Question

A crane which has a 30m long jib inclined at 70degree to the horizontal is used to lift a load W at the free end as shown in Fig.1. The job is secured at the top end by a cable and pinned at the bottom end to the base such that only in-plane displacement is allowed (i.e consider I about axis zz). It has a hollow rectangular cross-section with a depth of 500mm, a width of 250mm and a wall thickness of 10mm. It is fabricated from steel with Young's modulus of 200 GPa. If W = 250kN, the factor of safety for the load with respect to in-plane buckling is given by:

Jib 30 m Cable t=10mm 500 mm 10 w 250 mm Pinned at base Section at X-X

1) 2.35

2) 1.78

3) 1.47

4) none of the above

Answer 1

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knauw 4 L2 2. /2 EN 23 4.9 2