硅酸盐学报

拉弯复合作用下超高性能混凝土抗疲劳性能

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方志 ¹^,² , 徐忠心 ¹ , 罗浩秦 ¹ , 唐子龙 ¹ , 刘琪 ³ , 刘新华 ³

硅酸盐学报 | 研究论文 2025,53(2): 367-379

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硅酸盐学报 |研究论文 2025 , 53 (2) : 367 -379

拉弯复合作用下超高性能混凝土抗疲劳性能

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方志¹^,², 徐忠心¹, 罗浩秦¹, 唐子龙¹, 刘琪³, 刘新华³

作者信息

^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

作者简介:

方志（1963—），男，博士，教授。

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

Zhi FANG¹^,², Zhongxin XU¹, Haoqin LUO¹, Zilong TANG¹, Qi LIU³, Xinhua LIU³

Affiliations

^1.College of Civil Engineering, Hunan University, Changsha 410082, China

^2.State Key Laboratory of Bridge Safety and Resilience (Changsha), Changsha 410082, China

^3.China Communications Construction Company Second Highway Consultants Co., Ltd., Wuhan 430056, China

FANG Zhi (1963-), male, Ph.D., Professor. E-mail: fangzhi@hnu.edu.cn

出版时间: 2025-02-20 doi: 10.14062/j.issn.0454-5648.20240185

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摘要

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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。

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

Abstract

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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, 9 specimens were tested for monotonic properties, and 16 specimens were tested for fatigue properties. The axially tensile and eccentrically tensile properties of UHPC were tested by C-shape specimens with corbel at both ends, and pure bending behaviors of UHPC were tested by four-point bending beams with identical cross-sections. The fatigue test was carried out under different eccentricity ratios and stress levels using a specially designed three-hinge truss device converting the tension loads to compression loads. Electrical resistance strain gauges were arranged at the extreme tensile edge of the specimens to measure the tensile strain before cracking. Two linear variable differential transformers (LVDTs) were continuously arranged in the extreme tensile edge of the specimen with a gauge length of 100 mm to measure the average tensile strain after cracking. The progression of crack width on the surface of specimen during fatigue testing was tracked using a hand-held crack detector with an accuracy of 0.01mm. The number of load cycles until fatigue failure under different stress levels was recorded, and further, the effects of eccentricity ratios and stress levels on fatigue life of UHPC were analyzed.

Results and discussion

It was found that the development of fatigue tensile strain and crack width on the tensile surface of the specimens with fatigue failure reveals three stages of increasing rapidly with a decrease of strain rate, a steady growth trend with an almost constant rate, and increasing suddenly following a fatigue fracture. The tensile strain of the specimen without fatigue failure converges to a stable value after the rapid development in the first stage and remains unchanged in the second stage. The fatigue strength of UHPC increases with the eccentricity ratio rising, which can be attributed to the effect of stress redistribution between adjacent stripes in the tensile region caused by the increasing strain gradient on the cross-section. Compared with the corresponding strength of axial tensile specimens, for specimens with eccentricity ratios of 0.1, 0.4 and ∞, the initial cracking strength is increased by 10%, 38%, and 51%; the ultimate strength is increased by 14%, 57%, and 134%; while the fatigue strength is increased by 11%, 46%, and 105%, which demonstrate that the increased magnitude of fatigue strength lies between that of initial crack strength and ultimate strength. When the stress level of the specimen is close to its fatigue strength, the cumulative damage of the specimen is obvious, and the residual strength after fatigue is significantly lower than the corresponding static strength. When the stress level of the specimen is significantly lower than its fatigue strength, the cumulative damage of the specimen is slight, and the residual strength after fatigue is only slightly lower than its corresponding static strength.

Conclusions

As eccentricity ratios rises, the fatigue strength σ_f and the fatigue strength ratio σ_f/f_e increase, while the fatigue strength ratio σ_f/f_p decreases, which means the stress level index S_e=σ_max/f_e relative to the initial crack strength can more reasonably reflect the variation of fatigue strength of UHPC with eccentricity ratios under combined tension and bending action. For the UHPC with steel fiber content of 2% under combined tension and bending action, a fatigue equation for predicting the fatigue life of UHPC under different eccentricity ratios and various stress levels is proposed.

Key words

ultra-high-performance concrete / eccentricity ratio / combined tensile and bending action / fatigue strength / fatigue equation

引用本文

方志, 徐忠心, 罗浩秦, 唐子龙, 刘琪, 刘新华. 拉弯复合作用下超高性能混凝土抗疲劳性能. 硅酸盐学报, 2025 , 53 (2) : 367 -379 . DOI: 10.14062/j.issn.0454-5648.20240185

Zhi FANG, Zhongxin XU, Haoqin LUO, Zilong TANG, Qi LIU, Xinhua LIU. Fatigue Resistance of Ultra-High-Performance Concrete Under Combined Tensile and Bending Action[J]. Journal of the Chinese Ceramic Society, 2025 , 53 (2) : 367 -379 . DOI: 10.14062/j.issn.0454-5648.20240185

基金

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国家自然科学基金项目(51938012)

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2025年第53卷第2期

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文章信息

doi: 10.14062/j.issn.0454-5648.20240185

接收时间：2024-03-05
首发时间：2026-10-22
出版时间：2025-02-20

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收稿日期：2024-03-05
修回日期：2024-03-22

基金

国家自然科学基金项目(51938012)

作者信息

^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

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240185

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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