Measuring acoustoelastic coefficients for stress evaluation in concrete

Abstract

This paper presents experimental studies to evaluate stress levels in concrete based on the acoustoelastic effect. Direct P wave interferometry (DPWI) was introduced to calculate the relative P wave velocity change and acoustoelastic coefficients by analyzing the direct P wave part signal only. Two laboratory experiments were performed on a concrete cylinder and a concrete beam, and a full-scale test was conducted on a 40-meter-long prestressed concrete bridge girder. The DPWI method provides a relatively high resolution and shows different acoustoelastic coefficients in the stressed and the unstressed directions. This property may be used to evaluate the stress level in existing prestressed concrete structures by comparing the velocity difference in different stress directions.