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Meher A Prasad
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Meher A Prasad
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Meher A Prasad
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Prasad, A. Meher
Prasad, A. M.
Meher Prasad, Anumolu
Prasad, Anumolu Meher
Meher, Prasad A.
Meher Prasad, A.
Meher, Prasad
Prasad, A. Prasad
Prasad, A.
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40 results
Now showing 1 - 10 of 40
- PublicationCalibration of a hysteretic model for glass fiber reinforced gypsum wall panels(01-01-2014)
;Janardhana, Maganti ;Robin Davis, P. ;Ravichandran, S. S.; Glass fiber reinforced gypsum (GFRG) wall panels are prefabricated panels with hollow cores, originally developed in Australia and subsequently adopted by India and China for use in buildings. This paper discusses identification and calibration of a suitable hysteretic model for GFRG wall panels filled with reinforced concrete. As considerable pinching was observed in the experimental results, a suitable hysteretic model with pinched hysteretic rule is used to conduct a series of quasi-static as inelastic hysteretic response analyses of GFRG panels with two different widths. The calibration of the pinching model parameters was carried out to approximately match the simulated and experimental responses up to 80% of the peak load in the post peak region. Interestingly, the same values of various parameters (energy dissipation and pinching related parameters) were obtained for all five test specimens. © 2014 Institute of Engineering Mechanics, China Earthquake Administration and Springer-Verlag Berlin Heidelberg. - PublicationDevelopment of a simplified damage model for beams aiding performance based seismic design(01-04-2011)
;Sreekala, R. ;Lakshmanan, N. ;Muthumani, K. ;Gopalakrishnan, N.Performance based design is an emerging area in earthquake engineering in which damage modeling of structural components plays an important role in achieving the performance objectives. Past researches in damage index evaluation indicated no obvious shear dependent trends on cyclic combined shear and flexure. Paper focuses in finding a simple and realistic indicator, which gives a reliable measure of the structural damage, and use it in the design stage calculations of medium and long period structures. Experiments consisting of monotonic and cyclic tests were conducted on a variety of concrete beams. Two available models for damage indices in the literature, namely Park and Ang model and the model suggested by Rao et al. (1998), were used to predict the damage indices. A simple set of relationships connecting damage index to the failure cyclic ductility ratio, shear span to depth ratio and cyclic amplitude have been derived. The above relationships have been validated on the test data generated during the present investigation. A procedure to evaluate the demand-monotonic ductility ratio at failure corresponding to a given state of damage and the shear span to depth ratio has been developed from the proposed curves. - PublicationNear fault earthquakes and behaviour of liquid storage tanks(01-01-2013)
;Sreekala, R.; ;Muthumani, K. ;Lakshmanan, N.Iyer, Nagesh R.Near fault earthquakes are common in recent years and are known for the unique strong ground motion characteristics. Dynamic behavior of liquid storage tanks during strong ground motion requires lot of research attention and sloshing is one of the major concerns in the design of liquid storage tanks. Simulated experimental investigations using 3D shake tables are rare in this field and the nonlinear dynamic behavior of the structure is of interest, especially during near fault earthquakes. The paper presents an experimental investigation under simulated conditions on a fixed base rectangular container with water. The tank has been designed to suit experimental requirements and the dimensions were selected to fit the structure in 2m- tri axial shaking table. The behavior of the system is identified during dynamic loading using harmonic excitation and simulated earthquake studies were carried out further on the 3D shaking table. Higher dynamic pressures on the walls and increased dynamic loads on the tank due to the pulse characteristics of ground motion have been verified during the investigation. Computational modeling has been carried out on the experiments conducted and the results are discussed. Dynamic free surface flow is simulated using moving mesh interface and the fluid motion is modeled with incompressible Navier-Stokes formulation. - PublicationUse of glass fibre reinforced gypsum panels with reinforced concrete infills for construction of walls and slabs(01-12-2016)
;Paul, Shinto ;Cherian, Philip; Use of rapid techniques for timely delivery of construction projects by adopting fast methodologies and alternate building materials is necessary in India, given the tremendous housing shortage. Further, the construction has to be affordable and also sustainable. The construction technique proposed in this paper, by making use of Glass Fibre Reinforced Gypsum (GFRG) panels (with reinforced concrete infilled cavities) to build homes, promises such a solution for rapid affordable mass housing in India. GFRG building system is a rapid building technology composed of prefabricated wall panel load bearing system. GFRG is also an eco-friendly building material which can be manufactured out of either natural or industrial gypsum. In India, these panels have been manufactured from the fertilizer by-product waste. As an outcome of the research done at IIT Madras on the feasibility of using these panels for affordable mass housing in India, a two-storeyed GFRG building of 184 square meter area was built at IIT Madras campus, as a demonstration of the suitability of this technology. This is described in this paper. - PublicationComparison of force-based and displacement-based methods for seismic design of buildings(01-04-2012)
