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Aerodynamic stability of cable-stayed-suspension hybrid bridges

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Journal of Zhejiang university-Science A(Applied Physics & engineering) 2005年第8期6卷 869-874页

作者：张新军孙炳楠 School of civil engineering and architecture Zhejiang University of Technology School of civil engineering and architecture Zhejiang University

Three-dimensional nonlinear aerodynamic stability analysis was applied to study the aerodynamic stability of a cable-stayed-suspension (CSS) hybrid bridge with main span of 1400 meters, and the effects of some design parameters (such as the cable sag, length of suspension portion, cable plane arrangement, subsidiary piers in side spans, the deck form, etc.) on the aerodynamic stability of the bridge are analytically investigated. The key design parameters, which significantly influence the aerodynamic stability of CSS hybrid bridges, are pointed out, and based on the wind stability the favorable structural system of CSS hybrid bridges is discussed.

关键词： Cable-stayed-suspension (CSS) hybrid bridge Aerodynamic stability Parametric analysis

Achievements and problems of geotechnical engineering investigation in China

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Journal of Zhejiang university-Science A(Applied Physics & engineering) 2011年第2期12卷 87-102页

作者： Zai-ming ZHANG beijing Geotechnical Institute (BGI) engineering Consultants Ltd. Beijing 100038 China College of architecture and civil engineering Beijing University of Technology Beijing 100124 China

As an industry and a discipline,geotechnical investigation in China differs from that in the USA and European countries in its course of emergence and evolution. For over half a century,Chinese geotechnical investigation professionals witnessed continuous technical advances as they undertook independently almost all of China's large-scale construction projects. Based on projects that won the "National Outstanding engineering Investigation" Gold Medal Awards since the year 2000,this paper discusses the achievements of geotechnical investigation in the context of comprehensive technical ability,project evaluation and analysis,hi-tech applications and engineering monitoring,and analyzes several factors that have hindered the industry's further development and alignment with international practice. Finally,some suggestions are given for future improvement.

关键词： Geotechnical engineering engineering investigation Technical advance

Capacity and failure mechanism of laterally loaded jet-grouting reinforced piles: Field and numerical investigation

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Science China(Technological Sciences) 2016年第5期59卷 763-776页

作者： HE Ben WANG Li Zhong HONG Yi College of civil engineering and architecture Zhejiang University

This study presents the results of field and numerical investigations of lateral stiffness, capacity, and failure mechanisms for plain piles and reinforced concrete piles in soft clay. A plastic-damage model is used to simulate concrete piles and jet-grouting in the numerical analyses. The field study and numerical investigations show that by applying jet-grouting sur- rounding the upper 7.5D （D = pile diameter） of a pile, lateral stiffness and beating capacity of the pile are increased by about 110% and 100%, respectively. This is partially because the jet-grouting increases the apparent diameter of the pile, so as to en- large the extent of failure wedge and hence passive resistance in front of the reinforced pile. Moreover, the jet-grouting pro- vides a circumferential confinement to the concrete pile, which suppresses development of tensile stress in the pile. Corre- spondingly, tension-induced plastic damage in the concrete pile is reduced, causing less degradation of stiffness and strength of the pile than that of a plain pile. Effectiveness of the circumferential confinement provided by the jet-grouting, however, diminishes once the grouting cracks because of the significant vertical and circumferential tensile stress near its mid-depth. The lateral capacity of the jet-grouting reinforced pile is, therefore, governed by mobilized passive resistance of soil and plastic damage of jet-grouting.

关键词： jet-grouting reinforced cast-in-place piles field test finite element analysis lateral bearing capacity lateral stiffness plastic damage failure mechanism

Two exact solutions of the DPL non-Fourier heat conduction equation with special conditions

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Acta Mechanica Sinica 2009年第2期25卷 205-210页

作者： Youtong Zhang Changsong Zheng Yongfeng Liu Liang Shao Chenhua Gou School of Mechanical and Vehicular engineering Beijing Institute of Technology 100081 Beijing China School of Mechanical-Electronic and Automobile engineering Beijing University of Civil Engineering and Architecture100044 Beijing China

This paper presents two exact explicit solutions for the three dimensional dual-phase lag （DLP） heat conduction equation, during the derivation of which the method of trial and error and the authors＇ previous experiences are utilized. To the authors＇ knowledge, most solutions of 2D or 3D DPL models available in the literature are obtained by numerical methods, and there are few exact solutions up to now. The exact solutions in this paper can be used as benchmarks to validate numerical solutions and to develop numerical schemes, grid generation methods and so forth. In addition, they are of theoretical significance since they correspond to physically possible situations. The main goal of this paper is to obtain some possible exact explicit solutions of the dual-phase lag heat conduction equation as the benchmark solutions for computational heat transfer, rather than specific solutions for some given initial and boundary conditions. Therefore, the initial and boundary conditions are indeterminate before derivation and can be deduced from the solutions afterwards. Actually, all solutions given in this paper can be easily proven by substituting them into the governing equation.

