TypeIV
Structural
- Jun 28, 2004
- 27
I am trying to determine how the AASHTO-LRFD code wants me to determine the lateral earth pressures(EH)against the outside walls of an reinforced concrete box culvert due to Earth Loads and Live Loads(HL93).
I have a box culvert that has complicated and unconventional transitions from a single "horseshoe" box to a double and a double to a triple with varying heights etc.
1.) For this type of structure I am wondering if Rankine or Coulomb method should be used for lateral earth pressures.(I've read some people who believe that one should use "At-Rest" earth pressures for RCB.) Do I need to apply the soil-structure interaction factor that AASHTO requires for vertical pressures?
2.) How does the code want the live loads to be distributed on the walls. The governing live load pressure on one of the transitions is 690 psf on the top slab. Should I assume a surcharge height of 690 psf/120 pcf = 5.75 ft and apply it as a uniform horizontal load?
3.) The soil borings indicate water will be present for a significant length of the 1700 ft structure. Should I assume a Ko of, say 0.5, and find the soil pressure with Pe=0.5*(gamma soil - 62.4 pcf) + 62.4 pcf?
Thank you for your time. Any information the forum can offer would be greatly appreciated.
I have a box culvert that has complicated and unconventional transitions from a single "horseshoe" box to a double and a double to a triple with varying heights etc.
1.) For this type of structure I am wondering if Rankine or Coulomb method should be used for lateral earth pressures.(I've read some people who believe that one should use "At-Rest" earth pressures for RCB.) Do I need to apply the soil-structure interaction factor that AASHTO requires for vertical pressures?
2.) How does the code want the live loads to be distributed on the walls. The governing live load pressure on one of the transitions is 690 psf on the top slab. Should I assume a surcharge height of 690 psf/120 pcf = 5.75 ft and apply it as a uniform horizontal load?
3.) The soil borings indicate water will be present for a significant length of the 1700 ft structure. Should I assume a Ko of, say 0.5, and find the soil pressure with Pe=0.5*(gamma soil - 62.4 pcf) + 62.4 pcf?
Thank you for your time. Any information the forum can offer would be greatly appreciated.
