35m/800t非对称整孔箱梁分幅架设试验研究

Experimental study on erection of 35m/800t asymmetric whole span box girder

宁波某高速公路工程项目采用"单车跨双幅梁上运梁,架桥机左右分幅架设35 m/800 t非对称整孔箱梁"技术方案.鉴于该技术方案为国内外首次采用,特开展架设施工过程中承压箱梁受力状态的试验测试和数值模拟分析.研究结果表明:架设施工过程中,最不利工况为运梁车运梁到位工况;最不利位置出现在跨中截面短翼缘侧底腹板交界处;且承压箱梁底板短翼缘侧纵向拉应力变化普遍大于长翼缘侧,存在一定的偏载效应,在施工过程中需引起注意;承压箱梁横向最大拉应力变化出现在箱梁横移到位,架桥机中支腿支点附近,此时架桥机中支腿荷载达到最大值;整体而言,承压箱梁混凝土应力未超限,运、架施工工艺安全可靠,并且架设效率高,值得类似工程借鉴和推广.

A highway project in Ningbo attempts to adopt the technical scheme of “one girder-transport-vehicle transports box girder across the left and right decks and the bridge machine erects the 35 m/800 t asymmetric whole span box girder”. In view of the first application of this technical scheme at home and abroad alike, this paper investigates the forced state about pressure bearing box girder during the erection by both experimental test and numerical simulation analysis. The results showed that the worst working condition during the erection is transporting the box girder to designed position. The junction of short flange and bottom of box girder web in mid-span section is the worst location for bearing load. Moreover, the change of the longitudinal tensile stress at the junction of short flange and bottom of pressure bearing box girder is generally larger than the long flange, for which the eccentric load effect should be paid attention to during the construction process. The change of the maximum transverse tension stress of the pressure bearing box girder appears when box girder is traversed to the designed position, where near the middle outrigger of bridge machine. At this time, the middle outrigger of bridge machine is bearing the largest load. Overall, during the construction process, the concrete stress of pressure bearing box girder has not exceeded the limited values. The results showed that new transportation and erection construction technology is safe, reliable and efficient, which is worth referencing and popularizing for similar projects.