MICROPLANE MODEL FOR CONCRETE .2. DATA DELOCALIZATION AND VERIFICATION

The new microplane model developed in the preceding companion paper is calibrated and verified by comparison with test data. A new approxima te method is proposed for data delocalization, i.e., decontamination o f laboratory test data afflicted by localization of strain-softening d amage and size effect. This method, applicable more generally to any t ype of constitutive model, is based on the series-coupling model and o n the size-effect law proposed by Bazant. An effective and simplified method of material parameter identification, exploiting affinity trans formations of stress-strain curves, is also given. Only five parameter s need to be adjusted if a complete set of uniaxial, biaxial, and tria xial test data is available, and two of them can be determined separat ely in advance from the volumetric compression curve. If the data are limited, fewer parameters need to be adjusted. The parameters are form ulated in such a manner that two of them represent scaling by affinity transformation. Normally only these two parameters need to be adjuste d, which can be done by simple closed-form formulas. The new model all ows good fit of all the basic types of uniaxial, biaxial, and triaxial test data for concrete.