关键词： Exact solution Dual-phase lag Non-Fourier Benchmark solution Heat conduction

A new method to determine the projected coordinate origin of a cone-beam CT system using elliptical projection

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Chinese Physics C 2010年第10期34卷 1665-1670页

作者：杨民靳旭玲李保磊 School of Mechanical engineering and Automation Beijing Univisity of Aeronautics and Astronautics Science School of beijing university of civil engineering and architecture

In order to determine the projected coordinate origin in the cone-beam CT scanning system with respect to the Feldkamp-Davis-Kress （FDK） algorithm, we propose a simple yet feasible method to accurately measure the projected coordinate origin. This method was established on the basis of the theory that the projection of a spherical object in the cone-beam field is an ellipse. We first utilized image processing and the least square estimation method to get each major axis of the elliptical Digital Radiography （DR） projections of a group of spherical objects. Then we determined the intersection point of the group of major axis by solving an over-determined equation set that was composed by the major axis equations of all the elliptical projections. Based on the experimental results, this new method was proved to be easy to implement in practical scanning systems with high accuracy and anti-noise capability.

关键词： cone-beam CT projected coordinate origin elliptical projection geometrical calibration

Defective NH2-UiO-66 for effective Pb（Ⅱ） removal:Facile fabrication strategy,performances and mechanisms

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Progress in Natural Science:Materials International 2024年第2期34卷 420-428页

作者： Meng-Yuan Liu Lu Zhang Yu-Hang Li Chong-Chen Wang Peng Wang Chen Zhao Huifen Fu beijing Key Laboratory of Functional Materials for Building Structure and Environment Remediation School of Environment and Energy Engineering Beijing University of Civil Engineering and Architecture

Defective NH2-UiO-66 adsorbent（named as NH2-UiO-66-SD） was successfully fabricated via post-synthesis method with the aid of both sodium carbonate anhydrous（Na2CO3） and diethylenetriaminepentaacetic acid（DTPA）,in which the defective structure was confirmed by various *** as-obtained defective NH2-UiO-66-SD exhibited outstanding Pb（Ⅱ） sorption capacity(172.21 mg g-1) and rapid diffusion rate(29.87mg g-1min-0.5) at room temperature with optimal pH being *** Pb（Ⅱ） sorption behavior was conformed to pseudo-second-order kinetics and Langmuir model,demonstrating that the chemical sorption of the monolayer played a dominant *** well,the thermodynamic parameters like standard Gibbs free energy change ΔG~o(-31.21 kJ mol-1),standard enthalpy change ΔH~o(12.79 kJ-1mol-1) and standard entropy change ΔS~o(146.73J mol-1K-1) revealed that the Pb（Ⅱ） sorption process of NH2-UiO-66-SD was spontaneous,endothermic and ***,the NH2-UiO-66-SD exhibited desirable desorption and recirculation performances（removal efficiencies>85 % in 5 runs） with ideal ***,the Pb（Ⅱ） sorption mechanism of NH2-UiO-66-SD mainly included the electrostatic attractions and coordinative ***,this work offered an intriguing method of fabricating defective NH2-UiO-66 adsorbent,which vastly enhanced adsorption efficiency for toxic metal ions elimination from wastewater.

