钢-UHPC组合桥面的疲劳性能研究

Fatigue Performance of Steel-UHPC Composite Bridge Deck

目的研究钢-UHPC组合桥面的疲劳裂纹类型和发展规律,分析疲劳裂纹对组合桥面板结构受力特性的影响,为钢-UHPC组合桥面的设计提供理论依据。方法依据实桥主桥钢桥面的构造参数,设计制作了两个足尺试验构件,进行静载、疲劳试验,并与有限元计算结果进行对比分析。结果有限元模型计算的各测点应力和位移与实测值基本吻合;纵肋与横隔板连接焊缝处容易发生疲劳裂纹,所有试件均在此处发现了裂纹;纵肋腹板裂纹较小时,对钢桥面受力性能影响较小;随着纵肋腹板裂纹、UHPC与钢桥面板脱层扩展,试件刚度显著下降,最大挠度增量达33%。结论纵向配筋不同的两个构件其受力特性和疲劳性能差异不大,建议UHPC层中纵向钢筋可按直径10 mm密配筋布置。

To investigate fatigue crack patterns and their influence on structural behavior of the steel-UHPC composite deck under cycling loading and enable the fatigue design specification.Two full-scale bridge deck specimens were designed and fabricated with the specific detailing and dimensions in accordance to the prototype bridge deck of a real bridge for static and fatigue tests.Compared with the test results,the FE-based computational results were found agree with the measured stress and displacement at the concerning points.The fatigue cracks observed were prone to occur at the joints between the longitudinal ribs and the transverse diaphragm for all specimens.It is concluded that when crack initiates in the rib web,very small change would occur in the rib stresses and in the deflection of bridge deck.But with further development of fatigue cracks in the rib web,and delamination between the UHPC layer and the steel deck,the flexural stiffness of the bridge deck specimen decreased significantly,and a 33%increment in the deflection was observed in the tests.The two specimens,though were not identical the same in longitudinal steel reinforcement,they appeared similar structural and fatigue performance.The optional rebars of 10 mm in diameter are suggested for the longitudinal steel reinforcement in UHPC layer.