Damage potential of near-fault records: sliding displacement against conventional Intensity Measures

The potential of a particular ground accelerogram to inflict damage to asymmetric strongly-inelastic systems is studied in the paper. An idealised analogue, the rigid block with frictional contact on an inclined base, is adopted as the generic representation of such systems. The inclined base (of (a sufficiently steep) angle) is shaken with numerous strong records bearing the effects of forward-directivity and/or fling-step. The accumulated slippage, D, of the block caused by each record is taken as the induced damage to the system. The relevance of a variety of 'Intensity Measures' of each accelerogram (ranging from PGA and PGV to Housner's and Arias' Intensities) in predicting this damage, is investigated statistically. It is shown that only a few of these 'Intensity Measures' are reasonably successful and their use could therefore be recommended, but only for statistical inference. A detailed deterministic analysis presented in the paper for one of these successful measures, Arias Intensity, reveals the unacceptably poor predictive power of this measure. Upper-bound curves of slippage provided in closed-form expressions, are an improvement over the state-of-practice Makdisi & Seed diagrams.