Flexure design for cap and strut in AASHTO Standard specification for load factored design is based on the strength envelope. Program considers the maximum positive and negative moments in design. The required steel area for each section is computed based on the maximum positive and negative moments. This required steel is then checked for minimum steel criteria of Art. 8.17.1. To satisfy, Art. 8.17.1.1 and At. 8.17.1.2, program computes and requires the reinforcement which at least equal to smaller of 1.2 Mcr and 1.33 Mu. Required steel as shown in the report is based on the actual moment and the minimum steel criteria. For capacity calculation, program first computes effective steel area. This effective area is obtained after adjusting the gross steel area taking into account development length. Section over reinforcement is checked as per Art. 8.16.3.1. The beam cross section capacity (φ Mn) at every location is then computed using strain compatibility with consideration of concrete material, and any available top and bottom bars. For this calculation, φ is used as specified for flexure on the A/D (Analysis/Design) Parameters screen. If the provided steel is less than required or more than maximum allowed, program flags the reinforcement. If the capacity of the section is less than demand moment, that is flagged too. Note that AASHTO LFD Art. 8.24.2 and 8.24.3 are not implemented in Substructure.