Fiber reinforced plastic (FRP) bars reinforced engineered cementitious composites (ECC) beams without stirrups own excellent torsional performance and good application prospect. However, the corresponding torsional strength design method is not available. In order to predict the torsional strength of the ECC beams, a theoretical design method is established in this research. The proposed design method is based on the variable-angle space truss (VAST) model, and the tensile resistance supplied by fibers is carefully considered. The established design method is verified through the experimental results. It can be found that the predicted values agree well with the experimental values. A parametric analysis is carried out. Ultimate torque (i.e., torsional strength) increases significantly with the increment of ECC strength grade or longitudinal reinforcement ratio. However, at the same cross-section area, ultimate torque decreases slightly with the increment of height/width ratio. In addition, the cost effectiveness of the ECC beams without stirrups is discussed. Compared with mortar beam with a stirrup reinforcement ratio of 0.7%, FRP bars reinforced ECC beams without stirrups have small cost/ultimate torque ratio (a reduction ratio of 39.14%–60.86%), indicating that the ECC beams without stirrups own satisfactory cost effectiveness. This study will provide a torsional strength design guideline for FRP bars reinforced ECC beams without stirrups.

中文翻译：

---

FRP筋无箍筋ECC梁抗扭强度设计方法及造价分析

纤维增强塑料（FRP）筋增强无箍筋工程水泥基复合材料（ECC）梁具有优异的抗扭性能和良好的应用前景。但目前还没有相应的扭转强度设计方法。为了预测ECC梁的扭转强度，本研究建立了理论设计方法。所提出的设计方法基于变角度空间桁架（VAST）模型，并仔细考虑了纤维提供的拉伸阻力。通过实验结果验证了所建立的设计方法。可以发现，预测值与实验值吻合较好。进行参数分析。极限扭矩（即扭转强度）随着ECC强度等级或纵向配筋率的增加而显着增加。但在相同截面积下，极限扭矩随着高宽比的增加略有减小。此外，还讨论了无箍筋 ECC 梁的成本效益。与箍筋配筋率为0.7%的砂浆梁相比，FRP筋加固无箍筋ECC梁的成本/极限扭矩比较小（减少率为39.14%~60.86%），表明无箍筋ECC梁具有良好的成本效益。本研究将为无箍筋 FRP 筋增强 ECC 梁提供扭转强度设计指南。