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Seismic performance of steel MRF building with nonlinear viscous dampers

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Frontiers of Structural and civil engineering 2016年第3期10卷 254-271页

作者： Baiping DONG James M. RICLES Richard SAUSE ATLSS engineering Research Center Department of Civil and Environmental Engineering Lehigh University Bethlehem PA 18015 USA

This paper presents an experimental study of the seismic response of a 0.6-scale three-story seismicresistant building structure consisting of a moment resisting frame （MRF） with reduced beam sections （RBS）, and a frame with nonlinear viscous dampers and associated bracing （called the DBF）. The emphasis is on assessing the seismic performance for the design basis earthquake （DBE） and maximum considered earthquake （MCE）. Three MRF designs were studied, with the MRF designed for 100%, 75%, and 60%, respectively, of the required base shear design strength determined according to ASCE 7-10. The DBF with nonlinear viscous dampers was designed to control the lateral drift demands. Earthquake simulations using ensembles of DBE and MCE ground motions were conducted using the real-time hybrid simulation method. The results show the drift demand and damage that occurs in the MRF under seismic loading. Overall, the results show that a high level of seismic performance can be achieved under DBE and MCE ground motions, even for a building structure designed for as little as 60% of the base shear design strength required by ASCE 7-10 for a structure without dampers.

关键词： seismic response steel MRF nonlinear viscous damper design basis earthquake real-time hybrid simulation

A numerical modelling approach to assess the behaviour of underground cavern subjected to blast loads

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International Journal of Mining Science and Technology 2018年第6期28卷 975-983页

作者： Saikat Kuili Vedala Rama Sastry Department of civil engineering National Institute of Technology Karnataka Department of Mining engineering National Institute of Technology Karnataka

The paper gives an insight into the behaviour of large underground caverns which are subjected to blast loads. Caverns are generally constructed in hard rock formation which compels us to use blasting methods for the excavation works. Comparative study was done between models with intact rock mass and discontinuities to assess the stability of cavern as a result of blast loads. Numerical modelling was performed with 3 dimensional distinct element code(3 DEC) to analyse the performance of cavern walls in terms of displacement and to compute peak particle velocities(PPV) both around the cavern periphery and at surface of models. Results showed that the velocity wave with higher frequency exhibited large displacements around the periphery of cavern. Computation of PPV showed that model with horizontal joint sets showed lower PPV in comparison to model with intact rock mass. PPV values were also analysed on the surface for model consisting vertical joints spaced at 4 m intervals. Comparative study of PPV on surface vertically above the blast location between models with horizontal joints spaced at 4 m and vertical joints at 4 m intervals were conducted. Results depicted higher magnitudes of PPV for model with vertical joints in comparison to model with horizontal joints.

关键词： Large underground caverns Hard rock formation Numerical modelling 3 dimenssional distinct element code Peak particle velocities

Improved prediction of slope stability using a hybrid stacking ensemble method based on finite element analysis and field data

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Journal of Rock Mechanics and Geotechnical engineering 2021年第1期13卷 188-201页

作者： Navid Kardani Annan Zhou Majidreza Nazem Shui-Long Shen civil and Infrastructure Discipline School of EngineeringRoyal Melbourne Institute of Technology(RMIT)MelbourneVictoriaAustralia Department of civil and Environmental engineering College of EngineeringShantou UniversityShantou515063China

Slope failures lead to catastrophic consequences in numerous countries and thus the stability assessment for slopes is of high interest in geotechnical and geological engineering researches.A hybrid stacking ensemble approach is proposed in this study for enhancing the prediction of slope *** the hybrid stacking ensemble approach,we used an artificial bee colony(ABC)algorithm to find out the best combination of base classifiers(level 0)and determined a suitable meta-classifier(level 1)from a pool of 11 individual optimized machine learning(OML)*** element analysis(FEA)was conducted in order to form the synthetic database for the training stage(150 cases)of the proposed model while 107 real field slope cases were used for the testing *** results by the hybrid stacking ensemble approach were then compared with that obtained by the 11 individual OML methods using confusion matrix,F1-score,and area under the curve,*** comparisons showed that a significant improvement in the prediction ability of slope stability has been achieved by the hybrid stacking ensemble(AUC?90.4%),which is 7%higher than the best of the 11 individual OML methods(AUC?82.9%).Then,a further comparison was undertaken between the hybrid stacking ensemble method and basic ensemble classifier on slope stability *** results showed a prominent performance of the hybrid stacking ensemble method over the basic ensemble ***,the importance of the variables for slope stability was studied using linear vector quantization(LVQ)method.

