Validation Study of a New Inelastic Material Model for Steel W-Shapes

The stiffness reduction of compact W-Shapes with an ECCS residual stress pattern was studied in detail using a fiber element model with over 2,000 elements. For a given moment, axial load and residual stress ratio, the distribution of stresses throughout the cross-section and associated reduced stiffness were evaluated and used to develop an inelastic material model for use as normalized tangent modulus expressions in MASTAN2. The material model's ability to develop realistic column strength curves over a range of W-Shape dimensions was studied. Ultimate load analyses were conducted on five benchmark frames using the new material model and were compared with the results obtained using advanced nonlinear finite element models. Discussion and recommendations are provided regarding the material model and its ability to determine the ultimate load capacity of different types of frames and loading conditions.

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