高龄混凝土桥梁方形带肋钢筋疲劳性能试验研究OA

To investigate the fatigue properties of square ribbed steel bars,based on a 86-year-old concrete bridge in Suzhou,high-cycle fatigue tests of 12 standard specimens and low-cycle fatigue tests of 8 standard specimens were conducted.The high-cycle and low-cycle fatigue properties of the square ribbed steel bars were determined by the fatigue failure loading cycles,stress-strain hysteretic curves,and low-cycle fatigue models.The experimental results indicate that the square ribbed steel bars can withstand over 10 million fa-tigue cycles under the tensile stress with a stress ratio of 0.2 and a stress range of 156 MPa,and over 2.5 mil-lion fatigue cycles under the tension-compression stress state with a stress ratio of-1.0 and a maximum stress of 195 MPa.When the loading strain range is 0.6%,the square ribbed steel bars exhibit continuous cyclic soft-ening behaviors,while they demonstrate brief cyclic softening behaviors followed by persistent cyclic harden-ing behaviors when the loading strain range exceeds 1.0%.The low-cycle fatigue properties of the square ribbed steel bars can be simulated by the modified Coffin-Manson model.The recommended values for the fa-tigue damage parameter,strength degradation parameter,and fatigue failure index are 0.283,0.449,and 0.396,respectively.