Question 2 (a) A simple circular hollow section (CHS) tubular K-joint of steel structure is subjected to an in-plane bending of 10 kNm on brace A only, as shown in Figure 2. The gap size between the two (2) braces is 50 mm. Determine the geometrical parameters of the joint. Calculate the hot spot stresses at the crown position of the chord and the brace. (b) The steel structure is installed in seawater with cathodic protection. Determine the number of stress cycle to failure based on the maximum hot stress range obtained in part (a). Use NORSOK standard.

10 kNm 45 diagonal brace A: 0 244.5 x 8 mm t = 275 N/mm A = 59.4 cm W. - 340 cm Gap size 50 mm 45% diagonal brace B 244.5 x 8 mm 1. = 275 N/mm A = 59.4 cm W-340 cm 1500 mm Chord 323.9 x 10 mm 1-355 N/mm2 A = 98.6 cm W-751 cm Figure 2(a) fi A: Yield stress of steel material Cross section area of steel member Section modulus of steel member In-plane-bending on one brace only Chord crown: (Eqn. (8)) Brace crown: (Egn. (9)) Note that all geometric parameters and the resulting SCF's relate to the loaded brace. Load type and fixity SCF equations conditions Eqn. No. Short chord correction In-plane bending Chord crown: 0.85 (sin o) (8) None 1.453 FORSyl-06 Brace crown: 1 +0,65B 704,10.09 -0.77(sin (0.06 - 1.16) () (9) None 1000 In air 100 Seawater with cathodic protection Stress range (MPa) 10 1 1.00E+04 1.00E+05 1.00E+08 1.00E09 1.00E+06 1.00E+07 Number of cycles S-N curves for tubular joints in air environment and in seawater with cathodic protection 10 kNm 45 diagonal brace A: 0 244.5 x 8 mm t = 275 N/mm A = 59.4 cm W. - 340 cm Gap size 50 mm 45% diagonal brace B 244.5 x 8 mm 1. = 275 N/mm A = 59.4 cm W-340 cm 1500 mm Chord 323.9 x 10 mm 1-355 N/mm2 A = 98.6 cm W-751 cm Figure 2(a) fi A: Yield stress of steel material Cross section area of steel member Section modulus of steel member In-plane-bending on one brace only Chord crown: (Eqn. (8)) Brace crown: (Egn. (9)) Note that all geometric parameters and the resulting SCF's relate to the loaded brace. Load type and fixity SCF equations conditions Eqn. No. Short chord correction In-plane bending Chord crown: 0.85 (sin o) (8) None 1.453 FORSyl-06 Brace crown: 1 +0,65B 704,10.09 -0.77(sin (0.06 - 1.16) () (9) None 1000 In air 100 Seawater with cathodic protection Stress range (MPa) 10 1 1.00E+04 1.00E+05 1.00E+08 1.00E09 1.00E+06 1.00E+07 Number of cycles S-N curves for tubular joints in air environment and in seawater with cathodic protection