What are some things the engineer of record can do to reduce RFIs on steel connection design and avoid costly changes after bid selection? During the June 2016 SE University Session, Best Practices to Improve Structural Construction Documents, Carol Post, PE, SE, LEED AP, with Thornton Tomasetti, and Cathleen Jacinto, PE, SE, with FORSE Consulting, gave several suggestions to reduce confusion surrounding delegated steel connections during the bid process.
While it is common for the steel fabricator to design the connections, Cathleen noted it is helpful to specify which connections have already been fully designed by the engineer, and which connections should be addressed by the contractor so that this item is correctly included for bid pricing. Using a note designating a “Fully Designed Connection” is a simple way to avoid confusion in this area.
Moment connections tend to be a large scope of work for the fabricator, so the engineer needs to be clear in providing all the necessary information needed before bid.
Simply specifying “Stiffener and Double Plates, as Required” does not provide the contractor with the information needed to determine their bid pricing. A breakdown of service dead, live, wind, and seismic loads are needed to find the governing load combination applied to the joint, and to then evaluate if the column is adequate to resist local effects. Carol and Cathleen presented their opinion that it is good practice for the engineer of record, rather than the contractor’s connection engineer, to determine if column reinforcement or upsizing the column is needed at moment connections to resist local effects. This is due to the fact that the engineer has the load breakdown needed at each moment connection. Alternately, the engineer can provide the service load breakdown for the contractor’s engineer to determine the load combinations that govern local limit states at moment connections. A link was provided to the Clean Columns tool on the AISC steelTOOLS website, which helps to determine the lightest column section that can be used for the intended loading, without having to add stiffeners or doubler plates.
While this tool can be very helpful to avoid this costly reinforcement, Cathleen also noted that care should be taken to make sure we are not being outbid by other designs when the bid is awarded based on total steel tonnage. It is important to educate the owner and other involved parties about the consideration to upsize columns in order to eliminate reinforcement in an effort to reduce fabrication and labor costs during construction.
When issuing a Beam Shear Reaction Table, another way to minimize RFIs is to do a quick double check of the posted reactions, particularly for shallow beams (W8, W10, W12’s). RFIs arise when beam sections are not adequate for the reactions posted. Cathleen mentioned it is common to see high shear reactions at shallow beams with thin webs that are not adequate for large copes, which can occur frequently at small beams. A check of the coped sections with the shear reactions posted could help to avoid RFIs where connection engineers discover beams are not adequate.
Using these helpful tips, engineers can certainly be active participants in reducing the RFIs generated during construction, and help minimize any confusion surrounding the design of steel connections.