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SP-274: Fiber Reinforced Self-Consolidating Concrete: Research and Applications最新文献

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Self-Consolidating High-Performance SFRC: An Example of Structural Application in Italy 自固结高性能SFRC:意大利结构应用实例
L. Ferrara, M. Prisco, N. Ozyurt
This paper discusses how the addition of fibers into a self-consolidating concrete (SCC) matrix can take advantage of the superior fresh state performance to achieve homogeneous dispersion of the discontinuous wirelike reinforcement. Such a positive synergy between SCC and fiber reinforced concrete (FRC) technologies is of paramount importance to promote reliable structural applications. It has been shown that, through a well balanced set of fresh state properties of the mix, fibers can be effectively oriented along the direction of the fresh concrete flow. Superior mechanical performance of the material is obtained in the same direction. A “tailored” orientation of the fibers may be pursued to obtain a deflection-, or even a strain-hardening, behavior that may be required by the specific application. With reference to a project on going in Italy, this paper details the steps of a “holistic” approach to the design of Self Consolidating High Performance Fiber Reinforced Concrete (SCHPFRC) elements. In this framework both the mix composition and the casting process are designed to the anticipated performance of the structural element, in the sight of an optimized material and structural efficiency. This would allow for the pursuit of desirable closer correspondence between the shape of an element and the function it performs in a structure assembly. A suitably balanced fresh-state performance of the fiber reinforced cementitious composite would allow to “mold” the shape of an element and to orient the fibers along the direction of the principal tensile stresses resulting from its structural function.
本文讨论了在自固结混凝土(SCC)基体中加入纤维如何利用其优异的新鲜状态性能来实现不连续线状钢筋的均匀分散。SCC和纤维增强混凝土(FRC)技术之间的这种积极协同作用对于促进可靠的结构应用至关重要。研究表明,通过一组平衡良好的混合料新鲜状态特性,纤维可以沿着新鲜混凝土流动的方向有效地定向。在同一方向上获得优越的材料力学性能。可以追求纤维的“定制”方向,以获得特定应用可能需要的挠曲,甚至应变硬化行为。本文以意大利正在进行的一个项目为例,详细介绍了采用“整体”方法设计自固结高性能纤维增强混凝土(SCHPFRC)构件的步骤。在这个框架中,混合成分和铸造工艺都是根据结构元件的预期性能设计的,以优化材料和结构效率。这将允许在元件的形状和它在结构组件中执行的功能之间追求理想的更紧密的对应关系。纤维增强胶凝复合材料的适当平衡的新鲜状态性能将允许“塑造”元件的形状,并使纤维沿着由其结构功能产生的主拉伸应力的方向定向。
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引用次数: 3
Investigation of Steel and Polymer Fiber-Reinforced Self-Consolidating Concrete 钢与聚合物纤维增强自固结混凝土的研究
M. Brown, H. Ozyildirim, W. L. Duke
This paper will discuss how self-consolidating concrete (SCC) promises to shorten construction time while reducing the need for skilled labor. However, experience has shown that SCC may be prone to shrinkage cracking, which could compromise durability. In conventional concrete, fiber reinforcement has been used to control cracking and increase post-cracking tensile strength and flexural toughness. These benefits could be achieved in SCC without compromising the workability or stability, provided that the amount of fiber reinforcement is optimized. This project sought to evaluate the feasibility of fiber reinforced self-consolidating concrete (FR-SCC) for structural applications. Tests were conducted in the laboratory to assess the fresh and hardened properties of FR-SCC containing various types and concentrations of fiber. The results presented in this paper indicate that SCC with high flowability and some residual strength beneficial for crack control can be prepared for use in transportation facilities. The results of the experiments further show that, at optimal fiber additions, FR-SCC mixtures can have the same fresh concrete properties as traditional SCC mixtures. FR-SCC also demonstrates a considerable improvement in the residual strength and toughness of a cracked section. Though not specifically measured, increase in residual strength and toughness is expected to lead to the control of crack width and length. The increase in the FR-SCCs’ cracked section performance indicates that it can be expected to have better durability in service conditions than an identical SCC without fibers. In transportation structures FR-SCC can be used in link slabs, closure pours, formed concrete substructure repairs; or prestressed beams where end zone cracking has been an issue.
