Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
GAPS IN THE STATE OF THE PRACTICE
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- 11.1 STRAIN WEDGE MODEL
| 11. GAPS IN THE STATE OF THE PRACTICE The most significant gap in the state of the practice is the lack of a single consistent analysis method for the various Limit States with specific guidance for the various related topics, e.g., seismic events, head fixity, group multipliers. As the goal of GEC 9 is to provide guidance on these subjects, discussion follows in Section 12. Also lacking is a single consistent design approach considering the available methods for example, some publications allow any method for any foundation or design stage, others suggest simplified analyses (Broms) for preliminary design or simple structures and more detailed analyses (p-y) for final design or complicated structures, and others provide no information or guidance at all. Included below are the related topics that due to the lack of information, consensus among professionals, or other reasons could be considered for further research. As the source material for the majority of this document is from DOTs, AASHTO, and FHWA, it is noted that it is preferential to bridge design. However, in the available manuals and publications that are more generally oriented, the discussion on laterally loaded deep foundations does not distinguish in detail differences between the structure type or application. For example, the publications generally do not distinguish different procedures or requirements based on whether the foundations are fora retaining wall, sound wall, excavation support, bridge abutment, bridge pier, or other structure. Loading conditions, such as seismic loads and vessel impact, are commonly addressed as extreme event conditions. 286 11.1 STRAIN WEDGE MODEL Based on our current literature review, there do not appear to be any fundamental problems or documented objections with use of the strain wedge model. The reason for its lack of predominance in current practice is unclear it may simply be that it was developed after the p-y method, and given the wide acceptability, usage, and familiarity with the p-y method, practitioners have been reluctant to change to a less known or less widely used method without being required by code or design standard. Most references that include a mention of the model recognize it maybe more relevant than the p-y methodology for short and/or large diameter elements, but only New York makes a formal recommendation for it as a preference. Washington DOT recently removed their recommendation, albeit with the stated reasons including alack of general acceptance by the professional community, similar to the presumption noted above. It is our opinion that further literature review or research with the goal of preparing a formal comparison between the two methods for short and/or large diameter piles could be worthwhile to advance this state of the practice. Download 6.03 Mb. Share with your friends:
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