factor can be calculated as afunction of the spacing between stringers using the equationLoad Fraction = S/DWhere S = Width of a precast beamIf the value of ((I/J) is great than 5.0, AASHTO recommends that a "more precisemethod" such as grillage analysis, be used. From the above, it can be seen that the valueof the distribution factor is greatly dependent on the cross-sectional geometry of theprecast panel. Both the moment of inertia and torsional constant are functions of the typeof panel/beam used. AASHTO provides a list of general constant values for use in thepreliminary design of a multibeam bridge.(1) As can be seen from the design perspective, the approach which AASHTO takes for thedistribution of loads has fostered some debate as to whether or not the method is tooconservative. Regardless of the merits of such arguments, the subsequent text will utilizethe AASHTO load distribution specification, when appropriate.The AASHTO code places the distribution of loads for concrete slabs within the samesection as that which describes the general design criteria for this element. For loaddistribution criteria pertaining to other less common flooring, such as timber flooring(wood), you can be referred to the AASHTO specifications directly for information....