本文将讨论如何自固结混凝土(SCC)承诺缩短施工时间,同时减少对熟练劳动力的需求。然而,经验表明,SCC可能容易发生收缩开裂,这可能会影响耐久性。在常规混凝土中,纤维增强用于控制开裂和提高开裂后的抗拉强度和弯曲韧性。只要优化纤维增强量,这些优点可以在不影响可加工性或稳定性的情况下在SCC中实现。本项目旨在评估纤维增强自固结混凝土(FR-SCC)用于结构应用的可行性。在实验室中进行了测试,以评估含有不同类型和浓度纤维的FR-SCC的新鲜和硬化特性。研究结果表明,可以制备出具有高流动性和一定残余强度、有利于裂缝控制的超细混凝土用于交通运输设施。实验结果进一步表明,在最佳纤维掺量下,FR-SCC混合料可具有与传统SCC混合料相同的新拌混凝土性能。FR-SCC在裂纹截面的残余强度和韧性方面也有相当大的改善。虽然没有具体测量,但残余强度和韧性的增加有望导致裂纹宽度和长度的控制。fr -SCC开裂截面性能的提高表明,在使用条件下,它比不含纤维的相同SCC具有更好的耐久性。在交通结构中,FR-SCC可用于连接板、闭合浇筑、成形混凝土下部结构修补;或预应力梁的端区开裂已经成为一个问题。
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引用次数: 6
Design and Construction Aspects of Steel Fiber-Reinforced Concrete Elevated Slabs 钢纤维混凝土高架板的设计与施工
B. Mobasher, X. Destrée
This paper discusses how applications of slabs supported on piles are quite common for areas where soil- structure interaction may create differential settlement or long term tolerance issues. An application for the use of steel fiber reinforced slabs that are continuous and supported on piles is also discussed in this paper. The experience and design methodology for slabs on piles is further extended to floor slabs of multi-story buildings, where a high dosage of steel fibers is used as the sole method of reinforcement. Suspended ground slabs are generally subjected to high concentrated point loading intensities as well as high uniformly distributed loadings and wheel loads. The span to depth ratios of the SFRSS is between 8 and 20 and depends on the loading intensity and the pile/column capacity. Standard procedures for obtaining material properties and finite element models for structural analysis of the slabs are discussed in the paper and methods of construction, curing, and full scale testing of slabs are also presented.
本文讨论了在土-结构相互作用可能产生差异沉降或长期容忍度问题的地区,如何应用桩上支承板。本文还讨论了连续桩支钢纤维加筋板的应用。桩上板的经验和设计方法进一步扩展到多层建筑的楼板,在那里使用高剂量的钢纤维作为唯一的加固方法。悬架楼板一般承受高度集中的点荷载强度以及高度均匀分布的荷载和轮荷载。SFRSS的跨深比在8 ~ 20之间,取决于荷载强度和桩/柱承载力。本文讨论了获得材料性能的标准程序和用于板结构分析的有限元模型,并介绍了板的施工、养护和全尺寸试验方法。
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引用次数: 9
Tensile Behavior of Steel Fiber-Reinforced Self-Compacting Concrete 钢纤维增强自密实混凝土的拉伸性能
V. Cunha, J. Barros, J. Sena-Cruz
The tensile behavior of a self-compacting concrete (SCC) reinforced with two hooked ends steel fiber contents was assessed in this paper by performing stable displacement control tension tests. Based on the stress-displacement curves obtained, the stress-crack width relationships were derived, as well as the energy dissipated up to distinct crack width limits and residual strengths. The number of effective fibers bridging the fracture surface was determined and was compared with the theoretical number of fibers, as well as with the stress at crack initiation, residual stresses and energy dissipation parameters. In general, a linear trend between the number of effective fibers and both the stress and energy dissipation parameters was obtained. A numerical model supported on the finite element method was developed in this paper. In this model, the fiber reinforced concrete is assumed as a two phase material: plain concrete and fibers randomly distributed. The plain concrete phase was modeled with 3D solid finite elements, while the fiber phase was modeled with discrete embedded elements. The adopted interface behavior for the discrete elements was obtained from single fiber pullout tests. The numerical simulation of the uniaxial tension tests showed a good agreement with the experimental results. Thus, this approach is able of capturing the essential aspects of the fiber reinforced composite’s complex behavior.
