Department of Civil Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

Drilled shaft foundations supporting mast arm assemblies are subjected to significant torsion and lateral load during severe wind loading (e.g., hurricane). Past centrifuge studies in granular soils suggest that the design of such foundations should be performed for a coupled load case, since the lateral resistance is considerably reduced by the concurrent application of torsion. However, current design practice still considers lateral load and torsion independently due to the lack of field verification of centrifuge results. This paper reports on a full-scale test program to investigate the coupled load behavior of drilled shafts. A novel load test setup (with a heavy-duty mast arm assembly) and instrumentation were used for the combined torsion and lateral loading (e.g., wind loading). The study revealed a significant reduction in lateral resistance due to the influence of torque as observed from previous centrifuge studies. Torsional resistance was reduced (approximately 20%) by the impact of lateral load when compared with the anticipated torsional resistance based on unit skin friction values, derived from the axial load test results (i.e., no influence of lateral load). A comparison of measured torsional resistance during the combined loading with the predicted values using different approaches was also made. O’Neill and Hassan’s beta (β) method (sand) and alpha method (clay) are found to predict the torsional resistance reasonably well (±10%), while all other methods based on the standard penetration test and cone penetration test considered in the study overpredicted or underpredicted the resistance. © 2016, Canadian Science Publishing. All rights reserved.

World University root node

Canadian Geotechnical Journal

Full-scale coupled torsion and lateral response of mast arm drilled shaft foundations

VII Brazilian Symposium on Rock Mechanics – SBMR

Geomechanical properties of volcanic rocks from Deccan Traps,India.

The compatibility strut-and-tie method (C-STM) is an efficient minimalist nonlinear modeling approach for shear-critical reinforced concrete members. This paper presents two key improvements to the C-STM to better model overall behavior through failure. First, modified softened diagonal concrete struts are incorporated directly into the analysis, thereby eliminating any need for post-processing analysis, to enable accurate modeling of the failure load. Second, modeling modifications are made so that the analysis may be conducted in displacement control, thereby permitting cyclic loading and post-peak (failure) load-displacement behavior to be predicted. The modifications are implemented in SAP2000 and verified with experimental results for both monotonic and cyclic loading cases. It is observed that the C-STM predicts the overall force-deformation behavior of the structure quite well. Additionally, the C-STM also predicts the internal strain-dependent behavior of the structure and gives insights into the cause of failure of the structure. © 2016 American Society of Civil Engineers.

Journal of Structural Engineering (United States)

Displacement-based compatibility strut-and-tie method and application to monotonic and cyclic loading

Structural Faults+Repair, Edinburgh, Scotland.

Modelling ASR/DEF Expansion Strains in Large Bridge Piers

Complex modulus of an asphalt mixture constitutes two components: E' representing the ability of the mixture to store energy (elastic behavior), and E" reflecting the capacity of the material to dissipate energy (viscous behavior). The main objective of this study was to develop predictive equations for the two components, E' and E", to better quantify and assess the performance of conventional and modified mixtures alternate to standard laboratory testing. The dataset used in this effort encompassed 163 conventional dense graded asphalt concrete (DGAC), 13 asphalt-rubber asphalt concrete (ARAC) gap-graded, and 9 asphalt-rubber friction course (ARFC) open-graded mixes covering 5,550 data points. Aggregate gradation, binder, and volumetric property parameters were used as predictor variables. Squared-error optimization mathematical techniques were employed in developing predictive models. The statistical goodness of fit measures of E' and E" predictive models were very good to excellent. Validation results of the predictive models reflected effectiveness in reproducing observed values with goodness-of-fit measures in the domain of fair to excellent. Sensitivity performance analyses were also carried out to demonstrate the performance of asphalt mixtures with respect to different material properties. © 2016 American Society of Civil Engineers.

Journal of Materials in Civil Engineering

Predictive models for storage modulus and loss modulus of asphalt mixtures

Conference on Sustainable Asphalt Pavement for Developing Countries (CONSAP {\ldots}

Investigation on Creep and Recovery Behaviour of Rubber Modified Asphalt Binders

One of the main issues with the infrastructure construction in seismic regions is liquefaction. This paper reports on a case study of liquefaction evaluation of a proposed building site in San Francisco, California. The risk of liquefaction was assessed considering the following site specific factors: ground water table, liquefaction hazard maps, soil type, soil density, and peak ground acceleration. The analysis revealed that the selected region has low risk of liquefaction. However, it is suggested that the uncertainty associated with the estimation of corrected SPT N value (e.g., spatial variability, other human errors, etc.) should be accounted by incorporating an additional site-specific reduction factor in the estimation of Cyclic Resistance Ratio (CRR) of the soil.

