Discussion on AASHTO LRFD Load Distribution Factors for Slab-on-Girder Bridges

The present study developed a new set of formulas for load distribution factors that are more rational than the current AASHTO LRFD formulas. A formula to quantify the intermediate diaphragm effect on live load distribution was also proposed. Preliminary coefficients of these formulas were obtained from curve fitting either with the values of AASHTO LRFD formulas or with the results from finite element modeling. The load distribution factors predicted with the proposed formulas were compared with those from AASHTO codes, field measurements, and finite element analysis with or without considering the effects of intermediate diaphragms. While the present study was intended to shed some light in developing future AASHTO LRFD design formulas, development of complete load distribution factors is out of the scope of the present study.