Failure modes degradation characteristics

Fig. 3.14a. Stress-rapture characteristic of HDPE pipes made of Hostalen GM 5010 T2. Compared to modem materials this outdated resin had very low resistance to stress crack and oxidative degradation. Therefore, the various failure modes could be observed within manageable testing times even at 60 °C. Zl, Z2, Z3 designate the sections of the hoop stress versus time-to-failure curve, which result from different failure modes Ductile failure with excessive deformation (Zl), stress crack formation and brittle failure (Z2) and oxidative degradation (Z3). The figure has been taken from reference (Koch et al. 1988)...

Ultimate Drift in RC Members Other characteristic point of RC member force-displacement response is the ultimate drift capacity for each failure mode considered. Ultimate drift capacity is generally evaluated at the drift characterizing a 20 % loss of the maximum shear strength (FIB 2003) attained in the element see Fig. 4. According to the failure mode, different empirical ultimate drift capacity formulations are available in the literature. Most experimental databases are characterized by cyclic tests and few monotonic tests. Thus, most of those empirical formulations account implicitly for cyclic degradation. 

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