Forces Acting on Arch Bridges: 8 Critical Loads Engineers Must Design For

1. Dead load (self-weight) – Deck, arches, supports; constant downward force.
2. Live load (traffic) – Vehicles, pedestrians; dynamic, variable.
3. Wind load – Lateral pressure; critical for long spans; causes vibration.
4. Thermal effects – Expansion/contraction from temperature cycles; induces stress.
5. Seismic forces – Earthquake ground motion; dynamic, multi-directional.
6. Hydrostatic load – Water pressure on piers; buoyancy on submerged parts.
7. Soil-structure interaction – Foundation settlement, liquefaction, lateral earth pressure.
8. Creep & shrinkage (concrete) – Long-term deformation, volume loss; redistributes stress.

All must be modeled, combined per code (AASHTO, Eurocode), and detailed for durability. Arch bridges convert vertical loads to thrust at abutments—making foundation design paramount.