Boundary Element Model Simulation Analysis of Acoustic Radiation Characteristics of Expansion Joint Structures Under Impact Loading

A coupled finite element–boundary element model was developed to investigate the acoustic response of a GQF-C bridge expansion joint under prescribed vertical wheel-impact loads. The parameterized loading relates force amplitudes and characteristic times to nominal static wheel load, vehicle speed and joint dimensions. Structural transient velocities were mapped onto an acoustic boundary element mesh to calculate near-field pressure histories and single-sided amplitude spectra. The parameter study considered static wheel loads of 30–45 kN and speeds of 20–60 km/h. For the 45 kN–20 km/h case, the largest sampled maximum absolute pressure occurred above the steel edge beam at F1–P3; the points beneath the rubber strip, P5, had the largest sampled pressures in Fields 2 and 3. At fixed speed, maximum absolute pressure and peak spectral amplitude increased approximately in proportion to static wheel load, while peak frequencies remained essentially unchanged. Increasing speed reduced the inter-peak delay at F1–P3, whereas pressure amplitudes varied non-monotonically as both the impact coefficient and load duration changed. A comparison of 5 mm and 7.5 mm discretizations showed close agreement in selected response measures, with sensitivity in some local pressure amplitudes and the F1–P3 peak frequency. These numerical results characterize the dependence of joint acoustic responses on the prescribed loading parameters and identify observation locations and acoustic features for experimental assessment.