Department of Civil Engineering

Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1927

Browse

End date: 2019Subject: search.filters.subject.Civil Engineering

Search Results

Now showing 1 - 10 of 457
  • No Thumbnail Available
    Item
    Effect of Skewness on Live Load Distribution in Webs of Concrete Box-Girder Bridges
    (IJTIMES, 2019) Kumar, Manoj
    The aim of the present paper is to study the effect of skewness on distribution of live load among the webs of the horizontally curved concrete box-girder bridges. In this paper, a 27.4 m long simply supported RC box-girder bridge has been considered to investigate the influence of skewness on box-girder with various curvatures. To this end, the central curvature angle of the bridge has been varied from 0° to 48° at an interval of 12° and the skew angle is swept from 0° to 50° at an interval of 10°. Using the three-dimensional Finite element analysis software CsiBridge, maximum vertical deflection under the webs of box-girder have been determined due to the IRC specified Class-70R tracked vehicular LL moving over the bridge at constant speed at maximum eccentricity specified by Indian Road Congress. Assuming the linear elastic behavior of the bridge, the live load has been distributed among the webs in the proportion of vertical deflections. The study revealed that the live load distribution among the webs is significantly affected by the skewness in conjunction with curvature. The results indicate that with increase in skewness, live load transferred to inner web decreases for almost all the curvature angles
  • No Thumbnail Available
    Item
    Influence of Environmental Conditions on the Performance of Bituminous Mixtures
    (ASME, 2018-05) Bhargava, Nishant
    Aging and moisture damage are considered as major environmental factors which affect the performance of bituminous mixtures. This study investigated the effect of aging and moisture invasion on the performance of bituminous mixtures in terms of tensile strength and rutting resistance. Two different types of aggregates sources and one unmodified bituminous binder with and without warm additive were used. Bituminous mixtures were subjected to two levels of aging conditions (short-term and long-term aged) and two levels of moisture conditions (1 and 3 freeze-thaw cycles). A total of 24 different combinations were investigated for tensile strength and permanent deformation characteristics. Mineralogical investigations characterized the crushed stone as calcareous and bank run as siliceous aggregates. Results from this study demonstrate that levels of aging had a significant impact on the tensile strength of bituminous mixtures with warm mix additive as compared to conventional bituminous mixtures. Fracture work density, a surrogate cracking parameter was able to adequately capture the influence of aggregate mineralogy on the moisture susceptibility of long term aged mixtures. In addition, moisture conditioning was found to influence fracture work density of mixtures more than aging. Further, the rutting resistance of mixtures was determined in terms of flow numbers obtained using Francken model. In general, the rutting resistance of conventional mixtures was relatively higher than a mixture with warm mix additive. As expected, the flow number of conventional mixtures increased with aging and further reduced with moisture conditioning. Interestingly, the flow numbers of bituminous mixtures with warm mix additive was not negatively impacted by moisture at short term aged conditions. However, flow number of both mixtures after long term aging exhibited a similar trend. Additionally, statistical analysis showed that an increase in freeze-thaw cycles from one to three did not significantly impact the tensile characteristics of the mixtures.
  • No Thumbnail Available
    Item
    Synergistic influence of aging and moisture on performance of warm mix asphalt
    (IJPRT, 2018) Bhargava, Nishant
    In this study, the influence of aging and moisture on the two different mechanical behaviors of warm mix asphalt was studied. The cracking and permanent deformation resistance were assessed in terms of tensile strength and flow number computed using a three stage model respectively. The influence of temperature on the tensile strength and both stress and temperature levels on the permanent deformation response of aged and moisture conditioned warm mix asphalt were investigated. Results show that moisture and increase in temperature had a negative impact on the tensile strength of warm mix asphalt while aging had a positive impact. However, the variation in tensile strength of mixtures was strongly related to variation in percent air voids. Aging and interestingly moisture conditioning were found to increase the resistance to permanent deformation of warm mix asphalt. Permanent deformation behavior of moisture conditioned samples was further studied to assess the impact of saturation. Results showed that the presence of moisture in samples increases the permanent deformation resistance. From the statistical analysis it was found that both the individual and interaction of aging and moisture had a significant effect on the tensile strength and flow numbers.
  • No Thumbnail Available
    Item
    Laboratory Investigation on the Effect of Emulsion Type and Additive on Microsurfacing Mix
    (ASME, 2019-10) Bhargava, Nishant
