Study On Flexural Fatigue Performance Of Hybrid Fiber Reinforced Concrete

The background of this thesis is based on scientific and research construction project of "hybrid fiber reinforced concrete and its application in wet joint of city's elevated rail bridge ".The study is supported by Sheshui No.1 bridge. For simply supported continuous beam bridge with wet joint,the weakest section is situated in wet joint. In order to meet the complicate force-bearing demand, we cast steel-polypropylene hybrid fiber reinforced concrete in wet joint.A few tests which led by Professor Lu zhean and Professor Wangji in Wuhan University of Technology have proved that steel-polypropylene hybrid fiber reinforced concrete has the better perforemance of toughness and fatigue. In order to find the difference in the perforemance of fatigue resistance between plain concrete and hybrid fiber reinforced concrete., we keep the concrete mix the same as construction site.Flexural strength tests of 10 samples are studied (1 OOmmx 100mmx400mm) to investigate the influence on flexural strength after adding steel fibre and polypropylene fibre.in addition,we use the method of PCM to calculate toughness index of plain concrete and hybrid fiber reinforced concrete.Fatigue tests of 31 samples (1 OOmmx 100mmx400mm) are studied to get fatigue life on three stress levels (0.75,0.8,0.85), The Weibull distribution parameters at every stress level are get by analyzing fatigue life,More,the fatigue lifes of different livabilities are simulated through using Weibull and both single-logarithmic and double-logarithmic fatigue equations of different livabilities are regressed to offer theory evidence for actual engineering.At last,the thesis collectes fatigue strain under cyclic loading through dynamic strain gauge, then get the characteristics of fatigue damage and damage evolution law through data processing.