Simplified computational methodology for analysis and studies on behaviour of incrementally launched continuous bridges

Sasmal, Saptarshi,Ramanjaneyulu, K.,Srinivas, V.,Gopalakrishnan, S. Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.17 No.2

Incremental launching method is one of the highly competitive techniques for construction of concrete bridges. It avoids costly and time consuming form work and centralizes all construction activities in a small casting yard, thus saving in cost and time against conventional bridge construction. From the quality point of view, it eliminates the uncertainty of monolithic behaviour by allowing high repetitiveness and industrial environment. But, from analysis and design point of view, the most characteristic aspect of incrementally launched bridges is that, it has to absorb the stresses associated with the temporary supports that are gradually taken on by the deck during its launch. So, it is necessary to analyse the structure for each step of launching which is a tedious and time consuming process. Effect of support settlements or temperature variation makes the problem more complex. By using transfer matrix method, this problem can be handled efficiently with minimal computational effort. This paper gives insight into method of analysis, formulation for optimization of the structural system, effect of support settlement and temperature gradient, during construction, on the stress state of incrementally launched bridges.

Biodegradable nanocomposites from maleated polycaprolactone/soy protein isolate blend with organoclay: Preparation, characterization, and properties

Sasmal, Abhisek,Sahoo, Debasish,Nanda, Rajashree,Nayak, Preetishree,Nayak, Padma L.,Mishra, Joy K.,Chang, Young-Wook,Yoon, Joon-Yong Wiley Subscription Services, Inc., A Wiley Company 2009 Polymer composites Vol.30 No.6

<P>New biobased, eco-friendly nanocomposites were prepared from maleated polycaprolactone/soy protein isolate blend (50/50 wt/wt) with organo-modified clay by melt compounding. The XRD, TEM, tensile, DMTA, and rheological properties of the nanocomposites were investigated. X-ray diffraction and transmission electron microscopy analysis revealed that the intercalated nanocomposite is formed and the silicate layers of the clay are uniformly dispersed at a nanometer scale in the polymer matrix. There is a great enhancement in tensile and dynamic mechanical properties of the nanocomposites. Rheological study revealed that the nanocomposite exhibits strong shear thinning behavior and clay particles form network in the melted state of the composites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers</P>

Computational methodology to determine the strength of reinforced concrete joint

Sasmal, Saptarshi,Vishnu Pradeesh, L.,Devi, A. Kanchana,Ramanjaneyulu, K. Techno-Press 2016 Advances in computational design Vol.1 No.1

Seismic performance of structures depends on the force flow mechanism inside the structure. Discontinuity regions, like beam-column joints, are often affected during earthquake event due to the complex and discontinuous load paths. The evaluation of shear strength and identification of failure mode of the joint region are helpful to (i) define the strength hierarchy of the beam-column sub-assemblage, (ii) quantify the influence of different parameters on the behaviour of beam-column joint and, (iii) develop suitable and adequate strengthening scheme for the joints, if required, to obtain the desired strength hierarchy. In view of this, it is very important to estimate the joint shear strength and identify the failure modes of the joint region as it is the most critical part in any beam-column sub-assemblage. One of the most effective models is softened strut and tie model which was developed by incorporating force equilibrium, strain compatibility and constitutive laws of cracked reinforced concrete. In this study, softened strut and tie model, which incorporates force equilibrium equations, compatibility conditions and material constitutive relation of the cracked concrete, are used to simulate the shear strength behaviour and to identify failure mechanisms of the beam-column joints. The observations of the present study will be helpful to arrive at the design strategy of the joints to ensure the desired failure mechanism and strength hierarchy to achieve sustainability of structural systems under seismic loading.

Numerical analysis of under-designed reinforced concrete beam-column joints under cyclic loading

Saptarshi Sasmal,Balthasar Novák,K. Ramanjaneyulu 사단법인 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.3

In the present study, exterior beam-column sub-assemblage from a regular reinforced concrete (RC) building has been considered. Two different types of beam-column sub-assemblages from existing RC building have been considered, i.e., gravity load designed (‘GLD’), and seismically designed but without any ductile detailing (‘NonDuctile’). Hence, both the cases represent the under-designed structure at different time frame span before the introduction of ductile detailing. For designing ‘NonDuctile’ structure, Eurocode and Indian Standard were considered. Non-linear finite element (FE) program has been employed for analysing the sub-assemblages under cyclic loading. FE models were developed using quadratic concrete brick elements with embedded truss elements to represent reinforcements. It has been found that the results obtained from the numerical analysis are well corroborated with that of experimental results. Using the validated numerical models, it was proposed to correlate the energy dissipation from numerical analysis to that from experimental analysis. Numerical models would be helpful in practice to evaluate the seismic performance of the critical sub-assemblages prior to design decisions. Further, using the numerical studies, performance of the sub-assemblages with variation of axial load ratios (ratio is defined by applied axial load divided by axial strength) has been studied since many researchers have brought out inconsistent observations on role of axial load in changing strength and energy dissipation under cyclic load.

