The mechanical properties and failure modes of concrete are affected by strain rate. Therefore, various experimental methods have been used to quantify the strain-rate dependency of concrete properties, such as the spalling test by using a Hopkinson bar. In the test, pullback velocity at the free-end surface of the specimen is usually measured to evaluate the dynamic tensile strength of concrete, instead of directly measuring the critical stresses at the damaged location(s) due to experimental constraints. Herein, such indirect measurements of tensile strength are compared with direct determinations of tensile strength based on lattice models of the spalling tests. To represent rate-dependent material behavior, rheological units are introduced within the lattice elements. The parameters of the rheological units are calibrated through comparisons with experimental data. The calibrated values remain unchanged in subsequent simulations, which can be regarded as virtual spalling tests at various high strain rates of loading. The separation of viscous and inertial contributions to apparent tensile strength provides insights into the dependence of actual tensile strength on high strain rates. The simulation results indicate indirectly measured dynamic tensile strength, as commonly done in practice, is sufficiently close to directly measured strength.

中文翻译：

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使用基于晶格的剥落试验模拟评估混凝土的动态抗拉强度

混凝土的力学性能和破坏模式受应变速率的影响。因此，各种实验方法已被用于量化混凝土性能的应变率依赖性，例如使用霍普金森杆的剥落试验。在试验中，通常测量试件自由端表面的回拉速度来评估混凝土的动态抗拉强度，而不是直接测量受实验约束的损坏位置的临界应力。在此，将这种拉伸强度的间接测量与基于剥落试验的晶格模型的拉伸强度的直接测定进行比较。为了表示与速率相关的材料行为，在晶格元素中引入了流变单位。通过与实验数据的比较来校准流变单元的参数。校准值在随后的模拟中保持不变，可以看作是在各种高应变率加载下的虚拟剥落试验。对表观拉伸强度的粘性和惯性贡献的分离提供了对实际拉伸强度对高应变率的依赖性的见解。模拟结果表明间接测量的动态拉伸强度，正如在实践中通常所做的那样，与直接测量的强度非常接近。对表观拉伸强度的粘性和惯性贡献的分离提供了对实际拉伸强度对高应变率的依赖性的见解。模拟结果表明间接测量的动态拉伸强度，正如在实践中通常所做的那样，与直接测量的强度非常接近。粘性和惯性对表观拉伸强度的贡献的分离提供了对实际拉伸强度对高应变率的依赖性的见解。模拟结果表明，在实践中通常进行的间接测量的动态拉伸强度与直接测量的强度非常接近。