Faculty Publications
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Item Stochastic Analysis to Assess Uncertainty in Pushover Analysis to Modeling Methods(American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2014) Panandikar, N.; Babu Narayan, K.S.The pushover analysis is a nonlinear static procedure wherein monotonically increasing loads are applied to the structure. It is a popular tool for seismic performance evaluation of existing, as well as new, structures. In the literature a lot of research work has been carried out on conventional pushover analysis and, after knowing deficiencies, efforts have been made to improve it. However, actual experimental test results to verify the analytically obtained pushover results are rarely available. Also, the procedure involves certain approximations that some amount of variation is always expected to exist in seismic demand prediction of pushover analysis. In this paper, an ttempt is being made to assess the uncertainty of pushover analysis results to modeling methods and results compared with experimentally obtained results based on tests carried out on a G+2 storied RCC framed structure. Stochastic analysis is carried out by considering uncertain parameters as the strength of concrete, strength of steel, cover to the reinforcement, hinge location and hinge length which are randomly generated and incorporated into the analysis. The hinge lengths are found using various hinge length formulations available in literature. The results are then compared with experimental observations. © 2014 American Society of Civil Engineers.Item Assessment of Pushover Response Parameters Using Response Surface Methodology(Springer Science and Business Media Deutschland GmbH, 2021) Panandikar, N.; Babu Narayan, K.S.B.Pushover analysis is a non-linear static method used for the seismic assessment of structures. The simplicity, efficiency in modelling and less computational time make this method popular. Lot of researchers has worked on conventional pushover analysis and after knowing deficiencies of the method have made efforts to improve it. From the literature, it is evident that actual experimental test results carried out so as to verify the analytically obtained pushover results are hardly available. Stress–strain models adopted for modelling of concrete and reinforcement greatly influences both the ultimate load and ultimate displacement for the structure under pushover loads. This paper focuses on assessment of pushover response parameters using response surface methodology (RSM). A three-storied RCC framed structure is tested and the experimental pushover results are available. Uncertain parameters considered include the concrete strength, steel strength, reinforcement cover and hinge location, which are randomly generated by performing stochastic analysis and their effect on responses, which include base shear and displacement is studied. Using Monte Carlo simulation in Sap-2000 design matrix is generated. Modelling and analysis of response parameters are carried out using RSM so as to obtain the characteristics of the pushover curve. The effect of material strength variation, hinge locations and hinge lengths, geometric modelling have been studied, incorporating confined model for concrete. The coefficients and equations that can be used to predict the responses are carried out by performing multiple regression analysis. The validation results demonstrated that the confined model is better than the unconfined. © 2021, Springer Nature Singapore Pte Ltd.Item Sensitivity of Pushover Curve to Material and Geometric Modelling-An Analytical Investigation(Elsevier Ltd, 2015) Panandikar, N.; Babu Narayan, K.S.Nonlinear static analysis or pushover analysis developed over the last two decades and became the preferred procedure for design and seismic performance evaluation, as this procedure is relatively simple and considers post-elastic behaviour. It provides information on seismic demands imposed by the design ground motion on the structural system and its components. Generation of pushover curve from analysis for reinforced concrete structure involves tremendous amount of computational efforts as the input data for analysis itself is quite exhaustive. The analysis results are very sensitive to the techniques employed in geometric and material modelling. This paper envisages presenting the sensitivity of pushover analysis results to geometric and material modelling parameters by comparing the analysis results with that of experimental investigations. Attempt has been made to understand the sensitivity of parameters like variation in material properties, inaccuracies in placement of reinforcement, effect of confinement of concrete and modelling techniques for elements and plastic hinges. SAP-2000 has been utilised in the current investigation and results have been highlighted suggesting strategies to enhance pushover analysis capabilities. © 2015 Elsevier B.V.