PEER has just published Report No. 2018/04: “Capturing Directivity Effects in the Mean and Aleatory Variability of the NGA-West2 Ground-Motion Prediction Equations.” It was authored by Jennie A. Watson-Lamprey, Slate Geotechnical Consultants.
Visit the PEER publications page to download a free color pdf of the document.
Abstract
We expect there to be locations around a rupture that experience both positive and negative directivity effects more than others. The concept was to develop a simple model of additional mean and standard deviation to add to existing published ground motion prediction equations to account for this. The directivity effect predicted by Chiou and Youngs [2014] using the directivity parameter DPP [Spudich et al. 2013] was selected as the basis for the model. A suite of rupture geometries for strike-slip and reverse ruptures was generated and the mean and standard deviation of the change in the 5% damped pseudo-spectral acceleration at sites out to rupture distances of 70 km was calculated. Models are presented for the change in mean and standard deviation for both strike-slip and reverse ruptures that use only simple parameters as inputs.