Analysis of corrugated steel web beam bridges using spatial grid modelling

Dong Xu,Yingsheng Ni,Yu Zhao 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.4

Up to now, Japan has more than 200 corrugated steel web composite beam bridges which are under construction and have been constructed, and China has more than 30 corrugated steel web composite beam bridges. The bridge type includes the simply supported beam, continuous beam, continuous rigid frame and cable stayed bridge etc. The section form has developed to the single box and multi-cell box girder from the original single box and single chamber. From the stress performance and cost saving, the span range of 50~150 m is the most competitive. At present, the design mostly adopts the computational analytical method combining the spatial bar system model, plane beam grillage model and solid model. However, the spatial bar system model is short of the refinement analysis on the space effect, such as the shear lag effect, effective distribution width problem, and eccentric load factor problem etc. Due to the similarity of the plane beam grillage method in the equivalence principle, it cannot accurately reflect the shearing stress distribution and local stress of the top and bottom plates of the box type composite beam. The solid model is very difficult to combine with the overall calculation. Moreover, the spatial grid model can achieve the refinement analysis, with the integrity of the analysis and the comprehensiveness of the stress checking calculation, and can make up the deficiency of the analytical method currently. Through the example verification of the solid model and spatial grid model, it can be seen that the calculation results for the stress and the displacement of two models are almost consistent, indicating the applicability and precision of the spatial grid model.

The Influence of E-commerce Logistics Service Quality on Customer Engagement Behavior

Dongxu ZHANG(Dongxu ZHANG),Zhuoqi TENG(Zhuoqi TENG),Mufeng LI(Mufeng LI),Renhong WU(Renhong WU) 국제융합경영학회 2023 융합경영연구 Vol.11 No.2

Purpose: With the rapid development of e-commerce, logistics services, as an important part of e-commerce shopping, have gradually attracted people's attention. Customer engagement behavior is a new topic in marketing, and its connotation is still being explored. The purpose of this paper is to study the relationship between logistics service quality and customer engagement behavior. Research design, data and methodology: This study employed the method of online questionnaire survey, with Chinese e-commerce platform users as the survey objects, 248 valid survey sample data were collected, and the method of factor analysis and structural equation model analysis was used to verify the research hypothesis model constructed in this paper. Results: The four dimensions of e-commerce logistics service quality have different influences on customer satisfaction, and the influence of availability on customer satisfaction is not significant. Convenience, assurance, and security have a significant positive impact on customer satisfaction; Customer satisfaction has a significant positive impact on the three dimensions of customer engagement behavior: customer repeat purchase behavior, online word-of-mouth, and customer referrals. Conclusion: The results of this study will provide useful reference for the managers of e-commerce companies to improve customer engagement behavior by improving the logistics service quality.

Real Time Object Tracking with Sparse Prototypes

Dongxu Gao,Jiangtao Cao,Zhaojie Ju,Xiaofei Ji 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.4

Sparse representation (compressive sampling) has achieved impressive results in object tracking by looking for the best candidate with minimum reconstruction error using the target template. However, it may fail in some circumstances such as illumination changes, scale changes, the object color is similar with the surrounding region, and occlusion etc., in addition, high computational cost is required due to numerous calculations for solving an l1 norm related minimization problems. In order to resolve above problems, a novel method is introduced by exploiting an accelerated proximal gradient approach which aims to make the tracker runs in real time; moreover, both classic principal component analysis algorithm and sparse representation schemes are adapted for learning effective observation model and reduces the influence of appearance change. Both qualitative and quantitative evaluation demonstrate that the proposed tracking algorithm has favorably better performance than several state-of-the-art trackers using challenging benchmark image sequences, and significantly reduces the computing cost.

