Â© 2009-2015 Jonathan Ochshorn. Tweet. Directions: Enter values for design (factored) moment, beam stem width, bw, effective depth, d, span, spacing, and slab thickness (not all parameters are used for all calculations). Note that design moment for slabs is calculated on a typical 1-ft wide section of the slab.Press update button. 2009-2015 Jonathan Ochshorn. Tweet. Directions: Enter values for design (factored) moment, beam stem width, bw, effective depth, d, span, spacing, and slab thickness (not all parameters are used for all calculations). Note that design moment for slabs is calculated on a typical 1-ft wide section of the slab.