关键词： Slope stability Machine learning(ML) Stacking ensemble Variable importance Artificial bee colony(ABC)

An Elastoplastic Damage Constitutive Model for Concrete

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China Ocean engineering 2013年第2期27卷 169-182页

作者：刘军林皋钟红 School of civil&Safety engineering Dalian Jiaotong University Faculty of Infrastructure engineering Dalian University of Technology

An elastoplastic damage constitutive model to simulate nonlinear behavior of concrete is presented. Similar to traditional plastic theory, the irreversible deformation is modeled in effective stress space. In order to better describe different stiffness degradation mechanisms of concrete under tensile and compressive loading conditions, two damage variables, i.e., tension and compression are introduced, to quantitatively evaluate the degree of deterioration of concrete structure. The rate dependent behavior is taken into account, and this model is derived firmly in the framework of irreversible thermodynamics. Fully implicit backward-Euler algorithm is suggested to perform constitutive integration. Numerical results of the model accord well with the test results for specimens under uniaxial tension and compression, biaxial loading and triaxial loading. Failure processes of double-edge-notched （DEN） specimen are also simulated to further validate the proposed model.

关键词： constitutive model elastoplastic-damage irreversible thermodynamics energy release rate concrete

Experimental study using the dilution incubation method to assess water biostability

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Journal of Environmental Sciences 2014年第10期26卷 1994-2000页

作者： Qiuhua Wang Tao Tao Kunlun Xin College of Environmental Science and engineering Tongji University School of civil engineering and Architecture East China Jiaotong University

Water biostability is of particular concern to water supply as a major limiting factor for heterotrophic bacterial growth in water distribution systems. This study focused on bacterial growth dynamics in the series dilution of water samples with TOC（total organic carbon） values determined beforehand. The results showed that the specific growth rate of Pseudomonas fluorescens P17 varied dramatically and irregularly with TOC value when TOC concentrations were low enough during the initial periods of incubation under given conditions. According to this relationship between bacterial growth rate and TOC, a dilution incubation method was designed for the study of water biostability. With the method under a given condition, a turning-point TOC value was found at a relatively fixed point in the curve between bacterial growth rate and TOC of water sample, and the variation of growth rate had different characteristics below the turning-point TOC value relative to that over this value. A turning-point TOC value similarly existed in all experiments not only with tap water, but also with acetate and mixed solutions. And in the dilution incubation method study, the affections were analyzed by condition factors such as inoculum amount,incubation time and nature of the organic carbon source. In very low organic carbon water environments, the variation characteristics of bacterial growth rate will be useful to further understand the meaning of water biostability.

关键词： Water biostability Heterotrophic bacteria Bacterial growth rate Dilution incubation method Total growth organic carbon

Experimental assessment and prediction of temporal scour depth around a spur dike

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International Journal of Sediment Research 2021年第1期36卷 17-28页

作者： Manish Pandey Manousos Valyrakis Meilan Qi Anurag Sharma Ajay Singh Lodhi Department of civil engineering National Institute of Technology School of engineering University of Glasgow School of civil engineering Beijing Jiaotong University Department of civil engineering Institute of Infrastructure Technology Research and Management 5. College of Agriculture Waraseoni District

Spur dikes are river training structures that have been extensively used worldwide for towards enhancing flood control and the stability of embankments and ***,scour around spur dikes can be a major problem affecting their stability and hydraulic *** precise computation of temporal scour depth at spur dikes is very important for the design of economical and safe spur *** study focuses on experimentally assessing the temporal variation of scour depth around a vertical wall spur dike and identifying the parameters,which mostly influence spur dike performance for a channel bed surface comprised of sand-gravel *** the current study,the authors did physical experiments in a flume based study to obtain new data,aimed at deriving a new predictive model for spur dike scour and comparing its performance to others found in the *** was found that the dimensionless temporal scour depth variation increases with an increase in(i) the threshold velocity ratio,(ii) the densimetric Froude number of the bed surface sediment mixture,(iii) the flow shallowness(defined as the ratio of the approach flow depth,y,to the spur dike’s transverse length,l),and(iv) the flow depth-particle size *** is also concluded that the temporal scour depth variation in the sediment mixture is influenced by the non-uniformity of sediment and decreases with an increase in the non-uniformity of the sediment mixture.A new mathematical model is derived for the estimation of temporal scour depths in sand-gravel sediment *** proposed equation has been calibrated and validated with the experimental data,demonstrating a good predictive capacity for the estimation of temporal scour depth evolution.