Numerical simulations of progression of damage in concrete embedded chemical anchors

S. Sasmal,R. Thiyagarajan,K.H. Lieberum,E.A.B. Koenders 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.4

In this paper, the performance of post-installed adhesive bonded anchor embedded in concrete is assessed using numerical simulations. This study aims at studying the influence of parameters on the performance of a chemically bonded anchorage system. Non-linear finite element modelling and simulations are carried out by properly using the material properties and phenomenon. Materials parameters such as characteristic length, fracture energy, damage criteria, tension retention and crack width of concrete and interface characteristics are carefully assigned so as to obtain a most realistic behaviour of the chemical anchor system. The peak strength of two different anchor systems obtained from present numerical studies is validated against experimental results. Furthermore, validated numerical models are used to study the load transferring mechanism and damage progression characteristics of various anchors systems where strength of concrete, strength of epoxy, and geometry and disposition of anchors are the parameters. The process of development of strain in concrete adjacent to the anchor and energy dissipated during the course of damage progression are analysed. Results show that the performance of the considered anchorage system is, though a combined effect of material and geometric parameters, but a clear distinction could be made on the parameters to achieve a desired performance based on strength, slip, strain development or dissipated energy. Inspite the increase in anchor capacity with increase in concrete strength, it brings some undesirable performance as well. Furthermore, the pullout capacity of the chemical anchor system increases with a decrease in disparity among the strength of concrete and epoxy.

Preparation and Characterization of Edible Films Based on Soy Protein Isolate-Fatty Acid Blends

Nayak, P.,Sasmal, A.,Nanda, P. K.,Nayak, P. L.,Kim, J.,Chang, Y. W. Taylor Francis 2008 Polymer-Plastics Technology and Materials Vol.47 No.5

Nanocomposites from Polycaprolactone (PCL)/Soy Protein Isolate (SPI) Blend with Organoclay

Nayak, P. L.,Sasmal, A.,Nayak, P.,Sahoo, S.,Mishra, J. K.,Kang, S. C.,Lee, J. W.,Chang, Y. W. Taylor Francis 2008 Polymer-Plastics Technology and Materials Vol.47 No.6

Detection of flaw in steel anchor-concrete composite using high-frequency wave characteristics

Rajanikant Rao,Saptarshi Sasmal 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.4

Non-monolithic concrete structural connections are commonly used both in new constructions and retrofitted structures where anchors are used for connections. Often, flaws are present in anchor system due to poor workmanship and deterioration; and methods available to check the quality of the composite system afterward are very limited. In case of presence of flaw, load transfer mechanism inside the anchor system is severely disturbed, and the load carrying capacity drops drastically. This raises the question of safety of the entire structural system. The present study proposes a wave propagation technique to assess the integrity of the anchor system. A chemical anchor (embedded in concrete) composite system comprising of three materials viz., steel (anchor), polymer (adhesive) and concrete (base) is considered for carrying out the wave propagation studies. Piezoelectric transducers (PZTs) affixed to the anchor head is used for actuation and the PZTs affixed to the surrounding concrete surface of the concrete-anchor system are used for sensing the propagated wave through the anchor interface to concrete. Experimentally validated finite element model is used to investigate three types of composite chemical anchor systems. Studies on the influence of geometry, material properties of the medium and their distribution, and the flaw types on the wave signals are carried out. Temporal energy of through time domain differentiation is found as a promising technique for identifying the flaws in the multi-layered composite system. The present study shows a unique procedure for monitoring of inaccessible but crucial locations of structures by using wave signals without baseline information.

Chronic abdominal wall sinus secondary to missed spilled gallstones in laparoscopic cholecystectomy: a harrowing experience

Saikrishna Aitha,Prakash Kumar Sasmal,Pankaj Kumar,Rutuja Challawar,Medhavi Sinha 대한내시경로봇외과학회 2024 Journal of Minimally Invasive Surgery Vol.27 No.1

Gallbladder perforation with spillage of gallstones is not uncommon during laparoscopic cholecystectomy. Stone spillage can cause several complications. We report a case of recurrent discharging sinuses on the right back 4 years after laparoscopic cholecystectomy in a 44-year-old female patients. She suffered for 9 years to undergo empirical treatment for suspected tuberculosis, including repeated attempts at sinus tract excision done at different hospitals. We did a computed tomography sinogram, which revealed the tract extending from the right flank into a cavity in the right subpleural space. We proceeded with the sinus tract excision which extended between the tips of the 10th and 11th ribs, spreading to the right subpleural space where pus mixed with multiple gall stones were retrieved. Spilled stones may result in complications, making diagnosis difficult and seriously harming the patient physically, mentally, and economically. The need for accurate documentation and patient knowledge of missing gallstones cannot be understated.

Computational fluid dynamics analysis of flow through immobilized catalyzed packed bed reactor for removal of 4-chlorophenol from wastewater

Sudhansu Sandhibigraha,Soumya Sasmal,Tarun Kanti Bandyopadhyay,Biswanath Bhunia 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.6

The computational fluid dynamics (CFD) simulation of the packed bed reactor (PBR) was carried out using ANSYS Fluent software. The various process parameters, such as inlet concentration of 4-chlorophenol (4-CP), flow rate, bed height, and porosity, were optimized to predict maximum biodegradation of 4-CP in immobilized catalyzed PBR. The geometrical mesh of the PBR was constructed using Gambit software, and a mesh size of 236995 was selected from the grid-independent study. A laminar flow model was used to understand the hydrodynamics as well as concentration profile of 4-CP inside the PBR using Fluent software. Through CFD, the effect of the flow rate, inlet concentration, and the bed height and porosity of the immobilized catalyst bed on the static pressure, mass imbalance, velocity, and stress-strain field inside the PBR was visualized. CFD simulation study predicted that maximum biodegradation of 4-CP was found in the presence of 500 mg/L of inlet concentration of 4-CP, 4 mL/min of flow rate, 18 cm of bed height and 0.375 of porosity. An experimental study was conducted for wastewater flow through the B. subtilis MF447840.1 immobilized catalyzed PBR to remove the 4-CP in the laminar flow region. It was evident that CFD simulated results agreed well with experimental values.