Question

Q1 The pin-jointed wood truss shown in Figure Q1a is subjected to a point load P 24 kN at joint B a) Show that the truss is statically determinant. Indicate zero force members. Determine the force in members BC, CF, GF of the truss [10 marks] b) The truss is made of wooden joists (Young modulus E 10 GPa) with a rectangular cross-section having dimensions of 47mm × 150mm. The vertical displacement of joint B is measured to be 10 mm. How much would the vertical displacement of joint B reduce if the thickness of members BC, CF, GF is doubled, while the rest of the frame remains unaltered? [15 marks] 3m 3m Tm 24kN Figure Q1

Answer 1

Sm tH 3m Ar 6 SA 5 indelarminay (2+l n-no , of members 13 13-13 Inde termi na cy -f Trun 0. static Thuss is statically Delawmi nale るeco -force members- e c D.

m013 Support. ケeathon) @ AG E RA = 18 kN Take the utPart (left part) Take mowntF o ex 3 18x4 fn

E lo GPa given Vertial d-place meur + joint Bs lomm. 23 0.5 0.333 To. 25 0.75x5· 0 25 1.25 (lom prevsie) ニ Join 'B Joint f 仁 0,883 ( Comp)

No& fel AE where ca in k→ foru. in manberduto Unit lod @.e' - tomm AE E PKL. A E AE AE A E A E members Pk L frd menbers xeXLF JAE 3 = 10-1 24x500x0 + A70,50 0.681 mm 10- 8. 5802 m m