Polymer matrix composites can reduce the structural weight and result in improved fuel efficiency... more Polymer matrix composites can reduce the structural weight and result in improved fuel efficiency and performance in transportation applications. Thermoplastic matrix composites have been used for semi-structural and engineering applications. In addition to the ease of fabrication using a wide range of forming processes, thermoplastic polymers are recyclable, which are the strong driving forces for their current and future applications. Rapid production of high quality components is the key to cost reduction in industrial applications. The present work is the first attempt of manufacturing syntactic foams, hollow particle filled lightweight composites, using an industrial scale Polymer Injection Molding (PIM) process. High Density Polyethylene (HDPE) is used as the matrix material and fly ash cenospheres as the filler. Development of syntactic foams with cenospheres serves dual purpose of beneficial utilization of industrial waste fly ash and reduction in the component cost. Pressure and temperature used in PIM are optimized to minimize cenosphere fracture and obtain complete mixing of cenospheres with HDPE. The optimized parameters are used for manufacturing syntactic foams with 20, 40 and 60 wt.% cenosphere without any surface treatment initially. With increasing cenosphere content, density and tensile strength reduce and modulus increases. A theoretical model based on a differential scheme is used to estimate the properties of cenospheres by conducting parametric studies because of inherent difficulties in direct measurement of cenosphere properties. Further, the influence of cenosphere surface treatment, functionalization of HDPE and blending method on tensile properties are investigated. Cenospheres are treated with silane and HDPE is functionalized with 10% dibutyl maleate. Tensile test specimens are cast with 20, 40 and 60 wt.% of cenospheres using injection molding. Modulus and strength are found to increase with increasing cenosphere content for composites with treated constituents. Highest modulus and strength were observed for 40 and 60 wt.% untreated mechanically mixed and treated brabender mixed cenospheres/HDPE blends, respectively. These values are 37 and 17% higher than those for virgin and functionalized HDPE. Theoretical models are used to assess the effect of particle properties and interfacial bonding on modulus and strength of syntactic foams. Brabender mixing method provided highest ultimate tensile and fracture strengths, which is attributed to the effectiveness of brabender in breaking particle clusters and generating the higher particle-matrix surface area compared to that by mechanical mixing method. Theoretical trends show clear benefits of improved particle-matrix interfacial bonding in the strength results. Effect of surface treatment and blending method on flexural properties is dealt next. Flexural test specimens are cast with 20, 40 and 60 wt.% of cenospheres using PIM. The flexural modulus and strength are found to increase with increasing cenosphere content. Particle breakage increases with the cenosphere content and the measured properties show increased dependence on processing method. Untreated constituents blended by mechanical mixing provide the highest benefit in flexural modulus. Modulus of syntactic foams is predicted by two theoretical models. Bardella-Genna model provides close estimates for syntactic foams having 20 and 40 wt.% cenospheres, while predictions are higher for higher cenosphere content, likely due to particle breakage during processing. The uncertainty in the properties of cenospheres due to defects contribute to the variation in the predicted values. Untreated constituents blended by mechanical mixing route as observed in tensile and flexural characterization registered higher tensile modulus and better flexural performance. Thereby, characterization of cenosphere/HDPE syntactic foams synthesized by mechanical mixing route for untreated constituents is dealt in the subsequent investigations. Quasi-static and high strain rate compressive response is investigated later. Thermoplastic matrix syntactic foams have not been studied extensively for high strain rate deformation response despite interest in them for lightweight underwater vehicle structures and consumer products. Quasi-static compression tests are conducted at 10 -4 , 10 -3 and 10 -2 s -1 strain rates. Further, a split-Hopkinson pressure bar (SHPB) is utilized for characterizing syntactic foams for high strain rate compression. The compressive strength of syntactic foams is higher than that of HDPE resin at the same strain rate. Yield strength shows an increasing trend with strain rate. The average yield strength values at high strain rates are almost twice the values obtained at 10 -4 s -1 for HDPE resin and syntactic foams. Further, HDPE matrix syntactic foams are characterized for their viscoelastic properties by dynamic mechanical analysis. Tests are conducted over 35-130°C temperatures and 1-100 Hz frequency range and combined using the time-temperature superposition principle to generate a set of isothermal master curves. Storage and loss modulus increase with increasing weight fraction of cenospheres, but with little difference between 40 and 60 wt.%, at all temperatures. The sensitivity of storage modulus to weight fraction of cenospheres increases with increasing frequency. Storage and loss modulus decrease with increasing temperature in the range of 35-130°C, while tan δ increases. The Williams-Landel-Ferry (WLF) constants are a linearly increasing function of cenosphere weight fraction. Structure-property correlations of all the investigated properties are presented with the help of exhaustive SEM images to understand underlying mechanisms. Finally, the potential for using the optimized parameters of injection molding process is demonstrated by casting several industrial components as a deliverable of this work.
