Vehicle Scanning Method for Bridges Enhanced by Dual Amplifiers

Abstract

Dual-function amplifiers are proposed for the first time herein for enhancing the capability of a scanning test vehicle for bridges. To start, closed-form solutions are derived for the dynamic responses of the amplifier-vehicle-bridge system with a moving test vehicle. Then, the dynamic amplification factors of the amplifier and vehicle are presented for assessing the bridge/vehicle and vehicle/amplifier transmissibility. It was known that the spectrum of the vehicle may be hindered for extracting the bridge frequencies because of vehicle frequency and rough pavement. Two differentially tuned amplifiers are called on to tackle the problem: one (i.e., the vehicle damper) is to suppress the effect of vehicle’s frequency, acting like the tuned mass damper (TMD), and the other (i.e., the bridge amplifier) is to enlarge the amplitude of bridge frequency of concern. Based on the parametric study, it is concluded that (1) the bridge amplifier performs better than the vehicle one in extracting bridge frequencies by increasing their visibility in the spectrum; (2) the effect of vehicle’s frequency can be suppressed by tuning the vehicle damper such that it functions like a TMD of the vehicle; (3) by tuning the bridge amplifier to any of the first few bridge frequencies, the latter can be well detected even for rough pavement.

Theoretical and Experimental Investigations of Identifying Bridge Damage Using Instantaneous Amplitude Squared Extracted from Vibration Responses of a Two-Axle Passing Vehicle

“…A numerical example with the vehicle and bridge parameters, outlined in Table 1, is investigated. These vehicle and bridge parameters are strictly selected to reflect the realistic conditions of highway bridges, consistent with widely accepted practices in VSM studies [8,10,12,16,22,23,26]. Notably, the parameter values remain constant in the following investigations unless otherwise noted.…”

“…This is because the size of the damage is equated to the element size for modeling damage through element stiffness loss. In this study, the chosen size for the damaged element is 0.5 m, a dimension commonly employed in the literature [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Consequently, a total of 50 elements constitute the 25 m simply supported beam.…”

“…Consequently, a total of 50 elements constitute the 25 m simply supported beam. In addition, a simulation time step of 0.001 s is also a common choice in VBI studies [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The first third frequencies of the bridge are ω b1 = 3.80 Hz, ω b2 = 15.22 Hz, and ω b3 = 34.24 Hz, respectively.…”

“…The speed of the test vehicle is a crucial factor influencing the feasibility of the VSM for damage identification [22][23][24][25][26][27][28]. This is because a higher vehicle speed results in fewer vehicle records passing over the bridge, which, in turn, negatively impacts the extraction of the bridge modal information using such limited data.…”

“…However, these filtering processes strongly rely on the expertise of the signal processor, posing a risk of inadvertently filtering out the vibrational signals of the bridge. Some studies have introduced a tuned mass damper with its frequency tuned to the vehicle frequency to suppress vehicle self-vibrations, thereby mitigating the overall impact of vehicle-induced vibrations [23]. Moreover, design strategies involving specialized test vehicles with frequencies significantly isolated from vehicle frequencies through the use of large-axle stiffnesses have been proposed.…”