Ultimate flexural and shear capacity of concrete beams with corroded reinforcement

Bhargava, Kapilesh,Ghosh, A.K.,Mori, Yasuhiro,Ramanujam, S. Techno-Press 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.27 No.3

Assessment of structural behaviour of corrosion affected structures is an important issue, which would help in making certain decisions pertaining to the inspection, repair, strengthening, replacement and demolition of such structures. The paper presents formulations to predict the loss of weight and the loss of cross-sectional area of the reinforcing bar undergoing corrosion based on the earlier study carried out by the present authors (Bhargava et al. 2006). These formulations have further been used to analytically evaluate the ultimate bending moment and ultimate shear force capacity of the corroded concrete beams. Results of the present study indicate that, a considerably good agreement has been observed between the experimental and the analytically predicted values for the weight loss and reduction in radius of the corroded reinforcing bars. A considerably good agreement has also been observed between the experimental and the analytically predicted values of ultimate bending moment and ultimate shear force capacity for the corroded concrete beams.

Facile synthesis of 1D-architecture of silver-vanadates in carbon nest for enhanced visible light driven photo-oxidation process

Das, Biraj,Sharma, Mukesh,Deka, Biplab K.,Hazarika, Ankita,Park, Young-Bin,Hazarika, Anil,Bhargava, Suresh K.,Bania, Kusum K. Elsevier 2018 Journal of environmental chemical engineering Vol.6 No.2

<P><B>Abstract</B></P> <P>Ag/AgCl/V<SUB>2</SUB>O<SUB>5</SUB> nanocatalysts with one dimensional (1D) architecture was synthesized in carboxylic acid functionalized multi-walled carbon nanotubes for methylene blue dye degradation. The growth of uniformly distributed nanoparticles along the carbon-nanotubes was revealed from high resolution transmission electron microscopy and atomic force microscopy analyses. Raman spectroscopy and transmission electron microscopy analyses also confirmed for the creation of defects in the multi-walled carbon nanotube. The hybrid nanocomposite appeared as a suitable photocatalyst for degradation of methylene blue dye absorbing the light in the visible range of solar spectrum. The presence of interactions within the nanoparticles and with the nanotubes was believed to enhance the photo-oxidation process. The creation of defects in the carbon nanotube on modification with Ag/AgCl/V<SUB>2</SUB>O<SUB>5</SUB> improved the photocatalytic activity by enhancing the photoelectron transfer process. About ∼90% of the total organic carbon of the dye molecule was found to decompose into CO<SUB>2</SUB>, H<SUB>2</SUB>O and inorganic ions within 25 min under sunlight.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ag/AgCl/V<SUB>2</SUB>O<SUB>5</SUB> with 1D architecture is synthesized in Multiwalled Carbon Nanotube. </LI> <LI> Ag/AgCl/V<SUB>2</SUB>O<SUB>5</SUB>-MWCNT appeared as suitable photocatalyst absorbing visible light of solar spectrum. </LI> <LI> Creation of defects in MWCNT enhanced the photocatalytic ability of the nanomaterial. </LI> <LI> The hybrid nanocomposite decompose methylene blue dye with high efficiency within 25 min under sunlight. </LI> <LI> The photocatalyst was recyclable for three consecutive cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P> <P>Complete mineralization of MB dye with Ag/AgCl/V<SUB>2</SUB>O<SUB>5</SUB>-MWCNT nanocomposite under sun light.</P>

Pd/Cu-Oxide Nanoconjugate at Zeolite-Y Crystallite Crafting the Mesoporous Channels for Selective Oxidation of Benzyl-Alcohols

Sharma, Mukesh,Das, Biraj,Sharma, Mitu,Deka, Biplab K.,Park, Young-Bin,Bhargava, Suresh K.,Bania, Kusum K. American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.40

<P>Solid-state grinding of palladium and copper salts allowed the growth of palladium/copper oxide interface at the zeolite-Y surface. The hybrid nanostructured material was used as reusable heterogeneous catalyst for selective oxidation of various benzyl alcohols. The large surface area provided by the zeolite-Y matrix highly influenced the catalytic activity, as well as the recyclability of the synthesized catalyst. Impregnation of PdO-CuO nanoparticles on zeolite crystallite leads to the generation of mesoporous channel that probably prevented the leaching of the metal-oxide nanoparticles and endorsed high mass transfer. Formation of mesoporous channel at the external surface of zeolite-Y was evident from transmission electron microscopy and surface area analysis. PdO-CuO nanoparticles were found to be within the range of 2-5 nm. The surface area of PdO-CuO-Y catalyst was found to be much lower than parent zeolite-Y. The decrease in surface area as well as the presence of hysteresis loop in the Nradsoprtion isotherm further suggested successful encapsulation of PdO-CuO nanoparticles via the mesoporous channel formation. The high positive shifting in binding energy in both Pd and Cu was attributed to the influence of zeolite-Y framework on lattice contraction of metal oxides via confinement effect. PdO-CuO-Y catalyst was found to oxidize benzyl alcohol with 99% selectivity. On subjecting to microwave irradiation the same oxidation reaction was found to occur at ambient condition giving same conversion and selectivity.</P>

