Shear bond failure in composite slabs– a detailed experimental study

Shiming Chen,Xiaoyu Shi,Zihao Qiu 국제구조공학회 2011 Steel and Composite Structures, An International J Vol.11 No.3

An experimental study has been carried out to reveal the shear-bond failure mechanism of composite deck slabs. Thirteen full scale simply supported composite slabs are studied experimentally, with the influence parameters like span length, slab depth, shear span length and end anchorage provided by steel headed studs. A dozen of strain gauges and LVDTs are monitored to capture the strain distribution and variation of the composite slabs. Before the onset of shear-bond slip, the longitudinal shear forces along the span are deduced and found to be proportional to the vertical shear force in terms of the shear-bond strength in the m-k method. The test results are appraised using the current design procedures. Based on the partial shear-bond connection at the ultimate state, an improved method is proposed by introducing two reduction factors to assess the moment resistance of a composite deck slab. The new method has been validated and the results predicted by the revised method agree well with the test results.

Analytical and Experimental Investigation of Flow Distribution in Manifolds for Heat Exchangers

Shiming Yang,Yonghao Luo 대한기계학회 1998 Heat transter conference Vol.6 No.1

ADAPTIVE MODEL FOLLOWING CONTROL FOR THE ROBOTICS MANIPULATORS

Shiming Tang,Sangyong Lee,Deokjung Kim 전력전자학회 1995 ICPE(ISPE)논문집 Vol.1995 No.10

A new method under certain criteria for choosing the adaptive gain matrices F, F1, M, M1, and weight matrices G and N for the adaptive model following control (AMFC) system has been developed. This design method provides a theoretical guidance and engineering formulas for finding a set of suitable gain and weight matrices during the adaptive process. The technique is demonstrated in a robotics manipulator, and the numerical aspects of determining and adjusting those matrices are also discussed.

PPNC: Privacy Preserving Scheme for Random Linear Network Coding in Smart Grid

( Shiming He ),( Weini Zeng ),( Kun Xie ),( Hongming Yang ),( Mingyong Lai ),( Xin Su ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3

In smart grid, privacy implications to individuals and their families are an important issue because of the fine-grained usage data collection. Wireless communications are utilized by many utility companies to obtain information. Network coding is exploited in smart grids, to enhance network performance in terms of throughput, delay, robustness, and energy consumption. However, random linear network coding introduces a new challenge for privacy preserving due to the encoding of data and updating of coefficients in forwarder nodes. We propose a distributed privacy preserving scheme for random linear network coding in smart grid that considers the converged flows character of the smart grid and exploits a homomorphic encryption function to decrease the complexities in the forwarder node. It offers a data confidentiality privacy preserving feature, which can efficiently thwart traffic analysis. The data of the packet is encrypted and the tag of the packet is encrypted by a homomorphic encryption function. The forwarder node random linearly codes the encrypted data and directly processes the cryptotext tags based on the homomorphism feature. Extensive security analysis and performance evaluations demonstrate the validity and efficiency of the proposed scheme.

Experimental study of moment redistribution and load carrying capacity of externally prestressed continuous composite beams

Shiming Chen,Yuanlin Jia,Xindi Wang 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.5

A comparative experimental study of prestressed continuous steel-concrete composite beams was carried out. Two continuous composite beams were tested, one of which was plain continuous steelconcrete composite beam, while the other was a composite beam prestressed with external tendons. Cracking behavior and the load carrying capacity of the beams were investigated experimentally. Full plasticity was developed in the mid-span section each beam, the maximum moments attained at the internal support sections however were governed by local buckling which was related to the slenderness of composite section. It was found that in hogging moment regions, the ultimate resistance of an externally prestressed composite beam would be governed by either distortional lateral buckling or local buckling, or interactive mode of these two buckling patterns. The results show that exerting prestressing on a continuous composite beam with external tendons will increase the extent of internal force and moment redistribution in the beam. The influences of local and distortional buckling on the behaviors of the composite continuous beams are discussed. The Moment redistribution and the load carrying capacity of the prestressed continuous composite beams are evaluated, and it is found that at the ultimate state, the moment redistribution in the prestrssed continuous composite beams is greater than that in non-prestressed composite beams.

