effect of reinforcement type on the tension stiffening model of ultra-high performance concrete (uhpc)

Ultrahigh performance concrete (uhpc) is a developing concrete and today is increasing to interest using it in structures due to its advantages such as highcompressive strength, modulus of elasticity, highly durability and lowpermeability. therefore, it is necessary to provide models for prediction of nonlinear behavior of this material. this study is aimed to investigate the tensionstiffening phenomenon for uhpc and to propose a model for the postcracking behavior of the reinforced concrete members under tension. for this purpose, in this study, 24 cylindrical concrete specimens reinforced with a rebar in its center were prepared using uhpc and two rebar types including steel and gfrp (glass fiber reinforced polymer). three specimen diameters (65 mm, 100 mm, and 125 mm), and two rebar diameters (12 mm and 16 mm) were considered. all specimens were tested under direct tension. according to the experimental data, a tensionstiffening model was proposed for uhpc. the proposed model has suitable correlation with experimental results.