PSI - Issue 70

Ajisha T T et al. / Procedia Structural Integrity 70 (2025) 27–34

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4.4. Performance levels FEMA356 guidelines defines the seismic response of the structural and non-structural components of a building in terms of plastic deformation and drift. To keep the analysis work within the objectives, only FEMA 356 is used for accessing the performance levels of structures. Table 2 Performance levels as per FEMA356 Performance Levels Description Immediate Occupancy (IO) • Very low level damage to the structural components, repaired may be required but not generally before acquiring the place • Minor buckling isnoticed in caseofsteel frames Life Safety (LS) • Damage to some extent is observed in the structural components and repair is required before acquiring the place. • Hinge formation and fracture in moment connection is notice able in steel frames. Collapse Prevention (CP) • Severe damage and total collapse is observed in the structural components. Building supports gravity loads after earthquake but acquiring the place is not allowed • Severe damage in beam and column panels is observed in case of steel frames The fundamental time period of the structures are obtained from it’s the first mode of vibration byper forming model analysis derived by eigen value method and is shown in table 3. Table 3 Fundamental time period of all models. SI. NO. TYPESOFMODEL TIME PERIOD(seconds) 1. Model1 2.86 2. Model2 2.65 3. Model3 2.34 All the models are considered in the analysis are subjected to four selected ground motion of PG Arranging from 0.2 to 0.7g. The study of the linear and nonlinear dynamic behaviour of structures by performing a series of RSA and NLTHA. Results of structural deformation in terms of lateral story deflection, IDR ,and plastic hinge formations are discussed in detail below. Similarly the effects of ground motion on structures are observed. 5.2.1. Lateral storey displacement From the result so f NLTHA analysis, the maximum lateral storey displacement for model 1, model 2 and model 3 are 1.60 m, 1.69 m, and 1.48 m respectively. Model 2 has experienced the larger storey displacement followed by model 1 and model 3. There is no significant difference in storey displacement between models experienced a 12.42% decrease in lateral storey displacement compared too the models. Comparing the average lateral storey displacement obtained from four ground motion, it is observed that model 3 has a 36.1% decrease in storey displacement. Therefore, it is clear that model 3 is efficient in resisting seismic loads. 5.2. Dynamic analysis 5. Results and discussion This chapter presents the linear andnonlinearresponsesofallmodelsconsideredforRSAandNLTHAanalysis. 5.1. Modal analysis