Probabilistic load modelling for long span bridges

Long span bridges are regularly subjected to the simultaneous presence of multiple vehicles, resulting in high traffic volumes, the behaviour of which is governed by drivers-vehicle interaction such as velocity and drivers' lane changing and overtaking. On a long span bridge, when the traffic is congested, driver behaviour leads to a lane distribution of car-truck mixes that may result in 'clustering' of heavy trucks in critical positions. Long span bridges may also be very sensitive to wind effects, which depend on general wind climate, the exposure of bridges and their elements to the natural wind and the geometry of the bridge. Therefore a realistic traffic and wind load analysis is essential for designing a long bridge. The application of more accurate load modelling, such as traffic micro-simulation considered simultaneously with wind simulation is introduced in this study. Traffic on a bridge is presented as a multi-vehicle system where each vehicle has its own set of driver-vehicle characteristics. A general framework for analyzing combined traffic and wind loading for long span bridges is developed and studied for the scenario-based cable-stayed bridge under normal and extreme load events.