Question

Select a 30-ft long pair of angles (double-angles), A36 steel, to support a tensile dead load of 65 k and a live load of 22 k for the case assigned. Assume the angles are separated back-to-back % in. by a connected gusset plate, and that the connection is welded. Neglect block shear, design for long legs back-to-back LLBB using and use a conservative shear lag factor of U = 0.85. Slenderness ratio is not exceed 300. Components of problem: • Sketch the section connected to the gusset plate to help you visualize the connection. (5 pts) Design of angles. (20 pts) Check for slenderness. (5 pts)

Answer 1

Design consideration.

1. Gross area is selected such that, it satisfies both yield and rupture strength.

2. Also section is selected such that r(min) of section satisfies slenderness limit.

Complete solution is shown below.

Solution : .3% in Gusset plate Po = 65k PR = 22K Pu= (t.ex pp) + (1.6 x P) = (1.2x65) + (16X0.2) Pu = 113.2k 17 Design yield strength OPn = 0.9 x Fyx Ag 113.d = 0.9x 36 x Ag Ag = 3.494 in 2 27 Design Rupture strength OPn = ons Fnx te 113.2 0.75 588 de

(te= 2.6 in) → AR- Uxan te = 0.85x An 2.6 = 0.85 An (An = 3.06 inz for welded connection Ana Ag 3.06 in ² Required Ag 3.494 in 37 Stendernes limit ki 300 30x 12 300 Inin Select 26 4x 4x VA = 3.86 > 3. 494 ok ok 1.78 las ok t 14 < thickness of Gunet plate tok