Structural Engineering and Construction

Shear and Bearing at Notch Joint of a Timber Truss

Situation
The truss shown in is made from timber Guijo 100 mm × 150 mm. The load on the truss is 20 kN. Neglect friction.

Allowable stresses for Guijo:
Compression parallel to grain = 11 MPa
Compression perpendicular to grain = 5 MPa
Shear parallel to grain = 1 MPa

 

2015-may-triangular-guijo-truss.gif

 

1.   Determine the minimum value of x in mm.

A.   180 C.   160
B.   150 D.   140

2.   Determine the minimum value of y in mm.

A.   34.9 C.   13.2
B.   26.8 D.   19.5

3.   Calculate the axial stress of member AC in MPa.

A.   1.26 C.   1.57
B.   1.62 D.   1.75

 

Force on Truss Members Due to Moving Loads | Solution by Influence Lines

Situation
The bridge truss shown in the figure is to be subjected by uniform load of 10 kN/m and a point load of 30 kN, both are moving across the bottom chord
 

2014-may-truss-equilateral-triangle-given.gif

 

Calculate the following:
1.   The maximum axial load on member JK.

A.   64.59 kN C.   -64.59 kN
B.   -63.51 kN D.   63.51 kN

2.   The maximum axial load on member BC.

A.   47.63 kN C.   -47.63 kN
B.   -74.88 kN D.   74.88 kN

3.   The maximum compression force and maximum tension force on member CG.

A.   -48.11 kN and 16.36 kN
B.   Compression = 0; Tension = 16.36 kN
C.   -16.36 kN and 48.11 kN
D.   Compression = 48.11 kN; Tension = 0

 

Truss With Tension-Only Diagonals

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

2016-may-truss-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

 

Truss With Flexible Cable Diagonals

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

2016-may-counter-doagonals.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

 

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