University:
McMaster University
Course:
MATLS 2H04 | Introduction to Materials Engineering
Academic year:

2023
Views:

302

Pages:

2
Author:

Sabrina S.

Built Up Members & Torsion 3.4 Built Up Members Lo parts which are made of multiple members Lo members can be joined together in a no. of ways adhesively bonded welded mechanically fastened Shear Flow Lo shear force per unit length dF = dm Sa y da I VQ I shear flow V: Shear force Q first moment of I second moment of area note: f a structure is held together w mechanical fasteners, you can calc the shear force, Fs, on each fastener by multiplying the shear flow, q. by the distance between each fastener, s Fs = 95 eg'll box-beam a built up member box it is composed of 4 sheets of wood that are nailed together SON Nails to each nail can support a 300 shear force find the max. spacing at B & C 50 the beam can support the BON Lond Nailo shear flow: 9 I inner square VQ bh I 12 bh 12 (0.075)८०-075) Shear force (0.08) (0.045)" 2295x10m 60 Consider nails B shear flow is resisted by both parts B & B' ... nails at B only need to support half of the total shear flow her from geometry yo = 30mm Q = yo' Ao = (0.03)(0.015 x 0.075) = 3.375 x 10^-5 m^3 q = VQ / I = (80 x 3.375 x 10^-5) / (2.295 x 10^-6) = 1176 N/m but nails at B only need to support half of this = 588 N/m spacing required = 30N / 588N/m = 0.051m = 51mm ... need nails every 51mm consider nails C Ac = (0.03)(0.015 x 0.045) = 2.025 x 10^-5 m^3 q = VQ / I = (80 x 2.025 x 10^-5) / (2.295 x 10^-6) = 705.9 N/m only need to support half => 352.95 N/m spacing required = 30 / 352.95 = 0.085m ... need nails every 85mm