Performance-based remaining life assessment of reinforced concrete bridge girders

M. B. Anoop,K. Balaji Rao,B. K. Raghuprasad 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.1

Performance-based remaining life assessment of reinforced concrete bridge girders subject to chloride-induced corrosion of reinforcement, is addressed in this paper. Towards this, a methodology that takes into consideration the human judgmental aspects in expert decision making regarding condition state assessment is proposed. The condition of the bridge girder is specified by the assignment of a condition state from a set of predefined condition states, considering both serviceability- and ultimate- limit states, and, the performance of the bridge girder is described using performability measure. A non-homogeneous Markov chain is used for modelling the stochastic evolution of condition state of the bridge girder with time. The thinking process of the expert in condition state assessment is modelled within a probabilistic framework using Brunswikian theory and probabilistic mental models. The remaining life is determined as the time over which the performance of the girder is above the required performance level. The usefulness of the methodology is illustrated through the remaining life assessment of a reinforced concrete T-beam bridge girder.

Effect of Closed Suction Drain on Blood Loss and Transfusion Rates in Simultaneous Bilateral Total Knee Arthroplasty: A Prospective Randomized Study

( Anoop Jhurani ),( Gautam M. Shetty ),( Vinay Gupta ),( Purvi Saxena B. Tech ),( Nidhi Singh M. Pharm ) 대한슬관절학회 2016 대한슬관절학회지 Vol.28 No.3

Purpose: Simultaneous bilateral total knee arthroplasty (TKA) is associated with excessive blood loss and morbidity arising from postoperative reduction in hemoglobin (Hb). The purpose of this prospective randomized study was to determine if drains have any effect on blood loss, postoperative reduction in Hb levels and transfusion rates compared to no drainage in simultaneous bilateral TKAs. Materials and Methods: Two hundred and thirty patients who underwent simultaneous bilateral TKA by a single surgeon were randomly allotted to drain or no-drain group (n=115 in each group). Postoperative Hb level, blood loss volume and transfusion rate were compared between the two groups. Results: The mean postoperative Hb level (p=0.38), blood loss volume (p=0.33) and transfusion rate (p=0.52) in the drain group were not significantly different compared to the no-drain group. No statistical difference was found in terms of complications, readmissions and mortality rates between the two groups. Conclusions: No significant difference was observed in the two groups with respect to blood loss and blood transfusion. Non-drainage does not offer an advantage over drainage with respect to conserving blood in simultaneous bilateral TKA.

Modelling of strains in reinforced concrete flexural members using alpha-stable distribution

K. Balaji Rao,M. B. Anoop,K. Kesavan,S. R. Balasubramanian,K. Ravisankar,Nagesh R. Iyer 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.5

Large fluctuations in surface strain at the level of steel are expected in reinforced concrete flexural members at a given stage of loading due to the emergent structure (emergence of new crack patterns). This has been identified in developing deterministic constitutive models for finite element applications in Ibrahimbegovic et al. (2010). The aim of this paper is to identify a suitable probability distribution for describing the large deviations at far from equilibrium points due to emergent structures, based on phenomenological, thermodynamic and statistical considerations. Motivated by the investigations reported by Prigogine (1978) and Rubi (2008), distributions with heavy tails (namely, alpha-stable distributions) are proposed for modeling the variations in strain in reinforced concrete flexural members to account for the large fluctuations. The applicability of alpha-stable distributions at or in the neighborhood of far from equilibrium points is examined based on the results obtained from carefully planned experimental investigations, on seven reinforced concrete flexural members. It is found that alpha-stable distribution performs better than normal distribution for modeling the observed surface strains in reinforced concrete flexural members at these points.

Prediction of negative peak wind pressures on roofs of low-rise building

K. Balaji Rao,M.B. Anoop,P. Harikrishna,S. Selvi Rajan,Nagesh R. Iyer 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.6

In this paper, a probability distribution which is consistent with the observed phenomenon at the roof corner and, also on other portions of the roof, of a low-rise building is proposed. The model is consistent with the choice of probability density function suggested by the statistical thermodynamics of open systems and turbulence modelling in fluid mechanics. After presenting the justification based on physical phenomenon and based on statistical arguments, the fit of alpha-stable distribution for prediction of extreme negative wind pressure coefficients is explored. The predictions are compared with those actually observed during wind tunnel experiments (using wind tunnel experimental data obtained from the aerodynamic database of Tokyo Polytechnic University), and those predicted by using Gumbel minimum and Hermite polynomial model. The predictions are also compared with those estimated using a recently proposed non-parametric model in regions where stability criterion (in skewness-kurtosis space) is satisfied. From the comparisons, it is noted that the proposed model can be used to estimate the extreme peak negative wind pressure coefficients. The model has an advantage that it is consistent with the physical processes proposed in the literature for explaining large fluctuations at the roof corners.

Prediction of negative peak wind pressures on roofs of low-rise building

Rao, K. Balaji,Anoop, M.B.,Harikrishna, P.,Rajan, S. Selvi,Iyer, Nagesh R. Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.6

In this paper, a probability distribution which is consistent with the observed phenomenon at the roof corner and, also on other portions of the roof, of a low-rise building is proposed. The model is consistent with the choice of probability density function suggested by the statistical thermodynamics of open systems and turbulence modelling in fluid mechanics. After presenting the justification based on physical phenomenon and based on statistical arguments, the fit of alpha-stable distribution for prediction of extreme negative wind pressure coefficients is explored. The predictions are compared with those actually observed during wind tunnel experiments (using wind tunnel experimental data obtained from the aerodynamic database of Tokyo Polytechnic University), and those predicted by using Gumbel minimum and Hermite polynomial model. The predictions are also compared with those estimated using a recently proposed non-parametric model in regions where stability criterion (in skewness-kurtosis space) is satisfied. From the comparisons, it is noted that the proposed model can be used to estimate the extreme peak negative wind pressure coefficients. The model has an advantage that it is consistent with the physical processes proposed in the literature for explaining large fluctuations at the roof corners.

An Improved Method for Estimation of Elastic Lateral Stiffness of Brick Masonry Shear Walls with Openings

S. R. Balasubramanian,K. Balaji Rao,Dhiman Basu,M. B. Anoop,C. V. Vaidyanathan 대한토목학회 2011 KSCE JOURNAL OF CIVIL ENGINEERING Vol.15 No.2

From a review of literature, it is found that while few methods are proposed by various researchers for estimation of lateral stiffness of brick masonry walls with openings, these methods are suitable for strong spandrel-weak pier condition. For weak spandrel-strong pier condition, these methods over estimate the stiffness. An improved method for estimation of stiffness of brick masonry shear walls with opening is presented in this paper. For the weak spandrel-strong pier condition, they overestimate the stiffness of the wall. The proposed method is applicable to both strong spandrel-weak pier and weak spandrel-strong pier conditions. It has been observed that the results of the proposed method are generally in good agreement with the results of finite element analysis and experimental results and are better than the other methods available in literature.