超高性能混凝土单轴拉、压循环作用下力学性能及其本构模型研究

MECHANICAL PROPERTIES AND CONSTITUTIVE MODEL OF ULTRA-HIGH PERFORMANCE CONCRETE MATERIAL UNDER UNIAXIAL TENSION AND COMPRESSION CYCLES

  • 摘要: 超高性能混凝土(ultra-high performance concretre,UHPC)是一种新型材料,具有抗拉、抗压强度高、开裂后应变硬化等特点,在装配式结构领域具有较为广阔的应用前景。为了明确UHPC在单轴循环荷载下的受力性能并提出适合的本构关系,通过大量的试验建立循环荷载下UHPC的本构模型,设计具有不同钢纤维掺量的棱柱体和狗骨直拉试件,开展不同加载制度的单轴压缩试验,分析试验结果以明确钢纤维掺量、养护方式和加载制度对UHPC单轴拉压力学性能的影响情况。试验结果表明,在受压方面,钢纤维体积含量为2%的UHPC峰值压应变明显高于钢纤维体积含量为1%和3%的UHPC峰值压应变。各UHPC试件的弹性模量明显大于普通混凝土的弹性模量。在受拉方面,UHPC呈现出一定的应变硬化现象,且达到峰值后拉应力下降较为缓慢,展现出一定的受拉延性。钢纤维体积含量和蒸养处理对UHPC试件的抗拉强度有明显的提高作用。最后,在试验数据的基础上,提出了UHPC受压和受拉的骨架曲线和滞回准则,并拟合了卸载(再加载)的计算公式,可用于有限元计算中UHPC的基本本构方程。

     

    Abstract: Ultra-high performance concrete (UHPC) is a new material with high tensile, compressive strength and strain hardening after cracking, which has a wide application prospect in the field of assembled structures. To clarify the mechanical properties of UHPC under uniaxial cyclic loads, prism and dog-bone specimens with different steel fiber content are designed. Through uniaxial compressive and tensile tests with different loading regimes, the effects of steel fiber content, of maintenance mode and, of loading regime on uniaxial mechanical properties of UHPC are analyzed. The test results show that: the peak compressive strain of UHPC with the steel fiber content of 2% is significantly larger than that of UHPC with the steel fiber content of 1% and 3%. The elastic modulus of each UHPC specimen is significantly higher than that of traditional concrete. Furthermore, UHPC shows strain hardening phenomenon and ductility in tensile experiment. The content of steel fiber and steam curing treatment can significantly improve the tensile strength of UHPC specimens. Finally, upon the test data, the skeleton curves and hysteresis criteria of UHPC under compression and tension are proposed, and the formulae for the process of unloading (reloading) are fitted, which can be used for the basic constitutive model of UHPC in the numerical calculation.

     

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