Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 5

年份

2022 2

2021 1

2019 2

关键词

模运算单元；可重构；高能效 1

检索范围：

排序：展示方式：

Experimental study on flexural behavior of ECC/RC composite beams with U-shaped ECC permanent formwork

Zhi QIAO, Zuanfeng PAN, Weichen XUE, Shaoping MENG

《结构与土木工程前沿（英文）》 2019年第13卷第5期页码 1271-1287 doi: 10.1007/s11709-019-0556-0

摘要： To enhance the durability of a reinforced concrete structure, engineered cementitious composite (ECC), which exhibits high tensile ductility and good crack control ability, is considered a promising alternative to conventional concrete. However, broad application of ECC is hindered by its high cost. This paper presents a new means to address this issue by introducing a composite beam with a U-shaped ECC permanent formwork and infill concrete. The flexural performance of the ECC/RC composite beam has been investigated experimentally with eight specimens. According to the test results, the failure of a composite beam with a U-shaped ECC formwork is initiated by the crushing of compressive concrete rather than debonding, even if the surface between the ECC and the concrete is smooth as-finished. Under the same reinforcement configurations, ECC/RC composite beams exhibit increases in flexural performance in terms of ductility, load-carrying capacity, and damage tolerance compared with the counterpart ordinary RC beam. Furthermore, a theoretical model based on the strip method is proposed to predict the moment-curvature responses of ECC/RC composite beams, and a simplified method based on the equivalent rectangular stress distribution approach has also evolved. The theoretical results are found to be in good agreement with the test data.

关键词： engineered cementitious composite (ECC) durability ECC/RC composite beam permanent formwork flexural performance theoretical method

HTML PDF 收藏

Flexural behavior of ECC hollow beams incorporating different synthetic fibers

Ahmmad A. ABBAS, Farid H. ARNA ’OT, Sallal R. ABID, Mustafa ÖZAKÇA

《结构与土木工程前沿（英文）》 2021年第15卷第2期页码 399-411 doi: 10.1007/s11709-021-0701-4

摘要： Twelve ECC beams with three different fiber types, along with four normal concrete beams, were tested in this study to evaluate the influence of cross-sectional hollowing on their flexural performance. The fiber types used were nylon monofilament (NM), low-cost untreated polyvinyl alcohol (PVA), and polypropylene (PP). Three different square hole sizes of 60, 80, and 100 mm with cross-sectional hollowing ratios of 0.16, 0.28, and 0.44, respectively, were adopted for each group of beams in addition to a solid beam. All beams were tested under four-point loading using a displacement-controlled testing machine. The test results showed that ECC beams can mostly withstand higher cracking and ultimate loads compared to their corresponding normal concrete versions. The results also showed that both the ductility and toughness of the ECC beams are higher than those of the normal concrete beams and that the ductility values of the hollow beams with a hole size of 60 mm are higher than those of the corresponding solid beams. Moreover, hollow ECC beams with hole sizes of 60 and 80 mm exhibited a higher ductility than a solid normal concrete beam.

关键词： hollow beam hollowing ratio ECC flexural strength ductility toughness

HTML PDF 收藏

Computational studies on the seismic response of the State Route 99 bridge in Seattle with SMA/ECC plastic

Jiping GE, M. Saiid SAIIDI, Sebastian VARELA

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 149-164 doi: 10.1007/s11709-018-0482-6

摘要： This paper reports a computational study on the seismic response of a three-span highway bridge system incorporating conventional and novel substructure details for improved seismic performance. The bridge has three continuous spans supported by two single-column piers and integral abutments founded on drilled shafts. It will be the first full-scale highway bridge to use superelastic shape memory alloy bars (SMA) and engineered cementitious composite (ECC) to mitigate column plastic hinge damage and minimize residual displacements after a strong earthquake. A three-dimensional computational model capturing the nonlinear constitutive response of the novel materials and the effects of dynamic soil-structure interaction was developed to assess the seismic response of the bridge in finite-element software OpenSees. Two versions of the same bridge were analyzed and compared, one with conventional cast-in-place reinforced concrete columns, and the other with top plastic hinges incorporating Nickel-Titanium (NiTi) SMA reinforcing bars and ECC. The novel SMA/ECC plastic hinges were found to substantially reduce damage and post-earthquake residual displacements in the bridge substructure, but led to larger maximum drifts relative to the bridge with conventional reinforced concrete plastic hinges. The analysis results suggested that the novel plastic hinges could lead to improved post-earthquake serviceability of bridges after intense earthquakes.

关键词： seismic design analytical simulation near-fault earthquakes shape memory alloy engineered cementitious composite self-centering

HTML PDF 收藏

一种用于RSA和ECC的高能效可重构非对称密码模运算单元 Research Article

别梦妮1,李伟1,陈韬1,南龙梅2,杨丹阳1

《信息与电子工程前沿（英文）》 2022年第23卷第1期页码 134-144 doi: 10.1631/FITEE.2000325

摘要： RSA和椭圆曲线密码（ECC）算法广泛应用于身份验证、数据安全和访问控制。本文分析了ECC和RSA算法基本操作并对模乘和模逆算法进行优化。所提模运算单元完成2048位RSA模乘和模逆功耗分别为21.92和23.36 mW，完成512位ECC双域模乘和模逆功耗分别为16.16 和15.88 mW。它比现有单一算法单元更高效、更灵活。将所提模运算单元嵌入64位RISC-V处理器，可实现RSA和ECC的密钥生成、加解密以及数字签名功能。实验结果表明，所提设计在G(p)和G(2m)上实现256位ECC点乘分别需要0.224和0.153 ms，实现1024位RSA求幂需要0.96 ms，满足高能效需求。

关键词：模运算单元；可重构；高能效

HTML PDF 收藏

Numerical investigation of the influence of casting techniques on fiber orientation distribution in ECC

Chung Nguyen VAN; Hai TRAN THANH; Thuc Nhu NGUYEN; Jianchun LI

《结构与土木工程前沿（英文）》 2022年第16卷第11期页码 1424-1435 doi: 10.1007/s11709-022-0870-9

摘要： Engineered cementitious composites (ECC), also known as bendable concrete, were developed based on engineering the interactions between fibers and cementitious matrix. The orientation of fibers, in this regard, is one of the major factors influencing the ductile behavior of this material. In this study, fiber orientation distributions in ECC beams influenced by different casting techniques are evaluated via numerical modeling of the casting process. Two casting directions and two casting positions of the funnel outlet with beam specimens are modeled using a particle-based smoothed particle hydrodynamics (SPH) method. In this SPH approach, fresh mortar and fiber are discretized by separated mortar and fiber particles, which smoothly interact in the computational domain of SPH. The movement of fiber particles is monitored during the casting simulation. Then, the fiber orientations at different sections of specimens are determined after the fresh ECC stops flowing in the formwork. The simulation results show a significant impact of the casting direction on fiber orientation distributions along the longitudinal wall of beams, which eventually influence the flexural strength of beams. In addition, casting positions show negligible influences on the orientation distribution of fibers in the short ECC beam, except under the pouring position.

关键词： ECC fiber orientation distribution casting direction casting position