Proceedings of the International Conference on …, 1999
XML is an emerging standard for data representa- tion and exchange on the World-Wide Web. Due to ... more XML is an emerging standard for data representa- tion and exchange on the World-Wide Web. Due to the nature of information on the Web and the inher- ent flexibility of XML, we expect that much of the data encoded in XML will be semistructured: the data may be irregular or ...
Usage of 2-Dimensional Gaussian Random Variables in Probabil-istic Seismic Risk Evaluation of RC Buildings
As more and more emphasis is being laid on inelastic analysis of RC framed structures subjected t... more As more and more emphasis is being laid on inelastic analysis of RC framed structures subjected to earthquake excitation; the pushover (non-linear static) analysis is in forefront compared to time history (nonlinear dynamic) analysis. The paper presents the overview of seismic provisions of IS1893 (Part 1)-2002 keeping probabilistic format in to consideration published by Bureau of Indian Standards with regard to seismic analysis and design. Since the country lie in earthquake prone area and many of the destructive earthquakes occurred in the history so far resulting in high number of casualties due to collapse of buildings and dwellings. Hence, the paper proposes the methodology in a probabilistic manner to assess the seismic risk/ performance of RC (Reinforced Concrete) building by considering uncertainties based on pushover analysis due to non-existence of code of practices in Indian context. Thus, the methodology may be used as guidelines for seismic risk evaluation of building structure.
American Journal of Civil and Structural Engineering, 2014
The behavior of structures subjected to earthquake excitations is probabilistic rather than deter... more The behavior of structures subjected to earthquake excitations is probabilistic rather than deterministic. Moreover, the origin of earthquakes, the inherency of earthquakes caused by fault movement, is stochastic as well. Hence, the uncertainty is in the whole property of earthquake records, such as peak ground acceleration and frequency content. In the next step, the whole property of structures, namely element details, material properties and hysteresis or ductility behaviors are probabilistic. The evaluation of structures cannot be concluded if all these uncertainties are addressed. The most important requirements in good concrete construction is that the use of quality of materials. In India, most of concrete is produced at the site rather than producing in ready mixed plants and, as different form the steel made in the factory. The quality also varies from site to site and at the same site, from day to day. The paper attempts to generate mechanical properties of structural elements as 2-dimensional Gaussian random variables, keeping coefficient of variance as code provisions and expresses the probability density functions of two continuous random variables X(f ck , characteristic strength of concrete) and Y(f y , yield strength of steel) as bivariate normal density function in probabilistic seismic risk evaluation of buildings.
