拉弯复合作用下超高性能混凝土抗疲劳性能  

Fatigue Resistance of Ultra-High-Performance Concrete Under Combined Tensile and Bending Action

作　　者：方志[1,2] 徐忠心 罗浩秦 唐子龙 刘琪 刘新华 FANG Zhi;XU Zhongxin;LUO Haoqin;TANG Zilong;LIU Qi;LIU Xinhua(College of Civil Engineering,Hunan University,Changsha 410082,China;State Key Laboratory of Bridge Safety and Resilience(Changsha),Changsha 410082,China;China Communications Construction Company Second Highway Consultants Co.,Ltd.,Wuhan 430056,China)

机构地区：[1]湖南大学土木工程学院,长沙410082 [2]桥梁安全与韧性国家重点实验室(长沙),长沙410082 [3]中国交建第二公路勘察设计研究院有限公司,武汉430056

出　　处：《硅酸盐学报》2025年第2期367-379,共13页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金项目(51938012)。

摘　　要：实际工程结构中,同时承受轴向拉力和弯矩作用的拉弯复合受力构件普遍存在。为明确拉弯复合作用下超高性能混凝土(UHPC)的抗疲劳性能,通过专门设计的三铰桁架拉压转换加载装置,对工程中常用的2%钢纤维体积掺量UHPC在不同偏心率下的疲劳性能进行了试验研究。结果表明:发生疲劳破坏的UHPC试件,其受拉边缘的应变和裂缝宽度均呈现较快发展、稳定发展和快速发展并破坏的3阶段发展规律。随着偏心率的增大,截面的应变梯度相应增大,使得试件受拉区相邻层间的应力重分布效应相应加强,进而导致UHPC的疲劳强度相应提高。相较于偏心率为0时的轴拉疲劳强度,偏心率为0.1、0.4时的拉弯疲劳强度和∞时的抗折疲劳强度则分别提高了11%、46%和105%。提出了考虑偏心率e/h影响的UHPC拉弯疲劳方程,可用其对不同偏心率和不同应力水平下2%钢纤维体积掺量UHPC的疲劳寿命进行较好预测。Introduction Ultra-High-Performance Concrete(UHPC),with ultra-high compressive strength and remarkable durability,holds great promise for constructing lightweight and high-performance structures.The ratio of live load effect to total load effect in the lightweight UHPC structure will be significantly increased,and higher cyclic stress amplitudes resulting in fatigue failure of the structure would occur accordingly.The combined tensile and bending stresses exist in certain components of practical engineering structures,such as UHPC bridge decks in the hogging moment region of the girder.Under overall load,the decks are subjected to a state akin to axial tension due to their limited thickness and considerable distance from the neutral axis of the girder.Yet,under the alternating localized wheel loads,the decks are subjected to cyclic bending stresses.Under the simultaneous application of the overall and local loads,UHPC bridge decks in the hogging moment region of the girder are actually subjected to combined tensile and bending stresses with variable amplitude.Many researchers have investigated the effects of steel fiber types,steel fiber content,and temperature on the bending fatigue properties of UHPC.However,there are limited studies on the axial tensile fatigue properties of UHPC,and investigations on the fatigue properties of UHPC under combined tensile and bending action are not found in the available literature.To determine the fatigue-resistant performance of UHPC with different tensile-bending stress ratios or the eccentricity ratio e/h of applied eccentric tension,an experimental study on the fatigue resistance performance of UHPC under combined tensile and bending action was conducted,and the corresponding fatigue strength was determined.Methods With the test parameter of eccentricity ratio e/h(0,0.1,0.4,and∞,e/h=0 refers to axial tension and e/h=∞to pure bending),25 specimens with a commonly used steel fiber content of 2%were designed,manufactured,and tested.Among these,9specimens were tested for m

关 键 词：超高性能混凝土 偏心率 拉弯复合作用 疲劳强度 疲劳方程 

分 类 号：TU528[建筑科学—建筑技术科学]