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(A)(B)▲▲Figure 7. Damage to southern abutment of the ANZAC DriveBridge, with back-rotation of approximately 6° and spreadingbetween abutment and adjacent walkway.(C)(D)▲▲Figure 8. ANZAC Drive Bridge pier damage, with crackingand spalling of cover concrete.base of the abutment was also less, resulting in an 18 to 24 cmgap between the abutment and the backfill. Additionally, thehorizontal gap between the abutment and a walkway runningalong the riverbank was much less relative to the south end.Both of the bridge piers suffered extensive but superficialcracking to the concrete columns and bent as well as the beamcolumnjoint region, with up to 2° of rotation (Figure 8). Whilethe damage first appeared extensive, with apparent shear cracking,further inspection showed that in reality these cracks werelimited to the concrete cover. Spalling of the cover concreteappeared to be primarily the result of rotation of the piles,causing stresses to be concentrated at the edges of the members.These rotations can be attributed to horizontal movement ofthe pile foundations toward the center of the river due to lateralspreading.Following the Christchurch event, SASW tests andDynamic Cone Penetration tests (DCPTs) were carried out▲▲Figure 9. ANZAC Drive Bridge field investigation: A) shearwave velocity (V s ) profile; B) liquefaction assessment using V s ,comparing the cyclic resistance ratio CRR 7.5 for the site to theDarfield (CSR 7.5 DAR) and Christchurch (CSR 7.5 CHC) cyclic resistanceratios; C) dynamic cone penetration test (DCPT) profile (i.e.,N DCPT and equivalent N 1,60cs ); D) liquefaction assessment usingequivalent N 1,60cs , comparing the CRR 7.5 for the site to the CSR 7.5DAR and CSR 7.5 CHC.50 m southwest of the south abutment. The DCPT N-values(N DCPT ) were converted to equivalent standard penetrationtest (SPT) N-values using a modified relationship to that proposedby Sowers and Hedges (1966). Then, the N-values werefurther corrected for rod length, hammer energy, effectiveconfining stress, and fines content following the proceduresoutlined in Youd et al. (2001). The resulting profiles from theSASW tests and DCPTs are shown in Figures 9A and 9C. TheV s data from the SASW test indicates a soft soil layer betweendepths of 1 and 6 m, and the water table at a depth of 1.5 m.The CRR 7.5 profiles for the site were determined usingboth the SASW and DCPT data, per Youd et al. (2001) andas outlined previously for the SASW. Using the PGAs listedin Table 1, the cyclic stress ratios (CSRs) for both the Darfieldand Christchurch earthquakes were calculated following theSeismological Research Letters Volume 82, Number 6 November/December 2011 957