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1 PDH · about 60 minutes · Course no. BR-D03 · Instructor: Michael Craig, PE
Michael Craig, PE is Senior Vice President and Southeast Director at Strinteg Corporation, leading bridge inspection and structural engineering across eight states and Puerto Rico. In 27+ years he has inspected over 4,000 structures and completed 3,000+ load ratings and 160+ load tests. He has managed repair and preservation design for complex bridges, including cable-stayed bridges. He holds PE licenses in twelve states, DC and Puerto Rico, SPRAT Level 1, and FAA Part 107 credentials.
Once the per-lane HL-93 effects are known (BR-D02), the designer has to decide how much of each lane a single girder carries. For common beam-slab bridges, the AASHTO LRFD Bridge Design Specifications give approximate live load distribution factors in Article 4.6.2.2. This course explains where the equations came from, the conditions for using them, the moment and shear equations for concrete decks on steel or concrete beams, the exterior girder rules (lever rule, e-factor and rigid-section check), the skew corrections, the handling of multiple presence and fatigue, and the signs that a refined analysis is needed. Equations and the worked example were checked against the FHWA Comprehensive Design Example for a Prestressed Concrete Girder Superstructure Bridge (Design Step 5.1) and University of Maryland course notes that reproduce the tables. A second example is an illustrative teaching problem with numbers computed for this course. Always check the edition and interim revisions your owner has adopted.