (FRC) as a functional material economically, hybrid beams having FRC in the bottom half and normal concrete in the top half of the beam section were designed. A total of 108 cylindrical specimens of conventional concrete, aramid fiber-reinforced concrete (AFRC), and steel fiber-reinforced concrete (SFRC) were tested to explore the effects of various fibers on the compressive and splitting tensile strengths. The effects of the fibers on the load carrying capacity and cracking behaviors of the beams were studied through two-step four-point bending tests of a control beam and five hybrid beams. The experimental results showed that the use of AFs and SF in concrete enhanced the splitting tensile strength, cracking behavior, and ductility. However, the use of fibers was found to have an insignificant effect on the compressive strength of concrete. Among the tested aramid and steel fibers, the performance of the twisted aramid fibers with 40 mm length (40-T) was the most impressive with respect to an enhancement of tensile strength, load capacity, and cracking behavior. Furthermore, a comparison of various properties of AFRCs and SFRC indicated that 40-T aramid fiber can be used as an alternative to steel fiber.
    Keywords: Aramid fiber, Fiber concrete, Functional material, Hybrid beam, Steel fiber
  • Treatment of Amman Slaughterhouse Wastewater by Anaerobic Baffled Reactor
    Bashar M. Al Smadi *, Wissam Al, Hayek, Husam A. Abu Hajar Pages 1445-1454
    The wastewater from Amman slaughterhouse was treated by a lab-scale (10.45 L) anaerobic baffled reactor. The performance of the treatment system was evaluated over 152 days by monitoring several parameters such as COD, BOD, solids’ concentration, and biogas production at two temperature scenarios. During the first 103 days, the reactor was operated at ambient temperatures ranging from 15 to 23 °C resulting in average COD and total solids’ removal efficiencies of 70% and 33%, respectively. Afterwards, the reactor temperature was controlled at 40 °C which resulted in improving the COD and total solids’ removal efficiencies to 90% and 44%, respectively. The gas production was minimal during the first 103 days as there was no observable biological activity at the relatively low operating temperatures. After the temperature was raised to 40 °C, the biogas production increased considerably to reach a steady state rate of 122 mL per day. The effluent produced from the anaerobic digestion of slaughterhouse wastewater was comparable to the Jordanian Standards for reclaimed water reuse in irrigation and surface water discharge.
    Keywords: Slaughterhouse wastewater, Anaerobic baffled reactor, Wastewater reuse, Wastewater treatment
  • Effects of Spraying Various Nanoparticles at Early Ages on Improving Surface Characteristics of Concrete Pavements
    Ali Akbar Shirzadi JavidEmail author, Parviz Ghoddousi, Maziar Zareechian, Asghar Habibnejad Korayem Pages 1455-1468
    In this study, the effects of spraying nanoparticles with different geometries (nano-SiO2, nano-halloysite, and nano-montmorillonite) on surface characteristics of concrete pavement in terms of microstructure. The initial and final setting times of mixtures were determined to investigate the proper spraying time for applying on the pavement surface at early ages. To precisely investigate the microstructural properties, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) were used. The results revealed that spraying nanoparticles improved the abrasion and skid resistance as well as transport properties of the concrete surface, especially at the initial setting time. According to the tribology testing, the surface friction coefficient of sprayed samples compared to the reference sample (not sprayed) was increased 28%, on average. AFM results verified that this growth is due to the improved surface roughness and van der Waals forces. Based on the FTIR results, the abrasion resistance of the samples gradually diminished by increasing the depth due to reduction of nanoparticles penetration, thus, reducing its positive effect. In addition, a good relationship with regression coefficient of 0.79 was found between the surface tensile strength and the abrasion resistance of the specimens.
    Keywords: Concrete pavement, Nano-SiO2, Nano-halloysite, Nano-montmorillonite, Abrasion resistance, Skid resistance
  • Evaluation of Software and Hardware Settings for Audio-Based Analysis of Construction Operations
    Chieh, Feng Cheng, Abbas Rashidi *, Mark A. Davenport, David V. Anderson Pages 1469-1480
    Various activities of construction equipment are associated with distinctive sound patterns (e.g., excavating soil, breaking rocks, etc.). Considering this fact, it is possible to extract useful information about construction operations by recording the audio at a jobsite and then processing this data to determine what activities are being performed. Audio-based analysis of construction operations mainly depends on specific hardware and software settings to achieve satisfactory performance. This paper explores the impacts of these settings on the ultimate performance on the task of interest. To achieve this goal, an audio-based system has been developed to recognize the routine sounds of construction machinery. The next step evaluates three types of microphones (off-the-shelf, contact, and a multichannel microphone array) and two installation settings (microphones placed in machines’ cabin and installed on the jobsite in relatively proximity to the machines). Two different jobsite conditions have been considered: (1) jobsites with single machines and (2) jobsites with multiple machines operating simultaneously. In terms of software settings, two different SVM classifiers (RBF and linear kernels) and two common frequency feature extraction techniques (STFT and CWT) were selected. Experimental data from several jobsites was gathered and the results depict an accuracy over 85% for the proposed audio-based recognition system. To better illustrate the practical value of the proposed system, a case study for calculating productivity rates of a sample piece of equipment is presented at the end.
    Keywords: Microphone arrays, Audio signal processing, Construction equipment, Activity recognition, Fourier transform
  • Dynamic Bus Scheduling Based on Real-Time Demand and Travel Time
    B. Anil Kumar, G. Hari Prasath, Lelitha Vanajakshi * Pages 1481-1489
    Dynamic scheduling of buses, which adapts to the current passenger demand and traffic conditions, will help in ensuring an efficient service to the commuters and maximizing the profit for operators. A fixed schedule with a constant headway, which is currently used widely, may lead to inadequate number of buses during peak periods and under-utilization of the system in off-peak periods. To overcome this, the present study proposes a demand and travel time responsive model to maximize the benefit of the operator by preparing an optimal schedule that can adapt to the variations in passenger demands and traffic conditions, subjected to minimizing the waiting time of the passengers, capacity constraints of the buses to achieve the maximum financial benefit as well as social satisfaction. For this, the study analyses the data received from real-time tracking devices that were fitted in a selected bus route in Chennai. Results showed that the waiting times were reduced up to 10 min per passenger and the percentage utilization of bus capacity was increased by 8% on an average across a day.
    Keywords: Bus scheduling, Anticipated headway, Maximum passenger waiting time, Expected time of arrival, Bus capacity utilization