PSI - Issue 60

Sarmili Swain et al. / Procedia Structural Integrity 60 (2024) 553–563

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Sarmili Swain / Structural Integrity Procedia 00 (2024) 000 –

000 proves detrimental for the survival/integrity of the building.

Fig. 9. Fire load (temperature) distribution across the beam cross-section for 30- and 60-minutes duration

4. Summary and Conclusions The present study is mainly focused on evaluation of structural integrity of RC building subjected to fire as a consequential event succeeding any unforeseen event (like an Accident, blast, earthquake etc.). Therefore, a hypothetical G+3 RC building designed as per IS: 456 (2000) for gravity loads have been considered. The structural model is subjected to progressive collapse mechanism (in terms of column loss scenarios) in accordance with GSA guidelines to represent building state during an unforeseen event. Further, the structural integrity of the building is analyzed for its exposure to fire duration under progressive collapse scenarios, representing outbreak of fire during any eventuality. Based on the analysis performed as discussed in section.3.1 the following can be observed: • The progressive collapse assessment of RC building model reveals that during loss of a critical load bearing member, the connecting structural components (beams and columns) experience significant increase in structural loads represented by the changes in bending moments depicted in Table 4 to Table 6. • It is evident that the Case 2 (failure of edge column) poses a higher probability (worst-case scenario) of progressive collapse compared to Case 1 (failure of corner column) and Case 3 (failure of center/middle column). • Furthermore, the computation of the DCR values during thermo-mechanical analysis involving exposure of structural components to fire scenarios simultaneously with progressive collapse cases: 1 to 3, the following can be envisaged o The structural components get deteriorated under fire load compared to ambient temperature. The increase in temperature and longer exposure time (greater than 30 minutes) lead to significant loss of strength in the components, making them more vulnerable in withstanding the structural loads coupled with severe decrease in cross section dimensions. Hence, results in severe loss of functionality and failure of structural integrity. Therefore, it is imminent to consider effects of fire duration on structural stability evaluation, as there is high probability of its occurrence as a consequential secondary event and has proved detrimental for the survival of the structure, in case of its existence for more than 30 minutes of duration. Further, the observations made in this work can be complemented with rigorous experimental & numerical validation to facilitate appropriate regulations for fire fire-resistant design of structures. Acknowledgments We sincerely thank the Ministry of Human Resource Development (MHRD) for the financial assistance in our Ph.D. program. Special thanks to the Department of Civil Engineering, National Institute of Technology, Warangal, for providing effective laboratory facilities and continuous support in research. References Ahmadi. R, Rashidian. O, Abbasian. R, Nav. F.M. and Usefi. N (2016)." Experimental and Numerical Evaluation of Progressive Collapse Behavior in Scaled RC Beam-Column Subassemblage". Shock and Vibration (https://doi.org/10.1155/2016/3748435), 1-17. Bazant.Z.P and Zhou.Y. (2002). "Why did the World Trade Center collapse?-Simple analysis". Journal of Engineering Mechanics, 128(doi: 10.1061/(ASCE)0733-9399(2002)128:1(2)), 2-6. Bhoite.S.M, Patil.S and Pote. N (2020). "Assessment of Progressive Collapse of G+7". International Journal of Engineering Research & Technology (IJERT), 9 Issue-9 (http://www.ijert.org ISSN: 2278-0181), 411-417. Bilow. D.N and Kamara.M (2003). U.S. General Services Administration (GSA); "Progressive collapse analysis and design guidelines for New federal office building and major modernization projects". Eurocode 1, EN 1991-1-2: Actions on structures -Part-1-2: General Actions- Actions on structures exposed to fire. (2002). European committee for standardization.