基于敏感分析的预制箱梁腹板斜裂缝机理研究

Research on the Mechanism of Inclined Cracks in the Web Plate of Prefabricated Box Girders Based on Sensitivity Analysis

预制小箱梁因其优异的受力性能,在高速公路中小跨径桥梁中广泛应用,经过多年运营后,主梁混凝土裂缝病害也越发突出。以某高速21座预制箱梁桥为调查对象,统计其基本病害,发现腹板斜裂缝是比较常见典型的病害。进一步分析其腹板斜裂缝发展规律和影响因素,从预应力损失、结构自重偏差、移动荷载提升方面进行敏感性分析,得出有效预应力损失过大是腹板产生斜裂缝的主要原因。

Prefabricated small box girders are widely used in small and medium-sized span bridges of expressways due to their excellent mechanical performance.After years of operation,the concrete crack disease of the main girder has become increasingly prominent.Taking 21 prefabricated box girder bridgesof an expressway as the investigation object,the basic diseases are counted,and it is found that the inclined cracks in the web plate are relatively common and typical diseases.The sensitivity analysis is made from the aspects of prestress loss,structural self-weight deviation,and moving load improvement by further analyzing the development law and influencing factors of inclined cracks in its web plate.It is concluded that excessive effective prestress loss is the main reason for inclined cracks in the web plate.