铁路连续槽形梁桥剪力滞效应分析

为探究铁路连续槽形梁桥的剪力滞效应,以峰福线大目溪大桥为例,基于有限元法分析其在不同工况下的剪力滞效应情况,提出该结构有效宽度的建议值,并且分析截面形式对槽形梁剪力滞效应的影响。结果表明:纵桥向桥面顶板和底板桥梁中心线位置的剪力滞效应在中支座截面较为显著。不同工况作用下,中支座截面和主跨跨中截面桥面板出现正负剪力滞效应交替现象,桥面顶板剪力滞效应相比底板较为显著;对于恒载+活载工况下,中支座截面正剪力滞效应出现在顶板边缘位置和底板中心线处,而主跨跨中截面正剪力滞效应出现在顶板中心线处和底板边缘位置。在恒载+活载、主力+附加力两种工况下的有效宽度比建议值,主跨跨中附近截面取0.83、0.80,边支座截面附近取1,中支座截面取0.74、0.73;对于截面形式不同的槽形梁,其跨中截面的剪力滞效应也表现出顶板相比底板更为突出,当采用箱形桥面板时,因其桥面板中腹板的存在,会导致其剪力滞效应比板式桥面板严重。

Analysis of Shear Lag Effect in Railway Continuous Channel Girder Bridge

A research was carried out on the shear lag effect induced by a railway continuous channel girder bridge. Taking the Damuxi Bridge on the Hengfeng-Fuzhou Railway as an example, the shear lag effect was estimated under the various conditions by employing the finite element method. The range of effective widths for the structure was proposed, and the influence of different section forms for channel girders on the shear lag effect was also illustrated. It is shown that the shear lag effect occurring at the centerline of the bridge in the longitudinal direction of the deck slab is becoming remarkable in the middle support section. The phenomenon of alternating positive and negative shear lag effects in the middle support section and the main span middle section of the deck slab, and the shear lag effect is more pronounced on the upper surface of the bottom slab than on the lower surface of the main span section along the cross-bridge under different conditions. Under constant + live load conditions, the positive shear hysteresis effect in the middle bearing section is observed at the edge of the top plate and at the centre line of the bottom plate, while the positive shear hysteresis effect in the mid-span section of the main span is observed at the centre line of the top plate and at the edge of the bottom plate. For the two kinds of condition acting on the deck slab, including dead load + live load and main force + additional force, the suggested values about the effective width ratio are 0.83 and 0.80 near the middle of the main span, both 1 near the side support, and 0.74 and 0.73 at the middle support, respectively. The shear lag effect is more significant occurring at the upper surface of the deck slab in the main span section than that on the lower surface for the different cross-sectional forms of channel girders. In addition, the shear lag effect is more significant compared to bridge deck plate due to the presence of web in the deck when the box shaped bridge decks are used for channel girder bridge.