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海水干湿循环作用下UHTCC动态压缩性能试验研究

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东南大学学报（自然科学版） 2024年第4期54卷 807-815页

作者：李庆华陈奕琨何晓宇姚福成徐世烺浙江大学高性能结构研究所杭州310058 浙江数智交院科技股份有限公司杭州310006 嘉兴港独山港口化工物流有限公司嘉兴314203

为研究应变率和海水干湿循环周期对超高韧性水泥基复合材料(UHTCC)动态压缩性能的影响,采用直径75 mm的分离式霍普金森压杆系统对0~120 d海水干湿循环作用后的UHTCC试件开展动态压缩试验.通过改进ZWT非线性黏弹性本构模型,提出了一种考... 详细信息

为研究应变率和海水干湿循环周期对超高韧性水泥基复合材料(UHTCC)动态压缩性能的影响,采用直径75 mm的分离式霍普金森压杆系统对0~120 d海水干湿循环作用后的UHTCC试件开展动态压缩试验.通过改进ZWT非线性黏弹性本构模型,提出了一种考虑海水干湿循环作用的UHTCC试件的动态本构模型.结果表明,UHTCC试件的动态抗压强度增强因子随着干湿循环周期的增加逐渐减小.在同一冲击气压下,随着干湿循环周期的增加,UHTCC试件的峰值应力和耗能先增大后减小,并分别在60和90 d时达到峰值.在相同干湿循环周期下,UHTCC试件的峰值应力、动态抗压强度增强因子和耗能均随应变率的增大而增大,表现出明显的应变率效应.改进的动态本构模型能够较好地描述海水干湿循环作用下UHTCC试件的动态压缩应力-应变关系.

关键词：超高韧性水泥基复合材料海水干湿循环动态压缩力学性能本构模型

Strengthening of the concrete face slabs of dams using sprayable strain-hardening fiber-reinforced cementitious composites

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Frontiers of Structural and Civil Engineering 2022年第2期16卷 145-160页

作者： Qinghua LI Xing YIN Botao HUANG Yifeng ZHANG shilang xu Institute of Advanced Engineering Structures and Materials Zhejiang UniversityHangzhou 310058China

In this study,sprayable strain-hardening fiber-reinforced cementitious composites(FRCC)were applied to strengthen the concrete slabs in a concrete-face rockfill dam(CFRD)for the first ***,numerical,and analytical investigations were carried out to understand the flexural properties of FRCC-layered concrete *** was found that the FRCC layer improved the flexural performance of concrete slabs *** cracking and ultimate loads of a concrete slab with an 80 mm FRCC layer were 132%and 69%higher than those of the unstrengthened concrete slab,*** the maximum crack width of 0.2 mm,the deflection of the 80-mm FRCC strengthened concrete slab was 144%higher than that of the unstrengthened concrete *** addition,a FE model and a simplified analytical method were developed for the design and analysis of FRCC-layered concrete ***,the test result of FRCC leaching solution indicated that the quality of the water surrounding FRCC satisfied the standard for drinking *** findings of this study indicate that the sprayable strain-hardening FRCC has a good potential for strengthening hydraulic structures such as CFRDs.

关键词： strain-hardening cementitious composites engineered cementitious composites sprayable shotcrete strengthening concrete-face rockfill dam digital image correlation

Experimental investigation and analysis on flexural performance of functionally graded composite beam crack-controlled by ultrahigh toughness cementitious composites

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Science China(Technological Sciences) 2009年第8期52卷 1648-1664页

作者： LI QingHua xu shilang State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

Based on the concept of functionally graded concrete,UHTCC(ultrahigh toughness cementitious composites)material with excellent crack-controlling ability is strategically substituted for part of the concrete,which surrounds the main longitudinal reinforcement in a reinforced concrete *** on bending behavior of such a functionally graded composite beam crack-controlled by UHTCC(abbreviated as UHTCC-FGC beam)have been carried *** establishing a theoretical cal-culation model,the paper discusses the results of four-point bending experiment on long composite beams without web reinforcement,and validates the theoretical formulae through experimental results of UHTCC-FGC beams with different thicknesses of UHTCC *** improving bearing capacity and saving steel reinforcements,the results indicate that UHTCC-FGC beams can also effectively control the deformation and enhance the ductility of *** last,the optimal thickness of UHTCC layer in UHTCC-FGC beams has been confirmed,which can not only save materials and improve mechanical performance of members,but also be very effective in preventing corrosion-induced damage and enhancing the durability of members by controlling crack width below 0.05mm under service conditions.

