An industrial building with a plan dimension of 30 feet × 30 feet and a height of 10 feet is subjected to a wind load of 20 psf. Two braced exterior walls parallel to the wind direction are used to resist the horizontal diaphragm force in the roof. Assuming diagonal tension counters in two of the

Question

An industrial building with a plan dimension of 30 feet × 30 feet and a height of 10 feet is subjected to a wind load of 20 psf. Two braced exterior walls parallel to the wind direction are used to resist the horizontal diaphragm force in the roof. Assuming diagonal tension counters in two of the three bays, determine the magnitude of force developed in each diagonal.

Accepted Answer

Recall from Section 3.3 that diagonal tension counters are always in pairs, because one counter will buckle as a result of compression loading. The method of sections was used earlier in determining the effective counter.

[latex] \omega=20 \space psf imes 5^\prime =100\# /ft.[/latex]

[latex] V=\frac{ \omega L}{2} = \frac{(100\# /ft.)( 30 \space ft. ) }{2 }=1,500\# [/latex]

In this case, counters [latex] AF[/latex] and [latex] CH[/latex] are effective in tension, whereas members [latex] BE[/latex] and [latex] DG[/latex] are assumed as zero-force members.

Utilizing the method of sections, draw an [latex] FBD[/latex] of the frame above section cut a-a.

[latex]AF_{x}=AF_{y}=\frac{AF}{\sqrt{2} } [/latex]

[latex]CH_{x}=CH_{y}=\frac{CH}{\sqrt{2} } [/latex]

Only the x components of members [latex]AF[/latex] and [latex]CH[/latex] are capable of resisting the 1,500# lateral force. Assuming [latex]AF_{x}=CH_{x}[/latex] then

[latex]\left[\sum{F_{x}=0 } ight] AF_{x}+CH_{x}=1,500\# [/latex]

[latex]AF_{x}=CH_{x}=750\# [/latex]

[latex]AF=CH=\frac{750}{\sqrt{2} }=1,061\# (T) [/latex]

Completing the analysis using the method of joints for trusses:

Question 4.7: An industrial building with a plan dimension of 30 feet × 30...

This Question has been Answered.

Already have an account?

Login

Related Answered Questions