Fiberglass Reinforced Plastic (FRP) - CAESAR II - Help

CAESAR II Users Guide

Language
English
Product
CAESAR II
Search by Category
Help
CAESAR II Version
12

The CAESAR II FRP pipe element models an orthotropic material whose properties can be defined by:

Ea - Axial Modulus-of-elasticity

Eh - Hoop Modulus-of-elasticity

nh/a - Poisson's ratio of the strain in the axial direction resulting from a stress in the hoop direction.

G - Shear Modulus (Not related to the Elastic Modulus and Poisson's ratio in the conventional manner.)

FRP pipe is specified by setting the Material box to 20. The material name displays and FRP properties from the configuration file display on the dialog box.

Some of the material parameters are renamed when the FRP material is selected: Elastic Modulus changes to Elastic Modulus/axial and Poisson's Ratio changes to "Ea/Eh*nh/a". The latter entry requires the value of the following expression: (Ea*nh/a) / Eh. This expression is equal to na/h, Poisson's ratio of the strain in the hoop direction resulting from a stress in the axial direction. The shear modulus G is defined by typing the ratio of G/Ea (shear modulus to axial modulus) on the special execution parameters screen. You can type only one ratio for each job.

The decrease in flexural stiffness at bends and intersections due to changes in the circular cross-section is typically negligible because the hoop modulus is usually considerably higher than the axial modulus for FRP pipe. Because of this, a default flexibility factor of 1 is used for these components. Similarly, because the fatigue tests performed by Markl on steel pipe are likely to have no bearing on FRP design, the software applies a SIF of 2.3 to all fittings. CAESAR II uses these recommendations for all FRP fittings unless you specifically override the defaults. You can override the defaults on a point-by-point basis or by forcing all calculations to adhere to the requirements of the governing code through a CAESAR II configuration parameter. Note that if the BS 7159, UKOOA, or ISO 14692 code is in effect, all SIFs and flexibility factors are calculated according to that code regardless of the configuration parameter settings.