An experimental and numerical approach for determining compression curves for plain and steel fiber reinforced concretes

ABSTRACT The stress-strain diagram of concrete is important for the design of concrete structures because compressive strength, peak deformation, modulus of elasticity and toughness can be obtained from this diagram. However, the stress-strain relationship is not commonly determined in concrete quality control trials, and usually, only compressive strength is determined. However, when more refined methods are used for designing concrete structures, such as physical nonlinear analysis with the finite element method, the stress-strain diagram is fundamental for structure analysis. In this case, the compression strain-strain curve should be determined in a laboratory, even if recommended curves from design codes are used. Thus, the objective of this paper is to propose a methodology to evaluate the compressive strain-strain diagram of plain and steel fiber reinforced concretes using low-cost test machines available in most concrete control laboratories. In addition, a numerical method is presented for inverse analysis of the strain-strain diagram, with the objective of estimating parameters for modeling concrete structures by means of damage mechanics.

摘要 混凝土应力-应变曲线（stress-strain diagram）对于混凝土结构设计具有重要意义，通过该曲线可获取抗压强度、峰值变形、弹性模量及韧性等关键力学参数。但在常规混凝土质量控制试验中，通常并不开展应力-应变关系测试，仅会测定抗压强度单一指标。然而，当采用更精细化的混凝土结构设计方法（如结合有限元法的物理非线性分析）时，应力-应变曲线是结构分析的核心基础依据。在此类场景下，即便采用设计规范推荐的曲线，仍需通过实验室测试获取受压应力-应变曲线。据此，本文提出一种测试方法，可依托多数混凝土质量控制实验室均配备的低成本试验机，测定素混凝土（plain concrete）与钢纤维增强混凝土（steel fiber reinforced concrete）的受压应力-应变曲线。此外，本文还提出一种用于应力-应变曲线反演分析的数值方法，旨在通过损伤力学（damage mechanics）手段为混凝土结构建模提供参数估计支持。