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From page 29...
... 29 chapter three Survey reSultS A survey was distributed to 62 transportation agencies, including transportation agencies for all 50 states, Puerto Rico, and the District of Columbia, as well as ten Canadian provinces and territories. The complete survey questionnaire is provided in Appendix A and complete survey results are presented in Appendix B, both web-only documents.
From page 30...
... 30 FIGURE 17 U.S. survey agencies.
From page 31...
... 31 motivations for and reasons against foundation reuse The 51 respondents who indicated their agencies have experience with foundation reuse were asked to select all circumstances that had motivated their agencies to reuse foundations from the responses listed in Figure 19. Economic issues were cited most frequently, by 40 of 51 respondents (78%)
From page 32...
... 32 regarding structural integrity, load capacity, scour effects, service life, and it is less expensive to build new foundations than to retrofit an existing foundation. The other respondent who indicated no foundation reuse experience selected "other" and reported geometric constraints.
From page 33...
... 33 bridge piers. Foundations for bridge abutments are also commonly reused, with 43 respondents (88%)
From page 34...
... 34 The frequency of bridge widening and bridge replacement, the most common applications for bridge foundation reuse, varies among agencies with such experience. For both applications, approximately half of respondents reported that their agency reuses foundations for each respective purpose once per year or less.
From page 35...
... 35 FIGURE 22 Average number of foundation reuse instances per year, n, for ABC/PBES projects. Numbers listed on chart are number of agencies reporting the corresponding frequency level.
From page 36...
... 36 Several other methods were frequently used. Twenty-five respondents (51%)
From page 37...
... 37 foundatIon ServIce lIfe The survey included a series of questions regarding service life for new and existing foundations. Twenty of 49 respondents (41%)
From page 38...
... 38 TABlE 10 EvAlUATION OF REMAINING SERvICE lIFE FOR ExISTING FOUNDATIONS Agency Response Alberta Pier condition is inspected (primarily visually) for signs of distress.
From page 39...
... 39 load capacity of foundations for reuse Methods used to predict the nominal resistance (load capacity) of existing foundations being considered for reuse are shown in Figure 26.
From page 40...
... 40 (19 of 49 respondents, 39%) , but reliability-based design methods are also common (15 of 49 respondents, 31%)
From page 41...
... 41 addition of drilled shafts (44%) , pier stem widening (44%)
From page 42...
... 42 • Two-thirds of respondents did not know how their agencies evaluated remaining service life when considering foundation reuse. Survey responses suggest remaining service life is typically considered implicitly in reuse decisions rather than explicitly evaluated.

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