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Measurement and comparison of snow density on ground and roof 9th

Measurement and comparison of snow density on ground and roo...

9th International Structural Engineering and Construction Conference: Resilient structures and Sustainable Construction, ISEC 2017

作者： Qingwen, Zhang Zhicheng, Ren Shiyu, Wang Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Harbin China School of Civil Engineering Harbin Institute of Technology Harbin China

ISBN: (纸本)9780996043748

With the intensification of global climate changing, the human and economic losses caused by snowstorms becomes higher and higher. Harbin, located in the north of China, has the geographical advantage of heavy snowfall, the density and the distribution of snow on the ground and roof were measured. In the aspect of snow density, the snow density on ground and roofs were measured. The snow is divided into three kinds, and the range of snow density is roughly determined. By comparing the two kinds of measurements on both fields, the effects of location, snow thickness and temperature on snow density are specified. Also, the differences of snow density on both ground and roof, new snow and old snow are got. The results show that the old snow density is greater than the new snow density. The snow density of the roof area is obviously larger than that of the ground area;the ground snow density increases with the accumulation of snowfall. Copyright © 2017 ISEC Press.

关键词： Snow

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controlled substructure identification of shear structure with virtual control system 11

Controlled substructure identification of shear structure wi...

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11th International Workshop on Structural Health Monitoring 2017: Real-Time Material State Awareness and Data-Driven Safety Assurance, IWSHM 2017

作者： Zhang, Dongyu Li, Hui Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Harbin China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

ISBN: (纸本)9781605953304

Substructure identification is a powerful tool to identify the parameters of a complex structure. Previously, the authors have developed an inductive substructure identification method for shear structures. However, it was found that the identification accuracy of this method is significantly influenced by certain characteristics of structural responses and, thus, it may not be able to always provide accurate estimation results. To solve this problem, a self-balanced virtual control system (VCS) is introduced into the structure, converting the original substructure identification to a controlled substructure identification problem. By optimally tuning the parameters of the VCS, the dynamic characteristics of the controlled structure can be changed and, thus, the goal of improving substructure identification accuracy is achieved. Finally, a numerical example of 6-story shear structure is utilized to effectiveness of the VCS based controlled substructure identification method.

关键词： Parameter estimation

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Design and validation of a smartphone based wireless structural vibration monitoring system 11

Design and validation of a smartphone based wireless structu...

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11th International Workshop on Structural Health Monitoring 2017: Real-Time Material State Awareness and Data-Driven Safety Assurance, IWSHM 2017

作者： Zhang, Dongyu Tian, Jiadong Li, Hui Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Harbin China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

ISBN: (纸本)9781605953304

Traditional structural health monitoring (SHM) system usually uses expensive professional sensors, data transmission and data acquisition systems. Thus, only very important structures are affordable to install a SHM system. In recent years, smartphones become very popular, which not only integrate high-performance vibration sensors, but also have powerful data acquisition, processing, storage and transmission capabilities, making it possible to utilize smartphones to carry out some SHM tasks. In this paper, the authors developed a software that can easily convert several android based smartphones into a wireless structural vibration monitoring system. The software consists of a server program and a client program. The smart phone installing the server program can remotely control the smartphones installing the client program via local WIFI network to perform the tasks of network timesynchronization and measuring structural responses. First, the architecture of this program is introduced in detail. Then, the time synchronizing algorithm for all client nodes in the software is discussed. Next, the accuracy of time synchronization of the smartphone based wireless sensing system is validated through an experiment. Finally, a shaking table experiment is conducted, the results of which demonstrate that the smartphone based wireless structural vibration monitoring system can quite accurately identify the modal parameters of the tested structure.

关键词： Smartphones

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Numerical simulation and experimental validation of moisture-heat coupling for saturated frozen soils

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Research in Cold and Arid Regions 2017年第3期9卷 250-257页

作者： Zhi Ming Li Jian Chen Kai Sun Bin Zhang Key Lab of Structures Dynamic Behavior and Control (Harbin Institute of Technology) Ministry of Education School of Civil Engineering Harbin Institute of Technology Heilongjiang Water Conservancy Science Research Institute

In seasonally frozen regions,freezing-and-thawing action is the main cause responsible for the destruction of canals,which is closely linked to the temperature gradient and water *** investigate the behaviour of soils under freezing-and-thawing actions,many numerical models have been established that consider the important coupling of moisture transport and temperature evolution;but they contain excessive parameters,some of which are rather difficult to *** on the well-known Harlan's theory,a simple moisture-heat coupling model was recently proposed to quantify the coupled moisture-heat transport performance of soils in terms of the central temperature and *** mathematical module of COMSOL Multiphysics was further employed to solve the governing equations *** validate our model,a thorough experimental scheme was carried out in our *** measured temperature distribution was found to be consistent with the predicted results.

