Approximate Natural Period Expression for Reinforced Concrete Tall Buildings in India

Many tall buildings are being constructed in different Indian cities to cater to the demand generated by the large number of people migrating from rural areas to urban centres. The safety of such tall buildings is ensured by designing them for dynamic loads, viz. wind and earthquake. To withstand these loads, computation of the natural period becomes essential. The current Indian seismic code IS 1893 (2016) has outlined a few empirical expressions based on different structural systems to compute the natural period. These expressions have been developed using data obtained from experiments performed on low to midrise buildings. Thus, verifying their applicability for tall structures before using them is important. To achieve this, in the present study ambient vibration testing was done on 28 reinforced concrete (RC) tall buildings in the Indian cities of Hyderabad and Mumbai, whose heights ranged from 50 to 150 m. These tests’ natural periods were compared with existing Indian and international codes. Based on the comparison, a novel empirical expression of RC tall buildings is proposed here.