The effects of failure mode and strain conditions of CFRP, concrete and stirrups on the shear capacity of reinforced beams bonded by geopolymer and epoxy are studied. In addition…
Abstract
Purpose
The effects of failure mode and strain conditions of CFRP, concrete and stirrups on the shear capacity of reinforced beams bonded by geopolymer and epoxy are studied. In addition, a prediction model of the ultimate bearing capacity of CFRP-shear-strengthened beams is proposed, which considers adhesive performance parameters adhesive performance parameter ßE and FRP width parameter ßw.
Design/methodology/approach
This paper presents an experimental study on ultimate bearing capacity of CFRP-shear-strengthened pre-cracked beams with geopolymer and epoxy resin, which considers parameters such as impregnated adhesives types and CFRP-strengthened scheme.
Findings
The failure modes of CFRP-strengthened beams bonded by geopolymer are the combination of the CFRP-concrete interface substrate failure and fracture failure of CFRP, and that of epoxy is the local substrate failures with small area. The ultimate load of CFRP-strengthened beams is directly affected by the failure modes. The ultimate bearing capacity of CFRP-strengthened beams with geopolymer is 91.4% of that of epoxy resin. Compared with ultimate bearing capacity of CFRP-strengthened beams with U-shaped, that of complete-wrapping increases by 2.5%. Moreover, the stirrup peak strain is reduced by more than 30% in CFRP-strengthened beams bonded with geopolymer and epoxy resin in comparison with the unstrengthened beam. The existing prediction model cannot accurately predict the CFRP shear capacity contribution of strengthened beams with different CFRP-strengthened schemes and adhesive properties. The estimated results are much lower than the test data, and the deviation is much larger than 20%.
Originality/value
Geopolymer alternative to epoxy as an adhesive is feasible and effective for CFRP reinforcement. Furthermore, the accuracy is improved by introducing parameters about adhesive properties based on the existing prediction model. The estimated results are in excellent agreement with the test data, and the deviation is controlled within −12.80%, and the model is suitable for predicting the shear capacity of FRP-strengthened beams with ßf = 90° in shear capacity database.
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The effects of carbon fiber reinforced polymer (CFRP) reinforcement form, adhesive type and pre-crack width on failure mode, shear capacity, deflection response, CFRP strain…
Abstract
Purpose
The effects of carbon fiber reinforced polymer (CFRP) reinforcement form, adhesive type and pre-crack width on failure mode, shear capacity, deflection response, CFRP strain response and crack patterns of strengthened specimens were investigated.
Design/methodology/approach
This paper presents a geopolymer adhesive that matches the performance requirements of CFRP adhesive, which is applied to pre-cracked beams reinforced with CFRP strips.
Findings
For specimens with varying structural properties, two failure modes, the CFRP-concrete interface substrate failure and the fracture failure of CFRP, are observed. Moreover, the shear capacity, ultimate deflection and bending stiffness of the U-shaped CFRP-strengthened beams are enhanced in comparison to the complete-wrapping CFRP-strengthened beams. With an increase in pre-crack width, the increase in shear capacity of RC beams shear-strengthened with CFRP strips is less than that of non-cracked beams, resulting in a limited influence on the stiffness of CFRP-strengthened beams. The comparison of experimental results showed that the proposed finite element model (FEM) effectively evaluated the mechanical characteristics of CFRP-strengthened RC beams.
Originality/value
Taking into consideration the reinforcement effect and the concept of environmental protection, the geopolymer adhesive reinforcement scheme is preferable to applying epoxy resin to the CFRP-strengthened RC beams.
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Wang Li, Xiuhua Gao, Xincheng Chen, Hongyan Wang, Changyou Zhu, Tong Li, Jun Wang, Hongyan Wu, Linxiu Du and Cairu Gao
This study aims to investigate the effect of different microstructures and its grain boundary character distribution (GBCD) on the corrosion behavior of weathering bridge steel.
Abstract
Purpose
This study aims to investigate the effect of different microstructures and its grain boundary character distribution (GBCD) on the corrosion behavior of weathering bridge steel.
Design/methodology/approach
The rust layer characteristics and corrosion resistance of specimens with different microstructures in the simulated industrial environment were studied by Electron Probe X-ray Micro-Analyzer, wavelength-dispersive spectrometer and electrochemical techniques. Electron backscatter diffraction technique was used to characterize the GBCD in steels with different microstructures.