Effects of longitudinal and transverse curvatures on optimal design of shell footbridge

Shiming Liu,Bin Huang,Yi Min Xie 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.1

Shell bridges have attracted extensive interest in engineering research and practice. This paper aims to evaluate the effects of longitudinal and transverse curvatures on the optimal design of the shell bridge. For this purpose, a slant-legged steel shell footbridge with the same initial and target volumes of steel was chosen to build parametric geometric models with different curvature radii, and then topology optimization was carried out using the bi-directional evolutionary structural optimization (BESO) technique to obtain optimized designs with high structural stiffness. Furthermore, linear static analysis and eigenvalue analysis demonstrate that the displacement, von Mises effective stress, and the first-order vertical vibration frequency satisfied all the requirements of design regulations. Numerical results indicate that not only the longitudinal curvature but also the transverse curvature have a significant effect on the optimized designs of steel shell footbridge. While the mean compliance increased with the transverse curvature radius, it first decreased and then increased with the longitudinal curvature radius.

试析中美冲突加剧的表现、 走向和原因

范士明 ( Shiming Fan ) 성균관대학교 성균중국연구소 2020 중국사회과학논총 Vol.2 No.1

中美两国之间近几年的冲突不仅体现在经贸领域,也日益演变成涉及战略与安全、地区热点问题、国内治理方式以及意识形态领域的广泛而深刻的冲突。贸易战引发了技术战、投资战、金融战等溢出效应,2020年1月第一阶段贸易协议的达成充其量只是一个暂时的缓和剂。在战略和安全上,中美两国都把对方作为主要的威胁和对手,在核力量、导弹能力、南海问题、网络安全等方面形成竞争和冲突。在诸多地区热点上,双方经常立场相左,尤其是美国对中国在东南欧、非洲、拉美、东南亚等实施的一带一路倡议展开批评和阻击。两国政府也经常批评对方的国内经济和社会治理,特别是美国领导人,要求中国进行国内结构性改革,并且试图干预香港、新疆等问题。在双边和全球层次上,中美两国间权力、国家利益和荣誉的对立和竞争日趋激烈。 中国学者对中美关系前景的讨论大致围绕三个问题展开: 一是美国对华政策和中美关系是否发生了“质变”,二是中美关系是否可能“脱钩”,三是中美两国之间是否会出现新冷战甚至落入“修昔底德陷阱”。绝大多数中美学者认为特朗普下的美国对华政策已经从以往的合作与竞争并存转向对华全面竞争乃至遏制,发生了“质变”,但有一些人对两国关系是否发生了“质变”判断相对谨慎,期待中国政府的应对能够减缓中美关系“质变”这一前景。对于中美两国在技术领域以及更大范围内的“脱钩”,几乎所有中国学者都持批评和反对态度,认为是不理性和不现实的,代价巨大。不过许多人也无奈地承认,脱钩正在发生,或许还会扩大。多数中国学者认为,由于能力、环境等限制,美苏之间发生的那种冷战不太可能在中美之间重复。可是也有人担心,某种新形式的冷战出现的可能性也不能排除。有大量的时事批评和学术文章,讨论中美两国能否超越所谓“修昔底德陷阱”。 在中国,对中美冲突加剧的原因,压倒性的解释是“老大和老二”的矛盾,即试图维持霸权的大国(美国)试图阻止新兴大国(中国)的崛起,是典型的结构现实主义权力政治的理解。但是这种解释有意或者无意地低估了很多美国人对中美冲突的理解,即中美矛盾是两种发展模式以及价值观念/意识形态的冲突。美国政府领导人认为,独特的中国模式让中国在两国竞争中受益,其背后的价值观念与美国完全不同,中美之争是两种模式之争。中国近些年在国内和国际上高调宣传中国道路、中国智慧、中国方案,或许加剧了美国的担心。如果中美两国的力量竞争叠加了意识形态冲突,结果可能是最具破坏性的。 The rising China-US conflict in recent years goes far beyond trade controversy and economic rivalry, shifting to much extensive and fundamental confrontations in the areas of strategy and security, regional issues, as well as ideology and domestic governance. The trade war has produced spillover effects into intensifying technological control and investment restrictions, and the phase one trade deal reached in January 2020 is nothing but a small allievant. China and the United States have targeted each other as the major security threat in their strategies and are wary about the nuclear and missile capacities of the other side. Cyber and maritime security issues become salient. The two governments are more often than not at odds on regional hot-spots in the world, particularly with that China’s Belt and Road Initiative has also been under continuous American criticism. At the same time, China and the US challenge each other’s domestic economic and social governance. Especially, American leaders require structural change in Chinese economy and try to intervene on the Hong Kong and Xin Jiang issues. The escalating competition between the two countries over power, benefits and pride are thus well demonstrated in multiple dimensions at bilateral and global levels. In China, scholars and observers focus on basically three indicators to discuss the direction of Sino-American relations: the changing nature of American China policy or China-US bilateral relationship, the possibility of China-US decoupling, and the likelihood of the emerging new Cold War or even the fall into the so-called Thucydides’ Trap of the two countries. Most Chinese scholars agree that American China policy has changed fundamentally under the Trump administration, from a half-cooperative and half-competitive line to an overwhelming confrontational/containing one, but some of them are reluctant to identify the relationship as being nature-changed, hoping that the Chinese government take rational measures to avoid a total head-on. Almost all Chinese observers criticize the US government for trying to decouple the relationship technologically, and in other areas. They believe that the total decoupling between the two countries is unaffordable for both and therefore is unrealistic. However, they also acknowledge that some kind of decoupling is already unfolding, and more might be on the way. Even though few Chinese scholars agree that the Cold War would come back between China and the US in its original terms, many still worry that a variant form of the Cold War is a real peril that the bilateral relations now is facing. Numerous comments and articles are devoted to the discussion of the Thucydides’ Trap and how China-US relations should overcome it. The rising conflict between the world Number One and Number Two economies is very much framed in China as a pure realpolitik game in which the status quo hegemon is trying to block an emerging new player. It however downplays, intentionally or not, the fact that many Americans see the conflict between China and the US as confrontations between two governance models supported by contrast values/ideologies. Behind China’s rise is its very unique system--- the China model---which for American leaders in the Trump administration has granted China the “unfair” advantages in the competition. China’s domestic and international promotion of the Chinese way in recent years and its “assertive” foreign policies may have fed that American perception. Ideological confrontation may drive the power competition to the worst scenario between the two countries.

