考虑拉伸刚化效应的纤维网格增强超高性能混凝土弯曲性能

Flexural Properties of Textile Reinforced Ultra-High Performance Concrete with Tension-Stiffening Effect

纤维网格增强超高性能混凝土(TR-UHPC)利用短切钢纤维与连续纤维网格协同增强机制进一步提高超高性能混凝土(UHPC)力学性能和应变硬化效应。为研究TR-UHPC薄板的弯曲性能及其设计方法,开展了四点弯曲试验,分析了钢纤维和纤维网格的协同增强增韧效应。在此基础上,提出了基于拉伸模型和弯曲模型的TR-UHPC弯曲构件设计方法,并分析了拉伸刚化效应对TR-UHPC构件受弯性能的影响。研究结果表明,TR-UHPC薄板的受弯承载力随着钢纤维掺量及纤维网格层数的增加而增大,而多组试件在钢纤维掺量为1.0%或1.5%时达到最高弯曲强度,钢纤维用量可有效降低。弯曲模型计算结果与试验数据吻合较好,并能够匹配拉伸模型的计算结果,该方法可在材料已知的条件下对构件的承载力进行预测,或根据构件性能需求进行材料调配,实现从材料到构件的协同设计。

Textile reinforced ultra-high performance concrete(TR-UHPC)utilizes the synergistic reinforcing mechanism of short steel fibers and textile to further improve the mechanical properties and strain hardening effect of ultra-high performance concrete(UHPC).To investigate the flexural properties of TR-UHPC and synergistic effects of textile and steel fibers,four-point bending tests were conducted.A design method for TR-UHPC flexural members based on a tension-stiffening model and a bending model was proposed.The effect of tension-stiffening on the flexural responses of TR-UHPC was analyzed.The results show that the flexural capacity of TR-UHPC specimens increases with the increase of steel fiber dosage.The maximum flexural strength can be obtained at a steel fiber volume fraction of 1.0%or 1.5%,indicating that the content of steel fiber can be effectively reduced.The prediction data by the proposed model are in reasonable agreement with the experimental results.The proposed model can be used to predict the load capacity of TR-UHPC flexural member with given materials,or guide the material design according to the demands of structural performance.