Changes in Frequency and Mode Shapes Due to Damage in Steel-Concrete Composite Beam.

Małgorzata Jarosińska,Stefan Berczyński

doi:10.3390/ma14216232

Małgorzata Jarosińska, Stefan Berczyński

Open Access

https://doi.org/10.3390/ma14216232

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Journal: Materials	Publication Date: Oct 20, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: West Pomeranian University of Technology

Abstract

This study presents an analysis of changes in the vibration frequency and mode of vibration of a composite beam due to damage. A steel–concrete composite beam was considered, for which numerical analysis (RFE model) and experimental tests were conducted. Two levels of damage were introduced to the beam. To determine the changes in the mode of vibration before and after the damage, the modal assurance criterion (MAC) and its partial variation (PMAC) were applied. The curvature damage factor (CDF) was used to determine the changes in the modal curvature. The natural frequencies were sensitive to the introduced damage. The results show that the MAC is not effective in determining the location of damage in the connection plane. Two different coefficients were introduced to locate the damage. The PMAC was used for sections of subsequent modes of vibration and allowed effectively locating the damage. The CDF considered simultaneous changes in the curvatures of all vibration modes and was effective in locating the damage in the connection plane.

Highlights

Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin, al
This study analyzed the sensitivity of frequency and mode shapes to damage to the connection of a steel–concrete composite beam
The sensitivity analysis of the selected modal parameters was performed on the basis of (1) experimental tests on a real-life composite beam, and (2) numerical simulations for the designed numerical model

Summary

Introduction

Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin, al. This study presents an analysis of changes in the vibration frequency and mode of vibration of a composite beam due to damage. The results show that the MAC is not effective in determining the location of damage in the connection plane. The CDF considered simultaneous changes in the curvatures of all vibration modes and was effective in locating the damage in the connection plane. In the case of composite structures, damage in the connection zone may not be detected during the inspection. Deterioration of the connectors over the years reduces the cooperation between the steel and concrete. This affects the load-bearing capacity of the structure and is crucial for the safe use of the building.

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