Types of Loads in Steel Structures for Bridges

Types of Loads on Bridges

• Self-Weight of Structure:

  • Comprises the inherent weight of the structural components including beams, trusses, and other load-carrying elements.

• Permanent Loads and Long-Term Effects:

  • Includes self-weight of non-structural elements such as road surfacing, footpaths, edge slabs, crash barriers, and system installations (ducts, pipes, lighting).
  • Essential to account for effects of creep and shrinkage immediately after the concrete slab is connected to the steel structure in composite bridges.

Creep and Shrinkage

• Creep and Shrinkage Considerations:
  • Critical in steel-concrete composite bridges where the connections between materials impact overall behavior and load handling.
  • Shrinkage of concrete can lead to additional stress and requires consideration in design.

Structural Weight Considerations

• Self Weight Composition:
  • For steel bridges, self-weight predominantly consists of the steel framework.
  • In composite bridges, the weight of the concrete slab is significant and must be evaluated to determine integrity and performance.

Support Settlement

• Indeterminate Structural Forms:
  • Each section in an indeterminate structure must accommodate supplementary moments and forces arising from potential support settlement, which can affect bridge stability and longevity.

Traffic and Climate Loads

• Direct Traffic Loads:
  • Imposed by regular use of the bridge, which includes vehicles, trains, and pedestrian traffic.
  • Essential to assess traffic loads for effective design and safety measures in bridge engineering.

This lecture covers the various types of loads that affect steel structures for bridges, including self-weight, permanent loads, long-term effects, and the effects of shrinkage and creep in steel-concrete composite bridges.