Reinforcement Corrosion in RC Hollow Piers: Destructive and Non-Destructive Tests

Abstract

In this work, cyclic-load tests on reduced-scale corroded reinforced-concrete hollow cross-section bridge piers have been experimentally performed and compared to the results of similar non-corroded piers. Piers were aged by using an imposed electric current and sodium chloride water solution before performing a mechanical cyclic-load test. The corrosion process has been detected with Non-Destructive Evaluation techniques by means of SonReb method (to check concrete degradation) and by measuring corrosion potential (to check steel degradation). The crack pattern was recorded by dedicated cameras, and an LVDT system was set up to monitor the cyclic-load test. Experimental results focused on degradation monitoring and mechanical performance under cyclic loads. During the cyclic-load mechanical test, the first cracks on the piers surface occurred diagonally, inclined at about 45°. This is the consequence of the failure mode change from ductile failure, as expected for slender designed piers, to brittle shear failure. The flexural failure occurred in the case of non-corroded piers. Presented tests can provide a useful contribution of experimental data to analyse the behaviour of corroded reinforced concrete hollow bridge piers, scarcely tested. In particular, the cyclic response can be a useful reference for the proposition/validation of nonlinear capacity models for the evaluation of the seismic capacity of corroded bridge piers.

Keywords: corrosion; experimental test; hollow bridge piers; monitoring; structural safety; theoretical model.

Figure 1

(a) Cross section (dimensions in mm) and (b) view of rectangular hollow pier with sodium chloride solution tank.

Figure 2

(a) Cross section (dimensions in mm) and (b) frontal view of circular hollow pier with sodium chloride solution tank.

Figure 3

Corroded Bars (red circles): (a) rectangular and (b) circular hollow pier.

Figure 4

Measurements’ points for SonReb method and corrosion potential: (a) rectangular and (b) circular hollow pier.

Figure 5

Cyclic load test setup scheme (dimensions in cm).

Figure 6

Ultrasound wave rate-time of ageing—rectangular pier.

Figure 7

Corrosion potential of bars in mV vs. Cu/CuSO₄—rectangular pier.

Figure 8

Ultrasound wave rate-time of ageing—circular pier.

Figure 9

Corrosion Potential of bars in mV vs. Cu/CuSO₄—circular pier.

Figure 10

Monitoring system for cyclic test: (a) rectangular pier and (b) circular pier.

Figure 11

Load-displacement diagram of the rectangular pier test.

Figure 12

Horizontal force-peak displacements envelope diagram of the circular pier test.

Figure 13

Load-drift diagram of the rectangular pier (for colour legend refer to Table 3).

Figure 14

Secant modulus of elasticity-drift diagram—rectangular pier.

Figure 15

Bending moment-curvature diagram at the height of 0.06 m from the base—rectangular pier.

Figure 16

Bending moment-curvature diagram at the height of 0.66 m from the base—rectangular pier.

Figure 17

Bending moment-curvature diagram at the height of 1.26 m from the base– rectangular pier.

Figure 18

Pier images during the cyclic test at time: (a) test beginning; (b) first shear cracking at fourth drift and (c) final crack pattern—rectangular pier.

Figure 19

Load-displacement diagram at fourth drift (positive values)—rectangular pier.

Figure 20

Pier images during the cyclic test at time: (a) test beginning, (b) first shear cracking at fourth drift and (c) final crack pattern—circular pier.

Figure 21

Load-displacement diagram at fourth drift (positive values)—circular pier.

Figure 22

Envelope of first cycles at different drifts and shear failure domain at different cross-section reductions—rectangular pier.