Highway Bridge Traffic Loading

Abstract

In this chapter, traditional approaches and recent advances in highway bridge traffic loading are described, which are of great significance for structural safety assessment of bridges. Indeed, it is widely accepted that consideration of site-specific traffic features can enable significant savings in maintenance operations. While short spans are governed by free-flowing traffic plus an allowance for the dynamic effects, long spans are governed by congested conditions. For the former, a promising research trend is the investigation of the dynamic vehicle-bridge interaction, which is shown to lead to dynamic effects much lower than previously thought. For the latter, advances in traffic flow modelling enable the simulation of realistic congestion patterns based on widely available free-flowing traffic data, thus partially overcoming a long-standing shortage of congestion data. Here, emphasis is given to the promising application of traffic microsimulation to long-span bridge loading, combined with a probabilistic approach based on the extreme value theory, to compute site-specific characteristic loading values.

Secondary cosmic positrons in an inhomogeneous diffusion model

“…An alternative idea was proposed in [20][21][22][23][24][25][26][27][28], stating that a modified diffusion model could explain the observed positron signal from a purely secondary origin. An interesting inspiration for this assumption is presented in [20,28].…”

“…An alternative idea was proposed in [20][21][22][23][24][25][26][27][28], stating that a modified diffusion model could explain the observed positron signal from a purely secondary origin. An interesting inspiration for this assumption is presented in [20,28]. Studying the spectrum of cosmic antiprotons which are expected to have (mainly) a secondary origin [29][30][31] an upper bound on the secondary positron spectrum is estimated which agrees with the data.…”