通过稳定位移控制拉伸试验,对双钩端钢纤维增强自密实混凝土的拉伸性能进行了评价。根据得到的应力-位移曲线,导出了应力-裂纹宽度关系,以及不同裂纹宽度极限下的能量耗散和残余强度。确定了有效纤维桥接断面的数量,并将其与理论纤维数量、裂纹起裂应力、残余应力和耗能参数进行了比较。总的来说,有效纤维数与应力和能量耗散参数之间呈线性关系。本文建立了基于有限元法的数值模型。在该模型中,纤维增强混凝土被假设为两相材料:普通混凝土和随机分布的纤维。普通混凝土相采用三维实体有限元建模,纤维相采用离散嵌入单元建模。采用单纤拉拔试验得到了离散单元的界面特性。单轴拉伸试验的数值模拟结果与试验结果吻合较好。因此,这种方法能够捕捉纤维增强复合材料复杂行为的基本方面。
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引用次数: 10
Experience with Self-Consolidating High-Performance Fiber-Reinforced Mortar and Concrete 有自固结高性能纤维增强砂浆和混凝土的经验
W. Liao, S. Chao, A. Naaman
This paper discusses how self-consolidating high performance fiber reinforced cementitious composites (SC-HPFRCC) combine the self-consolidating property of self-consolidating concrete (SCC) in their fresh state, with the strain-hardening and multiple cracking characteristics of high-performance fiber-reinforced cement composites (HPFRCC) in their hardened state. The paper introduces two different classes of SC-HPFRCC: concrete based and mortar based. They all contain 30 mm long steel fibers in volume fractions of 1.5% and 2%, and exhibit strain- hardening behavior in tension. These mixtures are highly flowable, non-segregating and can spread into place, fill the formwork, and encapsulate the reinforcing steel in typical concrete structures. Six concrete based SC-HPFRCC mixtures, with compressive strengths ranging from 35 to 66 MPa (5.1 to 9.6 ksi), were successfully developed by modifying SCC mixtures recommended in previous studies and using the available local materials. Spread diameter of the fresh concrete based SC-HPFRCC mixtures measured from the standard slump flow test was approximately 600 mm (23.6 in.). Strain-hardening characteristics of the hardened composites were ascertained from direct tensile tests. Three mortar based SC-HPFRCC mixtures with 1.5% steel fiber content were also developed and exhibited average compressive strengths of 38, 50 and 106 MPa (5.5, 7.2 and 15.3 ksi), respectively. Recent structural large scale laboratory applications (structural wall, coupling beams, panels etc.) made of SC-HFPRCC have demonstrated the applicability of these mixtures.
