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Flexural strength of post-tensioned concrete-filled fiber-reinforced polymer rectangular tube beams 后张纤维增强聚合物混凝土矩形管梁的抗弯强度
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-06-01 DOI: 10.15554/pcij67.4-02
A. A. Ahmed, Mohamed Hassan, R. Masmoudi, M.-Iqbal Khan
This study extends an extensive research program carried out at the University of Sherbrooke to design and assess the potential use of rectangular, concrete-filled fiber-reinforced-polymer tube (CFFT) beams post-ten­sioned with steel tendons in bridge applications. This paper describes research to enhance the flexural perfor­mance of post-tensioned CFFT beams. Five rectangular post-tensioned CFFT beams were tested up to failure, and the effects of attaching a thin carbon-fiber-rein­forced polymer (CFRP) laminate embedded in tension flange and its total reinforcement ratio as well as tube structure fiber laminate were investigated. Last, a simpli­fied design approach is proposed based on strain com­binability and force equilibrium to estimate the flexural moment capacity of the tested beams. The specimens with two inclined fiber patterns in the hoop direction or added CFRP laminate strips embedded in the bottom flange of the tubes exhibited substantially greater flexur­al strength, absorbed energy, and serviceability perfor­mance than the control specimens. The ductility index and energy ratio ranged from 8.3 to 10.6 and from 82% to 87%, respectively, which indicates ductile behavior. Also, adding CFRP laminate strips embedded in the bottom flange of the tubes enhanced the flexural strength by 17% on average compared with post-tensioned CFFT without CFRP laminate. The specimen with the CFRP laminates in the bottom flange of the tube achieved flexural strength and energy absorption that was com­parable to the flexural strength and energy absorption of the specimen with two layers of inclined fiber patterns. The findings suggest that the design can be optimized to achieve more efficient post-tensioned CFFT structural members. The proposed design approach successfully predicts the flexural strength of the tested beams with an average of 1.05 ± 0.05 for the partially confined concrete model and an average of 1.11 ± 0.07 for the unconfined concrete model.
这项研究扩展了舍布鲁克大学开展的一项广泛的研究计划,旨在设计和评估钢筋束后张紧的矩形纤维增强聚合物混凝土管(CFFT)梁在桥梁应用中的潜在用途。本文介绍了提高后张CFFT梁抗弯性能的研究。对5根矩形后张CFFT梁进行了破坏试验,研究了在受拉翼缘中嵌入碳纤维增强聚合物(CFRP)薄层及其总配筋率以及管结构纤维层压板的影响。最后,提出了一种基于应变可比性和力平衡的简化设计方法来估计受试梁的弯矩承载力。在环向上具有两个倾斜纤维图案或在管的底部法兰中嵌入CFRP层压板的试样表现出比对照试样高得多的弯曲强度、吸收能量和使用性能。韧性指数和能量比分别在8.3-10.6和82%-87%之间,表明了韧性行为。此外,与没有CFRP层压板的后张CFFT相比,在管的底部法兰中添加CFRP层合板条平均提高了17%的抗弯强度。在管的底部法兰中具有CFRP层压板的试样获得了与具有两层倾斜纤维图案的试样的弯曲强度和能量吸收相当的弯曲强度与能量吸收。研究结果表明,可以对设计进行优化,以实现更高效的后张CFFT结构构件。所提出的设计方法成功地预测了受试梁的抗弯强度,部分约束混凝土模型的平均值为1.05±0.05,无侧限混凝土模型的均值为1.11±0.07。
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引用次数: 1
Practical ultra-high-strength concrete for precast concrete applications 用于预制混凝土的实用超高强度混凝土
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-05-01 DOI: 10.15554/pcij67.3-01
Ahmed Al Mohammedi, C. Murray, Canh N. Dang, W. Hale
This paper focuses on developing ultra-high-strength concrete (UHSC) with mechanical properties compara­ble to those of ultra-high-performance concrete (UHPC) and with production procedures similar to those used for high-strength concrete. A concrete mixture was developed to achieve a compressive strength of 17 ksi (117 MPa) at 28 days without using silica fume and with a slump flow as high as 35 in. (889 mm). Another concrete mixture with compressive strength of 20 ksi (138 MPa) was designed using only 130 lb/yd3 (77.1 kg/m3) of silica fume. In addition to these two mixtures, a UHPC mixture was also designed with a compressive strength of 24 ksi (165 MPa). Laboratory tests were conducted to investi­gate predictions of modulus of elasticity, flexural strength, creep, and shrinkage for the developed mixtures. This paper demonstrates that using UHSC and 0.7 in. (18 mm) diameter strands will produce adequate flexural strength to design 300 ft (91.4 m) long prestressed concrete I-girders that have service stresses within safe limits
本文致力于开发力学性能与超高性能混凝土(UHPC)相当、生产程序与高强度混凝土相似的超高强度混凝土(UHSC)。开发了一种混凝土混合物,在不使用硅灰的情况下,在28天内达到17ksi(117MPa)的抗压强度,坍落度高达35英寸(889mm)。另一种抗压强度为20ksi(138MPa)的混凝土混合物仅使用130 lb/yd3(77.1kg/m3)的硅灰进行设计。除了这两种混合物外,还设计了抗压强度为24ksi(165MPa)的UHPC混合物。进行了实验室试验,以研究所开发混合物的弹性模量、弯曲强度、蠕变和收缩的预测。本文证明,使用UHSC和0.7英寸(18毫米)直径的绞线将产生足够的弯曲强度,以设计300英尺(91.4米)长的预应力混凝土工字梁,其使用应力在安全范围内
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引用次数: 2
Seismic design force level for precast concrete diaphragms 预制混凝土隔板抗震设计力水平
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-01-01 DOI: 10.15554/pcij67.2-01
S. K. Ghosh
This paper provides guidance for determining seismic design force level for topped precast concrete diaphragms. This has been a controversial topic ever since ASCE/SEI 7-16, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, introduced a section titled “Alternative Design Provisions for Diaphragms” and mandated its use for precast concrete diaphragms in buildings assigned to seismic design category C, D, E, or F.
