【摘要】 为了研究截面几何参数对混凝土薄壁桥塔温度应力的影响,基于某悬索桥混凝土桥塔实测日照温差,通过有限元方法分析了不同塔壁厚度、塔壁长宽比和塔壁内外表面角隅处倒角等条件下桥塔截面的温度应力,结果表明:改变塔壁厚度、塔壁长宽比和塔壁内侧角隅处倒角对桥塔温差应力均有不同程度的影响;在塔壁内外正温差条件下,桥塔内表面角隅处的温度应力随塔壁厚度的增加而增大;负温差条件下,塔壁外表面的温度应力随塔壁厚度的增加而减小;改变塔壁截面长宽比对改善塔壁截面温度应力的效果不明显;正温差条件下,在塔壁内侧截面角隅处设置倒角,可有效降低塔段内表面的温度应力,在考虑混凝土体积与抗压刚度的情况下,其倒角尺寸建议在0.3 m×0.3 m～0.5 m×0.5 m之间;负温差作用下,塔壁厚度比是重要设计参数,其取值不宜太大,较大的塔壁厚度比可以降低桥塔中心处温度应力,但同时会导致角隅处温度应力集中,混凝土体积增加,塔壁长宽比变小,从而导致桥塔的抗压刚度降低。在设计柱状薄壁箱形结构截面时,满足结构承载能力和工程造价的前提下,要充分考虑日照温差应力对薄壁箱型结构的影响,其研究成果可推广应用于其他桥型的混凝土空心薄壁箱型桥塔或桥墩截面设计中。更多还原

【Abstract】 In order to study the influence of sectional geometric parameters on the thermal stress in concrete thin-walled bridge pylon, based on the measured sunshine thermal difference of a suspension bridge concrete pylon, the thermal stress of bridge pylon section under different pylon wall thicknesses, aspect ratio of pylon wall and chamfers of inner and outer surface corners of pylon wall are analyzed by finite element method. The result shows that(1) the change of wall thickness, aspect ratio and chamfer of inner surface corners of pylon wall have different influences on the thermal difference stress in bridge pylon;(2) under the condition of positive thermal difference between inside and outside of pylon wall, the thermal stress at the inner surface corners of the pylon increases with the increase of wall thickness;(3) under the condition of negative thermal difference, the thermal stress at the outer surface decreases with the increase of wall thickness;(4) the aspect ratio of pylon wall section is almost independent of the thermal stress;(5) under the condition of positive thermal difference, the chamfering at the inner corners of pylon wall can effectively reduce thermal stresses at the inner surfaces of pylon sections, its value is suggested to be 0.3 m×0.3 m-0.5 m×0.5 m considering the volume and compressive stiffness of concrete;(6) under the condition of negative thermal difference, the pylon wall thickness ratio is an important design parameter, and its value should not be too large, while larger thickness ratio can reduce the thermal stress in the center of the pylon, but meanwhile it will lead to the concentration of thermal stresses in the corners, the increase of concrete volume and the decrease of aspect ratio of the pylon wall, which will lead to the decrease of compressive stiffness of the pylon. When designing the cross-section of columnar thin-walled box structure, the influence of sunshine thermal difference stress on thin-walled box structure should be fully considered on the premise of satisfying the bearing capacity of the structure and engineering cost. The study result can be extended and applied to the section design of concrete hollow thin-walled box pylon or piers of other bridge types.更多还原