Estimation of semi-rigid joints by cross modal strain energy method

Shuqing Wang,Min Zhang,Fushun Liu 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.6

We present a semi-rigid connection estimation method by using cross modal strain energy method. While rigid or pinned assumptions are adopted for steel frames in traditional modeling via finite element method, the actual behavior of the connections is usually neither. Semi-rigid joints enable connections to be modeled as partially restrained, which improves the quality of the model. To identify the connection stiffness and update the FE model, a newly-developed cross modal strain energy (CMSE) method is extended to incorporate the connection stiffness estimation. Meanwhile, the relations between the correction coefficients for the CMSE method are derived, which enables less modal information to be used in the estimation procedure. To illustrate the capability of the proposed parameter estimation algorithm, a four-story frame structure is demonstrated in the numerical studies. Several cases, including Semi-rigid joint(s) on single connection and on multi-connections, without and with measurement noise, are investigated. Numerical results indicate that an excellent updating is achievable and the connection stiffness can be estimated by CMSE method.

New accuracy indicator to quantify the true and false modes for eigensystem realization algorithm

Shuqing Wang,Fushun Liu 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.5

The objective of this paper is to apply a new proposed accuracy indicator to quantify the true and false modes for Eigensystem Realization Algorithm using output-based responses. First, a discrete mass-spring system and a simply supported continuous beam were modelled using finite element method. Then responses are simulated under random excitation. Natural Excitation Technique using only response measurements is applied to compute the impulse responses. Eigensystem Realization Algorithm is employed to identify the modal parameters on the simulated responses. A new accuracy indicator,Normalized Occurrence Number-NON, is developed to quantitatively partition the realized modes into true and false modes so that the false portions can be disregarded. Numerical simulation demonstrates that the new accuracy indicator can determine the true system modes accurately.

Estimation of semi-rigid joints by cross modal strain energy method

Wang, Shuqing,Zhang, Min,Liu, Fushun Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.6

We present a semi-rigid connection estimation method by using cross modal strain energy method. While rigid or pinned assumptions are adopted for steel frames in traditional modeling via finite element method, the actual behavior of the connections is usually neither. Semi-rigid joints enable connections to be modeled as partially restrained, which improves the quality of the model. To identify the connection stiffness and update the FE model, a newly-developed cross modal strain energy (CMSE) method is extended to incorporate the connection stiffness estimation. Meanwhile, the relations between the correction coefficients for the CMSE method are derived, which enables less modal information to be used in the estimation procedure. To illustrate the capability of the proposed parameter estimation algorithm, a four-story frame structure is demonstrated in the numerical studies. Several cases, including Semi-rigid joint(s) on single connection and on multi-connections, without and with measurement noise, are investigated. Numerical results indicate that an excellent updating is achievable and the connection stiffness can be estimated by CMSE method.

New accuracy indicator to quantify the true and false modes for eigensystem realization algorithm

Wang, Shuqing,Liu, Fushun Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.5

The objective of this paper is to apply a new proposed accuracy indicator to quantify the true and false modes for Eigensystem Realization Algorithm using output-based responses. First, a discrete mass-spring system and a simply supported continuous beam were modelled using finite element method. Then responses are simulated under random excitation. Natural Excitation Technique using only response measurements is applied to compute the impulse responses. Eigensystem Realization Algorithm is employed to identify the modal parameters on the simulated responses. A new accuracy indicator, Normalized Occurrence Number-NON, is developed to quantitatively partition the realized modes into true and false modes so that the false portions can be disregarded. Numerical simulation demonstrates that the new accuracy indicator can determine the true system modes accurately.

Structural damage identification using an iterative two-stage method combining a modal energy based index with the BAS algorithm

Shuqing Wang,Yufeng Jiang,Mingqiang Xu,Yingchao Li,Zhixiong Li 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.1

The purpose of this study is to develop an effective iterative two-stage method (ITSM) for structural damage identification of offshore platform structures. In each iteration, a new damage index, Modal Energy-Based Damage Index (MEBI), is proposed to help effectively locate the potential damage elements in the first stage. Then, in the second stage, the beetle antenna search (BAS) algorithm is used to estimate the damage severity of these elements. Compared with the well-known particle swarm optimization (PSO) algorithm and genetic algorithm (GA), this algorithm has lower computational cost. A modal energy based objective function for the optimization process is proposed. Using numerical and experimental data, the efficiency and accuracy of the ITSM are studied. The effects of measurement noise and spatial incompleteness of mode shape are both considered. All the obtained results show that under these influences, the ITSM can accurately identify the true location and severity of damage. The results also show that the objective function based on modal energy is most suitable for the ITSM compared with that based on flexibility and weighted natural frequency-mode shape.

