9. Combinations

This section defines load combinations for design checks and load rating per AASHTO LRFD specifications.

Load combinations combine individual load cases with appropriate factors for different limit states (Strength, Service, Fatigue, etc.).

Combination Definitions

Definition	Description
Result Extraction (From Stages)	Extract results from construction stages for combination
Design Load Combinations	Limit states, load combination tables, and rating tables

Load Cases Combined

• Non-composite Dead Load: Girder self-weight during erection

• Composite Dead Load: Deck, barriers, and wearing surface

• Live Load: HL-93 with dynamic allowance

• Wind Load: Structure and live load wind effects

• Temperature: Uniform temperature change effects

Limit States

Limit State	Purpose
Strength I	Basic load combination without wind
Strength III	Load combination with wind
Service I	Normal operational loads
Service II	Steel yield control
Fatigue	Repetitive live load cycles