OBJECTIVE: This paper Deals with the to uneven constructions undergo extra harm than their common... more OBJECTIVE: This paper Deals with the to uneven constructions undergo extra harm than their common counterpart seismic design codes, & limitation compulsory. METHODS/ANALYSIS within twist influence ability, Altitude irregularity has been observed in the direction of reason story failure due to non distribute of demand-to-supply ratios resting on the additional hand, reason non columns. In this paper the structure chosen for study is a building. The building which mathematical models for the same are generated in structural fundamentals, M40 G be rigid. Seismic loads were considere a 4 to7 storey RC structure with typical ground slope choosing building that which produce less torsion effect for set configuration in horizontal & also used that which resist during earthquake and building that which produce less torsion effect for setback-step back with irregular This paper Deals with the seismic activity field investigation undergo extra harm than their common counterpart limitations on top of sudden changes within mass & METHODS/ANALYSIS: Irregularity within sizes pressures sharing about rigidity, & twist influence ability, as mass irregularity is likely to pressure compulsory require ltitude irregularity has been observed in the direction of reason story failure due to non supply ratios the length about length of the elevation. Plan irregularity, resting on the additional hand, reason non-uniform demand-to-capacity ratios bounded by the columns. In this paper the structure chosen for study is a 4 to 7 storey commercial complex which is located in seismic zone III, IV, & V on Medium soil sites mathematical models for the same are generated in ETABS software 0 Grade of material is used. The floor Diaphragms are unspecified to eismic loads were considered acting along either of the 2 major directions. Using ETABS storey RC structure with typical ground slope choosing angle range building that which produce less torsion effect for setback & step vertical direction is modeled and analyzed. " And isolated bearing is also used that which resist during earthquake and building that which produce less torsion effect step back with irregular configuration.
Earthquakes are the most destructive natural disaster causing lot of casualties, injuries and eco... more Earthquakes are the most destructive natural disaster causing lot of casualties, injuries and economic losses leaving behind a trail of panic. Earthquake risk assessment is needed for disaster mitigation, disaster management, and emergency preparedness. Vulnerability of building is one of the major factors contributing to earthquake risk. The vulnerability functions framed for a particular building is input parameter for loss estimation. Procedure for developing fragility curves of specific building type is discussed. Seismic fragility curves were developed and damage probability threshold has been constructed for the chosen problems
Polymer matrix composites can reduce the structural weight and result in improved fuel efficiency... more Polymer matrix composites can reduce the structural weight and result in improved fuel efficiency and performance in transportation applications. Thermoplastic matrix composites have been used for semi-structural and engineering applications. In addition to the ease of fabrication using a wide range of forming processes, thermoplastic polymers are recyclable, which are the strong driving forces for their current and future applications. Rapid production of high quality components is the key to cost reduction in industrial applications. The present work is the first attempt of manufacturing syntactic foams, hollow particle filled lightweight composites, using an industrial scale Polymer Injection Molding (PIM) process. High Density Polyethylene (HDPE) is used as the matrix material and fly ash cenospheres as the filler. Development of syntactic foams with cenospheres serves dual purpose of beneficial utilization of industrial waste fly ash and reduction in the component cost. Pressure and temperature used in PIM are optimized to minimize cenosphere fracture and obtain complete mixing of cenospheres with HDPE. The optimized parameters are used for manufacturing syntactic foams with 20, 40 and 60 wt.% cenosphere without any surface treatment initially. With increasing cenosphere content, density and tensile strength reduce and modulus increases. A theoretical model based on a differential scheme is used to estimate the properties of cenospheres by conducting parametric studies because of inherent difficulties in direct measurement of cenosphere properties. Further, the influence of cenosphere surface treatment, functionalization of HDPE and blending method on tensile properties are investigated. Cenospheres are treated with silane and HDPE is functionalized with 10% dibutyl maleate. Tensile test specimens are cast with 20, 40 and 60 wt.% of cenospheres using injection molding. Modulus and strength are found to increase with increasing cenosphere content for composites with treated constituents. Highest modulus and strength were observed for 40 and 60 wt.