A form of limit states design used by AASHTO LRFD specifications is known as?

• A. Load and Resistance Factor Design
• B. Limit States Design
• C. Laminate
• D. Lane Loading

Answer: (A)

Load and Resistance Factor Design is the named form of limit states design used in AASHTO LRFD. In this approach, nominal loads (dead, live, wind, etc.) are multiplied by load factors to create design demands, while the material resistances are multiplied by resistance factors to form design resistances. This pairing provides a consistent reliability level across all limit states (such as ultimate and serviceability) and under different load combinations. AASHTO LRFD explicitly uses this term, distinguishing it from the more general idea of limit states design, which does not specify the factoring scheme. The other options don’t describe the design methodology: laminate is a composite material concept, and lane loading refers to a specific load model rather than the design philosophy.