Numerical analysis of the axially loaded concrete filled steel tube columns with debonding separation at the steel-concrete interface

Chen Shiming,Zhang Huifeng 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.13 No.3

The interaction between steel tube and concrete core is the key design considerations for concrete-filled steel tube columns. In a concrete-filled steel tube (CFST) column, the steel tube provides confinement to the concrete core which permits the composite action among the steel tube and the concrete. Due to construction faults and plastic shrinkage of concrete, the debonding separation at the steel-concrete interface weakens the confinement effect, and hence affects the behaviour and bearing capacity of the composite member. This study investigates the axial loading behavior of the concrete filled circular steel tube columns with debonding separation. A three-dimensional nonlinear finite element model of CFST composite columns with introduced debonding gap was developed. The results from the finite element analysis captured successfully the experimental behaviours. The calibrated finite element models were then utilized to assess the influence of concrete strength, steel yield stress and the steel-concrete ratio on the debonding behaviour. The findings indicate a likely significant drop in the load carrying capacity with the increase of the size of the debonding gap. A design formula is proposed to reduce the load carrying capacity with the presence of debonding separation.

Experimental study of moment redistribution and load carrying capacity of externally prestressed continuous composite beams

Chen, Shiming,Jia, Yuanlin,Wang, Xindi Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.5

A comparative experimental study of prestressed continuous steel-concrete composite beams was carried out. Two continuous composite beams were tested, one of which was plain continuous steel-concrete composite beam, while the other was a composite beam prestressed with external tendons. Cracking behavior and the load carrying capacity of the beams were investigated experimentally. Full plasticity was developed in the mid-span section each beam, the maximum moments attained at the internal support sections however were governed by local buckling which was related to the slenderness of composite section. It was found that in hogging moment regions, the ultimate resistance of an externally prestressed composite beam would be governed by either distortional lateral buckling or local buckling, or interactive mode of these two buckling patterns. The results show that exerting prestressing on a continuous composite beam with external tendons will increase the extent of internal force and moment redistribution in the beam. The influences of local and distortional buckling on the behaviors of the composite continuous beams are discussed. The Moment redistribution and the load carrying capacity of the prestressed continuous composite beams are evaluated, and it is found that at the ultimate state, the moment redistribution in the prestrssed continuous composite beams is greater than that in non-prestressed composite beams.

Seller Investment Incentive on Heterogeneous Platforms Under Competition

Xuan Jiang,Shiming Deng 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.5

This paper sets an analytical model to study the scenario that two differentiated sellers simultaneously trade on two competitive heterogeneous platforms—for-profit platform and open platform. Three research questions are discussed: (1) If sellers trade on both competitive heterogeneous platforms, how should he/she price on the different platforms and what are the impact factors? (2) How do the fees charged by for-profit platforms to sellers and consumers affect sellers’ pricing and consumers’ selection on platforms? (3) What is the difference of seller’s investment incentives between for-profit platforms and open platforms? This paper finds that if the total fees charged by for-profit platforms keep constant, the split-up between the fees to sellers and consumers will not affect consumers’ selection of platforms. Both the fees charged by the for-profit platform and consumers distribution between platforms will affect sellers’ decision on pricing and investment on heterogeneous platforms.