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SSRN 2024年

作者： Liu, Zi-Yu Chen, Shi-Tong Zhi, Mo-Mo Cheng, Shuai-Qi Fan, Xin Collaborative Innovation Center for Performance and Security of Large-scale Infrastructure Shijiazhuang Tiedao University Shijiazhuang China Hebei Eng. Innovation Center for Traffic Emergency and Guarantee Shijiazhuang Tiedao University Shijiazhuang China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

Throughout the utilization of assembled emergency steel bridge piers, there is a significant discrepancy in the load carried between different columns, which can lead to premature failure of individual columns and potentially trigger the collapse of the entire structure. Currently, there is no mature method for calculating and implementing load distribution. Based on an improved Fourier series and energy principle, this paper proposes a universal calculation method for the load distribution of columns in assembled emergency steel piers. A specific assembled emergency steel pier is selected as the research subject to conduct model tests and simulation experiments. Through mutual verification of theory, experiments, and simulations, this study analyzes the key factors affecting the load distribution of columns, examines the mechanisms and patterns of their impacts, and explores general principles for the even distribution of loads. The research shows: As the column height or diameter-to-thickness ratio increases, the proportion of load borne by the corner columns and transverse edge columns increases, while the central and longitudinal edge columns see a reduction in their load proportions. A pier-beam linear stiffness ratio based on an overall consideration is proposed. As the height of the columns or the diameter-to-thickness ratio increases, the pier-beam linear stiffness ratio tends to decrease. Using the coefficient of variation of column loads as the standard for evaluating the pier-beam linear stiffness ratio, the recommended threshold for the application of the pier-beam linear stiffness ratio in engineering should be between 3 and 3.86. © 2024, The Authors. All rights reserved.

关键词： Steel bridges

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Analyzing Convective Heat Transfer in Combined Solar Chimneys: A Theoretical and Numerical Study of key Influencing Parameters

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SSRN 2024年

作者： Cui, Huimin Han, Mengjiao Zhang, Jitao Han, Zhiming Liu, Qingkuan State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China Department of Mathematics and Physics Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China

Combined solar chimneys represent a potent mechanism for harnessing solar energy to bolster natural ventilation in green building designs. This study focuses on the impact of structural parameters and external conditions on the ventilation and heat transfer performance of such systems. Through scaling analysis and numerical simulations, we investigate the flow dynamics and heat transfer mechanisms. We examine the mechanism and the influence of three critical control parameters: inlet size ratio (h/H), ratio of inclined to vertical section lengths (L/H), and Rayleigh number (Ra). Our findings indicate that ventilation and heat exchange performance exhibit an initial increase followed by a decline as the inlet size ratio expands from 0.10 to 0.40. Optimal ventilation efficiency is observed at a Rayleigh number of 1.98×1014 with an inlet size ratio of 0.15. Conversely, a low ratio of inclined to vertical section lengths (L/H=0.20) correlates with suboptimal ventilation performance. Both ventilation intensity and efficiency are positively correlated with increases in Ra. This research quantitatively delineates these relationships, providing a theoretical foundation for the design of natural ventilation systems in sustainable buildings using combined solar chimneys. © 2024, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Analyzing Convective Heat Transfer in Combined Solar Chimneys: A Theoretical and Numerical Study of key Influencing Parameters

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SSRN 2024年

Combined solar chimneys represent a potent mechanism for harnessing solar energy to bolster natural ventilation in green building designs. This study focuses on the impact of structural parameters and external conditions on the ventilation and heat transfer performance of such systems. Through scaling analysis and numerical simulations, we investigate the flow dynamics and heat transfer mechanisms. We examine the influence of five critical control parameters: inclination angle (α), inlet size ratio (h/H), ratio of inclined to vertical section lengths (L/H), Rayleigh number (Ra), and the temperature difference between indoor and outdoor environments (Δθ). Our findings indicate that ventilation intensity escalates with increasing inclination angle, particularly within the range of 15°to 75°, achieving standard requirements at angles of 30° or greater. Ventilation and heat exchange performance exhibit an initial increase followed by a decline as the inlet size ratio expands from 0.10 to 0.40. Optimal ventilation efficiency is observed at a Rayleigh number of 1.98×1014 with an inlet size ratio of 0.15. Conversely, a low ratio of inclined to vertical section lengths (L/H=0.20) correlates with suboptimal ventilation performance. Both ventilation intensity and efficiency are positively correlated with increases in Ra and Δθ. This research quantitatively delineates these relationships, providing a theoretical foundation for the design of natural ventilation systems in sustainable buildings using combined solar chimneys. © 2024, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Enhancing Solar Chimney Performance with Novel Passive Optimization Strategies for Dual Carbon Goals

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SSRN 2024年

作者： Han, Mengjiao Cui, Huimin Han, Zhiming Liu, Qingkuan School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Mathematics and Physics Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China