Findings
Results revealed a significant difference in the corrosion susceptibility among the four microstructures, with corrosion rates decreasing in the following order: ferrite + pearlite > ferrite + bainite > bainite > martensite. The variation in corrosion resistance is primarily influenced by the microstructure type and the proportion of special grain boundaries, rather than the alloying elements. The proportion of Σ3 boundaries within the coincidence site lattice boundaries is positively correlated with improved corrosion resistance. A higher Σ3 boundary fraction resulted in a lower effective grain boundary energy, elevated self-corrosion potential, increased polarization resistance and reduced areas of localized galvanic corrosion; this led to enhanced inhibition of the electrochemical corrosion reaction, consequently reducing the corrosion rate.
Originality/value
This study elucidates and quantifies the intrinsic relationship between microstructure, GBCD and corrosion rate. This understanding is crucial for enhancing the corrosion resistance of weathering bridge steels in industrial atmospheric corrosion environments.
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Xuhui Wang, Kewei Liu, Kai Wang, Jian Gong, Yanjun Wang and Yajiang Fan
Urban parks play a key role in recreational activities, public health, and ecosystem services in urban areas. Using GIS and Fragstats, this study investigated the spatiotemporal…
Abstract
Urban parks play a key role in recreational activities, public health, and ecosystem services in urban areas. Using GIS and Fragstats, this study investigated the spatiotemporal dynamics of urban parks in Xi'an, China from 1949 to 2015 and the corresponding driving forces. The results show that the number and area of parks in Xi'an increased constantly during this period, especially from 2000 to 2015. Up to 2015, small green spaces, usually adjacent to streets, occupied the largest proportion among all types of parks. Archaeological parks were the largest in total area, but wetland parks were leading in average size of a single park. The density of parks was negatively correlated with their distance to the Clock Tower at the center of Xi'an. The dynamics of urban parks in highly urbanized areas were significantly different from that of their counterparts in suburban areas. Driving forces such as urban planning, urbanization and green space policies, and milestone events in the city's development jointly had a great effect on the distribution of parks in Xi'an. The research outcomes will support the upcoming Green Space Planning of Xi'an and benefit the pursuit of sustainability and human wellbeing.
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Shufeng Tang, Zhijie Chai, Xin Wang, Hong Chang and Xiaodong Guo
In view of the unknown environmental parameters and uncertain interference during gripping by the manipulator, it is difficult to obtain an effective gripping force with the…
Abstract
Purpose
In view of the unknown environmental parameters and uncertain interference during gripping by the manipulator, it is difficult to obtain an effective gripping force with the traditional impedance control method. To avoid this dilemma, the purpose of this study is to propose an adaptive control strategy based on an adaptive neural network and a PID search optimization algorithm for unknown environments.
Design/methodology/approach
The method is based on a variable impedance model, and a new impedance model is established using a radial basis function (RBF) neural network to estimate unknown parameters of the impedance model. The approximation errors of the adaptive neural network and the uncertain disturbance are effectively suppressed by designing the adaptive rate. In the meantime, auxiliary variables are constructed for Lyapunov stability analysis and adaptive controller design, and PSA is used to ensure the stability of the adaptive impedance control system. Based on the Lyapunov stability criterion, the adaptive im-pedance control system is proved to have progressive tracking convergence property.
Findings
Through comparative simulations and experiments, the superiority of the proposed adaptive control strategy in position and force tracking has been verified. For objects with low flexibility and light-weight (such as a coke, a banana and a nectarine), this control method demonstrates errors of less than 10%.
Originality/value
This paper uses RBF neural networks to estimate unknown parameters of the impedance model in real-time, enhancing system adaptability. Neural network weights are updated online to suppress errors and disturbances. Auxiliary variables are designed for Lyapunov stability analysis. The PSA algorithm is used to adjust controller parameters in real-time. Additionally, comparative simulations and experi-ments are designed to analyze and validate the performance of controller.
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Shufeng Tang, Yongsheng Kou, Guoqing Zhao, Huijie Zhang, Hong Chang, Xuewei Zhang and Yunhe Zou
The purpose of this paper is to design a climbing robot connected by a connecting rod mechanism to achieve multi-functional tasks such as obstacles crossing and climbing of power…
Abstract
Purpose
The purpose of this paper is to design a climbing robot connected by a connecting rod mechanism to achieve multi-functional tasks such as obstacles crossing and climbing of power transmission towers.
Design/methodology/approach
A connecting rod type gripper has been designed to achieve stable grasping of angle steel. Before grasping, use coordination between structures to achieve stable docking and grasping. By using the alternating movements of two claws and the middle climbing mechanism, the climbing and obstacle crossing of the angle steel were achieved.
