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A client wishes to use an existing steel beam to lift a 1 tonne load using a sling. The 3 m long beam is measured as UB 203x133 visually observed at both ends to be secure with end-plates with all four bolts present.

calculation

For conservatism assume the lowest credible strength steel i.e. S275 steel and the lightest section i.e. UB 203 x 133 x 25. From the Blue Book for $L_{ef}$ = 3 m, the design moment capacity $M_{Rd}$ = 54.6 kNm ($c_1$ = 1.00).

There is no dead load on the beam. Use partial safety factor $\gamma$ = 1.6 for imposed load.

Design load $F_{Ed}$ = 10 kN x 1.6 = 16

By inspection beam is OK in shear. All 4 bolts present in each end plate so connection is OK. Check beam in bending.

Treat the beam as simply supported and assuming sling midspan:

$M_{Ed} = \frac{PL}{4} = \frac{16 \times 3}{4} = 12$ kNm < 54.6 kNm $\therefore$ lift OK

Please provide feedback on this assessment with a criticism or suggestions for improvement.

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  • $\begingroup$ Don't insurance requirements mean a beam which has been tested with an SWL stated for it? $\endgroup$
    – Solar Mike
    Sep 18, 2019 at 13:50
  • $\begingroup$ For lifting, you need to include a dynamic amplification factor. $\endgroup$
    – ingenørd
    Sep 18, 2019 at 16:04

1 Answer 1

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If you use the sling with a winch you have to consult the winch's manufacturer instructions usually printed on a tag or side of the winch.

Usually, they recommend a dynamic load factor of 3 to 4 which will make your factored load moment 40kN but still less than allowable 54.6kN.

A ton is 9.81kN, but rounding up is ok.

the rest of your work seems to be ok.

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