Counter Diagonals

Situation
Diagonals BG, CF, CH, and DG of the truss shown can resist tension only.
 

2016-may-design-truss-with-tension-diagonals.gif

 

If W = 3 kN and P = 0, find the following:
1.   the force in member CF.

A.   4.76 kN C.   4.67 kN
B.   4.32 kN D.   4.23 kN

2.   the force in member BF.

A.   3.2 kN C.   3.4 kN
B.   3.3 kN D.   3.5 kN

3.   the force in member DH.

A.   2.8 kN A.   2.5 kN
B.   2.8 kN D.   2.7 kN

 

Situation
Flexible cables BE and CD are used to brace the truss shown below.
 

2016-may-design-3panel-truss-counter-diagonals.gif

 

1.   Determine the load W to cause a compression force of 8.9 kN to member BD.

A.   7.80 kN C.   26.70 kN
B.   35.64 kN D.   13.35 kN

2.   Which cable is in tension and what is the tensile reaction?

A.   BE = 12.58 kN C.   BE = 6.29 kN
B.   CD = 6.29 kN D.   CD = 12.58 kN

3.   If W = 20 kN, what will be the tensile reaction of member CE?

A.   6.67 kN C.   0
B.   13.33 kN D.   10 kN

 

Problem 438 - Truss With Redundant Members

Problem 438
The center diagonals of the truss in Figure P-438 can support tension only. Compute the force in each center diagonal and the force in BC, DE, and FG.
 

438-counter-braces.gif

 

Problem 437 - Truss With Counter Diagonals

Problem 437
The center panel of the truss in Figure P-437 contains two flexible cables. What load P will cause a compressive force of 20 kN in BD? Then determine which tension diagonal BE or CD is acting and the force in it.
 

437-counter-diagonals.gif

 

Problem 436 - Howe Truss With Counter Braces

In Figure P-420, assume that counter diagonals act from B to E and from E to F in addition to the counter diagonals CD and DG shown in the figure. Assuming that these counter diagonals can support tension only, determine which diagonals are acting and the force in each.
 

420-howe-truss.gif

 

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