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Empirical models and design codes in prediction of modulus of elasticity of concrete

Behnam VAKHSHOURI, Shami NEJADI

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 38-48 doi: 10.1007/s11709-018-0479-1

摘要： Modulus of Elasticity (MOE) is a key parameter in reinforced concrete design. It represents the stress-strain relationship in the elastic range and is used in the prediction of concrete structures. Out of range estimation of MOE in the existing codes of practice strongly affect the design and performance of the concrete structures. This study includes: (a) evaluation and comparison of the existing analytical models to estimating the MOE in normal strength concrete, and (b) proposing and verifying a new model. In addition, a wide range of experimental databases and empirical models to estimate the MOE from compressive strength and density of concrete are evaluated to verification of the proposed model. The results show underestimation of MOE of conventional concrete in majority of the existing models. Also, considering the consistency between density and mechanical properties of concrete, the predicted MOE in the models including density effect, are more compatible with the experimental results.

关键词： modulus of elasticity normal strength normal weight concrete empirical models design codes compressive strength density

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Concepts and implementation of strain-based criteria in design codes for steel structures

Reidar BJORHOVDE

《结构与土木工程前沿（英文）》 2012年第6卷第3期页码 210-216 doi: 10.1007/s11709-012-0165-7

摘要： A uniaxial tension test is commonly used to determine the mechanical properties of steel, but it has no meaning for the response of the material in a structure. The test was developed as a consensus solution by producers, fabricators, designers and code writers, to have a standard by which similar materials could be compared to a common base. It does not represent the actual behavior of the steel in a structure, and was never intended to do so. To study the true behavior of the structure and how the material responds it would be better to determine the strains and deformations that will take place during actual service condition. Such characteristics reflect the real behavior, whether in the elastic or inelastic range. If stresses or forces are needed, these are easily determined by the value of the strain and the relevant material modulus, along with the type of cross section, whether elastic or inelastic. The paper addresses the properties of a range of structural steels, how these are incorporated into design standards and how the standards define deformation characteristics and demands for bolted and welded connections.

关键词： steel stress-strain characteristics tension test strain design actual behavior improved design codes

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A prototype online database-enabled design framework for wind analysis/design of low-rise buildings

Dae Kun KWON,Ahsan KAREEM,Deepak KUMAR,Yukio TAMURA

《结构与土木工程前沿（英文）》 2016年第10卷第1期页码 121-130 doi: 10.1007/s11709-015-0329-3

摘要： This study presents a development of an advanced cyberbased database-enabled design module for low-rise buildings (DEDM-LR) which provides estimation of the wind-induced responses for main wind force resisting frames by making direct use of pressure time histories measured at a large number of pressure taps over a suite of building models. These responses may be considered in lieu of code-specified load effects in which the overall accuracy may be influenced by the inherent simplifications in codes. In addition, this new automated approach is particularly attractive and advantageous as it allows a web-based online analysis/design via intuitive user-friendly interfaces for both the input and output in terms of familiar web-style forms that are nowadays very common in most of web-based services. Presently, the DEDM-LR hosts an aerodynamic database developed by the Tokyo Polytechnic University (TPU), Japan for a variety of building configurations like flat, gable, and hip roofs under suburban terrain flow condition with immediate application to other databases. The paper shows the efficacy and validity of the DEDM-LR by walking through its details and examples on selected gable-roofed buildings. The architecture of DEDM-LR platform offers the ability to pool resources by hosting other databases that may become available in the near future.

关键词： wind loads low-rise building pressure measurement aerodynamics building design structural response building codes information technology (IT)

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Experience gained in analyzing severe accidents for WWER RP using CC SOCRAT

