AISC LRFD 1.pdf

Sect. J1.] GENERAL PROVISIONS 518. Placement of Welds and BoltsGroups of welds or bolts at the ends of any member which transmit axial force intothat member shall be sized so that the center of gravity of the group coincides withthe center of gravity of the member, unless provision is made for the eccentricity.The foregoing provision is not applicable to end connections of statically-loadedsingle angle, double angle, and similar members.9. Bolts in Combination with WeldsIn new work, A307 bolts or high-strength bolts proportioned as bearing-typeconnections shall not be considered as sharing the load in combination with welds.Welds, if used, shall be proportioned for the entire force in the connection. Inslip-critical connections, high-strength bolts are permitted to be considered as sharingthe load with the welds. These calculations shall be made at factored loads.In making welded alterations to structures, existing rivets and high-strength boltstightened to the requirements for slip-critical connections are permitted to beutilized for carrying loads present at the time of alteration and the welding needonly provide the additional design strength required.10. High-Strength Bolts in Combination with RivetsIn both new work and alterations, in connections designed as slip-critical connectionsin accordance with the provisions of Section J3, high-strength bolts arepermitted to be considered as sharing the load with rivets.11. Limitations on Bolted and Welded ConnectionsFully pretensioned high-strength bolts (see Table J3.1 or J3.1M) or welds shall beused for the following connections:Column splices in all tier structures 200 ft (60 m) or more in height.Column splices in tier structures 100 (30 m) to 200 ft (60 m) in height, if the leasthorizontal dimension is less than 40 percent of the height.Column splices in tier structures less than 100 ft (30 m) in height, if the least horizontaldimension is less than 25 percent of the height.Connections of all beams and girders to columns and of any other beams andgirders on which the bracing of columns is dependent, in structures over 125 ft(38 m) in height.In all structures carrying cranes of over five-ton (50 kN) capacity: roof-trusssplices and connections of trusses to columns, column splices, column bracing,knee braces, and crane supports.Connections for supports of running machinery, or of other live loads whichproduce impact or reversal of stress.Any other connections stipulated on the design drawings.In all other cases connections are permitted to be made with A307 bolts orsnug-tight high-strength bolts.For the purpose of this section, the height of a tier structure shall be taken as thevertical distance from the curb level to the highest point of the roof beams in thecase of flat roofs, or to the mean height of the gable in the case of roofs having aslope of more than 25 percent. Where the curb level has not been established, orwhere the structure does not adjoin a street, the mean level of the adjoining landLRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION