Bolt row capacities

The design moment resistance of a bolted end-plate connection is determined by the summation of the moments of resistance of each bolt row multiplied by it's lever arm as measured from the assumed centre of compression. The effective design tension capacity of each bot row is determined from the smallest tensile capacity of the bolt in tension, column web in tension, column flange in bending, the end-plate bending or the tension capacity of the beam web. If the connection fails in compression, a reduction in the tensile capacity is then made to maintain equilibrium. This is achieved by a reduction in the tensile capacity of the bolt rows. The procedure involves first determining the potential resistance of each row, such that each row is first checked in isolation, then in combination with successive rows above it, since the capacity of combined bolt rows may be less than the capacity of a single row due to the failure pattern of the end plate. This approach requires sufficient ductility in the connection to allow the connection to develop the design strength of the lower bolts. To achieve this, limits are placed on the thickness of the column flange or end-plate relative to the strength of the bolts. If this ductility criterion is not achieved, the force distribution in the bolts is limited to an elastic triangular distribution.

Where MasterKey: Connections includes a design with insufficient moment to develop a compression and tension zone, a modified bolt force distribution is calculated to account for the fact there is only a compression (or only tension) zones, with the axial force being split equally between the zones.