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41 (coherency) analyses. The scattering analyses will be used to Include over 1,800 strong motion records (horizontal and examine height-dependent average acceleration factors. vertical components); Contain records from recent (before 2001) large-magnitude earthquakes around the world (events in Japan, Turkey, and 5.2 Newmark Displacement Taiwan); Correlations Represent earthquake records in WUS and CEUS; and The following section provides a summary of work done Contain earthquake records for rock and soil site conditions. to refine Newmark-displacement correlations that will be used in the retaining wall, slopes and embankments, and This strong motion database has been used to update the cor- buried structures analyses discussed in later chapters. These relations between permanent seismic displacement (Newmark correlations often are presented in the form of charts or Sliding Block Method) and strong motion record characteris- equations that can be used by the designer to estimate the tics developed during the NCHRP 12-49 Project. The update amount of displacement based on an acceleration ratio at a involved accounting for the much larger database compared to site. The acceleration ratio is defined as the ratio of the ac- the limited database used by Martin and Qiu (1994) in devel- celeration at which a slope or retaining wall starts to slide oping the charts shown in the NCHRP 12-49 Project report. to the peak ground acceleration. The current AASHTO The database also was used to check relationships for PGV LRFD Bridge Design Specifications has a discussion of the based on S1, as described later in this chapter. Newmark method in Appendix A of Section 11. Various updates of the Newmark relationship have been made. One 5.2.2 Description of Ground of the more recent relationships was developed as part of Motion Database the NCHRP 12-49 Project (NCHRP Report 472, 2002). The fol- lowing subsections present refinements to the NCHRP 12-49 The ground motion database was developed from the strong work based on a strong motion database that covers CEUS, motion catalog compiled as part of the United States Nuclear as well as WUS. Regulatory Commission (USNRC) publication NUREG/ CR-6728 Technical Basis for Revision of Regulatory Guidance on Design Ground Motions: Hazard- and Risk-Consistent Ground 5.2.1 Approach for Updating Motion Spectra Guidelines (McGuire et al., 2001). The catalog Newmark Charts is available on two CDs, one for WUS and the other one for One major step in establishing performance criteria for de- CEUS. Data are compiled in terms of magnitude, distance, and sign purposes is to estimate the displacement of a retaining soil type bins, as follows: structure or slope due to the design earthquake. When a time history of the design earthquake is available, earthquake- Two regions: WUS and CEUS; induced displacements can be calculated using the Newmark's Two site conditions: rock and soil; sliding block method. This approach involves integrating the Three magnitude bins: 4.56, 67, and 78; and earthquake record twice for the region above the yield accel- Four distance bins: 010 km, 1050 km, 50100 km, and eration, where the yield acceleration is the point where the 100200 km. factor of safety in sliding is 1.0. For routine retaining struc- tures or slope designs, however, a design motion time his- The earthquake records are reasonably distributed in the tory is often not available, and the designer relies on design range of practical interest. Figure 5-5 shows the distribution motion parameters such as PGA and PGV. of the strong motion records in the catalog. Research has shown there is a reasonable correlation be- Each record includes the following data: tween these ground motion parameters and calculated per- manent displacement from the Newmark method. A rela- Acceleration, velocity, and displacement time histories; tionship that was developed for the NCHRP 12-49 Project Relative displacement, relative velocity, pseudo relative was updated using the records from recent earthquakes. To velocity, absolute acceleration, and pseudo absolute accel- establish a nationwide relationship for permanent displace- eration spectra (5 percent damped); and ment, it was necessary to use ground motions with charac- Time interval and duration of Arias intensity for various teristics representative of CEUS and WUS earthquake records ranges. in the analyses. A database of strong ground motion records was used to It should be noted that due to the limited number of record- study the design ground motion criteria for the NCHRP 12-70 ings east of the Rocky Mountains, a majority of CEUS records Project. The main characteristics of this database: are based on WUS records with a scaling factor.