SA-based concrete seismic stress monitoring: The influence of non-uniform stress fields

Abstract

The influence of non-uniform stress fields on seismic stress monitoring utilizing piezoelectric-based smart aggregates (SA) is investigated in this research. To demonstrate the typical non-uniform stress field in concrete structures, a loading scheme of combined action of reversed cyclic lateral loads and axial compression was implemented on a column. Three identical reinforced concrete (RC) columns were made, each with a height of 1600 mm and a cross section of 400 mm by 400 mm, with 20 SAs embedded in each. A monitoring error evaluation method was proposed to investigate the accuracy of the SA-based seismic stress monitoring under non-uniformity stress condition. The monitoring error was investigated by comparing nominal SA stress with the equivalent stress based on the moment equilibrium of the monitored cross section. Nominal stress is expressed in a linear combination of the stresses measured by equally-spaced SAs positioned in the cross section, and is largely determined by the outermost SA in the section where the stress field is the most irregular. The loading test was conducted on the columns with a drift ratio up to 4%. The experiment demonstrates that the influence of non-uniform stress fields can be ignored in RC structures using SA stress monitoring.