关键词： saturated frozen soil moisture-heat coupling freezing-and-thawing action canal

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Wind load prediction of large-span dry coal sheds based on grnn and its application 9th

Wind load prediction of large-span dry coal sheds based on g...

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9th International Structural Engineering and Construction Conference: Resilient structures and Sustainable Construction, ISEC 2017

作者： Sun, Ying Yang, Lin Wu, Yue Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education School of Civil Engineering Harbin Institute of Technology Harbin China School of Civil Engineering Harbin Institute of Technology Harbin China

ISBN: (纸本)9780996043748

The distribution and fluctuation of wind load on large-span dry coal sheds are complicated. Wind load on typical shape of roofs can be sometimes determined based on the wind tunnel tests carried out on roofs of similar shape. To expand the application scope of the test data, Generalized Regression Neural Network (GRNN) is introduced. The prediction models on large-span dry coal are given, where the wind load is expressed by eight parameters: mean, RMS, skewness, kurtosis of wind pressure coefficients, three auto-spectral parameters (including descendent slope in high frequency range, peak reduced spectrum and reduced peak frequency) and coherence exponent for cross-spectra. Cross validation and trails are carried out to determine the parameter in the GRNN model. Further, the wind load prediction is applied on a dry coal shed shell. The wind-induced responses are calculated and compared with the results of wind tunnel tests, with extremely close result. Therefore, it can be concluded that GRNN is feasible in predicting wind load on roof structures. Copyright © 2017 ISEC Press.

关键词： Neural networks

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Study on the performance of reinforced concrete blocks treated by styrene-acrylic emulsion

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Chemical Engineering Transactions 2018年 66卷 85-90页

作者： Zhu, Jing Zheng, Wenzhong Xie, Lili Wu, Yunqiang Zhang, Yongxin Fu, Junxiang Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration Harbin150080 China College of Civil Engineering and Architecture Harbin University of Science and Technology Harbin150080 China Key Lab of Structures Dynamic Behavior and Control of the Ministry Education Harbin Institute of Technology Harbin150090 China

This paper introduces a method of improving the performance of reinforced concrete blocks and reveals the reinforcing effect of fibers. It is pointed out that the plant fibers treated by styrene-acrylic emulsion can effectively improve the interfacial bonding conditions, for the modified straw fibers which were treated by alkali processing and acrylic coating, their performance has been significantly improved, which is conducive to absorbing energy and improving the strength of the material. This paper focuses on introducing three types of reinforced concrete blocks, it’s known that the bridging effect can effectively prevent the development of micro cracks. The occurrence of cracks increases the macroscopic tensile strain of the material and increases the ductility and toughness of the matrix. Studying plant fiber reinforced blocks will help promote the application of this new wall materials. Copyright © 2018, AIDIC Servizi S.r.l.

关键词： Tensile strain

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Chemical composition of calcium-silicate-hydrate gels: Competition between kinetics and thermodynamics

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Physical Review Materials 2019年第6期3卷 065603-065603页

作者： Tao Du Hui Li Qi Zhou Zhe Wang Gaurav Sant Joseph V. Ryan Mathieu Bauchy Key Lab of Structures Dynamic Behavior and Control (Harbin Institute of Technology) Ministry of Education 150090 Harbin China School of Civil Engineering Harbin Institute of Technology 150090 Harbin China Physics of AmoRphous and Inorganic Solids Laboratory (PARISlab) Department of Civil and Environmental Engineering University of California Los Angeles California 90095 USA Laboratory for the Chemistry of Construction Materials (LC2) Department of Civil and Environmental Engineering University of California Los Angeles California 90095 USA California Nanosystems Institute (CNSI) University of California Los Angeles California 90095 USA Energy and Environment Directorate Pacific Northwest National Laboratory Richland Washington 99352 USA

Although concrete is the world's most widely used manufactured material, basic questions persist regarding the nature of its binding phase, namely, the calcium-silicate-hydrate (C-S-H) gel. Here, based on reactive molecular dynamics simulations, we address the following fundamental question: Is the chemical composition of C-S-H controlled by the kinetics or thermodynamics of its precipitation? As a major outcome of this study, we demonstrate that the average stoichiometry of the C-S-H gel forming upon the hydration of ordinary portland cement (i.e., Ca/Si = 1.75) is determined by the composition of the C-S-H phase presenting the fastest precipitation kinetics, rather than the highest thermodynamic stability.