;Varughese, Jiji Anna; Displacement-based design (DBD) methods are emerging as the latest tools for performance-based seismic design and as a viable alternative to conventional force-based design method (FBD). FBD starts with an estimation of base shear force, which is calculated based on the fundamental period and ductility capacity of the structure. This base shear force is distributed to the various floor levels based on the fundamental mode shape, and the structure is designed for these lateral loads. Unlike FBD, DBD method requires explicit consideration of displacements. Typically, DBD determines a target displacement demand and then calculates the required base shear capacity to achieve this demand. In this method, the lateral loads at various floor levels are obtained based on an assumed inelastic displacement profile. This paper presents the findings of a study that uses the FBD method and DBD method to design a typical four-storeyed and a nine-storeyed regular frame. The performances of the frames were assessed using nonlinear time history analysis and their relative performances are reported. - PublicationVertical geometric irregularity in stepped building frames(01-08-2010)
;Sarkar, Pradip; Stepped building' frames, with vertical geometric irregularity, are now increasingly encountered in modern urban construction. This paper proposes a new method of quantifying irregularity in such building frames, accounting for dynamic characteristics (mass and stiffness). The proposed regularity index' provides a basis for assessing the degree of irregularities in a stepped building frame. This paper also proposes a modification of the code specified empirical formula for estimating fundamental period for regular frames, to estimate the fundamental time period of the stepped building frame. The proposed equation for fundamental time periods is expressed as a function of the regularity index. It has been validated for various types of stepped irregular frames. © 2010 Elsevier Ltd. - PublicationTowards a sustainable infrastructure through smart dampers(01-04-2010)
;Sreekala, R. ;Muthumani, K.; ;Gopalakrishnan, N.Sathishkumar, K.Development of new technologies for seismic protection will better support the sustainable urban systems. The paper aims in bringing out the efficacy of a Shape Memory Alloy (SMA) device in seismic protection of simply supported short span bridges for strong ground motions. The damper cum restraining device with re-centering capabilities, developed within the laboratory has been pilot tested to verify its performance before actual implementation in the site. Experimental and analytical investigations were carried out on an equivalent Single Degree of Freedom (SDOF) system for a particular narrow band spectrum representing strong ground motion. From the studies it is found that the developed smart damper is very effective for seismic performance enhancement of critical facilities like bridges thus offering great benefits for the sustainable development of urban systems. - PublicationEffect of track on the dynamics of railway steel plate girder bridges(01-12-2011)
;Agarwal, Sharad Kumar ;Narayanan, G.; Railway steel plate girder (SPG) bridges generally are provided with open track which does not have ballast cushion. Tracks consisting of steel channel sleepers with under sleeper pads are being used in Indian Railways. In the present work the combined track-girder system is modelled as two beams connected with uniformly distributed springs and dampers. A computer program in MATLAB has been developed to examine the effect of track on the behaviour of girder. A train of ten wagons travelling on a ten-span bridge is studied. Shifts in the fundamental frequencies of the girder due to inclusion of track in modelling are analyzed. The significant findings are that: (i) the natural frequencies of combined track-girder system differ from those of the girder alone and (ii) in the case of multiple simply supported spans, the presence of the track in dynamic modelling influences the dynamic behaviour of neighbouring spans. Finally, the dynamic behaviour of the girder is studied using moving force model (MFM) for different velocities and a comparison is made for two cases, viz. (i) girder alone modelled neglecting the track stiffness and damping, but considering the track mass; and (ii) girder and track modelled as two beams connected through uniformly distributed springs and dampers, i.e., both the track stiffness and mass are considered. For case (ii), mid-span acceleration varies from 20% to 80% and impact factor for displacement varies from 26% to 96%, of those of case (i). The results confirm that the presence of track in dynamic modelling influences the dynamic behaviour of the open deck SPG. - PublicationAssessment of Strut-and-Tie Methods to Estimate Ultimate Strength of RC Deep Beams(01-01-2017)
;Adrija, D. ;Geevar, Indu; Reinforced concrete (RC) deep beams are structural members characterized by relatively small shear span to depth (a/d) ratios. Sectional analysis as well as design procedures are not valid for these members due to the complex interaction of flexure and shear. The strut-and-tie method (STM) has been widely accepted and used as a rational approach for the design of such disturbed regions (D regions) of reinforced concrete members, where traditional flexure theory cannot be used. The flow of stress is idealized as a truss consisting of compressive struts (concrete) and tension ties (reinforcing steel) transmitting the loads to the supports. Usually, STM considers only equilibrium. Hence, there is no unique solution for a given system, as one can find more than a single truss geometry admissible for a given force field. Therefore, the model which gives the maximum capacity can be considered as the most appropriate one. This paper attempts to predict the ultimate strength of deep beams failing in diagonal compression as well as tension, from the experimental database available in literature based on STM. A modified approach has been used, considering the crushing and splitting failures of the diagonal strut separately. Crushing failure of the diagonal strut has been predicted using a plastic Strut-and-tie model with varying compression zone depth. A localized STM has been considered to predict the splitting failure of the diagonal strut. - PublicationInvestigation of shear behaviour of vertical joints between precast concrete wall panels(01-01-2015)
;Biswal, Aparup; An experimental program is undertaken to study the behaviour of vertical joints between precast wall panels. The parameters such as type of transverse reinforcement in the joint, amount and distribution of joint reinforcements, shape of the join and strength of the joint grout are considered in this experimental program. The testsetup, specimens, instrumentation are reported in this paper. The results of a typical test are presented.