Nonsingular Terminal Sliding Mode Control Based on Adaptive Time Delay Estimation for Permanent Magnet Linear Synchronous Motor

Dongxue Fu,Ximei Zhao,Hao Yuan 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.1

In the presence of uncertainties, the position tracking performance of permanent magnet linear synchronous motor (PMLSM) will be affected to varying degrees. The time delay estimation (TDE) method can estimate and eliminate the influence of uncertain factors. In order to automatically find the input gain under the optimal TDE error, an adaptive time delay estimation (ATDE) method is proposed by introducing adaptive control. Combined with the nonsingular terminal sliding mode control method, the convergence speed and robust performance of the system are further improved. In addition, through rigorous mathematical analysis, the stability of state variables is proved. Finally, some experimental results are given to prove the effective performance of the control method.

Behaviour and design of Grade 10.9 high-strength bolts under combined actions

Dongxu Li,Brian Uy,Jia Wang,Yuchen Song 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.3

The use of high-strength steel and concrete in the construction industry has been gaining increasing attention over the past few decades. With it comes the need to utilise high-strength structural bolts to ensure the design load to be transferred safely through joint regions, where the space is limited due to the reduced structural dimensions. However, research on the behaviour of high-strength structural bolts under various loading combinations is still insufficient. Most of the current design specifications concerning high-strength structural bolts were established based on a very limited set of experimental results. Moreover, as experimental programs normally include limited design parameters for investigation, finite element analysis has become one of the effective methods to assist the understanding of the behaviour of structural components. An accurate and simple full-range stress-strain model for high-strength structural bolts under different loading combinations was therefore developed, where the effects of bolt fracture was included. The ultimate strength capacities of various structural bolts obtained from the present experimental program were compared with the existing design provisions. Furthermore, design recommendations concerning the pure shear and tension, as well as combined shear and tension resistance of Grade 10.9 high-strength structural bolts were provided.

Analysis and design of demountable steel column-baseplate connections

Dongxu Li,Brian Uy,Farhad Aslani,Vipul Patel 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.4

This paper aims to investigate the demountability of steel column-baseplate connections subjected to monotonic and cyclic loading. This paper presents the finite element analysis of steel column-baseplate connections under monotonic and cyclic loading. The finite element model takes into account the effects of material and geometric nonlinearities. Bauschinger and pinching effects were also included in the developed model, through which degradation of steel yield strength in cyclic loading can be well simulated. The results obtained from the finite element model are compared with the existing experimental results. It is demonstrated that the finite element model accurately predicts the initial stiffness, ultimate bending moment strength of steel column-baseplate connections. The finite element model is utilised to examine the effects of axial load, baseplate thickness, anchor bolt diameter and position on the behaviour of steel column-baseplate connections. The effects of various parameters on the demountability of steel column-baseplate connections are investigated. To achieve a demountable and reusable structure, various design parameters need to be considered. Initial stiffness and moment capacity of steel columnbaseplate connections are compared with design strengths from Eurocode 3. The comparison between finite element analysis and Eurocode 3 indicates that predictions of initial stiffness for semi-rigid connections should be developed and improved design of the connections needs to be used in engineering practice.

Behaviour and design of bolted endplate joints between composite walls and steel beams

Dongxu Li,Brian Uy,Jun Mo,Huu-Tai Thai 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.1

This paper presents a finite element model for predicting the monotonic behaviour of bolted endplate joints connecting steel-concrete composite walls and steel beams. The demountable Hollo-bolts are utilised to facilitate the quick installation and dismantling for replacement and reuse. In the developed model, material and geometric nonlinearities were included. The accuracy of the developed model was assessed by comparing the numerical results with previous experimental tests on hollow/composite column-to-steel beam joints that incorporated endplates and Hollo-bolts. In particular, the Hollo-bolts were modelled with the expanded sleeves involved, and different material properties of the Hollo-bolt shank and sleeves were considered based on the information provided by the manufacture. The developed models, therefore, can be applied in the present study to simulate the wall-to-beam joints with similar structural components and characteristics. Based on the validated model, the authors herein compared the behaviour of wall-to-beam joints of two commonly utilised composite walling systems (Case 1: flat steel plates with headed studs; Case 2: lipped channel section with partition plates). Considering the ease of manufacturing, onsite erection and the pertinent costs, composite walling system with flat steel plates and conventional headed studs (Case 1) was the focus of present study. Specifically, additional headed studs were pre-welded inside the front wall plates to enhance the joint performance. On this basis, a series of parametric studies were conducted to assess the influences of five design parameters on the behaviour of bolted endplate wall-to-beam joints. The initial stiffness, plastic moment capacity, as well as the rotational capacity of the composite wall-to-beam joints based on the numerical analysis were further compared with the current design provision.

