单箱多室鱼腹形截面混凝土箱梁的偏载效应

Eccentric Load Effect of Single-box Multi-cell Fish-bellied Section Concrete Box Girder

摘要:

鱼腹形箱梁的横向偏载较普通箱梁更为复杂，其偏载系数能否沿用现行近似计算方法进行计算值得深入研究。以某一跨单箱多室鱼腹形截面混凝土箱梁桥为工程背景，采用梁格法进行受力分析，提出按各梁肋的实际荷载横向分布系数来计算箱梁偏载系数的简化公式，并与经验系数法、偏心压力法和修正偏心压力法等近似处理方法的计算结果进行对比。结果表明：与有限元单位力法结果相比，梁格单位力法的计算值和经验系数法的估计值均偏小，偏心压力法和修正偏心压力法的计算值均偏大，因此采用偏心压力法和修正偏心压力法来近似计算此类箱梁的偏载系数偏于安全。根据有限元单位力法计算结果，建议单箱多室鱼腹形截面混凝土箱梁的偏载系数取1.2。

Abstract:

The lateral eccentric load of fish-bellied box girder is more complex than that of the ordinary box girder. Whether the current approximate calculation method can be used for its eccentric load coefficient is worthy of further study. Based on the engineering background of a single-span single-box multi-cell fish-bellied section concrete box girder bridge, the beam grillage method is used to analyze the stress. A simplified formula is proposed to calculate the eccentric load coefficient of box girder according to the actual load transverse distribution coefficient of each girder rib, which is compared with the calculation results of approximate processing methods such as empirical coefficient method, eccentric pressure method and modified eccentric pressure method. The result shows that compared with the result of the FEM unit force method, the calculated value of the beam grillage unit force method and the estimated value of the empirical coefficient method are both smaller, and the calculated values of eccentric pressure method and modified eccentric pressure method are both too large. Therefore, it is safe to use the eccentric pressure method and the modified eccentric pressure method for approximately calculating the eccentric load coefficient of this kind of box girder. According to the calculation result of the finite element unit force method, it is suggested that the eccentric load coefficient of single-box multi-cell fish-bellied section concrete box girder should be 1.2.