循环荷载作用下钢桥面铺装疲劳损伤失效行为研究

针对钢桥面铺装工程中普遍采用的改性沥青(Stone Matrix Asphalt,SMA)、浇筑式沥青(Guss asphalt,GA)、环氧沥青(Epoxy asphalt,EP)混合料双层铺装结构,进行了循环车载作用下钢桥面与沥青混凝土铺装疲劳损伤特性理论分析与试验研究。基于疲劳损伤度,研究了钢桥面铺装疲劳损伤失效行为和疲劳开裂过程中损伤场、应力和应变场动态演变机制,推导出疲劳失效时的损伤场、应力和应变场计算表达式,并给出钢桥面铺装疲劳寿命理论公式。以三座钢箱梁桥桥面铺装(润扬长江大桥2005,南京长江三桥2005,苏通大桥2008)为例,对不同铺装结构组合方案下的复合梁进行疲劳试验分析和使用寿命理论预测。实例研究结果表明,钢桥面铺装疲劳损伤失效行为预估模型合理可行;相较于改性沥青、浇筑式沥青,环氧沥青混合料具有较强高的强度低变形能力,更适合于大跨径钢桥面铺装抗疲劳的设计要求;由环氧沥青混合料组合而成的“双层环氧沥青混凝土”和“浇注式沥青混凝土(下层)+环氧沥青混凝土(上层)”的抗疲劳性能优于其它沥青混合料铺装结构组合方案,同等厚度组合情况下疲劳使用寿命可延长1倍~2倍以上;“双层环氧沥青混凝土”已应用于润扬长江大桥、南京长江三桥和苏通长江大桥钢桥面工程,并已成功运行10年以上,其跟踪观测结果良好。

Fatigue damage failure behavior of steel bridge pavement under cyclic loading

Aiming at SMA, GA and EP mixtures double-layer pavement structure adopted commonly in steel bridge pavement engineering, theoretical analysis and tests were conducted for fatigue damage characteristics of steel bridge surface and asphalt concrete pavement under cyclic vehicle loads. Based on the fatigue damage degree, fatigue damage failure behavior of steel bridge pavement and dynamic evolution mechanism of damage field, stress and strain ones in fatigue cracking process were studied, and calculation expressions for damage, stress and strain fields during fatigue failure were deduced. The fatigue life theoretical formula for steel bridge pavement was derived. Steel box girder bridge pavements of Runyang Yangtze River Bridge 2005, Nanjing Yangtze River Third Bridge 2005 and Sutong Yangtze River Bridge 2008 were taken as examples, fatigue tests and predictions using the fatigue life theory were conducted for composite girders under different pavement structure combination schemes. The actual examples’ study results showed that the prediction model for steel bridge pavement fatigue damage failure behavior is reasonable and feasible; compared with SMA and GA, EP has higher intensity and stronger low-deformation ability, and it is more suitable to meet anti-fatigue design requirements of long-span steel bridge pavement; the anti-fatigue performances of double-layer EP and "upper layer EP +lower layer GA" are superior to those of other pavement structure schemes, and their fatigue life is 1-2 times longer than other’s with the same thickness; double-layer EP is applied in pavements of the three bridges mentioned above, these bridges’ pavements operate successfully for more than 10 years, and their follow-up observation results are good.