Analytical model of corrosion-induced cracking of concrete considering the stiffness of reinforcement

Bhargava, Kapilesh,Ghosh, A.K.,Mori, Yasuhiro,Ramanujam, S. Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.16 No.6

The structural deterioration of concrete structures due to reinforcement corrosion is a major worldwide problem. Service life of the age-degraded concrete structures is governed by the protective action provided by the cover concrete against the susceptibility of the reinforcement to the corrosive environment. The corrosion of steel would result in the various corrosion products, which depending on the level of the oxidation may have much greater volume than the original iron that gets consumed by the process of corrosion. This volume expansion would be responsible for exerting the expansive radial pressure at the steel-concrete interface resulting in the development of hoop tensile stresses in the surrounding cover concrete. Once the maximum hoop tensile stress exceeds the tensile strength of the concrete, cracking of cover concrete would take place. The cracking begins at the steel-concrete interface and propagates outwards and eventually resulting in the through cracking of the cover concrete. The cover cracking would indicate the loss of the service life for the corrosion-affected structures. In the present paper, analytical models have been developed considering the residual strength of the cracked concrete and the stiffness provided by the combination of the reinforcement and expansive corrosion products. The problem is modeled as a boundary value problem and the governing equations are expressed in terms of the radial displacement. The analytical solutions are presented considering a simple 2-zone model for the cover concrete viz. cracked or uncracked. A sensitivity analysis has also been carried out to show the influence of the various parameters of the proposed models. The time to cover cracking is found to be function of initial material properties of the cover concrete and reinforcement plus corrosion products combine, type of rust products, rate of corrosion and the residual strength of the cover concrete. The calculated cracking times are correlated against the published experimental and analytical reference data.

Seismic response and failure modes for a water storage structure - A case study

Bhargava, Kapilesh,Ghosh, A.K.,Ramanujam, S. Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.1

The present paper deals with the seismic response analysis and the evaluation of most likely failure modes for a water storage structure. For the stress analysis, a 3-D mathematical model has been adopted to represent the structure appropriately. The structure has been analyzed for both static and seismic loads. Seismic analysis has been carried out considering the hydrodynamic effects of the contained water. Based on the stress analyses results, the most likely failure modes viz. tensile cracking and compressive crushing of concrete for the various structural elements; caused by the seismic event have been investigated. Further an attempt has also been made to quantify the initial leakage rate and average emptying time for the structure during seismic event after evaluating the various crack parameters viz. crack-width and crack-spacing at the locations of interest. The results are presented with reference to peak ground acceleration (PGA) of the seismic event. It has been observed that, an increase in PGA would result in significant increase in stresses and crack width in the various structural members. Significant increase in initial leakage rate and decrease in average emptying time for the structure has also been observed with the increase in PGA.

Review : Longitudinal Muscle Dysfunction in Achalasia Esophagus and Its Relevance

( Ravinder K Mittal ),( Su Jin Hong ),( Valmik Bhargava ) 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2013 Journal of Neurogastroenterology and Motility (JNM Vol.19 No.2

Muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. Goal of this review is to summarize the role of longitudinal muscle in physiology and pathophysiology of esophageal sensory and motor function. Simultaneous manometry and ultrasound imaging that measure circular and longitudinal muscle contraction respectively reveal that during peristalsis 2 layers of the esophagus contract in perfect synchrony. On the other hand, during transient relaxation of the lower esophageal sphincter (LES), longitudinal muscle contracts independently of circular muscle. Recent studies provide novel insights, i.e., longitudinal muscle contraction of the esophagus induces LES relaxation and possibly descending relaxation of the esophagus. In achalasia esophagus and other motility disorders there is discoordination between the 2 muscle layers. Longitudinal muscle contraction patterns are different in the recently described three types of achalasia identified by high resolution manometry. Robust contraction of the longitudinal muscle in type II achalasia causes pan-esophageal pressurization and is the mechanism of whatever little esophageal emptying that take place in the absence of peristalsis and impaired LES relaxation. It may be that preserved longitudinal muscle contraction is also the reason for superior outcome to medical/surgical therapy in type II achalasia esophagus. Prolonged contractions of longitudinal muscles of the esophagus is a possible mechanism of heartburn and “angina like” pain seen in esophageal motility disorders and possibly achalasia esophagus. Novel techniques to record longitudinal muscle contraction are on the horizon. Neuro-pharmacologic control of circular and longitudinal muscles is different, which provides an important opportunity for the development of novel pharmacological therapies to treat sensory and motor disorders of the esophagus.