《能源前沿（英文）》 2021年第15卷第4期页码 872-886 doi: 10.1007/s11708-021-0796-2

摘要： The current Russian regulatory documents on the safety of nuclear power plant (NPP) specify the requirements regarding design basis accidents (DBAs) and beyond design basis accidents (BDBAs), including severe accidents (SAs) with core meltdown, in NPP design (NP-001-15, NP-082-07, and others). For a rigorous calculational justification of BDBAs and SAs, it is necessary to develop an integral CC that will be in line with the requirements of regulatory documents on verification and certification (RD-03-33-2008, RD-03-34-2000) and will allow for determining the amount of data required to provide information within the scope stipulated by the requirements for the structure of the safety analysis report (SAR) (NP-006-16). The system of codes for realistic analysis of severe accidents (SOCRAT) (formerly, thermohydraulics (RATEG)/coupled physical and chemical processes (SVECHA)/behavior of core materials relocated into the reactor lower plenum (HEFEST)) was developed in Russia to analyze a wide range of SAs at NPP with water-cooled water-moderated power-generating reactor (WWER) at all stages of the accident. Enhancements to the code and broadening of its applicability are continually being pursued by the code developers (Nuclear Safety Institute of the Russian Academy of Sciences (IBRAE RAN)) with OKB Gidropress JSC and other organizations. Currently, the SOCRAT/1 code can be used as a base tool to obtain realistic estimates for all parameters important for computational justification of the reactor plant (RP) safety at the in-vessel stage of SAs with fuel melting. To perform analyses using CC SOCRAT/1, the experience gained during execution of thermohydraulic codes is applied, which allows for minimizing the uncertainties in the results at the early stage of an accident scenario. This study presents the results of the work performed in 2010–2020 in OKB Gidropress JSC using the CC SOCRAT/1. Approaches have been considered to develop calculational models and analyze SAs using CC SOCRAT. This process, which is clearly structured in OKB Gidropress JSC, provides a noticeable reduction in human involvement, and reduces the probability of erroneous results.

关键词： system of codes for realistic analysis of severe accidents (SOCRAT) design basis accidents (DBAs) severe accidents (SAs) computer code (CC) nuclear power plant (NPP) design water-cooled water-moderated (WWER) modeling model safety requirements

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State-of-the-art on resistance of bearing-type bolted connections in high strength steel

Guoqiang LI, Yifan LYU, Yanbo WANG

《结构与土木工程前沿（英文）》 2020年第14卷第3期页码 569-585 doi: 10.1007/s11709-020-0607-6

摘要： With the recent development of material science, high strength steel (HSS) has become a practical solution for landmark buildings and major projects. The current codes for design of bearing-type bolted connections of steel constructions were established based on the research of conventional steels. Since the mechanical properties of HSS are different from those of conventional steels, more works should be done to develop the appropriate approach for the design of bearing-type bolted connections in HSS. A review of the research carried out on bearing-type bolted connections fabricated from conventional steel and HSS is presented. The up-to-date tests conducted at Tongji University on four connection types fabricated from three grades of HSS with nominal yield strengths of 550, 690, and 890 MPa are presented. The previous research on failure modes, bearing resistance and the design with consideration of bolt hole elongation are summarized. It is found that the behavior of bolted connections in HSS have no drastic difference compared to that of conventional steel connections. Although the ductility is reduced, plastic deformation capacity of HSS is sufficient to ensure the load redistribution between different bolts with normal construction tolerances. It is also found that behavior of each bolt of multi-bolt connections arranged in perpendicular to load direction is almost identical to that of a single-bolt connection with the same end distance. For connections with bolts arranged in parallel to load direction, the deformation capacity of the whole connection depends on the minimum value between the end distance and the spacing distances in load direction. The comparison with existing design codes shows that Eurocode3 and Chinese GB50017-2017 are conservative for the design of bolted connections in HSS while AISC 360-16 may overestimate the bearing resistance of bolted connections.

关键词： High strength steel bolted connection bearing behavior design codes

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Investigation on modeling parameters of concrete beams reinforced with basalt FRP bars

Jordan CARTER, Aikaterini S. GENIKOMSOU

《结构与土木工程前沿（英文）》 2019年第13卷第6期页码 1520-1530 doi: 10.1007/s11709-019-0580-0

摘要： Fiber-reinforced polymer (FRP) bars are widely used as internal reinforcement replacing the conventional steel bars to prevent from corrosion. Among the different types of FRP bars, basalt FRP (BFRP) bars have been used in different structural applications and, herein, three already tested concrete beams reinforced with BFRP bars are analyzed using three-dimensional (3-D) finite element analysis (FEA). The beams were tested in four-point bending. In the FEA the behavior of concrete is simulated using the “Concrete-Damaged Plasticity” model offered in ABAQUS software. The research presented here presents a calibrated model for nonlinear FEA of BFRP concrete beams to predict their response considering both the accuracy and the computational efficiency. The calibration process showed that the concrete model should be regularized using a mesh-dependent characteristic length and material-dependent post-yield fracture and crushing energies to provide accurate mesh-size independent results. FEA results were compared to the test results with regard to failure load and crack patterns. Both test the results and the numerical results were compared to the design predictions of ACI 440.1R-15 and CSA S806-12, where CSA S806-12 seems to overestimate the shear strength for two beams.

