SEISMIC ANALYSIS OF A G+10 BUILDING USING ETABS SOFTWARE

Abstract

The project report details a comprehensive investigation on the seismic analysis of a structure, utilizing the capabilities of ETABS for detailed analysis. The study aims to evaluate the seismic behavior of the structure and highlight the advantages of non-linear static analysis (Pushover Analysis) over linear static analysis. The building is initially analyzed using both linear and non-linear static methods, and the results are compared to demonstrate the superiority of non-linear analysis in capturing the structural response. The structure is then subjected to various irregularities, including soft stories at levels 3, 6, and 9, and mass irregularities (double live load) at the same levels. Non-linear analysis reveals that soft stories have a more significant impact on the structure's seismic behavior compared to mass irregularities. Key structural response parameters such as story displacement, story drifts, base shear, performance points (target displacements), performance levels, are examined in two lateral directions. Initially, the regular structure's performance levels indicate that the target displacement exceeds the limit value. However, enhancing the concrete grade reduces the target displacement to an acceptable level, deeming the structure safe. The target displacement value obtained from the push over analysis (in case of Retrofitted model) for the X-direction is 351.03 mm, and for the Y-direction, it is 363.02 mm. The target displacement values for both the x and y directions are still below the maximum displacement limit value of 0.02 x building height = 0.02 x 35.2 m = 0.704 m or 704 mm. The results showed that base shear value in the Y-direction (1972.52 KN) is greater than base shear value in X-direction (1945.94 KN). This indicates that the building’s strong axis is in the X-direction and the weak axis is in the Y-direction. The revised configuration (modification in columns’ size and orientation) ensures that the structure meets the desired performance objectives, with all hinges operating within acceptable limits (less than the collapse prevention state).