Seismic response and failure modes for a water storage structure − A case study

Kapilesh Bhargava,A. K. Ghosh,S. Ramanujam 국제구조공학회 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.1

The present paper deals with the seismic response analysis and the evaluation of most likely failure modes for a water storage structure. For the stress analysis, a 3-D mathematical model has been adopted to represent the structure appropriately. The structure has been analyzed for both static and seismic loads. Seismic analysis has been carried out considering the hydrodynamic effects of the contained water. Based on the stress analyses results, the most likely failure modes viz. tensile cracking and compressive crushing of concrete for the various structural elements; caused by the seismic event have been investigated. Further an attempt has also been made to quantify the initial leakage rate and average emptying time for the structure during seismic event after evaluating the various crack parameters viz. crack-width and crack-spacing at the locations of interest. The results are presented with reference to peak ground acceleration (PGA) of the seismic event. It has been observed that, an increase in PGA would result in significant increase in stresses and crack width in the various structural members. Significant increase in initial leakage rate and decrease in average emptying time for the structure has also been observed with the increase in PGA.

Role of Bee-attractants on Honeybee Visitation of Ridge Gourd Luffa acutangula L. (Cucurbitaceae)

Jayaramappa, K. V,Bhargava. H. R 한국양봉학회 2013 韓國養蜂學會誌 Vol.28 No.2

Line X Tester Analysis for Economic Characters in the Bivoltine Silkworm, Bombyx mori L .

Begum, Naseema,Bhargava, A. S. K.,Ahsan, M. M.,Datta, R. K.,Rao, D. Raghavendra 한국잠사학회 1997 한국잠사곤충학회지 Vol.39 No.2

In a line X tester crossing programme (24 lines and 2 testers) the general combining ability(GCA) and specinc combining ability (SCA) effects were analyzed for five economic characters in the bivoltine silkworm,Bombyx mori L. The results showed desired GCA effects in 934D1(9500), 934B (9789) and 934A1(9855) for cocoon yield per 10,000 larvae brushed by number. Likewise, the lines found to be superior based on GCA effects for other characters were as follows; 931D (14.040 Kgs), 935E (17.023 Kga.), 934D1 (15.643 Kgs.) and 934B (15.687 Kgs.) for cocoon yield by weight: 931D (1.717 g) and 930E (1.796 g) for single cocoon weight; 932B(0.330 g) for single shell weight; 932B (18.7%), 933A (18.86%) and 935A (19.89%) for shell ratio. SCA effects showed the superiority of 932D X KA (9822 cocoon yield per 10,000 larvae brushed by number); 932A X NB4D2 (16.933 Kgs. cocoon yield per 10000 larvae brushed by weight); 931C X KA (1.911 g single cocoon weight); 934 X NB4D2 (0.371 g single shell weight and 21.0% shell ratio). The analysis indicated non-additive gene action for all the five characters.

Botanicals Mediated Reproductive Enhancement in Mulberry Silkworm (Bombyx mori L.)

Kumar P. M. Pratheesh,Bhargava S.K.,Prabhakar C.J.,Kamble C.K. Korean Society of Sericultural Science 2007 International Journal of Industrial Entomology Vol.14 No.1

Ethanol extract of 20 botanicals in 3 concentrations i.e., 2.5%, 5% and 10% were evaluated for their efficacy to improve reproductive performance of mulberry silkworm (Bombyx mod L.) through feeding botanical enriched mulberry leaves during $2^{nd}$ day of $4^{th}$ age as well as $1^{st}$ and $3^{rd}$ day of $5^{th}$ age larvae. The preliminary screening was done by ranking the botanicals based on influence in most important reproductive contributing parameters such as single cocoon weight, effective rate of rearing, pupation rate, fecundity and recovery of eggs/kg cocoon. Five botanicals viz., Asparagus recemosus, Achyranthes aspera, Tribulus terrestris, Withania somnifera, Parthenium histerophorus ranked first were further evaluated at 8% 5% and 3% concentrations to confirm their effectiveness and standardize effective concentration. Among the rearing parameters, mature larval weight, shell ratio and number of cocoons/kg were not significantly influenced by the treatments. However, reproductive parameters such as effective rate of rearing (wt), pupation rate (%), fecundity (No.) and egg recovery (g)/kg cocoon were significantly (P<0.05) influenced by the botanicals. Higher fecundity and egg recovery were obtained on treatment with Withania somnifera irrespective of concentrations. However at 5% concentration, pupation rate, fecundity as well as egg recovery were found significantly higher than that of other concentrations, confirming its effectiveness for improving reproductive efficiency.