关键词： basalt Fiber-reinforced polymer bars reinforced concrete beams finite element analysis damaged plasticity model design codes

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Comparison and harmonization of building wind loading codes among the Asia-Pacific Economies

Yaojun GE, Shuyang CAO, Xinyang JIN

《结构与土木工程前沿（英文）》 2013年第7卷第4期页码 402-410 doi: 10.1007/s11709-013-0230-x

摘要： This paper reviews wind loading codes and standards in the Asia-Pacific Region, in particular in the 15 countries and areas. A general description of wind loading model is given as a famous wind loading chain described by four variables including velocity pressure, exposure factor, pressure coefficient, and gust response factor. Through the APEC-WW Workshops and the extensive calculations for three examples of low, medium and high rise buildings, these four important variables of wind loads are evaluated and compared with statistical parameters, mean values and coefficients of variation. The main results of the comparison show some differences among the 15 economies, and the reasons and further incorporation are discussed and suggested.

关键词： wind loading codification velocity pressure exposure factor pressure coefficient gust response factor

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基于游程长度控制约束的可见光通信编码设计 Research Articles

李宗艳,余鸿路,单宝玲,邹德旋,李世银

《信息与电子工程前沿（英文）》 2020年第21卷第9期页码 1397-1411 doi: 10.1631/FITEE.1900526

摘要：在可见光通信系统中，游程长度受限码可用于促进可靠的数据传输并提供无闪烁照明。本文提出新颖的高码率游程长度受限码，以改善传输系统的误码率性能以及减少光信号闪烁。基于有限状态机设计原理，通过优化最小汉明距离和利用状态分裂法获取较小状态数，提出两种游程长度受限码编码方案以获得高编码增益。在游程长度受限码的编码设计方案中，码字集的构造至关重要；在码字集的设计中引入集合划分算法准则。详细描述各种游程长度受限码的闪烁特性和最小汉明距离，并基于直方图比较不同码字的闪烁性能。最后，基于开关键控调制的可见光通信系统对所提游程长度受限码作仿真验证及性能分析。仿真结果表明，与现有游程长度受限码相比，在闪烁控制约束下，所提游程长度受限码的误码性能更优。

关键词：可见光通信；游程长度受限码；有限状态机；最小汉明距离

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平坦快衰落条件下天线数较多时空时格码的设计

耿嘉,曹秀英,毕光国

《中国工程科学》 2006年第8卷第6期页码 48-54

摘要：

空时格码技术是近年来无线通信领域的一个研究热点，空时格码的设计准则问题一直是该技术的一个难点。在平坦快衰落条件下且天线数目较多时，基于最小平方欧式距离最大化的空时格码设计准则虽然优于经典的距离－积准则，但仍不完善。从平方距离分布与平方距离和方－方和比分布的角度对此进行了改进，得到改进的准则以及性能为目前最优的新码。还对快慢2种衰落条件下码性能差异的原因给出了新的解释，并将改进的码设计准则应用于智贪码的设计。

关键词：空时格码准则平坦快衰落距离分布

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偏振模色散对高速光码的影响

饶敏,孙小菡,张明德

《中国工程科学》 2002年第4卷第11期页码 67-70

摘要：

研究一阶、二阶偏振模色散（PMD）对10 Gb/s和40 Gb/s的光传输系统性能的影响，考虑PMD的统计特性，基于基本偏振态（PSP）理论数值模拟了非归零码（NRZ）和归零码（RZ）在传输过程中产生的脉冲畸变以及系统Q值的变化。结果表明，传输速率越高PMD对系统性能的影响越显著，二阶PMD也将不可忽略。另外，RZ码传输性能明显优于NRZ码并且可通过预啁啾进行改善。

关键词：偏振模色散（PMD）非归零码（NRZ）归零码（RZ）频率啁啾

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An improved low-complexity sum-product decoding algorithm for low-density parity-check codes

Michaelraj Kingston ROBERTS,Ramesh JAYABALAN

《信息与电子工程前沿（英文）》 2015年第16卷第6期页码 511-518 doi: 10.1631/FITEE.1400269

摘要： In this paper, an improved low-complexity sum-product decoding algorithm is presented for low-density parity-check (LDPC) codes. In the proposed algorithm, reduction in computational complexity is achieved by utilizing fast Fourier transform (FFT) with time shift in the check node process. The improvement in the decoding performance is achieved by utilizing an optimized integer constant in the variable node process. Simulation results show that the proposed algorithm achieves an overall coding gain improvement ranging from 0.04 to 0.46 dB. Moreover, when compared with the sum-product algorithm (SPA), the proposed decoding algorithm can achieve a reduction of 42%-67% of the total number of arithmetic operations required for the decoding process.