Dynamic analysis of three adjacent bodies in twin-barge floatover installation

Wang, Shuqing,Li, Xiliang Techno-Press 2014 Ocean systems engineering Vol.4 No.1

Floatover technology has been widely used in offshore installation, which has many substantial advantages compared with the traditional derrick barge. During the topside offloading of a twin-barge floatover installation, the transport barge is side by side moored between two floatover barges. In this paper, the twin-barge model with the connecting hawsers and pneumatic fenders is established. Coupled dynamic analysis is carried out to investigate the motions of the barges under wind, wave and current environments. Particular attention is paid to the effects on system responses with different frictional performance of fender, axial stiffness of the hawsers and environmental conditions. The research results can be used for optimizing the parameters of the system and reducing the risk of topside offloading.

PROLONG THE SERVICE LIFE OF SWITCH RAIL BY IMPROVED INDUCTION HEAT TREATMENT

Xinwei Zhan,Shuqing Wang 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-

Switch rail is a very important part on the railway track, which not only accounts for the safety of the passing trains but also greatly influences the speed of the train. The higher the speed and the loads of the train the more it demands on the properties of the switch rail. Research shows that the higher mechanical properties of switch rail the longer the service life. Induction heat treatment is a good way of improving the mechanical properties of metallic materials. But the switch rail’s section area changes gradually across the lengthways, which is difficult for induction heating especially for the small section. And the mechanical property of small section of the switch rail is the most important for its service life. The induction heat treatment used past always brings the low hardness on small section which can cause low service life of switch for wearing, or too high hardness because of martensite microstructure which can cause the shelling or even breaking of the switch rail. To prolong the service life of switch rail by higher mechanical properties, we researched the improved induction heat treatment for switch rail by adjusting speed of heating, and adopting compressed air cooling. The results showed that switch rail obtain almost the same high hardness across the length way after the improved induction heat treatment, which is very helpful to extend the service life of switch rail.

A novel multistage approach for structural model updating based on sensitivity ranking

Yufeng Jiang,Yingchao Li,Shuqing Wang,Mingqiang Xu 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.6

A novel multistage approach is developed for structural model updating based on sensitivity ranking of the selected updating parameters. Modal energy-based sensitivities are formulated, and maximum-normalized indices are designed for sensitivity ranking. Based on the ranking strategy, a multistage approach is proposed, where these parameters to be corrected with similar sensitivity levels are updated simultaneously at the same stage, and the complete procedure continues sequentially at several stages, from large to small, according to the predefined levels of the updating parameters. At every single stage, a previously developed cross model cross mode (CMCM) method is used for structural model updating. The effectiveness and robustness of the multistage approach are investigated by implementing it on an offshore structure, and the performances are compared with nonmultistage approach using numerical and experimental vibration information. These results demonstrate that the multistage approach is more effective for structural model updating of offshore platform structures even with limited information and measured noise. These findings serve as a preliminary strategy for structural model updating of an offshore platform in service.

Behavior of three-tube buckling-restrained brace with circumference pre-stress in core tube

Yang Li,Haiyan Qu,Shaowen Xiao,Peijun Wang,Yang You,Shuqing Hu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.2

The behavior of a new Three-Tube Buckling-Restrained Brace (TTBRB) with circumference pre-stress (σθ,pre) in core tube are investigated through a verified finite element model. The TTBRB is composed of one core tube and two restraining tubes. The core tube is in the middle to provide the axial stiffness, to carry the axial load and to dissipate the earthquake energy. The two restraining tubes are at inside and outside of the core tube, respectively, to restrain the global and local buckling of the core tube. Based on the yield criteria of fringe fiber, a design method for restraining tubes is proposed. The applicability of the proposed design equations are verified by TTBRBs with different radius-thickness ratios, with different gap widths between core tube and restraining tubs, and with different levels of σθ,pre. The outer and inner tubes will restrain the deformation of the core tube in radius direction, which causes circumference stress (σθ) in the core tube. Together with the σθ,pre in the core tube that is applied through interference fit of the three tubes, the yield strength of the core tube in the axial direction is improved from 160 MPa to 235 MPa. Effects of gap width between the core tube and restraining tubes, and σθ,pre on hysteretic behavior of TTBRBs are presented. Analysis results showed that the gap width and the σθ,pre can significantly affect the hysteretic behavior of a TTBRB.

The role of WRKY47 gene in regulating selenium tolerance in Arabidopsis thaliana

Xi Wu,Manzhi Tao,Yun Meng,Xiangyu Zhu,Liangwen Qian,Alia Shah,Wei Wang,Shuqing Cao 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.1

Selenium stress has a serious impact on the growth of plants. However, the available understanding on the mechanism of Se stress response is still insufficient. In this study, we found that the WRKY47 gene plays an important role in maintaining Se homeostasis and tolerance in Arabidopsis thaliana. Expression of WRKY47 is induced by Se stress. The wrky47 mutants are sensitive to Se stress, and this sensitivity is associated with a decrease in the transcription levels of Se-detoxify genes HMT1 and HMT3. Surprisingly, the WRKY47-overexpression lines also showed increased sensitivity to Se stress and had increased Se content; this correlates to an increase in the transcription level of Se-uptake gene PHT1;4 but not Se-detoxify genes HMT1 and HMT3. Our results suggest that gain- and loss-of-function mutations in WRKY47 enhance the sensitivity of A. thaliana plants to Se stress through different mechanisms.