Paradigms of application, phenomena affecting creep deformations, and comparisons to measurements on structures

Abstract

In this chapter, we explain by examples how to apply in practice the methods presented in the preceding chapters. We compare the calculation results to the measurements on structures and assess the errors of various methods. The most revealing examples aiding progress are those of major serviceability loss. First, we discuss the La Lutrive Bridge, which was an early documented example of excessive creep deflections. Then, we present a striking paradigm of excessive creep deflections and prestress loss, offered by the Koror–Babeldaob (KB) Bridge, which has recently been analyzed in detail at Northwestern University. In this context, we outline the way to adapt commercial finite element software to concrete creep analysis and comment on algorithmic aspects. We also discuss the effects of wall thickness, cracking, and temperature (including the effect of solar heating of prestressing steel embedded in concrete) and explain the method of determining the model parameters. Evidence of excessive deflections from 69 other bridges is summarized and interpreted. Finally, we give a préci of recent results on cyclic creep, with application to prestressed box girder bridges, and show that its effects on deflections are negligible, especially for large spans, while its effects on stress redistributions and cracking may be appreciable for medium spans.