# 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.

Compression parallel to grain = 11 MPa

Compression perpendicular to grain = 5 MPa

Shear parallel to grain = 1 MPa

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

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.

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.

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 |