PSI - Issue 60

Sarmili Swain et al. / Procedia Structural Integrity 60 (2024) 553–563 Sarmili Swain / Structural Integrity Procedia 00 (2024) 000 – 000 5 In the linear elastic approach, the allowable values for primary and secondary elements are with DCR ≤ 2.0 for typical structural configurations and DCR ≤ 1.5 for atypical structural configurations. If the values are beyond these limits, the structure is considered to be severely damaged or collapsed, based on the DCR criteria. 557

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(a) Case 1

(b) Case 2

(c) Case 3

Fig. 3. Plans view of three different cases of sudden loss of column Hence, in the present study, the progressive collapse is triggered/initiated by the instantaneous removal of ground floor columns in a G+3 building at various locations, and the structural integrity is analyzed accordingly. The progressive collapse analysis is carried out under two conditions: normal (Ambient temperature) condition and for different fire durations. The following cases are considered for initiating progressive collapse: Case 1: Instantaneous removal of ground floor column at Corner location Case 2: Instantaneous removal of ground floor column at Edge Case 3: Instantaneous removal of ground floor column at Center/Middle Interior. The linear static analysis will be carried out for each case to assess the behaviour of the building under progressive collapse scenarios and further assessed to fire conditions. Fig. 3 illustrates the three different analytical cases of progressive collapse. 2.3 Using SAFIR The finite element package SAFIR is used to assess the thermal analysis of the structures or buildings for various elevated temperatures (Nwosu, 1999) . Here in this study, the three-dimensional (3D) (G+3) building model is modelled and analyzed for thermal analysis using the ISO 834 fire curve (EN-1991-1-2; 2002) as per Euro codes. The material properties, building elevation considered in the analysis are presented in Fig. 4 and Table 3 respectively. Considering the progressive collapse analysis, the three different cases which were presented in the GSA guidelines are implemented using the SAFIR program. The fire scenarios considered are ambient temperature (zero minutes), 30 minutes and 60 minutes respectively. Thermo-mechanical analysis of the building model is carried out considering the simultaneous application of fire for all the structural components (considering all the fire scenarios), for each case of progressive collapse to realise collapse potential of the structure utilizing the SAFIR software tool. The Demand Capacity ratios (DCR) are then evaluated for the structural components in all the three different progressive collapse cases. Further, the structures ability to resist progressive collapse under simultaneous application of fire coupled with critical loss of structural member is determined.