Ground Motion Selection and Modification: An Overview of Recent Progress for Building Structures and the Implications for Lifeline Structures

Modal Pushover-Based Scaling of Two Components of Ground Motion Records for Nonlinear RHA of Structures

“…To account for higher-mode contributions to response and the lengthening of the apparent vibration period after the structure deforms into the inelastic range, the scaling factor for a ground motion record can be chosen to minimize the difference between its elastic response spectrum and the target spectrum over a period range (Kennedy et al 1984, Malhotra 2003, Alavi and Krawinkler 2004, Naeim et al 2004, Youngs et al 2007, PEER 2009). The period ranges recommended include 0.2 T 1 to 1.5 T 1 (ASCE 2005), and T min to μT1, where T min is the period of the highest vibration mode that contributes significantly to the response, and 3 is the displacement ductility demand imposed on the structure (Beyer and Bommer 2007).…”

“…Because the preceding methods do not consider explicitly the inelastic behavior of the structure, they may not be appropriate for near-fault sites where the inelastic deformation can be significantly larger than the deformation of the corresponding linear system. For such sites, scaling methods that are based on the inelastic deformation spectrum or consider the response of the first-mode inelastic SDF system are more appropriate (Luco and Cornell 2007, Tothong and Cornell 2008, PEER 2009).…”

Cyclic Load Protocol for Anchored Nonstructural Components and Systems

“…The hazard deaggregation is used to guide the selection of ground motion records, which are subsequently scaled to represent the target design spectrum. The selection and scaling of ground motions is a broad and currently debated topic, however, based on the recommendations of ASCE 7-05 (2006), those of Bommer and Acevedo (2004) and similarly done in Haselton's Group I (2009), it was decided that the selected ground motion records should conform to the following criteria: Strong motions records should be compatible with the tectonic regime anticipated at the site and of similar anticipated source mechanisms (i.e., strike-slip, reverse, or normal). Magnitude-distance ( M , R ) pairs of the selected records should be compatible with results of the deaggregation analysis from the probabilistic seismic hazard for the site of interest. With regard to magnitude selection, records were sought with magnitudes within 0.2 units of the target magnitude, as the dependency on seismological characteristics and its site-specific record selection is not as critical when undertaking nonlinear analysis (Iervolino and Cornell, 2005), The selected ground motion records should be compatible with the soil characteristics of the site of interest (namely site class C, with a shear wave velocity in the upper 30 m ranging from 360 m/s to 760 m/s).…”

How Many Records Should be used in an ASCE/SEI-7 Ground Motion Scaling Procedure?

“…Because the ASCE/SEI-7 ground motion scaling method does not consider explicitly the inelastic behavior of the structure (that is, strength), it may not be appropriate for structures with short periods or for structures located in near-field sites where the inelastic deformation can be significantly larger than the deformation of the corresponding linear system. For such cases, scaling methods that are based on the inelastic deformation spectrum or methods that consider the response of the first-“mode” inelastic SDOF system are more appropriate (Luco and Cornell, 2007; Tothong and Cornell, 2008; PEER, 2009). Kalkan and Chopra (2010, 2011, 2012) used these concepts to develop a modal pushover-based scaling (MPS) procedure for selecting and scaling earthquake ground motion records in a form convenient for evaluating existing structures and proposed designs of new building structures.…”