关键词： UHTCC crack control functionally graded experimental research validation durability

Theoretical analysis on bending behavior of functionally graded composite beam crack-controlled by ultrahigh toughness cementitious composites

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Science China(Technological Sciences) 2009年第2期52卷 363-378页

作者： xu shilang LI QingHua State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

Ultrahigh toughness cementitious composites (UHTCC) obviously show strain hardening property under tensile or bending loading. The failure pattern of the UHTCC components exhibits multiple fine cracks under uniaxial tensile loading with prominent tensile strain capacity in excess of 3%, with merely 60 μm average crack width even corresponding to the ultimate tensile strain state. The approach adopted is based on the concept of functionally-graded concrete, where part of the concrete, which surrounds the main longitudinal reinforcement in a RC (reinforced concrete) member, is strategically replaced with UHTCC with excellent crack-controlling ability. Investigations on bending behavior of functionally-graded composite beam crack controlled by UHTCC has been carried out, including theo- retical analysis, experimental research on long composite beams without web reinforcement, validation and comparison between experimental and theoretical results, and analysis on crack control. In addition to improving bearing capacity, the results indicate that functionally-graded composite beams using UHTCC has been found to be very effective in preventing corrosion-induced damage compared with RC beams. Therefore, durability and service life of the structure could be enhanced. This paper discusses the development of internal force and crack propagation during loading process, and presents analysis of the internal force in different stages, moment-curvature relationship from loading to damage and calculation of mid-span deflection and ductility index. In the end, the theoretical formulae have been validated by experimental results.

关键词： UHTCC (ultrahigh toughness cementitious composites) crack control functionally graded bending behavior theoretical analysis

Theoretical analysis and experimental investigation on flexural performance of steel reinforced ultrahigh toughness cementitious composite (RUHTCC) beams

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Science China(Technological Sciences) 2009年第4期52卷 1068-1089页

作者： xu shilang ZHANG XiuFang State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

UHTCC (ultrahigh toughness cementitious composite), which is a kind of ultrahigh toughness cemen- titious composites material, exhibits pseudo strain hardening feature when subjected to tension load, and has enormous ductility and prominent crack dispersal ability. Accordingly, UHTCC can improve mechanical behavior of ordinary concrete structure especially its durability, and has been regarded as historical breakthrough to traditional cementitious materials. In this paper, the study focuses on flexure behavior of steel reinforced beam made of UHTCC. Based on the plane section assumption, along with two equilibrium equations of force and moment, the formulae to calculate the flexural load capability for the reinforced ultrahigh toughness cementitious composite (RUHTCC) beam were developed under the assumption that the compression stress- strain relationship in the UHTCC material is a bilinear model. Following this, the simplified formulae were further evolved by effective rectangle stress distribution approach in order to facilitate design of practical engineering. Two effective parameters introduced in effective rectangle approach were determined. The mathematical expressions to evaluate limited rein- forcement ratio, flexural stiffness as well as ductility index were proposed, too. Last, two series of dif- ferent reinforcement ratios of the RUHTCC beams were tested in four-point flexure loading. For com- parison purposes, ordinary RC (reinforced concrete) beams also were prepared. Both moment curva- ture curves and load mid-span displacement curves were recorded and compared with the theoretical calculations. A good agreement between them was found, which validates the proposed theoretical formulae. For ductility index, a slightly big difference between the experimental values and the calcu- lated ones exists. The experimental results show that, compared to control RC beams, the RUHTCC beam can improve both flexural capacity and ductility index, and the degree of i

关键词： ultrahigh toughness cementitious composites (UHTCC) RUHTCC beam flexural capacity crack width ductility index reinforcement ratio

Numerical simulation and experimental study on electrothermal properties of carbon/glass fiber hybrid textile reinforced concrete

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Science China(Technological Sciences) 2011年第9期54卷 2421-2428页

作者： xu shilang YU WenTing SONG ShiDe College of Civil Engineering and Architecture Zhejiang University Hangzhou 310058 China The 3rd Railway Survey and Design Institute Tianjin 300251 China State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China

Carbon/glass fiber hybrid textile reinforced concrete is a relatively new composite material with good mechanical capacity and excellent electrical *** small-scale slab heating experiments and numerical simulation are presented in this *** variation curves obtained during heating indicate the effects of environmental temperature,heat-conducting layer thickness and electric heating *** of temperature rising between the situations with and without thermal isolation layer is given as *** results indicate that the textile can form a good conductive heating network and generate enough heat to raise the temperature in the concrete when connected to a power supply,while the resistance of the slab remains stable during the *** results are in good accordance with the *** time snow-melting experiment was conducted to verify the feasibility of *** electrothermal properties of textile can be utilized for deicing and snow melting in a safe,environmentally friendly and efficient way.

