Predicting the various modal parameters of reinforced concrete beams for different near surface mounting sensor arrangements

Abstract

Vibration-based structural health monitoring of reinforced concrete structures gained a lot of interest among the research community in recent years to develop modern methods of vibration-based damage detection (VBDD) techniques. This research is part of an ongoing effort to enhance VBDD techniques with a focus on investigating sensor arrangements. As a part of the research work, three 1/4th reduced-scale reinforced concrete girders were manufactured. The specimens were examined under static and modal testing. Two sensor arrangements consisting of 68 and 54 piezoelectric sensors were applied, and experimental modal analysis (EMA) was carried out with incremental loading in three steps. Three key modal parameters, i.e. (1) natural frequency, (2) modal damping, and (3) mode shapes obtained from EMA are then compared with the results of finite element analysis (FEA). Through the FEA, the optimum arrangement of sensors producing modal parameters is investigated. The trend in variations of modal parameters with progressing damage is assessed. The FEA results presented average discrepancies of 11.2 % and 18.8 % for natural frequencies for sensor arrangement #1 and sensor arrangement #2, respectively compared with the EMA results. Furthermore, it is found that natural frequency decreased with an increase in the damage state. Mode shape curvature changed after damage, however inconsistent variations in damping values are found with increasing damage levels.

Keywords

• Progressive damage
• Non-destructive testing
• Sensor arrangement
• Modal parameters
• Finite element analysis