Critical speed for the dynamics of truck events on bridges with a smooth road surface

Abstract

Simple numerical models of point loads are used to represent single and multiple vehicle events on two-lane bridges with a good road profile. While such models are insufficiently complex to calculate dynamic amplification accurately, they are presented here to provide an understanding of the influence of speed and distance between vehicles on the bridge dynamic response. Critical combinations of speed as a function of main bridge natural frequency and meeting point of two vehicles travelling in opposite directions are identified. It is proposed that such simple models can be used to estimate the pattern of critical speeds versus dynamic amplification for heavy trucks on a bridge with a relatively smooth surface. The crossing of a threedimensional spring-dashpot truck is simulated over a bridge plate model to test this hypothesis for a range of road roughness. Further validation is carried out using the site-specific mean pattern associated to field measurements due to the passage of a truck population. The latter is found to be closely resembled by the theoretical pattern derived from simple point load models. Keywords

Vehicle-Bridge Dynamic Interaction Using Finite Element Modelling

“…2) and 3-D FE models. A 3-D FE model can be made of 3-D solid elements (Kwasniewski et al, 2006;Deng & Cai, 2010) Plate bridge models have been used to investigate VBI by Olsson (1985), Kirkegaard et al (1997), Henchi et al (1998), Zhu & Law (2002), Cantero et al (2009) and González et al (2010). They are based on thin plate theory, which assumes the normal and shear strains in the 'z' direction (perpendicular to the plate plane) to be negligible.…”

Identification of sudden stiffness changes in the acceleration response of a bridge to moving loads using ensemble empirical mode decomposition

“…It is assumed that the values of vehicle tyres and suspensions' stiffness and viscous damping are the same for all wheels and axles. The mechanical properties of the vehicle are based on values available in the literature [42,46,47] and given in Table 1. …”

“…The dynamic forces of the vehicle are obtained by imposing the equilibrium of forces and moments acting on the vehicle and expressing them in terms of their DOFs [41,46,47]. The equation of motion of the vehicle dynamic system is given by: …”

Structural analysis of bridges with time-variant modulus of elasticity under moving loads

“…The displacement is affected by the speed of the load similarly to strain. The relationship between dynamic amplification and speed consists of a series of peaks and valleys, i.e., critical speeds causing higher amplification due to constructive interference of the oscillatory inertial forces of the bridge with the static response (i.e., reaching a maximum at the same point) and other speeds causing destructive interference and reducing this amplification (González et al, 2010). For the speeds under investigation, maximum displacement tends to increase with speed of the load except for 25m/s.…”