EFFECT OF LOADING RATE ON SOFTENING BEHAVIOR OF LOW-RISE STRUCTURAL WALLS

Cracked reinforced concrete in compression has been observed to exhibi t lower strength and stiffness than uniaxially compressed concrete. Th e so-called compression softening effect responsible is thought to be related to the degree of transverse cracking and straining present. It significantly affects the strength, ductility and load-deformation re sponse of a concrete element. A number of experimental investigations have been undertaken to determine the degree of softening that occurs, and the factors that affect it. At the same time, a number of diverse analytical models have been proposed by various this behavior. III th is paper, the softened truss model thoery for low-rise structural shea rwalls is employed using the principle of the stress and strain transf ormations. Using this theory the softening parameters for the concrete struts proposed by Hsu and Belarbi as well as by Vecchio and Collins are examined by 51 test shearwalls available in literature. It is foun d that the experimental shear strengths and ductilities of the walls u nder static loads are, in average, very close to the theoretical value s: however, the experiment shear strengths and ductilities of the wall s under dynamic loads with a low (0.2 Hz) frequency are generally less than the theoretical values.