本文为顶部预制混凝土隔板抗震设计力水平的确定提供了指导。自从ASCE/SEI 7-16《建筑物和其他结构的最小设计荷载和相关标准》引入了“隔膜的替代设计规定”一节,并规定在抗震设计类别为C、D、E或F的建筑物中使用预制混凝土隔膜以来,这一直是一个有争议的话题。
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引用次数: 1
Full-scale flexural testing of slabs made of modular structural concrete insulated panels 模块化结构混凝土隔热板板的全尺寸弯曲试验
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-01-01 DOI: 10.15554/pcij67.2-03
M. Acharya, Karma Gurung, M. Mashal
Structural concrete insulated panels (SCIPs) are an alternative construction technology to traditional wood framing and masonry units for use in residential homes and low-rise structures. SCIPs can be used to erect structurally sound buildings that are economi­cal, energy efficient, and durable while incorporating sandwich technology. This study presents a novel type of SCIP that can be fabricated using off-the-shelf components. A precasting technology for such modular SCIPs is proposed. Full-scale experimental testing of one-way SCIP slabs with three different span lengths (short, medium, and long) was carried out to investigate flexural behavior, strength, ductility, and failure mechanisms. Testing showed good performance of modular SCIPs under gravity loads. Appropriate splicing details for longer-span SCIPs are developed and tested. Results show that the SCIPs tested in this research can provide a moment capacity equal to 66% of the capacity of a fully composite section.
结构混凝土隔热板(SCIPs)是传统木结构和砖石结构单元的替代建筑技术,用于住宅和低层结构。SCIPs可以用来建造经济、节能、耐用的结构良好的建筑,同时结合三明治技术。本研究提出了一种新型的SCIP,可以使用现成的组件制造。提出了一种模块化scip的预制技术。对三种不同跨度(短、中、长)的单向SCIP板进行了全尺寸实验测试,以研究其抗弯性能、强度、延性和破坏机制。试验结果表明,模块化SCIPs在重力载荷下具有良好的性能。开发并测试了适合长跨度SCIPs的剪接细节。结果表明,本研究测试的SCIPs可提供相当于全复合截面容量66%的弯矩容量。
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引用次数: 2
Optimized ultra-high-performance concrete horizontally curved bridge superstructure 优化的超高性能混凝土水平弯曲桥梁上部结构
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-01-01 DOI: 10.15554/pcij67.2-02
M. Alawneh, M. Tadros, C. Sun
Horizontally curved bridges have been mostly built with steel plate I-girders or tub girders. In the past 15 years, curved concrete girders have been successfully used in several states, including Nebraska, Colorado, and Flor­ida. This paper addresses the design of curved concrete girder bridges using ultra-high-performance concrete (UHPC) by combining state-of-the-art spliced girder technology and UHPC technology. It also proposes a number of unique features that result in further simplifi­cation of precast concrete production and construction. Critical design criteria are discussed. The system devel­opment of curved UHPC girder bridges and necessary construction steps are elaborated through a numerical example of a three-span bridge, which shows greatly reduced concrete quantities when compared with re­cently constructed curved concrete girders. With UHPC designed as proposed here, horizontally curved bridges are expected to be cost competitive with conventional concrete and more economical than structural steel.
