# Integration of Conventional Sensors and Laser Doppler Vibrometry for Structural Modal Analysis: An Innovative Approach

## TL;DR

This paper introduces a new system combining laser sensors and traditional accelerometers to analyze how structures vibrate, offering a better solution for large or hard-to-reach buildings.

## Contribution

The novel contribution is a hybrid system integrating Laser Doppler Vibrometry with conventional sensors for more effective structural modal analysis.

## Key findings

- The hybrid system successfully identified natural frequencies and vibration modes of tested structures.
- Non-contact LDV measurements combined with accelerometers provided accurate dynamic behavior data.
- The approach is effective for large-scale or inaccessible structures where traditional methods are impractical.

## Abstract

This study aims to demonstrate the feasibility of a hybrid measurement system that combines Laser Doppler Vibrometry (LDV) and conventional accelerometers for operational modal analysis (OMA) of civil engineering structures. The proposed approach addresses the limitations of traditional accelerometer-based systems, particularly for large-scale or inaccessible structures, by integrating non-contact LDV measurements with conventional sensor data. Experimental tests were conducted on a cantilever beam and a pedestrian laboratory footbridge to validate the hybrid system. The LDV was used to measure velocity at key points, while accelerometers provided complementary reference acceleration measurements. Reflective targets were employed to facilitate non-contact data collection, allowing for the subsequent reuse of these targets for repeated measurements. The velocity data from the LDV were differentiated to obtain acceleration and integrated to estimate displacement, enabling a direct combination with accelerometer data. ARTeMIS Modal software was utilized to process and analyze the collected data, successfully identifying the natural frequencies and vibration modes of both structures. The results demonstrate that the LDV–accelerometer hybrid system effectively captures the dynamic behavior of structures, offering a comprehensive solution for modal analysis without extensive sensor deployment. This approach provides significant advantages in scenarios where traditional methods are impractical, positioning the hybrid system as a promising tool for dynamic analysis and infrastructure monitoring of complex structures.