    In this article, the effect of emulsion type and additive on the performance of microsurfacing mix is evaluated both for initial mix characteristics and long-term performance. Three mix formulations were used for microsurfacing performance assessment, including cationic slow set (CSS) 1-h, cationic quick set (CQS) 1-h Mix 1 with additive, and CQS 1-h Mix 2 without additive. Here, the additive used primarily imparts rapid setting and acts as an adhesion promoter. Also, for each formulation, microsurfacing performance was assessed at 4 emulsion contents. The initial properties were evaluated in terms of workability, set and cure time of the mix, and filler–emulsion compatibility. On the other hand, long-term performance of the mix was assessed in terms of resistance to raveling and rutting. It was found that the emulsion type had a major effect on cohesion development where the mix with CSS 1-h emulsion had relatively lower cohesion than CQS 1-h Mix 1. The abrasion loss and sand adhesion were also affected by emulsion type, which could probably be attributed to better compatibility of CQS 1-h emulsion with the aggregates used in this study. It was also interesting to note that although the performance of CQS 1-h Mix 1 was acceptable, the addition of additive resulted in substantial improvement of both workability and performance. The filler–emulsion compatibility increased from 4 to 12 points with the use of additive. The abrasion loss was reduced by 262 to 663 % depending on the emulsion content. Statistical analysis at the 5 % significance level also showed that both emulsion type and additive had a significant influence on microsurfacing performance in terms of mixing time, consistency, cohesion, raveling, and rutting resistance. However, the resistance to moisture damage provided by additive resulted in insignificant differences between CSS 1-h and CQS 1-h Mix 1.
  • No Thumbnail Available
    Item
    State of the art review on design and performance of microsurfacing
    (Taylor & Francis, 2019-04) Bhargava, Nishant
    Over the years, microsurfacing had gained popularity owing to the effectiveness, economic and environmental benefits as a pavement preventive maintenance treatment. The review study explores the merits and demerits of mix design procedures along with modifications suggested by various studies. Subsequently, studies on the performance of microsurfacing had been extensively reviewed and significant parameters contributing to variation in performance were identified. Literature review indicated that the microsurfacing mix design, unlike conventional hot mix asphalt, was complicated due to chemically controlled curing system and additional components involving microsurfacing production. Despite simple test procedures, most commonly adopted mix design parameters such as mixing and setting time, and torque-measurements exhibit operator specific variability in test results. In order to overcome such issues, mechanical modifications for mixing and automated measurements of parameter values were proposed by several researchers. Laboratory investigations on microsurfacing performance highlighted that the inclusion of process control parameters and environmental conditions to mimic field conditions could further improve the evaluation of microsurfacing durability. In terms of field performance, even though microsurfacing contribute to road safety, issues related to noise and reflective cracking would require further research for better understanding and possible solutions. Hence, the evaluation of synergistic influence of parameters on microsurfacing performance by simulating production and environmental conditions in a laboratory would allow better quantification of the associated failures and help to find probable solutions.
  • No Thumbnail Available
    Item
    Resilience Based Earthquake Design of Buildings: Current Practice, Problems, and Opportunities in Indian Scenario
    (ASCE, 2018) Muthukumar, G.
    Resilience based design (RBD) gives an advantage in designing for both direct and indirect losses. It was observed that most significant losses to the economy is due to indirect losses incurred due to long downtime—inability of common mass to resume to their jobs and return home. With the use of RBD methods it is possible to control the downtime and its losses. In Indian scenario one of the major problem associated with carrying out RBD is lack of ground motion database and guidelines for selection and scaling ground motions. It is required to have hazard consistent ground motions to perform non-linear time history analysis (NLTHA) and using this analysis results, downtime assessment such as repair cost, repair time along with direct loss could be assessed. In this paper, current practices and their limitation in resilience based earthquake design are discussed along with the selection of proper ground motion and scaling methods. This paper also suggests various alternative methods such as use of SPO2IDA in cases where hazard consistent ground motion cannot be produced easily.
  • No Thumbnail Available
    Item
    Post-Earthquake Assessment of Buildings Using Deep Learning
    (2019-07) Muthukumar, G.
    Classification of the extent of damage suffered by a building in a seismic event is crucial from the safety perspective and repairing work. In this study, authors have proposed a CNN based autonomous damage detection model. Over 1200 images of different types of buildings-1000 for training and 200 for testing classified into 4 categories according to the extent of damage suffered. Categories are namely, no damage, minor damage, major damage, and collapse. Trained network tested by the application of various algorithms with different learning rates. The most optimum results were obtained on the application of VGG16 transfer learning model with a learning rate of 1e-5 as it gave a training accuracy of 97.85% and validation accuracy of up to 89.38%. The model developed has real-time application in the event of an earthquake.