The development of green buildings plays a pivotal role in achieving "dual carbon" goals. This study focuses on the Combined Solar Chimney (CSC) as an effective method for utilizing solar energy to enhance building ventilation and heat exchange, thereby reducing air-conditioning energy consumption. We introduce two innovative passive optimization measures: deflectors and segmented heat-absorbing walls. Using numerical simulations, we analyze the impact of five control parameters—the angle and length of the straight deflector, the central angle of the curved deflector, the number of heat-absorbing wall segments, and the Rayleigh number (Ra)—on CSC performance. Our findings detail the temperature distribution and the vertical vortex dimensions to elucidate underlying mechanisms. Results indicate that air changes per hour (ACH) can be significantly improved with the implementation of deflectors and segmented walls. Optimal deflector configurations are identified as a 25° angle, a 0.375 length-to-width ratio (l/W), and a 60° central angle. The study recommends using two heat-absorbing wall segments for practical applications. When both measures are applied, ventilation performance can be enhanced by up to 25.71%. Additionally, this research establishes quantitative relationships between the control parameters, ACH, and heat exchange efficiencies, providing a theoretical foundation for practical engineering designs. © 2024, The Authors. All rights reserved.

关键词： Solar chimneys

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Simultaneous resonance of Duffing oscillator with fractional-order derivative

Simultaneous resonance of Duffing oscillator with fractional...

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第八届国际振动工程会议

作者： Hang Li Yongjun Shen Department of Mechanical Engineering Shijiazhuang Tiedao University State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University

Duffing-type oscillators can describe many issues in engineering vibration, such as the vertical vibration of pantograph carbon strip suspension system, the response of coupled pitch-roll ship and the nonlinear phenomena of rotor system, and the multiple-term frequency excitation is common case in these issues. For instance, the carbon belt suspension system of pantograph, it is excited by two kinds of harmonic excitations related to the distance between droppers and the span of catenary respectively. In this paper, the simultaneous resonance of fractional-order Duffing oscillator excited by two-term frequency is studied, and the fractional-order term is introduced due to the fact that many materials or devices in engineering exhibit obvious viscoelasticity, which could be accurately described by fractional-order *** approximately analytical solution of the system is obtained by the method of multiple scales, and the amplitude-frequency curve equation and phase-frequency curve equation of the steady-state response are derived from the analytical solution. Furthermore, Lyapunov’s first method is used to quantitatively calculate the stability condition of the steady-state response, based on this, the stability of the simultaneous resonance is analyzed. The effects of nonlinear factor and fractional-order term on the steady-state response is also analyzed by numerical simulation, and the general effects mechanism of the fractional-order term on the mass-spring-damping（MSD） system is revealed, i.e., the equivalent linear stiffness and equivalent linear damping of the fractional-order term are embodied simultaneously in the MSD system, and the focus and intensity of the effects are determined by fractional order and coefficient respectively.

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Snow Load Shape Coefficients and Snow Prevention Method on Stepped Flat Roofs

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SSRN 2023年

作者： Zhang, Zhibo Ma, Wenyong Li, Qiang Li, Sai State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang051132 China Key Laboratory of Road and Railway Engineering Safety Ministry of Education Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Hebei 050043 China

Excessive snow load and nonuniform snow deposition are the main factors leading to building collapses. The snow load shape coefficient represents the dimensionless snow load, and its value is related to the unbalanced distribution of snow. There are differences in the codes of different countries for applying snow load shape coefficients on stepped flat roofs. Therefore, through the combination of field measurements and numerical simulations, this study probed into the snow accumulation processes and snow load shape coefficients on stepped flat roofs, and thus proposed a viable design option to minimize the potential for any drift. It is found that the windward drift on the lower roof is similar to a "triangle" shape, while the downwind drift is close to being evenly distributed. Based on these, the equation of snow load shape coefficients is summarized, which combines with the discrepancies between counties’ codes and the regularity of snow distributions. In this study, the dynamic grid technology under the Eulerian framework is used to predict snow accumulation on stepped flat roofs. The formation mechanism of snow erosion and deposition in each process is analyzed with the wind field. Finally, an effective approach to prevent snow on stepped flat roofs is conceived. © 2023, The Authors. All rights reserved.

关键词： Snow

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Ride Comfort and Energy Harvesting of Inflatable Hydraulic-Electric Regenerative Suspension system for Heavy-Duty Vehicles

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SSRN 2023年

作者： Zhang, Buyun Luo, Minglu Li, Shaohua Tan, Chin-An Liu, Zhiqiang Automotive Engineering Research Institution Jiangsu University Jiangsu Zhenjiang212013 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China Department of Mechanical Engineering Wayne State University DetroitMI48202 United States School of Automotive and Traffic Engineering Jiangsu University Jiangsu Zhenjiang212013 China

