This paper addresses a new design of steel fibre reinforced ultra-high performance concrete (UHPC) composites by implanting the fibres into modified Andreasen and Andersen (MAA) particle packing model. A novel method for determining the equivalent spherical diameter of steel fibres is proposed, which preserves the effect on the wet particle packing of an UHPC system, when there are equal volume fractions of steel fibers or these extra spherical particles. Then, the employed steel fibres are treated as spheroidal particles, and implanted into the MAA model for the design of a new UHPC. To demonstrate that the newly designed UHPC has superior performance, its macro and micro properties are analyzed in detail. The obtained experimental results reveal that the utilized steel fibre (L = 13 mm, d = 0.2 mm) can be treated as a spheroidal particle with a diameter of 5.65 mm in the MAA model. Moreover, based on the method proposed in this study, the negative effect of steel fibres on the packing system of UHPC can be minimized, which can enrich the basic design theory of UHPC composites.

本文通过将纤维植入改进的Andreasen和Andersen（MAA）颗粒填充模型中，解决了钢纤维增强超高性能混凝土（UHPC）复合材料的新设计问题。提出了一种确定钢纤维等效球形直径的新方法，当存在相等体积分数的钢纤维或这些额外的球形颗粒时，该方法保留了对UHPC系统湿颗粒堆积的影响。然后，将使用的钢纤维视为球形颗粒，并植入到MAA模型中以设计新的UHPC。为了证明新设计的UHPC具有卓越的性能，将对其宏观和微观特性进行详细分析。获得的实验结果表明所使用的钢纤维（L = 13 mm，d = 0。在MAA模型中，可以将直径为2 mm的球体视为直径为5.65 mm的球形颗粒。此外，基于本研究提出的方法，可以最大程度地减少钢纤维对UHPC填料系统的负面影响，从而丰富UHPC复合材料的基本设计理论。