AASHTO Standards: The Engineering Foundation of North American Infrastructure
[*]


  1. LRFD Philosophy: Balancing Load and Material Resistance


AASHTO (American Association of State Highway and Transportation Officials) provides the engineering foundation for North America's bridges and highways. The standards download for the «Bridge Design Specifications» (often provided via state DOT portals) introduces the LRFD methodology. This is a «Limit State» design philosophy that uses statistically derived factors to ensure safety.

The fundamental LRFD equation is:

$$\sum \eta_i \gamma_i Q_i \leq \phi R_n$$

Where $Q_i$ represents force effects (Live Load, Dead Load,

( Читать дальше )