关键词： Adsorption Defect Mechanism NH2-UiO-66 Pb(II)

Finite element response sensitivity analysis of three-dimensional soil-foundation-structure interaction (SFSI) systems

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Earthquake engineering and engineering Vibration 2018年第3期17卷 555-566页

作者： Gu Quan Liu Yongdou Li Yong Lin Chun School of architecture and civil engineering Xiamen University Department of civil and Environmental engineering University of Alberta

The nonlinear finite element（FE） analysis has been widely used in the design and analysis of structural or geotechnical *** response sensitivities（or gradients） to the model parameters are of significant importance in these realistic engineering *** the sensitivity calculation has lagged behind,leaving a gap between advanced FE response analysis and other research hotspots using the response *** response sensitivity analysis is crucial for any gradient-based algorithms,such as reliability analysis,system identification and structural *** various sensitivity analysis methods,the direct differential method（DDM） has advantages of computing efficiency and accuracy,providing an ideal tool for the response gradient *** paper extended the DDM framework to realistic complicated soil-foundation-structure interaction（SFSI） models by developing the response gradients for various constraints,element and materials *** enhanced framework is applied to three-dimensional SFSI system prototypes for a pilesupported bridge pier and a pile-supported reinforced concrete building frame structure,subjected to earthquake loading *** DDM results are verified by forward finite difference method（FFD）.The relative importance（RI） of the various material parameters on the responses of SFSI system are investigated based on the DDM response sensitivity *** FFD converges asymptotically toward the DDM results,demonstrating the advantages of DDM（e.g.,accurate,efficient,insensitive to numerical noise）.Furthermore,the RI and effects of the model parameters of structure,foundation and soil materials on the responses of SFSI systems are investigated by taking advantage of the sensitivity analysis *** extension of DDM to SFSI systems greatly broaden the application areas of the d gradient-based algorithms,*** model updating and nonlinear system identification of complicated SFSI systems.

关键词： finite element method response sensitivity analysis direct differentiation method finite difference method soil-foundation-structure interaction

Machine learning method to predict dynamic compressive response of concrete-like material at high strain rates

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Defence Technology（防务技术） 2023年第5期23卷 100-111页

作者： Xu Long Ming-hui Mao Tian-xiong Su Yu-tai Su Meng-ke Tian School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'anChina School of civil engineering Liaoning Petrochemical UniversityFushunChina beijing Microelectronics Technology Institute BeijingChina

Machine learning(ML)methods with good applicability to complex and highly nonlinear sequences have been attracting much attention in recent years for predictions of complicated mechanical properties of various *** one of the widely known ML methods,back-propagation(BP)neural networks with and without optimization by genetic algorithm(GA)are also established for comparisons of time cost and prediction *** the aim to further increase the prediction accuracy and efficiency,this paper proposes a long short-term memory(LSTM)networks model to predict the dynamic compressive performance of concrete-like materials at high strain *** explicit analysis is performed in the finite element(FE)software ABAQUS to simulate various waveforms in the split Hopkinson pressure bar(SHPB)experiments by applying different stress waves in the incident *** FE simulation accuracy is validated against SHPB experimental results from the viewpoint of dynamic increase *** order to cover more extensive loading scenarios,60 sets of FE simulations are conducted in this paper to generate three kinds of waveforms in the incident and transmission bars of SHPB *** training the proposed three networks,the nonlinear mapping relations can be reasonably established between incident,reflect,and transmission *** measures are used to quantify the network prediction accuracy,confirming that the predicted stress-strain curves of concrete-like materials at high strain rates by the proposed networks agree sufficiently with those by FE *** is found that compared with BP network,the GA-BP network can effectively stabilize the network structure,indicating that the GA optimization improves the prediction accuracy of the SHPB dynamic responses by performing the crossover and mutation operations of weights and thresholds in the original BP *** eliminating the long-time dependencies,the proposed LSTM network achieves better results than the BP

关键词： Deep learning LSTM network GA-BP network Dynamic behaviour Concrete-like materials

Application of a Support Vector Machine Algorithm to the Safety Precaution Technique of Medium-low Pressure Gas Regulators

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Journal of Thermal Science 2018年第1期27卷 74-77页

作者： HAO Xuejun AN Xaioran WU BO HE Shaoping beijing university of civil engineering and architecture Beijing 100044China beijing Gas Group Co. LtdBeijing 100035China

In the gas pipeline system, safe operation of a gas regulator determines the stability of the fuel gas supply, and the medium-low pressure gas regulator of the safety precaution system is not perfect at the present stage in the Bei- jing Gas Cxroup; therefore, safety precaution technique optimization has important social and economic signific- ance, In this paper, according to the running status of the medium-low pressure gas regulator in the SCADA sys- tem, a new method for gas regulator safety precaution based on the support vector machine （SVM） is presented. This method takes the gas regulator outlet pressure data as input variables of the SVM model, the fault categories and degree as output variables, which will effectively enhance the precaution accuracy as well as save significant manpower and material resources.

关键词： gas regular fault diagnosis safety precaution SVM parameter optimization