Wang Guang-Ming, Zhu Li, Ji Xin-Lin, Ji Wen-Yu
School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China.
Materials (Basel). 2020 Jul 22;13(15):3253. doi: 10.3390/ma13153253.
Curved steel-concrete composite box beams are widely used in urban overpasses and ramp bridges. In contrast to straight composite beams, curved composite box beams exhibit complex mechanical behavior with bending-torsion coupling, including constrained torsion, distortion, and interfacial biaxial slip. The shear-lag effect and curvature variation in the radial direction should be taken into account when the beam is sufficiently wide. Additionally, long-term deflection has been observed in curved composite box beams due to the shrinkage and creep effects of the concrete slab. In this paper, an equilibrium equation for a theoretical model of curved composite box beams is proposed according to the virtual work principle. The finite element method is adopted to obtain the element stiffness matrix and nodal load matrix. The age-adjusted effective modulus method is introduced to address the concrete creep effects. This 26-DOF finite beam element model is able to simulate the constrained torsion, distortion, interfacial biaxial slip, shear lag, and time-dependent effects of curved composite box beams and account for curvature variation in the radial direction. An elaborate finite element model of a typical curved composite box beam is established. The correctness and applicability of the proposed finite beam element model is verified by comparing the results from the proposed beam element model to those from the elaborate finite element model. The proposed beam element model is used to analyze the long-term behavior of curved composite box beams. The analysis shows that significant changes in the displacement, stress and shear-lag coefficient occur in the curved composite beams within the first year of loading, after which the variation tendency becomes gradual. Moreover, increases in the central angle and shear connection stiffness both reduce the change rates of displacement and stress with respect to time.
曲线钢 - 混凝土组合箱梁广泛应用于城市立交桥和匝道桥。与直组合梁相比，曲线组合箱梁呈现出包括约束扭转、畸变和界面双轴滑移在内的复杂弯扭耦合力学行为。当梁足够宽时，应考虑径向的剪滞效应和曲率变化。此外，由于混凝土板的收缩和徐变效应，曲线组合箱梁中已观测到长期挠度。本文根据虚功原理提出了曲线组合箱梁理论模型的平衡方程。采用有限元法得到单元刚度矩阵和节点荷载矩阵。引入龄期调整有效模量法来考虑混凝土徐变效应。这个26自由度的有限梁单元模型能够模拟曲线组合箱梁的约束扭转、畸变、界面双轴滑移、剪滞和时变效应，并考虑径向的曲率变化。建立了一个典型曲线组合箱梁的精细有限元模型。通过将所提出的梁单元模型的结果与精细有限元模型的结果进行比较，验证了所提出的有限梁单元模型的正确性和适用性。所提出的梁单元模型用于分析曲线组合箱梁的长期性能。分析表明，在加载的第一年，曲线组合梁的位移、应力和剪滞系数发生显著变化，之后变化趋势逐渐变缓。此外，圆心角和剪力连接刚度的增加均降低了位移和应力随时间的变化率。
