Estimating failure probability of IBBC connection using direct coupling of reliability approach and finite element method

Abstract

This paper aims to produce estimates of probabilities of exceeding specified structural performance thresholds for two types of I beam to box column (IBBC) connections used in steel moment resisting frames (SMRF), when subjected to earthquake ground motions, and to conduct sensitivity analysis of affecting parameters. This is done through coupling the finite element and reliability theory approaches, which allows the analyst to define all uncertainties associated with model parameters. In order to take into account, the record to record variability, incremental dynamic analysis was carried out and statistical properties of the random variable of seismic loading were obtained for the second story of a sample 12-story SMRF at the global collapse state. Variability in geometry, material strength, as well as seismic loading, were then taken into account and considered as inputs of a probabilistic finite element model of IBBC connection. Two damage states were identified based on experimental observations for the two types of connections considered. Consequently, two damage indices and two limit state functions corresponding to each damage state were defined. Finally, the probability of each damage state and union of them were calculated using finite element analysis coupled with reliability theory approaches. In addition, through sensitivity analysis, important random variables, which have more influence on connection performance were addressed. According to the results obtained, the conclusion was that finite element reliability method can allow an advanced safety assessment of IBBC connection.