Expansion joints are subjected to traffic loads, and the fatigue strength of their components is therefore of paramount importance. Reliable design requires a thorough understanding of the stress-strain state of the system.
Reliable fatigue assessment requires knowledge of the maximum actions, the combination of simultaneously acting loads, and the strength of structural components. This paper presents a system-independent method for determining stresses in individual expansion joint members due to traffic loading.
Loads on Expansion Joints
Bridge expansion joints are subjected to a complex set of actions: vertical wheel loads from vehicles, horizontal braking and centrifugal forces, as well as thermal movements and seismic effects.
The system-independent stress determination method allows fatigue strength of individual joint members to be assessed without the need to model the entire structure.
Design Method
The proposed method is based on decomposition of actions and independent analysis of each joint member. This makes it applicable to different types of expansion joints — finger, lamellar and modular — without significant changes to the analysis model.
- Normal stresses from bending under wheel loads
- Shear stresses from horizontal actions
- Fatigue stresses under cyclic loading
- Stress concentrations at weld zones
Practical Significance
The developed approach was used in the design and verification of expansion joints in the Maurer MF (Modular Finger) series, which are successfully in service on bridges with spans exceeding 200 metres.