3D打印混凝土永久模板叠合梁抗弯性能研究

Bending behavior of composite beam with 3D printed concrete permanent formwork

为深入研究3D打印混凝土永久模板叠合梁受力性能,开展3D打印混凝土永久模板叠合梁四点弯曲试验,在叠合梁与现浇梁对照分析的基础上,考虑打印工艺造成的力学性能各向异性和打印层条界面存在微细观缺陷,建立数值模型,针对混凝土应力分布、荷载挠度曲线开展仿真分析,考虑材料强度、打印层条界面几何尺寸估计开展叠合梁设计参数敏感性分析。结果表明:打印模板上部层间缺陷是影响叠合梁抗弯承载能力及破坏失效的关键部位,3D打印混凝土层条界面几何尺寸影响叠合梁应力分布。随着层条界面厚度估计值增大,应力集中程度逐渐降低,承载能力逐渐增大。打印基体和现浇混凝土强度对打印模板叠合梁结构极限荷载的影响不显著,钢筋强度对叠合梁承载能力作用显著。

To investigate the mechanical properties of composite beams with 3D printed concrete permanent formwork, four-point bending test was carried out firstly in this study.Then, based on the comparative analysis of 3D printed composite beams and cast-in-place beams, numerical simulation models were established considering the anisotropy of mechanical properties and micro defects in 3D printed concrete caused by printing process.The stress distributions and load deflection curves of beams were simulated.The sensitivity analysis of design parameters on the property of the composite beam was carried out with comprehensive consideration of the material strength and the geometric size of the printed strip and layer interfaces.The results indicated that the interlayer defects of the upper part of the printed formwork are the key parts that affect the bending resistance and the failure of the composite beam.The estimated geometric dimensions of the interfaces affect the stress distribution of composite beams in the numerical simulations.As the estimated thickness of interfaces increases, the stress concentration decreases, and the load-bearing capacity increases.The strengths of 3D printed and cast-in-place concretes have no significant effect on the ultimate load of composite beam, while the strength of reinforcement may significantly affect the bearing capacity of composite beam.