关键词：钢筋混凝土加热实验数值模拟电热性能玻璃纤维碳纤维纺织混合

Production and mechanical properties of aligned multi-walled carbon nanotubes-M140 composites

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Science China(Technological Sciences) 2009年第7期52卷 2119-2127页

作者： xu shilang GAO LiangLi JIN WeiJun State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China Institute of Analytical Chemistry College of ChemistryBeijing Normal UniversityBeijing 100875China

This study investigated the production of M140, aligned multi-walled carbon nanotubes (A-MWNTs) reinforced M140 composites (A-MWNTs-M140) and their mechanical properties including their compressive and bending properties as well as their microstructure characteristic of bend fracture surface. M140 was first produced by speed change mixing technics with commercial materials, water-bath curing at normal temperature. In addition, two different A-MWNTs dispersions including carbonyl disper- sions of A-MWNTs (C-A-MWNTs) and aqueous dispersions of A-MWNTs (A-A-MWNTs) with the addition of 0.01wt% A-MWNTs were utilized to obtain enhanced mechanical properties with respect to plain M140. The results indicated that the use of A-MWNTs dispersions allows increasing compressive strength and flexural strength by 8.4% and 5.4%, respectively for the C-A-MWNTs-M140, and by 15.9% and 20.7% for the A-A-MWNTs-M140, respectively. The SEM and EPMA examinations of fracture surface also showed that the bond interface between the nanotubes and matrix is moderate and the main reinforcing mechanisms are microfilling effect, CNTs pull-out and debond. The aqueous dispersion of A-MWNTs is an appropriate method and is more compatible with the M140.

关键词： A-MWNTs reinforcing mechanisms compatibility M140 mortar composites strength

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TRC加固砖砌体墙抗剪承载力分析

土木工程学报 2022年第S01期55卷 190-195页

作者：荆磊尹世平徐世烺内蒙古工业大学内蒙古呼和浩特010051 中国矿业大学江苏徐州221116 浙江大学高性能结构研究所浙江杭州310058

砌体墙是砌体结构的主要承载构件,在地震等自然灾害中容易因抗剪承载力不足发生破坏。纤维编织网增强混凝土(textile-reinforced concrete,TRC)加固是提高砌体结构安全性的有效方法之一。本文主要通过斜压剪切试验研究TRC加固砖砌体墙... 详细信息

砌体墙是砌体结构的主要承载构件,在地震等自然灾害中容易因抗剪承载力不足发生破坏。纤维编织网增强混凝土(textile-reinforced concrete,TRC)加固是提高砌体结构安全性的有效方法之一。本文主要通过斜压剪切试验研究TRC加固砖砌体墙的抗剪承载力,分析TRC加固使用纤维编织网层数以及单、双侧加固对抗剪承载力的影响。基于试验研究结果,主要分析TRC加固后砖砌体墙的失效模式、剪应力-应变曲线、抗剪强度以及抗剪承载力计算与设计方法等。结果表明:TRC加固可以有效控制砖砌体墙产生的裂缝,墙体失效时的完整性得到保证,并未发生倒塌;TRC加固墙体具有良好的峰值后行为与延性特征,抗剪强度相较于未加固墙体得到有效提升;采用ACI 549.4R建议方法获得的抗剪承载力设计值非常保守,通过在设计阶段将抗剪承载力分为正常使用极限状态(SLS)和承载力极限状态(ULS)可以有效缓解设计值的保守性。研究结果可以为TRC在砌体结构加固领域的应用提供试验与理论依据。

关键词：纤维编织网增强混凝土砖砌体墙加固修复抗剪承载力

Correlation between tension softening relation and crack extension resistance in concrete

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Frontiers of Structural and Civil Engineering 2009年第3期3卷 323-329页

作者： Xiufang ZHANG shilang xu Department of Civil and Hydraulic Engineering Dalian University of TechnologyDalian 116024China

Changes of the material fracture toughness with crack propagation can be described by a crack extension resistance curve,one of the fundamental fracture criteria in crack ***,experimental observation of the fracture behavior in concrete was used to develop a new fracture criterion,the crack extension GR resistance curve,to analyze crack propagation during the entire concrete fracture *** variation of the crack extension resistance is mainly associated with the energy consumption in the fracture process zone ahead of the stress-free crack *** crack extension resistance is then a function of the softening curve,which is a basic mechanical property in the fracture process *** relationship between the softening curve and the crack extension GR resistance curve is then analyzed based on results of three-point bending beams *** results indicate that the characteristic points of the crack extension resistance GR curve is closely related to the characteristic point on used tension softening curve.

关键词： concrete fracture process zone crack exten-sion GR resistance tension softening curve