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针对钢桥面板顶板与U肋构造细节,通过振动疲劳试验机开展20个试件的弯曲疲劳试验,研究钢材强度对连接焊缝疲劳强度的影响,同时采用名义应力法与热点应力法,结合我国JTG D64—2015、日本JSSC颁布的《道路钢桥设计指南》、国际焊接协会IIW document XIII-1965-03/XV-1127-03给出的S-N曲线,对试验结果的疲劳强度进行评定。研究表明:随着钢材强度的提高,疲劳寿命略有缩短,裂纹扩展寿命的缩短幅度大于萌生寿命;高强钢的疲劳强度与传统钢材总体相当,97.7%存活率下Q345q D试件与Q420q D试件的疲劳强度相差在10%以内;基于热点应力法评估顶板与U肋细节时,建议采用75 MPa强度等级疲劳曲线。
According to the structural details of roof and U rib of steel bridge deck, the bending fatigue test of 20 specimens was carried out by vibration fatigue testing machine to study the influence of steel strength on the fatigue strength of the joint weld. At the same time, the nominal stress method and hot spot stress method were used, JTG D64-2015, Guidelines for Design of Road Steel Bridges promulgated by Japan’s JSSC, and SN curves given by the International Welding Society IIW document XIII-1965-03 / XV-1127-03. The fatigue strength of the test results was evaluated. The results show that with the increase of the strength of the steel, the fatigue life slightly shortened and the life span of the crack growth shortened more than the life of the steel. The fatigue strength of the high strength steel is generally the same as that of the traditional steel. The Q345q D specimen and Q420q D test The difference between the fatigue strength of the pieces is less than 10%. When the details of the roof and the U-rib are evaluated based on the hot spot stress method, it is recommended to use the 75-MPa strength grade fatigue curve.