Under some circumstances it is desirable to select beam sizes that are deeper or wider than would otherwise be required for capacity or deflection. Minimum beam depth and flange width can be specified on a beam-by-beam basis using the Layout > Beams > Size Restriction command in the RAM Modeler. During optimization the program will reject any sizes whose depths or widths are not within than the values specified.

The minimum beam depth can also be controlled by specifying a maximum allowable span-to-depth ratio using the Criteria > Design Defaults command. This is a global criteria, affecting the optimization of all gravity beams. It is not a Code requirement, but a common rule-of-thumb. If a criteria is specified, the program will reject any sizes whose depth is too small to satisfy the criteria.

When a maximum depth restriction is specified, RAM Steel Beam first determines the optimum beam size. If the optimum size exceeds the user defined depth restriction, the program selects the lightest section smaller than that depth which is adequate. If no beams smaller than the given depth are adequate, the depth restriction criteria is ignored and the optimum size is selected.

The depth restriction specified by the user is an absolute depth, not a nominal depth. These assignments are made in RAM Modeler using the Layout > Beams > Size Restriction command.