中文摘要：

针对桥梁钢Q345q D的力学性能及高周疲劳特性,分别使用直径10,mm的圆棒试件和沙漏型试件进行了轴向拉伸试验及轴向疲劳试验,得到Q345q D完整的材性数据及应力-寿命曲线（S-N曲线）.考虑到材料疲劳寿命离散性较大,为了便于工程应用,采用单侧容限统计方法,研究在给定置信度下各应力水平对应的Q34q D的安全疲劳寿命,得出了同时考虑置信度和存活率的设计疲劳曲线.研究结果表明桥梁钢Q345q D在常温下具有较好的疲劳性能,随应力水平的降低疲劳寿命明显增大,疲劳寿命曲线迅速趋于水平,疲劳极限在Smax=273278,MPa之间.

英文摘要：

The mechanical properties and high cycle fatigue behavior of bridge steel Q345qD were studied.A number of axial tensile tests and axial fatigue tests were conducted using 10,mm-diameter round bar specimens and hourglass specimens respectively.The accurate data of material properties and stress-life curve(S-N curve)were ob-tained.Taking into account the large discreteness of material fatigue life,in order to facilitate engineering applica-tions,unilateral tolerance statistical methods were adopted to study the Q345qD safety fatigue life at a given confi-dence level for each stress level.The safe life fatigue curves with confidence and survival rate were also obtained.The results show that the bridge steel Q345qD has good fatigue properties at room temperature.The fatigue life increases significantly with the decrease of stress level and the fatigue curve tends to reach the horizontal level quickly.The fatigue limit lies within the range ofSmax=273-278,MPa.