Question

1. The members of truss are attached together by pins having 5 cm in diameter and 10 cm in length. The truss is supported by a frictionless pin at one end (joint A) and a roller system at the other joint k). The load Lis equal to 5 kN. The section view of the truss member is below and it is homogeneous all along the truss. Elastic modulus is 200 GPa, shear modulus is 75 GPa for the truss. (a) Find the reaction forces at joints A and K. (b) Compute the force in member FG of the loaded truss. State if it is in compression or (c) Calculate the stress and strain values (both longitudinal and transversal) for the member FG. tension. 15 cm 20 cm L L L L L Truss member Section view L L 2 L E G L 2 D H 6 m J BS 2 m 12 m AL K M L RQ ро N 8 panels at 3 m

Answer 1

solution (a) sine. this is a symmetric struction Hence, RA=Rk Balancing forces in Y-dish RATRB = LTLILILILI LILAL + 1 . RAXRB = 82=805) = 40KN - RA=RB= 20KN (1) (1-5kN) 5KN 5kN (6) Method of section of 5KN 71.5601 2-2.5kN 5kN 6th For B 2n). A 'R Р FON o RAZEKNI 3m 3m 3 3in sk Take moment at 'o' Cow A.CW (Ffa Cas 18-45° x6)+(20x12) = (2.5X12)+(589)+(546)+(543) 1 Fra = -21.08 kN (compressia)) stress = 6 6= TFG Stress 670.702 MPG 21.08 KN 0 2x0.15 Area strain (E) G-EE Ei6 - 0.702MPa 200 x103 m Pa strain {= 3.513 4166 CScanned with Cams

longitudaal strain = 3.513x106 Poisson ratio u= E= Transkoye strain El Longitudual strain. E = 200x10I MPa a=75x10 Impa E=2a Cl+M) 200x10] 275103 (HM) M=0.33 .: U= EL El Ez= MEI = 0.333X3.517XING Ez= 1171x106 ( Trausvose strain) CScanned with CamScanner

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