Suitability of subsequently installed vibrating wire sensors for direct stress measurement in concrete and mortar

Abstract

Over the past decades, a major part of the building infrastructure has aged and is now in need of repair. In order to ease the repair backlog and to be able to distinguish between urgent and long-term repair needs, it is advisable to install a monitoring system to the structure. This monitoring is, among others, often based on periodical strain or deformation measurements, as they provide a direct indication of the effect of external loads on the structure (crack opening or heavy deformations). Still, most of the available monitoring systems cannot be installed subsequently or they are limited to measurements on the surface. For monitoring the structural behaviour inside specific components, the use of a sensor system based on the vibrating wire measuring principle appears promising. This sensor system has proven itself in geotechnical engineering. However, there is no profound experience of using this system in concrete structures. Therefore, the aim of the work presented in this paper was to investigate the suitability of these sensors for stress measurement in concrete and mortar. We will furthermore give an outlook on a possible application for monitoring reinforced concrete structures.