L = length of connection in the direction of loading, in Larger values of U are permitted when justified by tests or other rational criteria. When the tension load is transmitted only by bolts or rivets: is transmitted only by bolts or rivets: A = An net area of member, in^2 When the tension load is transmitted only by longitudinal welds to other than a plate member, or by longitudinal welds in combination with transverse welds: A = Ag gross area of member, in^2 When the tension load is transmitted only by transverse welds: A = area of directly connected elements, in2 U = 1.0 where l = length of weld, in w = plate width (distance between welds), in For ASD the effective net area is defined as follows: When the load is transferred directly by fasteners or welds into each of the cross section elements, Eq. (6.16) applies. For a bolted connection when the load is introduced into some but not all of the elements of a cross section, A = UA (6.19) e n For a welded connection when the load is introduced into some but not all of the elements of a cross section, A = UA (6.20) e g U is defined by the following: U = 0.90 for W, M, or S shapes with width of flanges at least two-thirds the depth of section and for structural tees cut from these shapes if connection is to the flange. U = 0.85 for W, M, or S shapes not meeting the preceding conditions, for structural tees cut from these shapes, and for all other shapes and built-up sections. Bolted or riveted connections should have at least three fasteners per line in the direction of applied force. U = 0.75 for all members with bolted or riveted connections with only two fasteners per line in the direction of applied force. When load is transmitted through welds transverse to the load to some but not all of the cross-sectional elements o W, M, or S shapes or structural tees cut from them, Ae = the area of the directly connected elements. When load is transmitted to a plate by welds along both edges at its end, the length of the welds should be at least equal to the width of the plate. Ae is given by Eq. (6.20) with U = 1.00 when l > 2w, 0.87 for 2w > l > 1.5w, and 0.75 for 1.5w > l > w, where l = length (in) of weld and w plate width (distance between edge welds, in). For design of built-up tension members, see Art. 6.29. Because of stress concentrations around holes, the AISC specifications establish stringent requirements for design of eyebars and pin-connected members. The tensile strength of pinconnected members for LRFD is given by See the AISC LRFD specification for other applicable requirements. All of the preceding design requirements assume static loads. Design strength may have to be decreased for alternating or cyclic loading (Art. 6.24). For allowable tension in welds, see Art. 6.14.3. The design strength of bolts and threaded parts is given in Table 6.19. High-strength bolts required to support loads in direct tension should have a large enough cross section that their average tensile stress, computed for the nominal bolt area and independent of any initial tightening force, will not exceed the appropriate design stress in Table 6.19. In determining the loads, tension resulting from prying action produced by deformation of the connected parts should be added to other external loads. (See also Arts. 6.15 and 6.20 to 6.24. For built-up tension members, see Art. 6.29.)

# Axial Tension

Tags:tension