关键词： Computational complexity Coding gain Fast Fourier transform (FFT) Low-density parity-check (LDPC) codes Sum-product algorithm (SPA)

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一款基于改进的步进式译码算法实现的流水线架构RS码译码器 Article

Xing-ru PENG,Wei ZHANG,Yan-yan LIU

《信息与电子工程前沿（英文）》 2016年第17卷第9期页码 954-961 doi: 10.1631/FITEE.1500303

摘要：概要：基于改进的步进式译码算法，我们为超宽带系统设计了一款流水线架构的Reed-Solomon（RS）码译码器。为了减小复杂度，改进的步进式译码算法将传统步进式译码算法中冗余的两部分进行了结合。此外，采用流水线架构，使得所设计的译码器以最小时延获得最大吞吐率。因此，对于RS（23,17）码，我们所设计的译码器面积比ME（modified Euclidean）架构和pDCME（pipelined degree-computationless modified Euclidean）架构分别减少了42.5%和24.4%。此外，与传统步进式译码器相比，我们设计的译码器能减少11.3%的面积，且关键路径延迟更低。

关键词： Reed-Solomon码；步进式译码算法；超宽带；流水线架构

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基于深度学习紧致二进制编码的指纹索引 None

Chao-chao BAI, Wei-qiang WANG, Tong ZHAO, Ru-xin WANG, Ming-qiang LI

《信息与电子工程前沿（英文）》 2018年第19卷第9期页码 1112-1123 doi: 10.1631/FITEE.1700420

摘要：随着指纹数据库迅速发展，有必要开发一种卓越的指纹索引方法满足系统高效性和准确性要求。实值特征的指纹索引已进行广泛研究，但二进制编码特征的研究相对较少，并且二进制编码特征更适合大规模指纹数据库的高效检索。首先，提出高效的有区分度的深度紧致二进制细节点圆柱体编码（deep compact binary minutia cylinder code，DCBMCC）作为指纹索引特征。具体分析了最新细节点圆柱体编码（minutia cylinder code，MCC），并发现其缺点。提出一种新颖的深度神经网络学习指纹索引特征DCBMCC，设置网络倒数第二层直接输出为二进制编码。将独立性、平衡性、量化损失最小和相似性保持等重要属性结合在学习过程中。最后，设计了基于多索引哈希（multi-index hashing，MIH）的指纹索引模式，从而在汉明空间中进行高效精确的搜索。此外，许多公开数据库上的实验表明，本文提出的方法是一个卓越的指纹索引方法，在穿透率非常低的情况下仍然具有非常小的错误率。

关键词：指纹索引；细节点圆柱体编码；深度神经网络；多索引哈希

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Reliability design method for steam turbine blades

SHI Jinyuan

《能源前沿（英文）》 2008年第2卷第4期页码 363-368 doi: 10.1007/s11708-008-0073-7

摘要： Based on theories of probability and statistics, and taking static stresses, dynamic stresses, endurance strength, safety ratios, vibration frequencies and exciting force frequencies of blades as random variables, a reliability design method for steam turbine blades is presented. The purport and calculation method for blade reliability are expounded. The distribution parameters of random variables are determined after analysis and numerical calculation of test data. The fatigue strength and the vibration design reliability of turbine blades are determined with the aid of a probabilistic design method and by interference models for stress distribution and strength distribution. Some blade reliability design calculation formulas for a dynamic stress design method, a safety ratio design method for fatigue strength, and a vibration reliability design method for the first and second types of tuned blades and a packet of blades on a disk connected closely, are given together with some practical examples. With these methods, the design reliability of steam turbine blades can be guaranteed in the design stage. This research may provide some scientific basis for reliability design of steam turbine blades.

关键词： design reliability force probability purport reliability design

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Assembly design system based on engineering connection

Wensheng YIN

《机械工程前沿（英文）》 2016年第11卷第4期页码 423-432 doi: 10.1007/s11465-016-0382-1

摘要：

An assembly design system is an important part of computer-aided design systems, which are important tools for realizing product concept design. The traditional assembly design system does not record the connection information of production on the engineering layer; consequently, the upstream design idea cannot be fully used in the downstream design. An assembly design model based on the relationship of engineering connection is presented. In this model, all nodes are divided into two categories: The component and the connection. Moreover, the product is constructed on the basis of the connection relationship of the components. The model is an And/Or graph and has the ability to record all assembly schemes. This model records only the connection information that has engineering application value in the product design. In addition, this model can significantly reduce the number of combinations, and is very favorable for the assembly sequence planning in the downstream. The system contains a connection knowledge system that can be mapped to the connection node, and the connection knowledge obtained in practice can be returned to the knowledge system. Finally, VC++6.0 is used to develop a prototype system called Connect-based Assembly Planning (CAP). The relationship between the CAP system and the commercial assembly design system is also established.

关键词： product design assembly design engineering connection assembly sequence planning