基于SVM的PC刚构桥施工期时变可靠度

Time-dependent Reliability of PC Rigid Frame Bridge During Construction Based on SVM

为了研究早龄期混凝土材料时变性能,通过现场24组主梁同步养生试块力学试验结果,得到了早龄期混凝土弹性模量的时变规律.基于支持向量机(support vector machine,SVM)建立了施工期预应力混凝土(prestressed concrete,PC)刚构桥标高控制可靠度模型,结合蒙特卡洛法计算了PC刚构桥标高控制可靠指标.结果表明:主桥同样状态下,混凝土弹性模量与龄期之间的关系呈现幂函数关系,PC刚构桥中悬臂阶段与最大悬臂阶段应以不同的自由端挠度偏差容许值控制,中悬臂阶段自由端挠度偏差容许值最大不高于4 mm,最大悬臂阶段自由端挠度偏差容许值最大不高于20 mm.

In order to study the material time-dependent performance of early age concrete, the relationship between the early age concrete elastic modulus and the maintain time were obtained by 24 sets of standard prismatic concrete specimens which were made in construction site,and by synchronous maintenance in the deck. Then the function formula between them was optimized. The elevation control reliability model was established based on SVM （ support vector machine）,the reliability index were calculated by Monte Carlo method. The result shows that power function describes the relationship between the curing time and the elastic modulus of early age concrete. The cantilever stage and the maximum cantilever stage is controlled by different allowable deviation of deflection. To middle cantilever stage, the maximum allowable value of the free end deflection is not higher than 4 mm, while the maximum allowable value of the maximum cantilever stage is not higher than 20 mm.