AISC LRFD 1.pdf

232 GENERAL PROVISIONS [Comm. J1.advisable to fully tension the bolts before the weld is made. If the weld is placedfirst, angular distortion from the heat of the weld might prevent the faying actionrequired for development of the slip-critical force. When the bolts are fullytensioned before the weld is made, the slip-critical bolts and the weld may beassumed to share the load on a common shear plane (Kulak, Fisher, and Struik,1987). The heat of welding near bolts will not alter the mechanical properties of thebolts.In making alterations to existing structures, it is assumed that whatever slip is likelyto occur in high-strength bolted bearing-type connections or riveted connectionswill have already taken place. Hence, in such cases the use of welding to resist allstresses, other than those produced by existing dead load present at the time of makingthe alteration, is permitted.It should be noted that combinations of fasteners as defined herein does not refer toconnections such as shear plates for beam-to-column connections which arewelded to the column and bolted to the beam flange or web (Kulak et al., 1987) andother comparable connections.10. High-Strength Bolts in Combination with RivetsWhen high-strength bolts are used in combination with rivets, the ductility of therivets permits the direct addition of the strengths of both fastener types.J2. WELDS1. Groove WeldsThe engineer preparing contract design drawings cannot specify the depth ofgroove without knowing the welding process and the position of welding. Accordingly,only the effective throat for partial-joint-penetration groove welds should bespecified on design drawings, allowing the fabricator to produce this effectivethroat with his own choice of welding process and position. The weld reinforcementis not used in determining the effective throat thickness of a groove weld (seeTable J2.1).2. Fillet Welds2a. Effective AreaThe effective throat of a fillet weld is based upon the root of the joint and the face ofthe diagrammatic weld, hence this definition gives no credit for weld penetration orreinforcement at the weld face. If the fillet weld is made by the submerged arc weldingprocess, some credit for penetration is made. If the leg size of the resulting filletweld exceeds 3 8-in. (10 mm), then 0.11 in. (3 mm) is added to the theoretical throat.This increased weld throat is allowed because the submerged arc process producesdeep penetration of welds of consistent quality. However, it is necessary to run ashort length of fillet weld to be assured that this increased penetration is obtained. Inpractice, this is usually done initially by cross-sectioning the runoff plates of thejoint. Once this is done, no further testing is required, as long as the welding procedureis not changed.LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION