Seismic Analysis and Design of Retaining Walls, Buried Structures, Slopes, and Embankments (2008) / Chapter Skim
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Pages 26-34
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From page 26... ...
4.1 Developments for Seismic Ground Motions The first area of development involved the ground motions used during the seismic design of retaining walls, slopes and embankments, and buried structures. The LRFD design procedure involves comparing the capacity of the design element to the seismic demand for various limit states (that is, strength, service, and extreme)
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From page 27... ...
Spectral curve shapes for generic sites covering both WUS and CEUS (Sandia, 2004)
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From page 28... ...
This development was accomplished using an available ground motion database, including spectrumcompatible time history development reflecting differences in WUS and CEUS conditions. 4.2 Developments for Retaining Walls The next major area of development involved improved methods for estimating the forces on and the displacement response of retaining walls.
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From page 29... ...
. The wave scattering analyses were conducted for multiple wall heights (for example, 30-foot, 60-foot, and 100-foot heights)
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From page 30... ...
However, additional parameters were needed in examining the coherence of inertial loads over potential sliding masses, including slope angle and shear wave velocities of slope material, and strength parameters ranging from those for cut slopes to fills. The analysis program used for wave scattering analyses involved QUAD-4M (1994)
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From page 31... ...
This preliminary assumption, however, was further evaluated during the completion of the initial phase of this study and verified by numerical analysis. The ovaling/racking deformations are induced along the transverse cross section when seismic waves propagate perpendicularly to the culvert/pipe axis.
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From page 32... ...
This is particularly important because given the same PGA value, the anticipated PGV for CEUS would typically be much smaller than that for the WUS. Results based on the PGA versus PGV study presented earlier in the work plan for the retaining walls, slopes, and embankments were used for the culvert structures.
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From page 33... ...
In estimating the PGD patterns for liquefaction-induced lateral spread, slopes/embankment slumping, and postliquefaction settlements, the procedures developed for retaining walls, slopes, and embankments can be used. Fault rupture has a relatively low occurrence frequency.
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From page 34... ...
Type of Investigation Purpose Establish Basis for Determining Ground Motions Suitable for CEUS and WUS Identifies consistent approach for defining ground motions to use for seismic evaluation of retaining walls, slopes and embankments, and buried structures, including modifications that account for permanent displacements. Develop Design Charts for Estimating Height-Dependent Seismic Coefficient Provides a rational basis for selecting seismic coefficient as a function of both wall height and slope height for different soil conditions.
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