Journal Papers

Dynamic behavior and characteristic failure response of low plasticity cohesive soil

2021-12-14T10:09:28Z

Dynamic behavior and characteristic failure response of low plasticity cohesive soil Thakur, Adarsh Singh; Pandya, Saloni; Sachan, Ajanta The present study evaluates the effect of stress history and loading conditions on dynamic behavior and failure characteristics of low plasticity cohesive soil. A series of two-way strain controlled cyclic triaxial tests were performed on soil samples collected from seismically active region of Gujarat (India). The effect of stress history and loading conditions on low plasticity soil was evaluated for OCR values of 1–4 and cyclic axial strain amplitude (εaεa) variation of 0.5%, 1%, 1.5%, and 2%, respectively. The low plasticity soil was observed to undergo liquefaction even at lower amplitude and higher OCR. Liquefaction resistance of soil was observed to increase with the increasing OCR (1–4) and decrease with the increment in cyclic strain amplitude (0.5%—2.0%). The rate of stiffness degradation exhibited bilinear response when pore pressure ratio (ru) was observed to be 0.85. This indicated the generation of cyclic instability prior to flow liquefaction in low plasticity cohesive soil. Two-staged failure response was observed due to the subsequent transition from cyclic instability behavior to flow liquefaction. The low plasticity cohesive soil was found to experience first ‘clay-like behaviour’ due to commencement of cyclic instability and then ‘sand-like behaviour’ due to initiation of flow liquefaction. The low plasticity cohesive soil was observed to experience cyclic instability between 0.85 < ru < 0.95, and then, flow liquefaction at ru > 0.95. International Journal of Civil Engineering volume, 167–185 (2021)

Propagating fragility curve for rc buildings via hazus methodology

2021-10-08T08:45:31Z

Propagating fragility curve for rc buildings via hazus methodology Patel, Nirav K; A Vasanwala, Sandip In this era where sustainability plays a key role, to design structures for resisting the earthquake in best probable manner is an inspiration for all designers. The recent trend for structural engineers is evolving in the direction of NSA (Nonlinear Static Analysis) in order to generate its ultimate building capacity. Frame structures are evaluated using NSA i.e. push-over analysis to interpret the phenomenon of plastic yielding being experienced within the structure. ATC-40 has well illustrated various performance levels of the buildings. When seismic loads are active due to shaking of ground, it is essential to assess the conditional probability of structural response. This can be done using conditional probability as a function and plotting fragility curves for structural response due to application of seismic activity or loading as a function. These fragility curves are useful not only for calamities before earthquake but also after earthquake to evaluate the seismic losses. The probability of whichever damage state being exceeded can be plotted using fragility curves which can be derived using empirical or analytical methods which rely on both the source of the data along with type of analysis. This paper addresses the analytical method using the guidelines given by the HAZUS MH technical manual. The work represented here is compiled by means of procedure for establishing the fragility curves for three typical Reinforced Concrete (RC) frame structures having variations resembling 3 storey intended for short-period structures, 6 storey used for medium-period structures and 12 storey representing long-period structures. For analyzing structures, FEM based software SAP2000 has been used as a tool. The present study contributes towards quantification of seismic fragility; henceforth fragility curves are co-related and plotted which provides a rational and consistent probabilistic treatment of damage or loss. The fragility curves are figured out to assess and interpret the results. © 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the Innovative Advancement in Engineering & Technology,2020

Analytical comparison of a gas turbine blade cooling using wet and dry air

2021-10-08T06:57:50Z

Analytical comparison of a gas turbine blade cooling using wet and dry air Patel, Snehal N.; Patel, Dilip S.; Pathak, Kedar A. Air cooling is widely used technique to shield the turbine aerofoils against hot flue gases. The cooling of a gas turbine blade using wet air and dry air as a coolant is analytically investigated. The investigation is carried out considering effect of rotation for inward and outward flow of coolant. Wet air cooling performance is compared with dry air cooling. It has been observed that wet air provides better cooling and the performance improves with increase in relative humidity. The temperature of blade at tip decreases from 1293.44 K to 1172.6 K when relative humidity of wet air is increased from 10% to 90%. CAS (division of the American Chemical Society (ACS)), Index Copernicus, 2016

Investigation of heat transfer in concentric annuli with perforated inserts

2021-10-08T06:28:38Z

Investigation of heat transfer in concentric annuli with perforated inserts Patel, Shailesh; Patel, Dilip S.; Pathak, Kedar A. The increasing necessity for saving energy and material imposed by the diminishing world resources and environmental concerns have prompted the development of more effective heat-transfer equipment with improved heat-transfer rates. The hydrodynamic boundary layer acts as main resistance for the transfer of heat from tube surface to fluid or vice-versa and many researchers are trying to improve the convective heat transfer rate with inserts in tubes to break the boundary layer and produce turbulence. In line with the aim, this paper presents results of an experimental investigation carried out to study the effect of relative roughness pitch and perforation of the spring roughness on heat transfer and friction factor for turbulent flow in an asymmetrically heated annular duct (radius ratio =0.39) with heated tube having spirally wound helical spring. The relative roughness pitch ranges from 4 to 8, while the relative coil pitch is 2.66–4.5. Thermal performance assessment at equal pumping power for the roughened and smooth annuli shows performance advantage of 32–83% for the Spring 2, while the lowest enhancement of 54–81% is seen for the Spring 12 in the flow Reynolds number range of about 4000–14000; the Nusselt number ratio, Nu/Nus, has been found to first increase with increase in the Reynolds number up to about 10000 and then decrease. The matching augmentation in the friction factor values is found over the bare pipe. Nusselt number and friction factor correlations have been developed for the most preferred type of perforated insert. CAS (division of the American Chemical Society (ACS)), Index Copernicus, Vol 9, Issue no 1, 2018, P.56-58