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ackets linking the piers and abutments to the deck. At thelocation of the bridge, the river undergoes a significant changeof direction with the north abutment on the inner bank andthe south abutment on the outer bank. This bridge was on theedge of the central city cordon setup after the Christchurchearthquake, and consequently, was inaccessible to the generalpublic and was used only by vehicles with cordon access.As discussed in Bradley et al. (2010), the soil profileunderlying the north end of the bridge can be approximated asfour distinct layers: (1) sand, ~4.5 m thick, N 1 = 10, V s = 130m/s; (2) sand with fines, ~6.5 m thick, N 1 =15, V s = 160 m/s;(3) sand, ~6.5 m thick, N 1 = 10, V s = 130 m/s; and (4) sand,N 1 = 30, V s = 220 m/s. The soil profile underlying the southend of the bridge is similar to the north end, minus layer (3).The bridge was undamaged by the Darfield earthquake,with no evidence of liquefaction on either side of the bridge.However, during the Christchurch earthquake, significantlateral spreading developed on the east side of the north abutment,with cracks running parallel to the riverbank and materialmoving south toward the river. The north abutment ofthe western bridge was very near the bend in the river, witha free face both perpendicular and parallel to the bridge.Lateral spreading was noted with movement occurring both tothe south and west. Settlements of approximately 0.5 m wereobserved on the north approach as well.Both north abutments showed back-rotation, which—combined with settlement of the river banks at the base ofthe abutments—exposed the abutment piles. The abutmentrotation caused the easternmost pile on the north abutment(Figure 13A) to fail in tension, with the tension face openingup and crack widths measured up to 10 mm. Spalling of thecover concrete on the bottom flange of the deck girder (Figure13B) developed as a result of relative movement of the superstructureand abutment. Minimal settlement of the approachwas observed at the south abutments. Large cracks were noted,however, in the abutment and wingwalls.This bridge had been previously identified as critical tothe bridge network, with an extensive field testing programperformed in the late 1990s. The program included multipleCPTs and standard penetration tests (SPTs) performed at theabutments of both the twin bridges. The subsequent analysesshowed that the north abutment of the eastern bridge was mostvulnerable to liquefaction and structural damage (Bowen andCubrinovski 2008a, 2008b; Bradley et al. 2010), with liquefactionpredicted in the relatively loose sandy soil between2.5 m and 17.5 m. These predictions are very consistent withthe observed response on the bridge during the Christchurchearthquake.DAMAGE NOT ASSOCIATED WITH LIQUEFACTIONMoving away from the Avon and Heathcote rivers, whereliquefaction-induced lateral spreading was the main cause ofdamage, four bridges suffered damage not related to the effectsof liquefaction. One bridge, Railway Bridge 3, was damageddue to the seismically induced lateral earth pressures acting on(A)(B)▲▲Figure 13. Fitzgerald Avenue Bridge damage: A) tension failureof abutment pile and exposure of reinforcement, B) spallingof bottom flange of deck girder.the abutments. Two bridges, Moorhouse Overbridge and PortHills Overbridge, were damaged due to shaking effects thatactivated the transverse response of the structure. The finalbridge, Horotane Overbridge, sustained damage as a result ofshaking and slope stability issues. The final three bridges didnot develop any significant superstructure damage in any of theearthquakes.Railway Bridge 3The Railway Bridge 3 was constructed in 1950 and consistsof a timber deck with brick masonry wingwall abutments,spanning a roadway between built-up railway embankmentsapproximately 3 m in height (Figure 2).The bridge was not damaged by the Darfield earthquake,but extreme shaking during the Christchurch earthquakeresulted in severe cracking and movement of the abutments.This caused deformation in the track ballast and tracks, result-960 Seismological Research Letters Volume 82, Number 6 November/December 2011