Conference Papers

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/28506

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Subject: search.filters.subject.Natural frequency

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    Experimental investigation on dynamic characteristics of structures founded on a dispersive soil
    (2008) Jayalekshmi, B.R.; Lohith, K.; Shivashankar, R.; Venkataramana, K.
    The objective of this paper is to evaluate the Soil-Structure-Interaction (SSI) effects on the seismic response of structures founded on Shedi soil of Dakshina Kannada. Shedi soil, which is a dispersive type of soil is highly vulnerable to dynamic loading in the saturated condition. Experimental investigations have been carried out on 1:10 scaled single bay three dimensional multistorey building models made of aluminium with its foundation resting on locally available Shedi soil (classifying as sandy silt) and sand in the saturated and dry conditions. The combined system of Soil-Foundation-Structure models is subjected to dynamic loading. The response of the model is measured at each floor level. This structural response is compared with that of a fixed base model to isolate the effect of soil structure interaction. The variations in natural frequency with various parameters such as different types of soil, degree of saturation of soil, number of storeys and the stiffening effect of walls are evaluated. The experimental results are presented and the modifications in dynamic characteristics due to the incorporation of soil flexibility are studied. Free vibration analysis of the three dimensional finite element model of the soil foundation structure system is carried out and the results are compared with the experimentally obtained values.
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    Investigation of static and dynamic properties of cenosphere reinforced polymer matrix composite beams
    (American Institute of Physics Inc. subs@aip.org, 2019) Bharath, J.; Joladarashi, S.; Nagiredla, S.; Kumar, H.
    Polymer Matrix Composites (PMC) plays a conspicuous role in engineering application. Cenosphere reinforced polymer matrix composite has higher strength, stiffness, lesser density and also saving in cost. These particulate composites are manufactured to meet several structural requirements. Thus there is a need to study their static and dynamic properties. In this work polymer epoxy polymer composites reinforced with cenosphere are fabricated and their static and dynamic properties are analyzed. Experimental investigation involves fabrication of specimen of polymer matrix reinforced with cenosphere by varying volume fractions of 25%, 30%, 35%, and 40%. Tensile and compressive properties are tested on UTM as per ASTM standard. Microstructures of composites are assessed with SEM and also Model analysis of cantilever beam is performed as per ASTM standard in Engineering Data Management System (EDM 7.0) of Crystal Instruments to study variation of natural frequency in each case. The natural frequency results are compared with the commercially available ANSYS FE software by assigning the material propertied obtained by static analysis. Thus effects of volume fraction of cenosphere on static and dynamic characteristics of particulate composites are studied. © 2018 Author(s).
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    Study of Dynamic Characteristics of Circular Liquid Storage Tanks Using Acoustic Principles
    (Springer Science and Business Media Deutschland GmbH, 2021) Nimisha, P.; Jayalekshmi, B.R.; Venkataramana, K.
    Liquid storage tanks are lifeline structures, which should be designed with utmost care. Any damage to a tank, which is used to store hazardous liquid is catastrophic. The estimation of fundamental natural frequencies of liquid storage tanks situated in seismic regions is important for a seismic design. The present study deals with the estimation of natural frequencies of circular steel liquid storage tanks with reference to codal provisions and numerical analysis by using acoustic principles with the aid of FEM software. The study has been carried out for circular tank of diameter 6 m and height 8 m with different liquid depths, viz. 1/3rd, 2/3rd and full tank conditions and stiffness conditions, incorporating the sloshing effect. The natural frequencies obtained by finite element analysis of tanks are compared with those values obtained as per various International codes, viz., IS 1893(part2):2014, API 650 and Eurocode 8. The results show that the convective mode frequencies are matching well whereas, there is slight variation in impulsive mode frequency values obtained as per IS 1893. © 2021, Springer Nature Singapore Pte Ltd.