Findings
Through a simple linkage mechanism, a climbing robot has been designed, greatly reducing the overall mass of the robot. It can also carry a load of 1 kg, and the climbing mechanism can perform stable climbing. The maximum step distance of the climbing robot is 543 mm, which can achieve the crossing of angle steel obstacles.
Originality/value
A transmission tower climbing mechanism was proposed by analyzing the working environment. Through the locking ability of the screw nut, stable clamping of the angle steel is achieved, and a pitch mechanism is designed to adjust the posture of the hand claw.
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Sorphasith Xaisongkham and Xia Liu
The main purpose of this research is to examine the impact of institutional quality and sectoral employment on environmental degradation in developing countries. This paper also…
Abstract
Purpose
The main purpose of this research is to examine the impact of institutional quality and sectoral employment on environmental degradation in developing countries. This paper also re-examined the validity of the Environmental Kuznets Curve (EKC) hypothesis and estimated the long run impact of explanatory variables on CO2 emissions.
Design/methodology/approach
In this paper, the balanced panel data for the period 2002–2016 was used based on data availability and applied two-step SYS-GMM estimators.
Findings
The results showed that institutional quality such as government effectiveness (GE) and the rule of law (RL) reduce CO2 emissions and promote environmental quality in developing countries. Interestingly, the authors found new evidence that employment in agriculture and industry has a positive impact on pollution, while employment in the service sector was negatively associated with CO2 emissions, and the validity of the EKC hypothesis was confirmed. In addition, the research suggests that strong institutional frameworks and their effective implementation are the most important panacea and should be treated as a top priority to counteract environmental degradation and achieve the UN Sustainable Development Goals.
Originality/value
This is the first study to examine the short run and long run effects of institutional quality and sectoral employment on environmental degradation using the balanced panel data for a large sample of developing countries. This paper also used a special technique of Driscoll and Kraay standard error approach to confirm the robustness results and showed the different roles of sectoral employment on environmental quality.
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Urvashi Suryavanshi, Rishi Chaudhry, Akshay Kumar Mishra and Mahender Yadav
This research mirrors a 360° probe into bibliometric review of various studies aimed to examine the relationship between financial inclusion and sustainable development (FI and…
Abstract
Purpose
This research mirrors a 360° probe into bibliometric review of various studies aimed to examine the relationship between financial inclusion and sustainable development (FI and SD). It also offers a conspectus of apex contributors, influential articles, key journals and potential avenues for further research in this crucial area of global progress.
Design/methodology/approach
The study is the abstract of a total 233 papers on the subject representing a period between 2012 and 2023 in the Scopus database in the domain. This investigation probes into publication trends, the most inexhaustible contributors by national journals, publications and authors. The study conducts keyword co-occurrence analysis and examines thematic evolution using Vosviewer and Biblioshiny.
Findings
The findings reveal four prominent clusters: (a) Financial growth with FI, (b) Economic Empowerment with Sustainable Goals, (c) Environmental Sustainability and (d) Microfinance and Digital Era. Furthermore, the study paves way for the future research agenda with the help of these research themes.
Originality/value
To the best of the authors’ knowledge, this paper is the first of its kind in deeply probing the literature on FI and SD from a bibliometric perspective. Hence the findings of this study is a powerful weapon for researchers and practitioners coupled with future research inquiries, offering valuable insights and establishing robust quantitative foundations for advancing knowledge in the realms of FI and SD.
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The purpose of this study is to exploring the factors influencing renewable energy consumption intentions and behaviors among eco-tourism visitors in Bangladesh, developing…
Abstract
Purpose
The purpose of this study is to exploring the factors influencing renewable energy consumption intentions and behaviors among eco-tourism visitors in Bangladesh, developing theory of sustainable consumption behaviors (TSCB).
Design/methodology/approach
Based on review of previous empirical studies and other literatures, and collection of 399 usable responses, the study is conducted through partial least squares structural equation modeling (PLS-SEM) by using Smart PLS3.3.3.
Findings
The study results divulge that renewable energy consumption intentions significantly influence renewable energy consumption behavior; and the carbon mitigation norms and energy saving norms significantly impact on renewable energy consumption intentions among eco-tourists in Bangladesh.
Practical implications
The findings imply that availability of renewable energy consumption options may attract tourists towards eco-tourism in Bangladesh.
Originality/value
This study is one of the first attempts to developing the theory of sustainable consumption, exploring the integrated impacts of carbon mitigation norms, energy saving norms and renewable energy consumption intentions on eco-tourists’ renewable energy consumption behaviors in Bangladesh.