关键词： Amorphous materials Gels Molecular dynamics

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General solutions for nonlinear differential equations: A deep reinforcement learning approach

arXiv

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arXiv 2018年

作者： Wei, Shiyin Jin, Xiaowei Li, Hui Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

Physicists use differential equations to describe the physical dynamical world, and the solutions of these equations constitute our understanding of the world. During the hundreds of years, scientists developed several ways to solve these equations, i.e., the analytical solutions and the numerical solutions. However, for some complex equations, there may be no analytical solutions, and the numerical solutions may encounter the curse of the extreme computational cost if the accuracy is the first consideration. Solving equations is a high-level human intelligence work and a crucial step towards general artificial intelligence (AI), where deep reinforcement learning (DRL) may contribute. This work makes the first attempt of applying (DRL) to solve nonlinear differential equations both in discretized and continuous format with the governing equations (physical laws) embedded in the DRL network, including ordinary differential equations (ODEs) and partial differential equations (PDEs). The DRL network consists of an actor that outputs solution approximations policy and a critic that outputs the critic of the actor's output solution. Deterministic policy network is employed as the actor, and governing equations are embedded in the critic. The effectiveness of the DRL solver in Schrödinger equation, Navier-Stocks, Van der Pol equation, Burgers' equation and the equation of motion are discussed. Copyright © 2018, The Authors. All rights reserved.

关键词： Deep learning

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Multivariate stationary non-Gaussian process simulation for wind pressure fields

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Earthquake Engineering and Engineering Vibration 2016年第4期15卷 729-742页

作者： Sun Ying Su Ning Wu Yue Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology School of Civil Engineering Harbin Institute of Technology

Stochastic simulation is an important means of acquiring fluctuating wind pressures for wind induced response analyses in structural engineering. The wind pressure acting on a large-span space structure can be characterized as a stationary non-Gaussian field. This paper reviews several simulation algorithms related to the Spectral Representation Method （SRM） and the Static Transformation Method （STM）. Polynomial and Exponential transformation functions （PSTM and ESTM） are discussed. Deficiencies in current algorithms, with respect to accuracy, stability and efficiency, are analyzed, and the algorithms are improved for better practical application. In order to verify the improved algorithm, wind pressure fields on a large-span roof are simulated and compared with wind tunnel data. The simulation results fit well with the wind tunnel data, and the algorithm accuracy, stability and efficiency are shown to be better than those of current algorithms.

关键词： stochastic simulation non-Gaussian process static transformation method wind pressure field

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Simplified design method and seismic performance of space trusses with consideration of the influence of the stiffness of their lower supporting columns

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 401-409页

作者： Fan Feng Sun Menghan Zhi Xudong Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology School of Civil Engineering Harbin Institute of Technology

Static and dynamic force performance of two types of space truss structures i.e. square pyramid space truss（SPST） and diagonal on square pyramid space truss（DSPST）, are studied to determine the effect of stiffness of their lower supporting members. A simplified model for the supporting columns and the equivalent spring mass system are presented. Furthermore, the feasibility of the simplified model is demonstrated through theoretical analysis and examples of comparative analysis of the simplified model with the entire model. Meanwhile, from the elastic analysis under frequently occurring earthquakes and elasto-plastic analysis under seldom occurring earthquakes subjected to TAFT and EL-Centro seismic oscillation it is shown that the simplified method can be encompassed in the results from the normal model. It also showed good agreement between the two methods, as well as greatly improved the computational efficiency. This study verified that the dynamic effect of the supporting structures was under considered in space truss design in the past. The method proposed in the paper has important significance for other space truss structures.

关键词： simplified supporting pyramid stiffness truss verified diagonal elasto columns seldom

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