I'm not sure if you are going to find any code provision that requires a certain bearing length onto masonry. However, other checks may govern the length of bearing such as bearing stresses, the capability of the masonry structure to support the eccentric load from a small bearing length, and the anchorage of said structural steel to masonry. A few places to check would be the Masonry Standards Joint Committee (MSJC) if in the U.S. Also, the attached website could have some valuable information.

• http://www.gobrick.com/TechnicalNotes/LinkstoTechnicalNotes/tabid/11294/Def

Section 5.3 of the steel joists specs requires that joists have a minimum bearing of 4" on masonry unless a detailed bearing analysis is performed. Steel beams generally have more load than joists. 4" would be a minimum for bearing. I generally use 250 psi bearing pressure and size my bearing plate to keep the average stress below this level. Because of beam rotation due to deflection it is a good idea to set your bearing plates back from the edge of the masonry by about 1/2" since the actual bearing stress is closer to a triangular load with the highest pressure at the edge of the masonry. If you don't do this you will frequently see the edge or the block bust off.