It is common practice for design engineers in the United States, especially the eastern part, to leave the design of simple shear connections up to the steel fabricator. The design engineer typically provides notes on the design drawings directing the fabricator to design the shear connections for: (a) one-half the maximum uniform load; (b) the maximum number of rows of bolts; or (c) the shear capacity of the beam. These types of statements can lead to overdesigned connections, and in unusual situations, underdesigned connections. Overdesigning connections adds cost to a project, while underdesigning compromises safety. A simple alternative to this practice is to place the actual reactions on the drawings for the fabricator to use in designing the connections. It is unknown how much extra cost is associated with this practice, and whether it creates significant safety problems. The Engineer of Record (EOR) reviews the connection design and this should catch unsafe designs, however additional time and work arenecessary to correct any problems that are uncovered.
The plans for an existing building are used to investigate this issue. The connections for the building are reviewed with the approach of designing for one-half maximum uniform load, as listed in the AISC LRFD Third edition Manual, and designing for the actual reactions. The estimated costs for each approach are then compared to see if savings can be achieved by using the actual reactions. In addition, the connections that were used in the building were compared to those designed for the actual reactions.
By breaking down the cost of the connections by number of rows of bolts, plate thickness, weld length, shop labor for fabrication, and field labor for installation, a definitive cost savings is determined for the building. The cost for designing the connections for one-half the maximum uniform load is $33,993. Designing for the actual reactions cost $31,227, and the cost of the connections used in the existing building is $46,272. Also, potential safety problems are identified.