Impact spectra for eccentrically prestressed beam of bending-stretching effect under moving load

In this study, the impact behavior of an eccentrically prestressed simply-supported concrete beam of prophase bending-stretching retention subjected to a constant moving load is investigated for structure impact resilience evaluation. The finite element method is adopted for beam behavior modeling and the Newmark-β time-domain integration technique is adopted for response computation. The geometric stiffness matrices, due to the prestressing axial compression and the prophase bending-stretching caused by eccentric prestressing and self-weight, are considered. Parametric study on varying prestressing force and eccentricity shows that eccentric prestressing will induce up to 58 % reduction of the fundamental frequency with the increase of the prestressing force. Moving-load induced impact for the considered eccentrically prestressed beam will amplify the peak bending moment by up to 53 %, while shift the position of peak dynamic response in the positive bending moment zone away from the midspan by more than ± 15 % of the span length. For the studied cases, the consideration of the eccentric prestressing will enlarge the shift of the moving load-induced peak bending moment position but will not induce the presence of new bending moment zone under moving load.