  • No Thumbnail Available
    Item
    Synthesis of graphite/PbO2 anode: electrodeposition process modeling for improved landfill leachate treatment using RSM and ANN approach
    (Springer, 2019-07) Mandal, Pubali
    Based on the hypothesis that the electrodeposition conditions may have effects on the developed electrode’s oxidation performance, the present study aimed at investigating the effects of a graphite/PbO2 anode preparation conditions (current intensity, Pb(NO3)2 concentration, HNO3 concentration, and temperature) on leachate treatment efficiency. Synthesis conditions were varied to improve the performance of the electrode, and leachate treatment efficiencies were evaluated using anodes prepared at different conditions. The Box–Behnken design was used as an experimental design for achieving the goal. The effect of variables on the system’s outcome was modeled by response surface methodology and artificial neural network. The variation in chemical oxygen demand (COD) removal efficiency from 7.81 to 24.58% for 2 h of electrolysis demonstrates significant influences of anode preparation conditions on its performance. The optimum conditions were attained as 0.64 A of current intensity, 0.16 mol L−1 of Pb(NO3)2, 0.16 mol L−1 of HNO3, and 76.98 °C of temperature. The PbO2 electrode developed at optimum conditions yielded 79 ± 1.7% COD removal efficiency of leachate at 8 h. The study results show that electrode synthesis conditions affect the oxidation ability of the electrode, and optimization of the same can significantly improve the treatment performance.
  • No Thumbnail Available
    Item
    A novel approach towards multivariate optimization of graphite/PbO2 anode synthesis conditions: Insight into its enhanced oxidation ability and physicochemical characteristics
    (Elsevier, 2018-08) Mandal, Pubali
    Electrochemical oxidation has drawn great interest for its potential application in degrading persistent organic pollutants (POPs) through electrogenerated hydroxyl radical at the surface of anode. This study aims at the preparation of an inexpensive graphite/PbO2 anode. For enhancing oxidation performance, preparation process parameters viz. Pb(NO3)2 concentration, potential, and time of electrodeposition of a graphite/PbO2 anode, electrodeposited from acidic electrolyte bath, were optimized targeting a POP, 2,4-dinitrophenol removal. The changes in morphological properties of the developed oxide films were analyzed using scanning electron microscopy (SEM) which manifested significant impacts of selected anode preparation process parameters. Furthermore, PbO2 film prepared at optimum conditions were characterized using SEM, atomic force microscopy (AFM), energy dispersive X-ray spectroscope (ESD) elemental mapping, and X-ray diffraction (XRD) for thorough investigation of crystal structures, elemental distribution over surface, and phase of PbO2. Angular structures in both SEM and AFM analysis and appearance of β-PbO2 characteristic peaks in XRD analysis confirmed formation of electrocatalytically active phase of PbO2. For further enhancing the oxidation ability, influencing experimental parameters viz. current intensity, pH, and NaCl concentration were optimized. After 2 h of electrolysis at optimum experimental conditions, COD and total organic carbon removal efficiency of 93.6 ± 0.63% and 71.7 ± 1.52% were obtained respectively.
  • No Thumbnail Available
    Item
    Review on landfill leachate treatment by electrochemical oxidation: Drawbacks, challenges and future scope
    (Elsevier, 2017-11) Mandal, Pubali
    Various studies on landfill leachate treatment by electrochemical oxidation have indicated that this process can effectively reduce two major pollutants present in landfill leachate; organic matter and ammonium nitrogen. In addition, the process is able to enhance the biodegradability index (BOD/COD) of landfill leachate, which make mature or stabilized landfill leachate suitable for biological treatment. The elevated concentration of ammonium nitrogen especially observed in bioreactor landfill leachate can also be reduced by electrochemical oxidation. The pollutant removal efficiency of the system depends upon the mechanism of oxidation (direct or indirect oxidation) which depends upon the property of anode material. Applied current density, pH, type and concentration of electrolyte, inter-electrode gap, mass transfer mode, total anode area to volume of effluent to be treated ratio, temperature, flow rate or flow velocity, reactor geometry, cathode material and lamp power during photoelectrochemical oxidation may also influence the system performance. In this review paper, past and present scenarios of landfill leachate treatment efficiencies and costs of various lab scale, pilot scale electrochemical oxidation studies as a standalone system or integrated with biological and physicochemical processes have been reviewed with the conclusion that electrochemical oxidation can be employed as a complementary treatment system with biological process for conventional landfill leachate treatment as well as a standalone system for ammonium nitrogen removal from bioreactor landfill leachate. Furthermore, present drawbacks of electrochemical oxidation process as a landfill leachate treatment system and relevance of incorporating life cycle assessment into the decision-making process besides process efficiency and cost, have been discussed.