Bolt failure study in a heavy steel plate lap shear joint

10/12/17 rev A

Don Blanchet

3B Associates

dwb3298@verizon.net

15” x 10” x 1” plates lap shear

¾ UNC-10 – 8 placesPrepared forCBL constructionVitoria , Brazil

Lift Rigging Safety

Goals

Evaluate the grade 5 ¾ inch bolts that are in use.

Demonstrate sequential bolt failure.

Set the maximum load capacity.

Heavy lift rigging fixture application factor of safety.

Bolt Torque

Results 8 bolts 2 failures

Results: 8 bolts 2 failures

Fixed endwelded

Load applied6000 lbs

Results 6 bolts 4 failures

Results: 6 bolts 4 failures

Fixed endwelded

Load applied6000 lbs

With a 3 ton load , the assembly will fail completely In sequence 2-bolts, 4-bolts, 2-bolts

Bolt Safe loading – 1.5 Tons

Bolts factor of safety 1.2or 20% margin of safety

Max stress in platesfactor of safety = 2.6

Recommendations

Stamp plates with “max load 1.5 tons”

Change from grade 5 to Grade 8 bolts