体外预应力钢-混结合梁桥温度效应分析

Temperature Effect of Steel-concrete Composite Girder Prestressed with External Tendons

针对简支体外预应力钢-混结合梁,考虑钢梁与混凝土之间的相对滑移,温度沿混凝土截面线性分布,体外预应力筋直线布置,剪力钉所受到的剪力和钢梁与混凝土板的相对滑移呈线性关系,推导出结合梁及体外预应力筋由温度效应产生的内力计算公式。通过算例与有限元分析进行对比,并讨论了在日照温度效应下,各种因素对体外预应力钢-混结合梁温度应力的影响。结果表明:公式法和有限元法计算结果吻合;日照温度效应使简支结合梁的混凝土板受压,钢梁顶部受拉,底部受压,对体外预应力筋应力影响很小;当剪力钉刚度足够大时,温度应力不随剪力钉刚度变化而变化,剪力钉布置和桥梁跨度对体外预应力钢-混结合梁温度应力的影响不大。

Considering shear slippage inhering at the interface between the steel beam and the concrete flange, stresses caused by temperature effect in steel-concrete composite girder prestressed with external tendons were investigated. It is assumed that the temperature is distributed linearly over the depth of the concrete slab but uniformly in the steel section, the external prestress tendons are straightly arranged and the shear-slip interaction at the interface between the concrete slab and the steel beam is linear. The analytical formulas of inner forces for the composite beam and the developed tendon stresses induced by the temperature effect were derived. A parametric study based on the analytical formulas was carried out, and the results were compared well with the results from the finite element analysis. Discussions and suggestions are finally drawn in respect to the stiffness of shear connectors, and the thermal stresses induced by temperature effect in steel-concrete composite girders. It is concluded that, thermal effect on a simply supported composite beam induced by the sun irradiation will make the concrete slab and bottom of the steel section in compression and the top of the steel section in tension, but very slight influence on the external tendons; if the stiffness of shear connectors along the beam is sufficient, the temperature stresses in the beam will not vary with the stiffness change of shear connectors, and the spacing and arrangement of the shear connectors as well as the span of the beam have negligible effect on the thermal stresses in the steel and concrete composite beams prestressed with external tendons.