Crack initiation phenomenology

For inelastic analysis, phenomenological axial, shear, and flexural constitutive relations should be specified, possibly with cracking and post-failure modeling capabilities and, if possible, interaction of axial/flexural and shear stresses. Where this is not possible and given that the variation of axial loads is not high for low-rise buildings, uncoupled values may be assumed based on initial state vertical load levels. 

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