Approximate distribution factors for concrete deck on steel or precast concrete I-girders and cast-in-place T-beams (cross-sections a, e, k). Interior & exterior girders, moment & shear, lever rule for the one-lane exterior case, optional skew correction. Metric inputs — formulas applied in code units exactly.
| Case | 1 lane | 2+ lanes | governing | × skew |
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Multiple presence is already inside the tabulated formulas; the lever-rule one-lane result includes m = 1.2. Apply the governing g to the HL-93 per-lane envelope to get per-girder demand, then carry both into the load-rating tool. Ranges of applicability are checked live — anything outside range is flagged, not hidden. Indicative preliminary values only — not a substitute for detailed design.