水平曲桥大多采用钢板工字梁或桶形梁建造。在过去的15年里,弯曲混凝土梁已经成功地在几个州使用,包括内布拉斯加州、科罗拉多州和佛罗里达州。本文结合当前最先进的拼接梁技术和超高性能混凝土(UHPC)技术,研究了采用超高性能混凝土(UHPC)设计弯曲混凝土梁桥。它还提出了一些独特的功能,从而进一步简化了预制混凝土的生产和施工。讨论了关键的设计准则。通过一个三跨桥梁的数值算例,阐述了弯曲UHPC梁桥的系统开发和必要的施工步骤,与近年来建造的弯曲混凝土梁桥相比,该桥的混凝土用量大大减少。通过UHPC的设计,水平弯曲的桥梁在成本上比传统的混凝土更有竞争力,比钢结构更经济。
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引用次数: 1
Expected compressive strength in precast, prestressed concrete design: A methodology to analyze regional strength results 预制、预应力混凝土设计中的预期抗压强度:一种分析区域强度结果的方法
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-01-01 DOI: 10.15554/pcij67.5-03
D. Mante, Levent Isbiliroglu, Andric Hofrichter, Robert W. Barnes, A. Schindler
Accurate predictions of concrete compressive strength are critical for designers to effectively estimate the camber, deflections, and prestress losses of precast, prestressed concrete elements. A methodology that relies on regional concrete bridge girder strength test results is proposed for predicting expected concrete compres­sive strength. Strength data collected from precast, prestressed concrete plants were manipulated by the use of a strength-difference approach to facilitate American Concrete Institute 214R-11 analysis methods. The data set was used to evaluate five other empirical prediction model forms. When implemented using an Alabama regional data set, the methodology resulted in markedly more accurate predictions of expected concrete strength at prestress transfer and at 28 days compared with cur­rent practice.
准确预测混凝土抗压强度对于设计师有效估计预制、预应力混凝土构件的弯曲、挠度和预应力损失至关重要。提出了一种基于区域混凝土桥梁梁强度试验结果的混凝土预期抗压强度预测方法。从预制和预应力混凝土工厂收集的强度数据通过使用强度差方法进行处理,以方便美国混凝土协会214R-11分析方法。该数据集用于评估其他五种经验预测模型形式。当使用阿拉巴马州的区域数据集实施时,与目前的实践相比,该方法对预应力转移和28天的预期混凝土强度的预测明显更准确。
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引用次数: 0
Flexural behavior of full-scale, carbon-fiber-reinforced polymer prestressed concrete beams 全尺寸碳纤维增强聚合物预应力混凝土梁的弯曲性能
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-01-01 DOI: 10.15554/pcij67.5-01
P. Poudel, A. Belarbi, B. Gencturk, M. Dawood
Highway bridge beams are subjected to aggressive environments, temperature fluctuations, and millions of loading cycles throughout their service life. The combi­nation of these effects can result in the reduction of the service life of structural components. In the past decades, more-durable composite materials, such as carbon-fiber-reinforced polymers (CFRPs) have been implemented in concrete structures to address problems related to environmental durability. To date, prestress­ing applications of CFRP in beams have been mostly investigated for rectangular cross sections, which are not representative of the geometry used in modern highway bridges. In addition, the construction and detailing aspects of CFRP prestressed concrete beams have not been investigated outside of laboratory conditions. This paper describes an experimental investigation conducted on eight 40 ft (12 m) long AASHTO Type I prestressed concrete beams with 3 ft (0.9 m) wide composite con­crete decks and detailed identically to highway bridge beams in practice. Three beams were pretensioned with carbon-fiber-composite cables, four beams with CFRP bars, and one with prestressing steel. The beams were tested under monotonic and fatigue loading. All CFRP prestressed concrete beams were designed to fail due to the rupture of the prestressing CFRP. The CFRP prestressed concrete beams exhibit several desirable features of the typical steel prestressed concrete beams in terms of serviceability and strength.
