Calculate line pipe concrete stiffness factor and effective EI from the concrete pipe EI ratio for general pipe.
The concrete stiffness factor is used to account for the effect of the concrete layer on the bending modulus EI and the natural frequency. The concrete stiffness factor is calculated from the ratio of concrete EI over pipe EI.
`CSF= A ((EIc) / (EIp))^0.75 `
`EI = EIp (1 + CSF) `
where :
CSF = concrete stiffness factor
EIc = concrete EI
EIp = pipe EI
EI = effective EI
A = 0.33 for asphalt coating and 0.25 for PP/PE coating
The concrete stiffness factor is calculated in accordance with DNVGL RP F105. Use the Result Plot option to plot the concrete stiffness factor (CSF) versus EI ratio and CSF type, or effective EI versus EI ratio and CSF type. Refer to the help pages for more details.
Reference : DNVGL RP F105 Free Spanning Pipelines (Download From DNVGL website)
Tool Input
- coptype : Cross Section Type
- EIcu : User Defined Concrete E x I
- EIC/EIPu : User Defined E x I Ratio
- csftype : Concrete Stiffness Factor Type
- Kcu : User Defined Coating Factor
- CSFu : User Defined Concrete Stiffness Factor
- EIp : Beam E x I
Tool Output
- CSF : Concrete Stiffness Factor
- EI : Effective E x I
- EIC/EIP : E x I Ratio