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.

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.

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.

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.

Block Sparse Low-rank Matrix Decomposition based Visual Defect Inspection of Rail Track Surfaces

( Linna Zhang ),( Shiming Chen ),( Yigang Cen ),( Yi Cen ),( Hengyou Wang ),( Ming Zeng ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.12

Low-rank matrix decomposition has shown its capability in many applications such as image in-painting, de-noising, background reconstruction and defect detection etc. In this paper, we consider the texture background of rail track images and the sparse foreground of the defects to construct a low-rank matrix decomposition model with block sparsity for defect inspection of rail tracks, which jointly minimizes the nuclear norm and the 2-1 norm. Similar to ADM, an alternative method is proposed in this study to solve the optimization problem. After image decomposition, the defect areas in the resulting low-rank image will form dark stripes that horizontally cross the entire image, indicating the preciselocations of the defects. Finally, a two-stage defect extraction method is proposed to locate the defect areas. The experimental results of the two datasets show that our algorithm achieved better performance compared with other methods.

Analysis on the safe distance between shield tunnel through sand stratum and underlying karst cave

Wei Wan,Shiming Gao,Lingfeng Liu,Wushuang Wen,Ping Li,Jianping Chen 한국자원공학회 2019 Geosystem engineering Vol.22 No.2

When a subway tunnel passes through a karst geological area, in order to ensure the stability of the tunnel, the safe distance between the tunnel and karst cave needs to be researched. This article is based on the construction project of Wuhan metro line 6 from Qianjincun station to Mayinglu station. In view of the geological condition of overlying sand and underlying limestone, by using numerical simulation and theoretical calculation and selecting a characteristic section, the influence law and degree of karst cave span, height-span ratio, and filling degree on the safe thickness of karst cave roof are studied and a forecasting model of the safe thickness of karst cave roof is established. Combined with dichotomy and numerical simulation, the critical horizontal safe distance beyond which cave collapse does not cause tunnel instability is calculated. The results show that: (1) the safe thickness of karst cave roof increases linearly with the increase of karst cave span, and decreases with the increase of height-span ratio and filling degree; (2) among the three factors, the effect of karst cave span is the most significant, the filling degree of karst cave is the second, and the influence of height-span ratio of karst cave is the weakest; (3) the proposed forecasting model passes the significance test, indicating that the model is very reasonable; and (4) the critical horizontal safe distance from the tunnel border to the karst cave boundary is 22.4 m. The research results can provide guidance for the design and construction of shield tunnels and karst cave treatment in karst areas.

Coexisting Attractors Generated from a New 4D Smooth Chaotic System

Qiang Lai,Shiming Chen 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.4

In this paper, a new 4D smooth chaotic system with coexisting attractors is proposed. The coexistingattractors which means two or more attractors generate simultaneously from different initial values is an importantnonlinear dynamics. It is found that the new system is rich in coexisting attractors by numerical simulation. Detailedinvestigation of the coexisting chaotic attractors, coexisting chaotic and periodic attractors, coexisting chaotic andpoint attractors, coexisting periodic and point attractors in the system are presented. It is shown that the system maycoexist four independent attractors by selecting appropriate parameters and initial values.

Cyano-substituted benzochalcogenadiazole-based polymer semiconductors for balanced ambipolar organic thin-film transistors

Shi, Shengbin,Wang, Hang,Chen, Peng,Uddin, Mohammad Afsar,Wang, Yuxi,Tang, Yumin,Guo, Han,Cheng, Xing,Zhang, Shiming,Woo, Han Young,Guo, Xugang The Royal Society of Chemistry 2018 Polymer chemistry Vol.9 No.28