本文讨论了自固结高性能纤维增强水泥复合材料(SC-HPFRCC)如何将自固结混凝土(SCC)在新鲜状态下的自固结特性与高性能纤维增强水泥复合材料(HPFRCC)在硬化状态下的应变硬化和多重开裂特性结合起来。本文介绍了两种不同类型的SC-HPFRCC:混凝土基和砂浆基。它们都含有30mm长的钢纤维,体积分数分别为1.5%和2%,并且在拉伸中表现出应变硬化行为。这些混合物具有高度流动性,不分离,可以扩散到位,填充模板,并在典型的混凝土结构中封装钢筋。通过修改先前研究中推荐的SCC混合物并使用当地可用材料,成功开发了六种基于混凝土的SC-HPFRCC混合物,其抗压强度范围为35至66 MPa(5.1至9.6 ksi)。从标准坍落度流动试验中测量的新混凝土基SC-HPFRCC混合物的扩散直径约为600毫米(23.6英寸)。通过直接拉伸试验确定了硬化复合材料的应变硬化特性。此外,还开发了三种钢纤维含量为1.5%的砂浆基SC-HPFRCC混合物,其平均抗压强度分别为38、50和106 MPa(5.5、7.2和15.3 ksi)。最近由SC-HFPRCC制成的结构大型实验室应用(结构墙,耦合梁,面板等)已经证明了这些混合物的适用性。
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引用次数: 10
Flow Characteristics of Macro-Synthetic Fiber-Reinforced Self-Consolidating Concrete 宏观合成纤维增强自固结混凝土的流动特性
D. Forgeron, A. Omer
This paper evaluated the flow characteristics of macro-synthetic fiber-reinforced self consolidating concrete (MSFRSCC). A total of 20 non-air entrainment self-consolidating concrete (SCC) mixtures with varying w/c ratios, macro-synthetic fiber lengths, and fiber dosages rates were evaluated.The flow characteristics of each mixture were evaluated using four typical SCC workability test methods: slump flow, filling capacity, L-box, and V-funnel tests. The plastic shrinkage cracking resistance, compressive strength and flexural strength of each mixture were also evaluated. The objective was to develop an understanding of the factors that influence the flow characteristics of MSFRSCC and determine if criteria set for conventional SCC can be applied to MSFRSCC. The testing results demonstrated that fiber lengths of 50 mm cause significant internal friction leading to mixture stability issues when attempting to increase the volume of high range water reducer to produce acceptable slump flow values without viscosity modifying admixtures. Reducing fiber length to 38mm led to reduction in the internal friction allowing satisfactory slump flow, filling capacity, and V-funnel flow time to be achieved with slight mixture modifications and no viscosity modifying admixtures were required. The addition of fibers did cause lower than acceptable L-Box test results where mixtures were made to change direction and flow between closely spaced bars. It was concluded that the slight increase in internal friction produced by the addition of fibers caused the low L-Box results and not any form of blockage. The plastic shrinkage test results showed that the addition of 0.40% fibers by volume led to as much as 70 % reduction in total crack area and up to 50% reduction in maximum crack width as compared to plain concrete. The results obtained from this research clearly shows that is it possible to develop highly crack resistant MSFRSCC mixtures for concrete structures.
对宏观合成纤维增强自固结混凝土(MSFRSCC)的流动特性进行了评价。共评估了20种不同w/c比、宏观合成纤维长度和纤维用量率的无空气夹带自固结混凝土(SCC)混合物。采用四种典型的SCC和易性试验方法:坍落度流动试验、填充能力试验、l -箱试验和v -漏斗试验,对每种混合物的流动特性进行了评价。并对各混合料的塑性收缩抗裂性能、抗压强度和抗弯强度进行了评价。目的是了解影响MSFRSCC流动特性的因素,并确定常规SCC的标准是否适用于MSFRSCC。测试结果表明,当试图增加大范围减水剂的体积以产生可接受的坍落度流动值时,纤维长度为50 mm会产生显著的内摩擦,从而导致混合物稳定性问题,而不使用粘度改性外加剂。将纤维长度减少到38mm可以减少内摩擦,从而在轻微的混合物改性和不需要粘度改性外加剂的情况下实现令人满意的坍落度流动、填充能力和v漏斗流动时间。添加纤维确实会导致低于可接受的L-Box测试结果,当混合物在紧密间隔的棒之间改变方向和流动时。由此得出结论,纤维的加入所产生的内摩擦的轻微增加导致了低的L-Box结果,而不是任何形式的堵塞。塑性收缩试验结果表明,与素混凝土相比,掺量0.40%的纤维可使总裂缝面积减小70%,最大裂缝宽度减小50%。本研究结果清楚地表明,开发高抗裂MSFRSCC混凝土结构混合料是可能的。
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引用次数: 5
Maximum Fiber Content and Passing Ability of Self-Consolidating Fiber-Reinforced Concrete 自固结纤维增强混凝土的最大纤维含量及通过能力
S. Grünewald, J. Walraven
This paper will discuss how self-consolidating fiber-reinforced concrete (SCFRC) combines the benefits of self-consolidating concrete (SCC) in the fresh state and an enhanced performance of fiber reinforced concrete (FRC) in the hardened state. The application of SCC improves the efficiency at building sites, allows rationally producing prefabricated concrete elements and improves the working conditions, the quality and the aesthetic appearance of concrete structures. By adding fibers to SCC bar reinforcement can be replaced, crack widths reduced, the durability improved and the load bearing capacity of a structure increased. An extensive research study was carried out on the characteristics and the mix design of SCFRC that consisted of three parts: the fresh as well as the hardened state of SCFRC and the influence of the production process determined in three full-scale studies. This paper discusses two aspects of the mix design of SCFRC: the maximum fiber content and the required spacing of reinforcement at which blocking does not occur. Based on the analysis of experimental results mix design tools are proposed that allow predicting the maximum fiber content and the passing ability of SCFRC, which is essential information to obtain a homogeneous distribution of the fibers in a structure.