Challenges and Innovations in Geotechnics

Estimation of liquefaction potential: A case study in San Francisco, California

In the Apalachicola-Chattahoochee-Flint (ACF) river basin in Alabama, Georgia, and Florida (USA), population growth in the city of Atlanta and increased groundwater withdrawal for irrigation in southwest Georgia are greatly affecting the supply of freshwater to downstream regions. This study was conducted to understand and quantify the effect of irrigation pumpage on the karst Upper Floridan Aquifer and river–aquifer interactions in the lower ACF river basin in southwest Georgia. The groundwater MODular Finite-Element model (MODFE) was used for this study. The effect of two drought years, a moderate and a severe drought year, were simulated. Comparison of the results of the irrigated and non-irrigated scenarios showed that groundwater discharge to streams is a major outflow from the aquifer, and irrigation can cause as much as 10 % change in river–aquifer flux. The results also show that during months with high irrigation (e.g., June 2011), storage loss (34 %), the recharge and discharge from the upper semi-confining unit (30 %), and the river–aquifer flux (31 %) are the major water components contributing towards the impact of irrigation pumpage in the study area. A similar scenario plays out in many river basins throughout the world, especially in basins in which underlying karst aquifers are directly connected to a nearby stream. The study suggests that improved groundwater withdrawal strategies using climate forecasts needs to be developed in such a way that excessive withdrawals during droughts can be reduced to protect streams and river flows. © 2016, Springer-Verlag Berlin Heidelberg.

Hydrogeology Journal

Effect of irrigation pumpage during drought on karst aquifer systems in highly agricultural watersheds: example of the Apalachicola-Chattahoochee-Flint river basin, southeastern USA [Effet de pompages pour l’irrigation en période de sécheresse sur les systèmes karstiques dans des bassins versants fortement agricoles: exemple du bassin versant Apalachicola-Chattahoochee-Flint, Sud Est des Etats-Unis d’Amérique] [Efeito do bombeamento para irrigação durante estiagem em sistema aquífero cárstico em bacia hidrográfica altamente agrícola: exemplo da bacia do rio Apalachicola-Chattaooche-Flint, sudeste dos EUA] [Efecto del riego por bombeo durante la sequía en los sistemas acuíferos kársticos de cuencas de altamente agrícolas: ejemplo de la cuenca del río Apalachicola-Chattahoochee-Flint, sureste de EE.UU]

Regionalization of model parameters by developing appropriate functional relationship between the parameters and basin characteristics is one of the potential approaches to employ hydrological models in ungauged basins. While this is a widely accepted procedure, the uniqueness of the watersheds and the equifinality of parameters bring lot of uncertainty in the simulations in ungauged basins. This study proposes a method of regionalization based on the probability distribution function of model parameters, which accounts the variability in the catchment characteristics. It is envisaged that the probability distribution function represents the characteristics of the model parameter, and when regionalized the earlier concerns can be addressed appropriately. The method employs probability distribution of parameters, derived from gauged basins, to regionalize by regressing them against the catchment attributes. These regional functions are used to develop the parameter characteristics in ungauged basins based on the catchment attributes. The proposed method is illustrated using soil water assessment tool model for an ungauged basin prediction. For this numerical exercise, eight different watersheds spanning across different climatic settings in the USA are considered. While all the basins considered in this study were gauged, one of them was assumed to be ungauged (pseudo-ungauged) in order to evaluate the effectiveness of the proposed methodology in ungauged basin simulation. The process was repeated by considering representative basins from different climatic and landuse scenarios as pseudo-ungauged. The results of the study indicated that the ensemble simulations in the ungauged basins were closely matching with the observed streamflow. The simulation efficiency varied between 57 and 61 % in ungauged basins. The regional function was able to generate the parameter characteristics that were closely matching with the original probability distribution derived from observed streamflow data. © 2015, Springer-Verlag Berlin Heidelberg.

Stochastic Environmental Research and Risk Assessment

Predictions in ungauged basins: an approach for regionalization of hydrological models considering the probability distribution of model parameters

This study addresses the design of nonlinear elastic springs that render an effective re-centering mechanism for a flat sliding base isolation system. A nonlinear stiffening behavior of the elastic spring offers added advantage of re-centering mechanism. The proposed spring-sliding system works in a similar fashion as that of the flat sliding base isolation system supplemented with re-centering mechanism for small to medium level of shaking. For high intensity shaking, the proposed system minimizes the peak bearing displacement in addition to keeping the bearing residual displacement close to zero. To demonstrate the concept of the proposed isolation system, a numerical study is conducted with a steel moment-resisting frame when subjected to ground motions of varying hazard levels. It has been found from this study that the proposed spring-sliding device is effective in limiting the peak bearing displacement and making the residual bearing displacement negligible for varying hazard levels. It has also been observed that the presence of nonlinear spring is in general beneficial in reducing the horizontal peak floor acceleration in comparison to the sliding only for ground motion with moderate hazard levels (i.e., 10% in 50 years). © 2016 Elsevier Ltd