<P>Due to their high-lying lowest unoccupied molecular orbitals (LUMOs), π-conjugated polymers based on benzothiadiazole and its derivatives typically are p-type. We report here the successful development of two narrow bandgap, ambipolar donor-acceptor copolymers, PDCNBT2T and PDCNBSe2T, which are based on new cyano-substituted strong electron acceptors, 4,7-dibromo-5,6-dicyano-2,1,3-benzothiadiazole (DCNBT) and 4,7-dibromo-5,6-dicyano-2,1,3-benzoselenadiazole (DCNBSe), respectively. Compared to their polymer analogues with fluorine substituents, the LUMO was lowered by a big margin of <I>ca.</I> 0.6 eV and the bandgap was reduced by 0.2-0.3 eV for the cyano-substituted polymers. Therefore, the cyano-substituted benzothiadiazole polymers showed very low-lying LUMO levels of <I>ca.</I> 4.3 eV. Benefiting from their narrow bandgaps of 1.1-1.2 eV and appropriately positioned LUMO levels, both polymers exhibit well balanced ambipolar transport characteristics in organic thin-film transistors, which differ from the p-type dominating transport properties of their fluorinated polymer analogues. A balanced hole/electron mobility of 0.59/0.47 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> was achieved for polymer PDCNBT2T, and a reduced hole/electron mobility of 0.018/0.014 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> was observed for the benzoselenadiazole-based PDCNBSe2T due to its lower crystallinity. These results show that the electron mobility can be enhanced by approximately two orders <I>versus</I> the electron mobility of the previously reported 4,7-di(thiophen-2-yl)-5,6-dicyano-2,1,3-benzothiadiazole-based polymer. This improvement was achieved by using the new acceptor units without additional electron-rich thiophene flanks, which allow a higher degree of freedom in selecting the donor co-unit and more effective tuning of energy levels of frontier molecular orbitals.</P>

PAPG: Private Aggregation Scheme based on Privacy-preserving Gene in Wireless Sensor Networks

( Weini Zeng ),( Peng Chen ),( Hairong Chen ),( Shiming He ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.9

This paper proposes a privacy-preserving aggregation scheme based on the designed P-Gene (PAPG) for sensor networks. The P-Gene is constructed using the designed erasable data-hiding technique. In this P-Gene, each sensory data item may be hidden by the collecting sensor node, thereby protecting the privacy of this data item. Thereafter, the hidden data can be directly reported to the cluster head that aggregates the data. The aggregation result can then be recovered from the hidden data in the cluster head. The designed P-Genes can protect the privacy of each data item without additional data exchange or encryption. Given the flexible generation of the P-Genes, the proposed PAPG scheme adapts to dynamically changing reporting nodes. Apart from its favorable resistance to data loss, the extensive analyses and simulations demonstrate how the PAPG scheme efficiently preserves privacy while consuming less communication and computational overheads.

Metabolic reprogramming and epigenetic modifications in cancer: from the impacts and mechanisms to the treatment potential

Xu Xuemeng,Peng Qiu,Jiang Xianjie,Tan Shiming,Yang Yiqing,Yang Wenjuan,Han Yaqian,Chen Yuyu,Oyang Linda,Lin Jinguan,Xia Longzheng,Peng Mingjing,Wu Nayiyuan,Tang Yanyan,Li Jinyun,Liao Qianjin,Zhou Yuju 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Metabolic reprogramming and epigenetic modifications are hallmarks of cancer cells. In cancer cells, metabolic pathway activity varies during tumorigenesis and cancer progression, indicating regulated metabolic plasticity. Metabolic changes are often closely related to epigenetic changes, such as alterations in the expression or activity of epigenetically modified enzymes, which may exert a direct or an indirect influence on cellular metabolism. Therefore, exploring the mechanisms underlying epigenetic modifications regulating the reprogramming of tumor cell metabolism is important for further understanding tumor pathogenesis. Here, we mainly focus on the latest studies on epigenetic modifications related to cancer cell metabolism regulations, including changes in glucose, lipid and amino acid metabolism in the cancer context, and then emphasize the mechanisms related to tumor cell epigenetic modifications. Specifically, we discuss the role played by DNA methylation, chromatin remodeling, noncoding RNAs and histone lactylation in tumor growth and progression. Finally, we summarize the prospects of potential cancer therapeutic strategies based on metabolic reprogramming and epigenetic changes in tumor cells.