Ambient Vibration Test on Reinforced Concrete Bridges

Z. Mohd Jaini,Sherliza Zaini Sooria,Koh Heng Boon,R. Yunus,Nurul Shazwin Idris,Ahmad Fahmy Kamarudin,S.N. Rahmat,N. Abd Rahman

doi:10.1051/matecconf/20164702012

Z. Mohd Jaini, Sherliza Zaini Sooria + Show 6 more

Open Access

https://doi.org/10.1051/matecconf/20164702012

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Abstract

An investigation was carried out to determine dynamic characteristic of reinforced concrete (RC) bridges by using ambient vibration test (AVT). The ambient vibration sources on bridges may come from traffic, wind, wave motion and seismic events. AVT describes the dynamic characteristics of the bridge and ground by measuring the natural frequencies using highly sensitive seismometer sensor. This test is beneficial due to light weight equipment and smaller number of operator required, cheap and easy to be handled. It is able to give a true picture of the bridge dynamic behavior without any artificial force excitation when vibration data is recorded. A three-span reinforced concrete bridge located in Sri Medan, Batu Pahat, Johor was measured by using microtremor equipment consist of three units of 1 Hz eigenfrequency passive sensors used in this test was performed in normal operating condition without excitation required from any active sources or short period noise perturbations. Ten measurements were conducted on the bridge deck and ten measurements on the ground surface in order to identify the natural frequencies of the bridge. Several peak frequencies were identified from three components of Fourier Amplitude Spectra (FAS) in transverse (North-South), longitudinal (East-West) and vertical (Up-Down) direction as well as squared average Horizontal to Vertical Spectral Ratio (HVSR) of ground response, computed by using Geopsy software. From the result, it was expected the bridge have five vibration modes frequencies in the range of 1.0 Hz and 7.0 Hz with the first two modes in the transverse and longitudinal direction having a frequency 1.0 Hz, the third mode is 2.2 Hz in transverse direction, fourth and fifth mode is 5.8 Hz and 7.0 Hz. For ground natural frequencies are in range 1.0 Hz to 1.3 Hz for North-South direction and 1.0 Hz to 1.6 Hz for East-West direction. Finally the results are compared with several empirical formulas for simple verification.

Highlights

MATEC Web of Conferences characteristics of the bridge
This study only focused on field measurement of ambient vibration from free vibration sources
Bridge responses were analyzed by applying Fourier Amplitude Spectra (FAS) and Horizontal to Vertical Spectral Ratio (HVSR) computational

Summary

Introduction

MATEC Web of Conferences characteristics of the bridge. Many researchers have used this technique because it is economic and practical to conduct.It is important to measure the dynamic characteristics for both newly constructed and existing bridge to understand better their dynamic behavior under normal traffic loads and during extreme loads such as those causes by seismic events or high wind [5]. It is important to measure the dynamic characteristics for both newly constructed and existing bridge to understand better their dynamic behavior under normal traffic loads and during extreme loads such as those causes by seismic events or high wind [5]. Dynamic characteristics in terms of natural frequencies, mode shape and damping ratios are important for accurately predicting the dynamic response of the structure at design and reassessment stage [2].

Results

Conclusion