ACI PRC-350.2-2021 Hazardous Material Containment in Concrete Structures—Report. 2.2.4.2 Pavement slabs—Pavement slabs typically capture precipitation and spills of hazardous materials in areas where vehicles or other concentrated loads are anticipated. Pavement slabs can be either prestressed or nonprestressed and designed as plates on elastic foundations. A qualifed geotechnical engineer should determine the properties of the subgrade, including soil classifcation and modulus of subgrade reaction. Acceptable analytical techniques include fnite element, fnite diference, and other techniques that give comparable results. Flexural and punching shear stresses should be used to design the conventional and prestressed reinforcement. Nonprestressed pavement slabs designed for vehicle loads of AASHTO H-10 or heavier should be at least 8 in. (200 mm) thick and should contain two layers of reinforce- ment in each direction. The slab thickness for lighter wheel loads may be according to Section 2.2.4.1. The reinforce- ment percentage should total at least 0.5% of the cross- sectional area in each orthogonal direction, with at least one-half, but not more than two-thirds, of this amount in the upper layer. ACI 350 provides requirements for the design of fexural reinforcement, including the additional “environ- mental durability factor,” where applicable. 2.2.7 Minimum nonprestressed reinforcement for prestressed concrete—The minimum nonprestressed rein- forcement in prestressed concrete containment structures should be 0.15 percent for secondary containment and 0.30 percent for primary containment when movement due to shrinkage is partially restrained, such as slabs-on-ground. It should be the same as recommended for nonprestressed concrete wherever movement due to shrinkage is fully restrained, such as when concrete is placed against and bonded to hardened concrete at a construction joint. 2.2.8 Roofs 2.2.8.1 Joints in roofs—Liquid-tight cast-in-place roofs should be placed without construction joints whenever possible. When joints in cast-in-place roofs are unavoid- able, they should be designed and detailed according to the recommendations of Sections 2.2.5 and 2.2.6. Joints between precast roof members should be designed and detailed for liquid-tightness with requirements provided by ACI 350 and Section 3.2 of this report. 2.2.8.2 Roof design—ACI 350 provides requirements for the design of domes and roof slabs for concrete liquid- containing structures. Roof slabs can be either prestressed or nonprestressed. Acceptable analytical techniques include fnite element, fnite diference, equivalent frame, and other techniques that give comparable results. Flexural and punching shear stresses should be used to design the section thickness and conventional and prestressed reinforcement. Flat nonprestressed roof slabs should be at least 6...
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