本文将讨论自固结纤维增强混凝土(SCFRC)如何结合自固结混凝土(SCC)在新鲜状态下的优点和纤维增强混凝土(FRC)在硬化状态下的增强性能。SCC的应用提高了建筑工地的效率,合理地生产预制混凝土构件,改善了混凝土结构的工作条件、质量和美观。在SCC钢筋中加入纤维可以替代钢筋,减小裂缝宽度,提高结构的耐久性和承载能力。对SCFRC的特性和配合比设计进行了广泛的研究,包括三部分:SCFRC的新鲜状态和硬化状态,以及三个全尺寸研究确定的生产工艺的影响。本文讨论了SCFRC配合比设计的两个方面:最大纤维含量和不发生堵塞的配筋间距。在对试验结果分析的基础上,提出了预测纤维最大含量和纤维通过能力的混合设计工具,这是获得纤维在结构中均匀分布的必要信息。
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引用次数: 4
Prediction of Stress Development and Cracking in Steel Fiber-Reinforced Self-Compacting Concrete Overlays Due to Restrained Shrinkage 约束收缩作用下钢纤维增强自密实混凝土覆盖层应力发展及开裂预测
Jonas Carlswärd, M. Emborg
This paper will discuss how shrinkage cracking of self-compacting concrete (SCC) overlays with and without steel fibers has been assessed through laboratory testing and theoretical analysis. Test results verified that steel fiber reinforcement has a crack width limiting effect. However, the contribution in case of fiber contents up to 0.75 volume percent was not found to be sufficient to distribute cracks in situations where bond to the substrate were nonexistent. Thus, even higher steel fiber contents (or other types of fibers) are required in order to control cracks. A distributed pattern of fine cracks was however obtained even for unreinforced SCC within bonded areas of the overlays. This implies that steel fibers, or other crack reinforcement, are not required if high bond strength is obtained. An analytical model, proposed to assess the risk of cracking and to predict crack widths in overlays, was found to give reasonable correlation with experimental results.
本文将讨论如何通过实验室试验和理论分析来评估加钢纤维和不加钢纤维的自密实混凝土(SCC)覆盖层的收缩开裂。试验结果验证了钢纤维加固具有限制裂缝宽度的作用。然而,在纤维含量高达0.75%体积百分比的情况下,发现纤维含量的贡献不足以在不存在与基体结合的情况下分布裂缝。因此,为了控制裂缝,需要更高的钢纤维含量(或其他类型的纤维)。然而,即使对于未加筋的SCC,在覆盖层的粘合区域内也可以获得细裂纹的分布模式。这意味着如果获得高粘结强度,则不需要钢纤维或其他裂纹增强材料。提出了一种分析模型,用于评估叠合层的开裂风险和预测叠合层的裂缝宽度,该模型与试验结果具有较好的相关性。
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引用次数: 4
期刊
SP-274: Fiber Reinforced Self-Consolidating Concrete: Research and Applications
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