为研究钢/聚丙烯（PP）混杂纤维增强超高性能混凝土（UHPC）矩形截面柱（200 mm×400 mm）在偏心受压作用下的承载与变形规律，设计偏压柱进行结构偏心受压试验，根据试验荷载-位移全过程响应及破坏特征，研究截面偏心距与纵向钢筋配筋率对试件破坏形态、承载力特征点及变形能力的影响，同时与C50试件的受力性能进行对比。结果表明： 1）相较普通混凝土偏压柱，钢/PP混杂纤维增强UHPC偏压柱承载性能显著提高，其屈服荷载、峰值荷载和极限荷载分别提高62.04%、58.13%和13.48%。2）偏心距由150 mm增至300 mm时，构件变形能力增强；纵筋配筋率由0.67%增至0.79%时，变形能力进一步提升，且承载力与配筋率呈正相关关系。3）受拉区开裂后混杂纤维仍能持续提供抗力，对偏压柱承载与变形发展具有重要贡献。最后，基于试验极限弯矩并结合截面承载力计算，反算得到受拉区等效系数k推算建议值。
Hybrid fibers provide a crucial approach to improving the fire resistance, stray current corrosion resistance, and bearing performance enhancement of ultra-high performance concrete(UHPC) segments. Eccentric compression represents the fundamental stress state of segments. This study investigates the bearing capacity and deformation behavior of rectangular-section columns (200 mm × 400 mm) made of steel/polypropylene (PP) hybrid fiber-reinforced ultra-high performance concrete under eccentric compression. Based on the full-range load-displacement response and failure characteristics observed in tests, the research reveals the influence of section eccentricity and longitudinal reinforcement ratio on the failure mode, characteristic load points, and deformation capacity of the specimens. The difference in mechanical performance compared to C50 reference specimens is also examined. Testing results are as follows: (1) Compared to ordinary concrete columns under eccentric compression, the steel/PP hybrid fiber-reinforced UHPC columns exhibit a significant improvement in bearing performance, with their yield load, peak load, and ultimate load increasing by 62.04%, 58.13%, and 13.48%, respectively. (2) Parameter analysis shows that when the eccentricity increases from 150 to 300 mm, the deformation capacity of the members is improved. When the longitudinal reinforcement ratio increases from 0.67% to 0.79%, the deformation capacity is further enhanced, and the bearing capacity shows a positive correlation with the reinforcement ratio. (3) The hybrid fibers enable the tensile zone to continue providing resistance after cracking, contributing significantly to the development of bearing capacity and deformation in eccentrically compressed columns. Based on the experimental ultimate moment and combined with section capacity calculations, a suggested value for the equivalent coefficient k in the tensile zone is derived through back-calculation.