关键词： Spur dike Sand-gravel sediment mixture Clear-water scour Time-dependent scour depth

Permanent displacement models of earthquake-induced landslides considering near-fault pulse-like ground motions

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Journal of Mountain Science 2019年第6期16卷 1244-1265页

作者： ZHANG Ying-bin XIANG Chen-lin CHEN Yan-long CHENG Qian-gong XIAO Li YU Peng-cheng CHANG Zhi-wang Key Laboratory of transportation Tunnel engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China State Key Laboratory for GeoMechanics and Deep Underground engineering China University of Mining&TechnologyXuzhou 221116China Department of Geotechnical engineering School of Civil EngineeringSouthwest Jiaotong UniversityChengdu 610031China Department of Geological engineering Southwest Jiaotong UniversityChengdu 610031China

The permanent displacement of seismic slopes can be regarded as an effective criterion for stability estimation. This paper studied the characteristics of permanent displacements induced by velocity pulse-like ground motions and developed an empirical model to readily evaluate the stability of seismic slopes in a near-fault region. We identified 264 velocity pulse-like ground motions from the Next Generation Attenuation(NGA) database using the latest improved energy-based approach. All selected ground motions were rotated to the orientation of the strongest observed pulse for considering the directivity of the pulse effect, so that the most dangerous condition for slopes was considered. The results show the velocity pulse-like ground motions have a much more significant effect on permanent displacement of slopes than non-pulse-like ground motions. A regression model based on a function of peak ground velocity(PGV), peak ground acceleration(PGA) and critical acceleration(ac), was generated. A significant difference was found by comparing the presented model with classical models from literatures. This model can be used to evaluate the seismic slope stability considering the effects of nearfault pulse-like characteristics.

关键词： Seismic slope Permanent displacement Pulse effect Earthquake-induced landslides Near-fault

CONTACT ANALYSIS FOR FIBER-REINFORCED, DELAMINATED LAMINATES WITH KINEMATIC NONLINEARITY

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Acta Mechanica Solida Sinica 2013年第4期26卷 388-402页

作者： Jianghong Xue Li Zi Hong Yuan Renhuai Liu Department of Mechanics and civil engineering Jinan University/Key Lab of Disaster Forecast and Control in Engineering Ministry of Education

A macro-micro analytical approach for the anti-penetrating contact problem at the interfaces of the delamination in symmetrically cross-plied,fiber-reinforced rectangular laminates is presented in this *** laminate is simply supported and subjected to a uniform transverse load with a through-width delamination buried at the center position.A contact factor is defined to characterize the contact effect and determined using the micro-mechanics of composite *** analyzing the kinematics of nonlinear deformation at the interfaces of the delamination,the contact force is *** solutions from perturbation analysis are *** is found that the deformation of the laminate involves a global deflection and a local *** antipenetrating contact effects are characterized by the local buckling and are intrinsic properties of the laminates,relying only on the geometries of the delamination and the material *** analyses show that the location and size of the contact areas and the distribution of the contact force are hardly affected by the aspect ratio.

关键词： rectangular laminate delamination contact effect perturbation approach nonlinear analysis

Displacement Response Reconstruction of Slender Flexible Structures Based on Cubic Spline Fitting Method

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China Ocean engineering 2019年第2期33卷 226-236页

作者： HAN Qing-hua MA Ye-xuan FENG Xin-xin XU Wan-hai State Key Laboratory of Hydraulic engineering Simulation and Safety Tianjin University School of civil engineering Tianjin University

How to reconstruct a dynamic displacement of slender flexible structures is the key technology to develop smart structures and structural health monitoring(SHM), which are beneficial for controlling the structural vibration and protecting the structural safety. In this paper, the displacement reconstruction method based on cubic spline fitting is put forward to reconstruct the dynamic displacement of slender flexible structures without the knowledge of modeshapes and applied loading. The obtained strains and displacements are compared with the results calculated by ABAQUS to check the method's validity. It can be found that the proposed method can accurately identify the strains and displacement of slender flexible structures undergoing linear vibrations, nonlinear vibrations, and parametric vibrations. Under the concentrated force, the strains of slender flexible structures will change suddenly along the axial direction. With locally densified measurement points, the present reconstruction method still works well for the strain concentration problem.

关键词： displacement reconstruction cubic spline fitting slender flexible structures linear vibrations parametric vibrations nonlinear vibrations