§8.1 Scope

No standard provision checks are performed in seismic provision mode. The engineer is responsible for confirming that all the members are capable of resisting the standard provision load combinations, in standard provision mode. Only the "added provisions" are performed in this special seismic mode.

§8.2 Joint Requirements

The plastic bending moment of each beam (Mp), and for beams framing into the flange, the moment resulting from the panel zone shear strength (Mpz) are reported. Mpz is calculated independently for each beam as Vn (panel zone strength) x Beam Depth (distance between center of flanges). The Mpz reported is the component of the panel zone moment in the direction that the beam frames into the column flange (less than the full panel zone moment if the beam is not parallel to the column web). If no panel zone value can be calculated or the beam frames into the column web then no value is shown for Mpz in the output.

The minimum of Mp (beam moment strength) and Mpz (panel zone strength at the joint under consideration) is used to calculate the required shear strength per 8.2b (1.2D + 0.5L + 0.2S + 2M/L). Where D is the dead load, L is the positive live load and S is snow load if it exists. Mpz is only considered if it has a positive magnitude.

§8.3 Panel Zone of Beam-to-Column Connections

The shear in the column above the joint is considered when calculating the panel zone shear force using the above generated load combination.

The panel zone strength is the minimum value calculated for all the beams framing into the column flanges.

Where a web plate (doubler) is provided its capacity is added to that of the column web when calculating the joint capacity. The depth of the web plate is taken as the clear height between the flanges of the column.

§8.4 Beam and Column Limitations

Round hollow structural section columns are limited to the compact width-thickness ratio from Table B5 in the AISC-LRFD specification.

The Pu value used in Table 8-1 is the maximum compression load on the element from all standard provision load combinations.

§8.5. Continuity Plates

Stiffeners are only designed for flange bending requirement of chapter K in LRFD 3rd Edition.

The required area of the stiffeners is calculated as the difference in the design force and the flange capacity (Rn) divided by the stiffener yield strength.

§8.6 Column-Beam Moment Ratio

Nominal strength of panel zone is taken as the value calculated in section 8.3.

The db value is taken as the average depth of all the fixed, steel lateral beams framing into the joint.

When calculating the shear capacity of a story for exception 2, all columns, not only those columns of the special moment frame type, are considered.