Experimental Study On The Mechanical Properties Of ECC Circular Section Short Columns Confined By Stirrup

Engineered fiber reinforced Cementitious Composite, whose abbreviation is ECC, has aroused widespread concern by domestic and foreign scholars for it displays excellent such as high toughness, high ductility and good control crack ability. At present, most of researches aimed at the analysis of uniaxial tensile or compressive properties of the unconstrained ECC and the study of constrain ECC are poorly. In this thesis, firstly, the conventional triaxial compression test on ECC and ECC short columns constrained by stirrups were conducted. Then the mechanical properties and failure mechanism of the latter were studied. Finally, the stress-strain calculation model was constructed, which based on parameters such as effective constraint index etc. All works were expected to provide basic data for engineering application of ECC. The main contents are as follows:1. According to test of ECC cylinder under triaxial compression, stress-strain curve of ECC under different water cement ratio and different confining pressure are obtained. The effect on ECC ultimate compressive strength and peak strain under different water cement ratio and different confining pressure were studied and the relation expression of ultimate compressive strength and peak strain and confining pressure were established.2. Through the axially compressive test of confined ECC circular section short columns, the stress-strain curve under different stirrup strength, ECC strength, stirrup spacing and PVA fiber content are obtained, and the influence of various parameters on stress-strain curve of confine ECC were studied.3. Theoretical equation of stirrup confine stress of circular section column was presented. The effect of effective constraint index and PVA fiber content on the peak strength, peak strain and ductility ratio were studied. The equation of peak stress, peak strain and effective constraint index, PVA fiber content of confine ECC is established.4. Based on the existing calculation model of the stress-strain curves of stirrup constraint concrete, the calculation model of the stress-strain curves which suits ECC short columns constrained by stirrup with a circular section was proposed.