基于NSGA-Ⅱ的开口肋钢-UHPC组合桥面多目标优化

Multi-objective Optimization of Open-Ribbed Steel-UHPC Composite Bridge Deck Based on NSGA-II

为研究开口肋正交异性钢-超高性能混凝土(UHPC)组合桥面的疲劳性能,通过子模型法建立实体-壳单元有限元模型,获得了轮载作用下疲劳敏感细节的应力响应。分析得出,所有疲劳细节应力水平均不大,除了纵肋-横隔板接头处横隔板细节属于有限寿命外,其余疲劳细节均可实现无限寿命。结合试验设计与响应面法,得到了横隔板侧细节应力幅的构造参数回归模型,可不开展数值分析,立即提取给定构造参数下的横隔板侧细节应力幅。为进一步实现横隔板侧细节的无限疲劳寿命设计,采用NSGA-Ⅱ算法对结构开展多目标优化。通过Pareto前沿面得出:横隔板侧应力幅越小,结构重量越大。在结构重量较小的条件下,能够实现无限疲劳寿命的设计参数为面板厚度10 mm、横隔板间距2.4 m且厚度不低于12 mm。

To investigate the fatigue behavior of an open-ribbed orthotropic steel-UHPC composite bridge deck,a solid-shell finite element model,based on the sub-model approach,was established to derive the stress response of fatigue-prone detail under wheel loading.The analysis indicates that the stress levels of all structural details are small,and all structural details,except the floorbeam detail at rib-to-floorbeam joint,can achieve an infinite life.By combining the experimental design and response surface method(RSM),a regression model of structural parameter for the stress range of floorbeam detail was obtained.The stress range of floorbeam detail,under specified structural parameters,can be quickly obtained without numerical analysis.To further achieve a design with infinite fatigue life for floorbeam detail,the NSGA-II algorithm was utilized to carry out the multi-objective optimization of the structure.The Pareto front shows that a smaller the stress range of floorbeam detail leads to a larger structure weight.The design parameters achieving an infinite-life design are the deck plate thickness of 10 mm,the floorbeam thickness of not less than 12 mm and the floorbeam spacing of 2.4 m,with a relatively small structure weight.