root gap before making the weld. The backer bar is commonly tack welded in place below each beam flange and not removed. In addition, these failures between the beam flange and column flange have resulted in shear failure of the high strength bolts connecting the shear tabs to the web of the beam for the support of the gravity loads.
In other instances, the crack again originates at the root of the groove weld, but enters the column flange and propagates through the full thickness and width of the flange and into the column web.
Subsequent attempts by the building industry to improve beam-to-column connections still rely on post-yield straining of large, highly-restrained, full-penetration, single-bevel groove welds performed under field conditions. Such highly-restrained welds do not provide a reliable mechanisminsert column sections and beam sections in their selected place in a structure. Such splice connections are located at structural points of reduced flexural stress. That is, the splice connections are located at some distance from the beam-to-column connection.
However, the invention herein is particularly effective when used in field retrofit modification wherein beams and columns require strengthening in place and wherein beam-to-column connections are to be strengthened in place, in structures having floors, walls and roofs already in place and attached to the beams and columns.
However, the invention herein may be used in new construction and may be constructed in place and on site.