Explain the concept of load path redundancy with an example.

• A. Redundancy provides alternate load paths so that a single element failure does not lead to collapse; for example, multiple girders sharing deck load and independent support paths.
• B. Redundancy means using only one girder to simplify design.
• C. Redundancy increases likelihood of brittle failure.
• D. Redundancy refers to redundancy of blueprints.

Answer: (A)

Load path redundancy means there are multiple routes for the forces in a structure to travel from where loads are applied to the supports. This lets the structure continue to carry load even if one element starts to fail, since other parallel paths can take over the load.

In a bridge with several parallel girders sharing the deck load, the deck, diaphragms, and cross-frames create connected paths that let load flow through more than one girder and into the supports. If one girder is damaged, the remaining girders and the deck connections still carry the traffic load to the bearings and piers. That spirit of alternate routes is what keeps the structure from collapsing all at once.

Relying on a single girder removes those alternate paths, increasing the risk of progressive failure. The idea that redundancy would automatically raise brittle failure isn’t correct in practice—redundancy is aimed at avoiding catastrophic failure by distributing forces. Redundancy of blueprints isn’t a structural concept in this context.