IntermediateTopic 68 of 112Civil & Structural
Bearings and expansion joints
Allow thermal movement and rotation in bridges.
In depth
Bearings (elastomeric, pot, spherical) transfer load while allowing rotation and movement; expansion joints accommodate thermal and shrinkage movement. Poor performance causes leakage, deck damage and structural distress. Movement range ΔL=αLΔT.
Key points
- Fixed vs guided vs free bearings
- Joint types: finger, modular, strip seal
- Maintenance access
ExampleA 100 m steel girder bridge moves about 50 mm over a 40 K temperature range.
What is Bearings and expansion joints?
Allow thermal movement and rotation in bridges.
Why is it important to understand bearings and expansion joints?
Bearings and expansion joints let bridges move with temperature and rotation, so they prevent cracking and damage to the structure.
What is the function of a bearing?
It transfers load from the superstructure to the substructure and allows movement or rotation in the chosen directions.
What happens if expansion joints fail?
Water and debris enter the joint, causing corrosion and damage to supports, and vehicles may suffer rough rides.
How is Bearings and expansion joints used in practice?
Typical applications include choosing elastomeric bearings for a short-span bridge, installing an expansion joint at the end of a long deck and designing a pot bearing for a bridge with large rotation.
What should I learn before Bearings and expansion joints?
Study "Bridge loading" first (topic 67 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
What are the key points of Bearings and expansion joints?
Fixed vs guided vs free bearings. Joint types: finger, modular, strip seal. Maintenance access.
Can you give an example of Bearings and expansion joints?
A 100 m steel girder bridge moves about 50 mm over a 40 K temperature range.
What comes after Bearings and expansion joints?
The next topic is "Dams", which builds directly on this one.
How difficult is Bearings and expansion joints?
It is classed as Intermediate in Civil & Structural (topic 68 of 112). It is an intermediate topic. Work through the beginner topics in Civil & Structural first.