Dynamic analysis of RCC chimneys subjected to near-fault ground motions

Abstract

Industries are a crucially important part of any country’s development. With the increase in industrialization, the chances of environmental pollution also increase. In industry, the main component is chimneys, which are used to reduce environmental pollution. In the present study, reinforced cement concrete (RCC) chimneys of different heights are investigated under near-fault ground motions. The RCC chimney is modelled using a simplified lumped mass method, where a comparison is carried out for single degree-of-freedom (SDOF) and multi degree-of-freedom (MDOF) systems. Chimneys of 180 m and 275 m heights are considered for six near-fault ground motions. The three models, Model 1 with varied diameter and thickness, Model 2 having varying diameter and uniform thickness, and Model 3 having uniform diameter and thickness are analyzed. The fundamental time period, top nodal displacement, top nodal acceleration, base shear force, and base bending moment are evaluated for all chimney models. The present analyses reveal that the time period of the chimney increases with its height. The displacement of the multi degree-of-freedom chimney system is slightly greater than that of the single degree-of-freedom system. It is also seen that in the case of Model 3, where the cross-sectional area and thickness are uniform throughout the height of chimney, the response quantities are more as compared to Model 1 and Model 2 where varying thickness and diameter, constant thickness and varying diameter are considered.