Damage detection in prestressed pile to bent cap connections

Abstract

South Carolina is one of the most seismically active states in the eastern U.S. Due to this high level of seismic activity, structural health monitoring is important to ensure a high level of confidence in the state's infrastructure. The University of South Carolina (U.SC) is currently studying the behavior of prestressed pile to bent-cap connections that are typical of construction used in the state. Bent caps are generally constructed with multiple piles. In these tests single pile specimens were created for both interior and exterior piles. Interior specimens were subjected to a constant compressive load while exterior specimens experienced both compressive and tensile loads. Acoustic Emission (AE) sensing was utilized on fullscale test specimens to investigate the feasibility of detecting and characterizing damage in these connections during a seismic event. Seven full-scale prestressed concrete piles have been embedded into cast-in-place (CIP) reinforced concrete bent caps and tested under reverse cyclic loading. AE data has been gathered with eight strategically placed AE sensors. Preliminary analysis of the data indicates that AE is promising method with respect to the detection of damage prior to detection by visual observation. AE activity is used to detect both the onset and location of cracking and to characterize the extent of damage at later stages of degradation. One focus of the work is to minimize the amount of AE data recorded for the development of wireless systems having low power consumption.