% untreated mechanically mixed and treated brabender mixed cenospheres/HDPE blends, respectively. These values are 37 and 17% higher than those for virgin and functionalized HDPE. Theoretical models are used to assess the effect of particle properties and interfacial bonding on modulus and strength of syntactic foams. Brabender mixing method provided highest ultimate tensile and fracture strengths, which is attributed to the effectiveness of brabender in breaking particle clusters and generating the higher particle-matrix surface area compared to that by mechanical mixing method. Theoretical trends show clear benefits of improved particle-matrix interfacial bonding in the strength results. Effect of surface treatment and blending method on flexural properties is dealt next. Flexural test specimens are cast with 20, 40 and 60 wt.% of cenospheres using PIM. The flexural modulus and strength are found to increase with increasing cenosphere content. Particle breakage increases with the cenosphere content and the measured properties show increased dependence on processing method. Untreated constituents blended by mechanical mixing provide the highest benefit in flexural modulus. Modulus of syntactic foams is predicted by two theoretical models. Bardella-Genna model provides close estimates for syntactic foams having 20 and 40 wt.% cenospheres, while predictions are higher for higher cenosphere content, likely due to particle breakage during processing. The uncertainty in the properties of cenospheres due to defects contribute to the variation in the predicted values. Untreated constituents blended by mechanical mixing route as observed in tensile and flexural characterization registered higher tensile modulus and better flexural performance. Thereby, characterization of cenosphere/HDPE syntactic foams synthesized by mechanical mixing route for untreated constituents is dealt in the subsequent investigations. Quasi-static and high strain rate compressive response is investigated later. Thermoplastic matrix syntactic foams have not been studied extensively for high strain rate deformation response despite interest in them for lightweight underwater vehicle structures and consumer products. Quasi-static compression tests are conducted at 10 -4 , 10 -3 and 10 -2 s -1 strain rates. Further, a split-Hopkinson pressure bar (SHPB) is utilized for characterizing syntactic foams for high strain rate compression. The compressive strength of syntactic foams is higher than that of HDPE resin at the same strain rate. Yield strength shows an increasing trend with strain rate. The average yield strength values at high strain rates are almost twice the values obtained at 10 -4 s -1 for HDPE resin and syntactic foams. Further, HDPE matrix syntactic foams are characterized for their viscoelastic properties by dynamic mechanical analysis. Tests are conducted over 35-130°C temperatures and 1-100 Hz frequency range and combined using the time-temperature superposition principle to generate a set of isothermal master curves. Storage and loss modulus increase with increasing weight fraction of cenospheres, but with little difference between 40 and 60 wt.%, at all temperatures. The sensitivity of storage modulus to weight fraction of cenospheres increases with increasing frequency. Storage and loss modulus decrease with increasing temperature in the range of 35-130°C, while tan δ increases. The Williams-Landel-Ferry (WLF) constants are a linearly increasing function of cenosphere weight fraction. Structure-property correlations of all the investigated properties are presented with the help of exhaustive SEM images to understand underlying mechanisms. Finally, the potential for using the optimized parameters of injection molding process is demonstrated by casting several industrial components as a deliverable of this work.
Proceedings of the International Conference on …, 1999
XML is an emerging standard for data representa- tion and exchange on the World-Wide Web. Due to ... more XML is an emerging standard for data representa- tion and exchange on the World-Wide Web. Due to the nature of information on the Web and the inher- ent flexibility of XML, we expect that much of the data encoded in XML will be semistructured: the data may be irregular or ...
Usage of 2-Dimensional Gaussian Random Variables in Probabil-istic Seismic Risk Evaluation of RC Buildings
As more and more emphasis is being laid on inelastic analysis of RC framed structures subjected t... more As more and more emphasis is being laid on inelastic analysis of RC framed structures subjected to earthquake excitation; the pushover (non-linear static) analysis is in forefront compared to time history (nonlinear dynamic) analysis. The paper presents the overview of seismic provisions of IS1893 (Part 1)-2002 keeping probabilistic format in to consideration published by Bureau of Indian Standards with regard to seismic analysis and design. Since the country lie in earthquake prone area and many of the destructive earthquakes occurred in the history so far resulting in high number of casualties due to collapse of buildings and dwellings. Hence, the paper proposes the methodology in a probabilistic manner to assess the seismic risk/ performance of RC (Reinforced Concrete) building by considering uncertainties based on pushover analysis due to non-existence of code of practices in Indian context. Thus, the methodology may be used as guidelines for seismic risk evaluation of building structure.