公路桥梁横梁在其使用寿命期间受到恶劣环境,温度波动和数百万次加载循环的影响。这些影响的结合会导致结构部件使用寿命的减少。在过去的几十年里,更耐用的复合材料,如碳纤维增强聚合物(CFRPs)已被应用于混凝土结构中,以解决与环境耐久性相关的问题。迄今为止,CFRP在梁中的预应力应用主要是针对矩形截面进行的研究,这并不代表现代公路桥梁中使用的几何形状。此外,CFRP预应力混凝土梁的施工和细节方面尚未在实验室条件外进行研究。本文描述了对8根40英尺(12米)长AASHTO I型预应力混凝土梁与3英尺(0.9米)宽的复合混凝土桥面进行的试验研究,并与实际公路桥梁梁的细节相同。其中3根梁采用碳纤维复合索,4根梁采用碳纤维布筋,1根梁采用预应力钢。对梁进行了单调加载和疲劳加载试验。所有CFRP预应力混凝土梁都被设计为由于预应力CFRP的破裂而失效。碳纤维布预应力混凝土梁在使用性能和强度方面表现出典型钢预应力混凝土梁的几个理想特征。
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引用次数: 0
Structural grouting of load-bearing precast concrete elements: Issues and solutions 承重预制混凝土构件结构注浆:问题及解决方法
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-01-01 DOI: 10.15554/pcij67.1-03
The purpose of this paper is to raise construction industry awareness regarding structural grouting of precast concrete projects in the United States. Incidents related to structural grouting have occurred with both precast concrete systems and other building systems. Designers, architects, owners, insurance carriers, and the construction industry in general are becoming increasingly aware of deficient grouting installation methods and verification procedures. Concerns include the timeliness of grout installation during the erection process, the lack of grout on some components of finished projects, and the poor quality of installed grout. These concerns pertain to horizontal connection joints of critical load-bearing elements between foundations and precast concrete columns and walls, stacked precast concrete columns, and stacked precast concrete walls. Current building codes and standards provide no requirements and limited guidance for the installation or special inspection of these critical horizontal joints. In an effort to address this gap in building codes and standards, as it specifically relates to precast concrete structural products, some precast concrete producers and erectors are implementing several strategies and new procedures, as noted and further developed in this paper.
本文的目的是提高美国建筑业对预制混凝土工程结构注浆的认识。预制混凝土系统和其他建筑系统都发生过与结构灌浆有关的事故。设计师、建筑师、业主、保险公司和整个建筑行业越来越意识到注浆安装方法和验证程序的不足。人们关注的问题包括在安装过程中灌浆的及时性,完工项目的一些部件没有灌浆,以及灌浆的质量不佳。这些问题涉及基础与预制混凝土柱和墙体、堆叠预制混凝土柱和堆叠预制混凝土墙之间的关键承重元件的水平连接接缝。目前的建筑规范和标准对这些关键水平接头的安装或特殊检查没有要求和有限的指导。为了解决建筑规范和标准中的这一差距,特别是与预制混凝土结构产品有关,一些预制混凝土生产商和安装商正在实施一些策略和新程序,如本文所述并进一步发展。
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引用次数: 0
Proposed lump-sum formulas for long-term prestress losses 提出长期预应力损失的一次性计算公式
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-01-01 DOI: 10.15554/pcij67.5-02
N. Al-Omaishi
The current American Association of State Highway and Transportation Officials’ AASHTO LRFD Bridge Design Specifications’ approximate formula for estimating long-term prestress losses is the outcome of the research work presented in National Cooperative Highway Research Program report 496. It is produced by simplifying the detailed method and taking into account the variability of concrete properties and the interaction between the precast concrete girder and cast-in-place deck. This paper presents two detailed parametric studies based on the average con­ditions for the design and construction of commonly used bridge girders. Three spans and, consequently, three levels of prestressing for each section have been considered. The first study establishes the creep multiplier Nc, whereas the second study evaluates the shrinkage multiplier Ns. Both multipliers are used in the lump-sum formulas for estimat­ing long-term prestress losses for different bridge girders. The multipliers produced by these studies are compared with that of the current AASHTO LRFD specifications’ approximate method, and new lump-sum formulas for long-term prestress losses are proposed.
目前美国国家公路和交通官员协会的AASHTO LRFD桥梁设计规范估算长期预应力损失的近似公式是国家合作公路研究计划报告496中提出的研究工作的结果。它是通过简化详细方法,并考虑到混凝土性能的变化以及预制混凝土梁与现浇甲板之间的相互作用而产生的。本文对常用桥梁主梁的设计和施工提出了两种基于平均条件的详细参数化研究方法。考虑了三个跨度,因此,每个部分的三个预应力水平。第一项研究建立蠕变倍率Nc,而第二项研究评估收缩倍率Ns。这两种乘数都被用于估算不同桥梁主梁长期预应力损失的一次性计算公式中。将研究所得的乘数与现行AASHTO LRFD规范的近似方法进行了比较,并提出了新的长期预应力损失的一次性计算公式。
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引用次数: 1
Differences in moment redistribution in concrete beams prestressed with bonded and unbonded tendons 有粘结和无粘结预应力混凝土梁弯矩重分布的差异
IF 1.1 4区 工程技术 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2022-01-01 DOI: 10.15554/pcij67.6-02
Katarzyna Mossor
Experimental tests using an innovative hybrid concrete and steel element were conducted to define a more precise method for determining the coefficient of moment redistribution in prestressed concrete beams. Based on the test results, formulas are proposed to determine moment redistribution coefficients for beams prestressed with bonded and unbonded tendons.
采用一种创新的混合混凝土和钢单元进行了试验测试,以确定一种更精确的方法来确定预应力混凝土梁的弯矩重分配系数。根据试验结果,提出了确定有粘结和无粘结预应力梁弯矩重分配系数的公式。
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引用次数: 0
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