Steel–concrete composite beams are commonly employed in civil constructions such as multi-storey building floors and long-span bridges. In case of significant span to depth ratios, excessive deflections and noticeable crack widths at the concrete slab may occur at the serviceability stage. In this context, internal or external pre-stressed tendons can be used as a remediation. In the latter case, significant effects of geometric non-linearity may arise due to the strain incompatibility between the external tendon and the composite member, resulting in a variable tendon eccentricity during deformation. In this paper, second-order effects are evaluated in eight pre-stressed steel–concrete composite beams for which experimental results are available. Hence, a three-dimensional finite element model using a Lagrangian description is proposed. The external tendons are represented by one-dimensional catenary elements, whereas the reinforced concrete slab and steel profile are modeled by shells finite elements. Slipping at the slab-beam interface and tendon-deviator locations are also included in the analysis. For the studied externally pre-stressed beams, the introduction of nonlinear geometric behavior yields lower collapses loads in relation to its linear counterpart, varying this difference between 6.4 and 9.1%.

钢混混凝土梁通常用于民用建筑中，例如多层建筑地板和大跨度桥梁。如果跨度与深度之比很大，则在使用阶段可能会在混凝土板上产生过度的挠度和明显的裂缝宽度。在这种情况下，内部或外部预应力筋可以用作补救措施。在后一种情况下，由于外部钢筋束和复合材料构件之间的应变不相容，可能会引起几何非线性的显着影响，从而在变形过程中产生可变的钢筋束偏心率。在本文中，对八种预应力钢-混凝土组合梁的二阶效应进行了评估，并获得了实验结果。因此，提出了使用拉格朗日描述的三维有限元模型。外部钢筋束由一维悬链线元素表示，而钢筋混凝土平板和钢型材则由壳有限元建模。分析中还包括在平板-梁界面处的滑移和肌腱偏移器的位置。对于研究的外部预应力梁，非线性几何行为的引入相对于其线性对应物产生更低的坍塌载荷，使此差异在6.4％和9.1％之间变化。