AWWA D120-09 pdf download.Thermosetting Fiberglass-Reinforced Plastic Tanks
4.5.5.2 Long-term rupture strength. Unless otherwise determined by tests, the long-term strength of the laminate under sustained load shall be taken as 50 percent of the short-term strength determined by tests specifi ed in Sec. 5.3.4 and 5.3.5.
4.5.6 Environment eff ects. T e eff ects of exposure to the service environ- ment, both internal and external, on the strength and stiff ness properties shall be accounted for in design, based on tests specifi ed in Sec. 5.4.
4.5.7 Stress concentrations. The design of the FRP tank shall account for localized stress concentrations occurring at points of geometric or material discon- tinuities and at points of concentrated loads such as supports and attachments.
4.5.8 Underground tanks. The design of underground FRP tanks shall account for the interaction of the tank structure and the surrounding soil, using accepted structural design methods for fl exible underground vessels. The design shall account for the stresses resulting from the diff erential stiff nesses of stiff ening ribs, tank heads, compartmentation bulkheads, joints, and other attachments, rela- tive to the stiff ness of the tank shell wall.
4.6.4 Modulus of elasticity. T e modulus of elasticity of the laminate mea- sured in either tension or fl exure in accordance with Sec. 5.3.4 and 5.3.5 shall be no less than 700,000 psi. T e initial, unaged fl exural modulus of elasticity shall be deter- mined for evaluating the laminate for environmental exposure and quality control.
4.6.5 Tensile strength. T e initial, unaged ultimate tensile strength of the laminate in the weakest direction when measured in accordance with Sec. 5.3.4 shall be no less than 6,000 psi. When the weakest direction of the laminate is in the direction of curvature, the tensile strength shall be determined on samples cut from a test cylinder or fl at laminate fabricated to eliminate curvature in the direc- tion of testing.
4.6.6 Flexural strength. The initial, unaged ultimate fl exural strength of the laminate in the weakest direction when measured in accordance with Sec. 5.3.5 shall be no less than 12,000 psi. T e initial, unaged fl exural strength shall be deter- mined for evaluating the laminate for environmental exposure and quality control.AWWA D120-09 pdf download.