Analysis of a Residential RC Building Subjected to Blast Load Using Time History Method

Abstract

Blast incidents in recent years, such as in the Russia-Ukraine war, indicate that most terrorist attacks target high-occupancy iconic and public buildings using high explosives. This assessment is essential for developing effective mitigation strategies to enhance the building's resilience and safety of buildings like Embassies, banks, hospitals, monumental buildings, headquarters etc. should be designed and analyzed to withstand blast effects within acceptable limits. The theoretical analysis will encompass a thorough review of prevailing design codes, standards, and guidelines concerning blast-resistant design. Furthermore, advanced computational tools will be employed to conduct numerical simulations, allowing for the simulation and analysis of the performance of reinforced concrete structures under blast loads. After collecting required data from the design of a proposed residential building for CUET professors and the soil condition from further field investigation we acquainted these data with ETABS 2018 software which was utilized in this study for load estimation and analysis purposes. After analyzing the model with standard load applications, the blast load for our chosen building (CUET Professor’s Building) subjected to different explosions (100kg, 200kg, and 300kg TNT equivalent weight) from different stand-off distances (10m and 20m) has been calculated with compliance of IS code 4991.The blast load application has been validated in ETABS software by doing a blast load analysis of a portal frame as an example. The time period and the displacement due to blast load obtained by the end of the time history analysis in the software are compared with the values obtained by manual calculation from the book “Dynamics of Structure” by Ray W. Clough which has a slight marginal error of 2.12% for time period value and 1.2% for the displacement value, which is acceptable. Thus, the further blast load applications were carried out using Time History analysis. The response of the building in terms of displacement and drift is more when the blast's standoff distance is less and the charge weight is more. Thus, the response is inversely proportional to the standoff distance and proportional to the charge weight.  Considering the values of different parameters, the cases of 100kg 20m blast and 200kg 20m blast are within the safe limit. In contrast, the rest of the cases exceed the allowable limit for this particular building. We have also stated a comparison between the severity of earthquake load to blast loads by plotting a story displacement and a story drift ratio curve.