Conference Papers
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Item Effect of diaphragm discontinuity on the seismic response of an rc building(Springer Science and Business Media Deutschland GmbH, 2021) Mable Vas, V.; Nagaraja, P.; Venkataramana, K.Although rigid floor diaphragm is a reasonable assumption for seismic analysis, certain building configurations may exhibit diaphragm flexibility. Detailed investigations have been carried out on modelling of flexible diaphragms compliant with various codes such as ASCE-07 and UBC 1997. Studies have shown that diaphragm flexibility amplifies both the deformation and the shear in the diaphragm. However, additional studies are essential to assess the magnitude of such amplification and to account for it in the design. The methodology is outlined by three major elements such as the choice of building models, the adopted method of analysis and the parameters studied. Buildings with large cut-outs and openings are observed to exhibit flexible behaviour. These models are analysed dynamically using a site-specific response spectrum developed from probabilistic seismic hazard analysis (PSHA) for Mangalore region (a coastal city in Karnataka, Southern India). The analysis is carried out using a G+10 RC building. The effect of percentage of openings in the diaphragm is studied using structural parameters such as storey drift, base shear and storey displacement with the help of ETABS 2015 software, and the optimum shape for these openings in a building plan is finalized. Further, time history analysis is performed over the models, and the results obtained through response spectrum and time history analysis are compared. The study highlights the importance of diaphragm flexibility in determining the seismic response of a building. This flexibility causes significant increase in the building period, which results in reduction in the earthquake-induced base shear. Since the seismic input used for the study was developed for the moderate seismic zone, the outcomes of this investigation are believed to have vast applications. © Springer Nature Singapore Pte Ltd 2021.Item Nonlinear Seismic Response Analysis of Mid-rise RC Buildings Founded on Soft Soil(Springer Science and Business Media Deutschland GmbH, 2024) Mathews, M.; Jayalekshmi, B.R.; Venkataramana, K.Multi-storeyed RC structures have become a significant part of modern construction. Damages induced by earthquake excitations on RC structures depend not only on the structural behaviour of the superstructure but also depend on the type of foundation and soil on which the structure is founded. The present study aims to understand the impact of soil-structure interaction on the seismic response of mid-rise RC buildings. Nonlinear static pushover analysis of RC frame buildings having 4 and 6 storeys has been conducted considering fixed base condition and flexible base. The effect of SSI is analysed by creating 3D building models using finite element software considering the SSI between the building model and the soil on which the building is founded. The nonlinear behaviour of the building components is incorporated in modelling using the concrete damaged plasticity model by defining the compression and tension damage parameters. The consideration of nonlinearity of soil and structure is found to alter the system’s dynamic characteristics by an increase in the natural period. The pushover analysis results indicate a comparable variation of the force–displacement curves for the building models with and without considering SSI and show an increase in the lateral displacement value while considering the SSI effect. The results presented in this study illustrate the inefficiency of fixed base modelling in assessing the dynamic response of mid-rise RC buildings by highlighting the disparity in the fundamental time period and flexibility of the building under the effect of SSI. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.