Seismic rehabilitation of substandard RC columns with partially deteriorated concrete using CFRP composites

Dongxu Hou,Zhimin Wu,Jianjun Zheng,Yao Cui 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.15 No.1

Many existing reinforced concrete (RC) columns in structures tend to become substandard RC ones due to updated standards or environmental changes. These substandard columns may alter the behaviors of the whole structure and therefore are in urgent need of seismic retrofitting. Owing to their superior advantages, carbon fiber reinforced polymer (CFRP) composites are widely used to retrofit RC columns. The applications mainly focus on various substandard RC columns, but few deals with substandard columns with deteriorated concrete, especially damaged by earthquake. The purpose of this paper is to investigate the seismic behaviors of CFRP reinforced partially deteriorated RC columns and to evaluate the effect of CFRP sheets on them. Six flexure-dominant columns were tested under a constant axial load and transverse cyclic displacements. It is found that the seismic behaviors of partially deteriorated columns can be recovered by wrapping CFRP sheets on them. Numerical analysis is then conducted using finite element methods and verified with experimental results. The effects of the axial load ratio, the ratio of the thickness of CFRP sheet to the column diameter, and the slenderness ratio on the seismic behaviors of CFRP reinforced RC columns are evaluated. Finally, a method is proposed to determine the required thickness of CFRP sheet.

Transmission Control to Accommodate Bursty Traffic in LPWANs

Dongxu Pei,Song Fan,Hu Jin 한국통신학회 2023 한국통신학회 학술대회논문집 Vol.2023 No.2

Down-Regulation of TGF-β Expression Sensitizes the Resistance of Hepatocellular Carcinoma Cells to Sorafenib

Dongxu Kang,최혜진,Zhezhu Han,오근혁,주연수,송재진 연세대학교의과대학 2017 Yonsei medical journal Vol.58 No.5

Purpose: Sorafenib, a multikinase inhibitor, is the standard therapy for patients with advanced-stage hepatocellular carcinoma (HCC). However, resistance develops to the treatment, therefore, we tried to unravel the underlying mechanism in the resistance of HCC cells to sorafenib via the development of more effective therapeutic strategies. Materials and Methods: Various liver cancer cell lines were treated with either sorafenib only or with sorafenib after infection of adenovirus expressing short hairpin RNA (shRNA) against transforming growth factor-β (TGF-β) and p38 activity was examined using western blotting. Results: p38 MAP kinase activity was inhibited by low concentrations of sorafenib, which could potentially lead to sorafenib resistancein HCC cell lines. Subsequently, we used constitutive form of MKK3/6 (MKK3/6E) to confirm that massive cell death was induced by the activation of p38, and demonstrated the ability to activate p38 without any stimulation. In addition, sorafenib resistancewas reduced by the activation of p38. Subsequently, we confirmed that TGF-β shRNA effectively recovered the phosphorylationof p38 inhibited by sorafenib, and increased the sensitivity of HCC cells to sorafenib, thereby inducing cell death and overcoming the resistance of HCC cells to sorafenib. Conclusion: Our study provides a new therapeutic strategy for HCC that overcomes the resistance of HCC to sorafenib by down-regulation of TGF-β