SW6 Calculation for Reinforcement of Manhole Cover Holes
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For a DN500 manhole with an opening of 161, use pipes of size 159x7. The calculation results are as follows: 1. A hole of 161 mm in the manhole cover is acceptable ； 2. The calculation for reinforcement of the opening in a 159x7 tube fails – A1+A2+A3=805.3 mm2 and A=3012 mm2. Some people say that the opening in the manhole cover is acceptable, so there’s no need to carry out reinforcement for the 159x7 opening. What should be done in this situation?
The opening in the manhole cover (clear hole) has passed the inspection; no reinforcement is required for the 159x7 opening