Heavy-duty vehicles (HDVs) experience severe vibrational environments when traveling on rough roads and dissipate considerable energy in the suspension system because of the dampers working, and the intense vibrations induced by the road roughness are transmitted to the vehicle body and the cockpit, greatly affecting the driver's ride comfort. Therefore, an inflatable hydraulic-electric regenerative suspension (IHERS), which can mitigate the vehicle’s vibration and recover some energy dissipated by the damper, was proposed in this study. The configuration and working principle of the IHERS was then interpreted and the corresponding mathematical model was established based on the hydraulic system's pressure drop and flow relationship. A half-car model with 5-degree-of-freedom including the cockpit was developed to assess the performance of the IHERS-equipped HDVs. Structural and non-structural parametric study of the influences on the IHERS was conducted in depth to better understand the damping forces. Simulation examples were taken to investigate the performance of energy recovery and dynamic behaviors of this type of vehicle, comparing to those of a vehicle with a traditional passive suspension. The results indicate that the equivalent damping coefficients range of IHERS fits within the HDVs’ damping force range. Moreover, the damping force can be adjusted by tuning the external resistance of IHERS, which can be used for control of semi-active suspension. The energy conversion efficiency increases up to 41.9% when the IHERS-equipped HDV travels on the class-C road at 20 m/s. The design of IHERS can improve the ride comfort, reducing vertical acceleration of the cockpit by 23.3% comparing to a traditional suspension, of an HDV. © 2023, The Authors. All rights reserved.

关键词： Energy harvesting

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Principal resonance analysis of piecewise nonlinear oscillator with fractional differential

Principal resonance analysis of piecewise nonlinear oscillat...

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第八届国际振动工程会议

作者： Meiqi Wang Wenli Ma Enli Chen Shaopu Yang State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University School of Mechanical Engineering Shijiazhuang Tiedao University

To analyze the piecewise non-linear system with fractional order differential, we introduced fractional order into the two piecewise systems to accurately describe the stress relaxation of viscoelastic materials. We also established a non-linear dynamic model with non-linear stiffness, damping, and fractional order multi-piecewise points. Under periodic excitation,the equation of amplitude frequency relationship of the system was obtained using the average method, and the amplitude frequency response characteristics under different damping, stiffness,and fractional order parameters were provided. The influence of non-linear factors and fractional order terms on the stability of the system was studied. The chaotic behavior of the system under different parameter disturbances was studied, and the results indicate that the system presents chaotic behavior with the change of disturbance parameters. Moreover, the decrease of linear damping will subject the system to a wider range of chaotic state.

关键词： Principal resonance analysis of piecewise nonlinear oscillator with fractional differential

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Design and evaluation of cab seat suspension system based on negative stiffness structure

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Journal of Southeast University(English Edition) 2021年第2期37卷 153-163页

作者： Liao Xin Zhang Ning Xing Haijun Zhang Wanjie School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang 050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang 050043 China School of Mechanical Engineering Southeast University Nanjing 211189 China

To improve the vibration-isolation performance of cab seats,the optimization model of the seat suspension system of construction machinery cabs is proposed based on the negative stiffness *** negative stiffness nonlinear kinetic equation is established by designing the seat negative stiffness suspension structure(NSS).Using MATLAB,the different parameters of the suspension system and their influences on the dynamic stiffness are *** ideal configuration parameter range of the suspension system is ***,the optimization model of NSS is proposed,and the vibration transmissibility characteristics are simulated and analyzed by different *** results show that the displacement and acceleration amplitudes of the optimized seat suspension system are evidently reduced,and the four-time power vibration dose value and root mean square calculation values in the vertical vibration direction of the seat decrease by 86%and 87%,*** effective amplitude transmissibility(SEAT)and the vibration transmissibility ratio values also ***,the peak frequencies of the vibration transmitted to the driver deviate from the key frequency values,which easily cause human ***,the design of the seat suspension system has no effect on the health condition of the driver after being *** findings also illustrate that the NSS suspension system has good vibration-isolation performance,and the driver's ride comfort is improved.

关键词： construction machinery negative stiffness structure seat suspension system dynamic properties ride comfort

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Modeling and Simulation for Microscopic Traffic Flow Based on Comprehensive Information of The Preceding And the Following Vehicles

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SSRN 2022年

作者： Wang, Yunze Wang, Yawen Zhang, Chunbo State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang05043 China Key Laboratory of Traffic Safety and Control of Hebei Province Shijiazhuang050043 China School of Traffic and Transportation Shijiazhuang Tiedao University Shijiazhuang050043 China

A new car-following model is proposed in this study, and it considers the comprehensive information of the preceding and the following vehicles (i.e., the CIPF model) including the headway, speed difference, and acceleration. This model can be considered as a further extension of the existing forward-backward velocity difference (FBVD) model. Based on the linear stability analysis of the CIPF model, the judgment basis of the traffic flow stability is obtained. Compared with the optimal velocity (OV) model, the full velocity difference (FVD) model, and the FBVD model, the CIPF model has the largest stable region and the smallest unstable region. Using the reductive perturbation method, the nonlinear analysis of the CIPF model is performed, and the modified Korteweg-de Vries (mKdv) equation, which is used to describe the traffic flow characteristics of the system near the critical point, is obtained. Finally, the numerical simulation results show that the CIPF model can respond to the state of traffic flow better and faster than the FBVD model in vehicle start and stop simulation, and can better alleviate traffic congestion and improve the traffic flow stability in the simulation of circular road. The kink-antikink wave described by mKdV equation is simulated in the unstable region after the pe © 2022, The Authors. All rights reserved.

关键词： Nonlinear analysis

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