Course: C55
Viewing: Lecture 5 Clarification
Subject:
Lecture 5 Clarification
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Sent by:
Berg Ellemers
Sent on:
07-Feb-2025
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Hi everyone,
We received a couple of good questions regarding the strut and tie example in Lecture 5. Please find the questions and answers below:
Question #1:
Q: On Slide 62, I thought that in a CCT node we are supposed to use 0.88*alpha_1*phi_c*m*f'c for all node checks (S6-19 Cl 8.10.5.1.b). How come the reaction from the bearing is checked with alpha_1*phi_c*m*f'c instead (S6-19 Cl 8.10.5.1.a)?
A: The 0.85 x phi_c x f’c
should be alpha_1 x phi_c x f’c = 21 MPa, since this is a support, and CSA S6
Clause 8.10.5.1 a) applies.
Question #2.1:
Q: On Slide 58, with the uneven truss, how do you determine the strut width at these locations since the strut geometries are slightly different from the standard figure from the code (S6-19 Figure 8.4.c)?
A: The geometry in the code is
simplified, and this will not be always the case. The nodal geometry is
best determined graphically by drawing out the struts with the determined
widths, obtain the nodal shape, and then determine the lengths of the
sides of the node.
Question #2.2:
Q: On a related question to above, on slide 61, the strut width appears to be 150mm but at which location was the strut being checked?
A: The strut was checked where
it was the narrowest, so near the top right node.