An implication of these results to design is that the number of reinforcement layers
may have to be increased at the top of the wall in order to keep tensile loads within allowable
limits.However, it should be noted that the allowable design tensile load under
dynamic loading is routinely taken as a greater percentage of the index strength of the
reinforcement than the percentage used for static loading design because of the short
duration of peak tensile loading during a seismic event.AASHTO(1992) guidelines can
be interpreted to permit the value of Tallow used for static loading designs to be increased
by 33% for the seismic loading condition. Rapid in-isolation wide-width strip tensile
loading of a typical high density polyethylene (HDPE) geogrid reinforcement reported
by Bathurst and Cai (1994) has demonstrated a potentially large increase in reinforcement
stiffness of the materialwhen compared to conventional rates of loading. This observation
suggests that HDPE geogridsmay be designed formuch greater strengths under
seismic loading than those values that result from the interpretation of AASHTO
recommendations.