American Journal of Civil and Structural Engineering, 2014
The behavior of structures subjected to earthquake excitations is probabilistic rather than deter... more The behavior of structures subjected to earthquake excitations is probabilistic rather than deterministic. Moreover, the origin of earthquakes, the inherency of earthquakes caused by fault movement, is stochastic as well. Hence, the uncertainty is in the whole property of earthquake records, such as peak ground acceleration and frequency content. In the next step, the whole property of structures, namely element details, material properties and hysteresis or ductility behaviors are probabilistic. The evaluation of structures cannot be concluded if all these uncertainties are addressed. The most important requirements in good concrete construction is that the use of quality of materials. In India, most of concrete is produced at the site rather than producing in ready mixed plants and, as different form the steel made in the factory. The quality also varies from site to site and at the same site, from day to day. The paper attempts to generate mechanical properties of structural elements as 2-dimensional Gaussian random variables, keeping coefficient of variance as code provisions and expresses the probability density functions of two continuous random variables X(f ck , characteristic strength of concrete) and Y(f y , yield strength of steel) as bivariate normal density function in probabilistic seismic risk evaluation of buildings.
OBJECTIVE: This paper Deals with the to uneven constructions undergo extra harm than their common... more OBJECTIVE: This paper Deals with the to uneven constructions undergo extra harm than their common counterpart seismic design codes, & limitation compulsory. METHODS/ANALYSIS within twist influence ability, Altitude irregularity has been observed in the direction of reason story failure due to non distribute of demand-to-supply ratios resting on the additional hand, reason non columns. In this paper the structure chosen for study is a building. The building which mathematical models for the same are generated in structural fundamentals, M40 G be rigid. Seismic loads were considere a 4 to7 storey RC structure with typical ground slope choosing building that which produce less torsion effect for set configuration in horizontal & also used that which resist during earthquake and building that which produce less torsion effect for setback-step back with irregular This paper Deals with the seismic activity field investigation undergo extra harm than their common counterpart limitations on top of sudden changes within mass & METHODS/ANALYSIS: Irregularity within sizes pressures sharing about rigidity, & twist influence ability, as mass irregularity is likely to pressure compulsory require ltitude irregularity has been observed in the direction of reason story failure due to non supply ratios the length about length of the elevation. Plan irregularity, resting on the additional hand, reason non-uniform demand-to-capacity ratios bounded by the columns. In this paper the structure chosen for study is a 4 to 7 storey commercial complex which is located in seismic zone III, IV, & V on Medium soil sites mathematical models for the same are generated in ETABS software 0 Grade of material is used. The floor Diaphragms are unspecified to eismic loads were considered acting along either of the 2 major directions. Using ETABS storey RC structure with typical ground slope choosing angle range building that which produce less torsion effect for setback & step vertical direction is modeled and analyzed. " And isolated bearing is also used that which resist during earthquake and building that which produce less torsion effect step back with irregular configuration.
Earthquakes are the most destructive natural disaster causing lot of casualties, injuries and eco... more Earthquakes are the most destructive natural disaster causing lot of casualties, injuries and economic losses leaving behind a trail of panic. Earthquake risk assessment is needed for disaster mitigation, disaster management, and emergency preparedness. Vulnerability of building is one of the major factors contributing to earthquake risk. The vulnerability functions framed for a particular building is input parameter for loss estimation. Procedure for developing fragility curves of specific building type is discussed. Seismic fragility curves were developed and damage probability threshold has been constructed for the chosen problems
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Papers by Ravi Kumar C.m
leaving behind a trail of panic. Earthquake risk assessment is needed for disaster mitigation, disaster management, and
emergency preparedness. Vulnerability of building is one of the major factors contributing to earthquake risk. The
vulnerability functions framed for a particular building is input parameter for loss estimation. Procedure for developing
fragility curves of specific building type is discussed. Seismic fragility curves were developed and damage probability
threshold has been constructed for the chosen problems
leaving behind a trail of panic. Earthquake risk assessment is needed for disaster mitigation, disaster management, and
emergency preparedness. Vulnerability of building is one of the major factors contributing to earthquake risk. The
vulnerability functions framed for a particular building is input parameter for loss estimation. Procedure for developing
fragility curves of specific building type is discussed. Seismic fragility curves were developed and damage probability
threshold has been constructed for the chosen problems