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Multivariate stationary non-Gaussian process simulation for wind pressure fields

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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An on-site evaluation method for corrosion degradation of in-service cable wires by image histogram matching 11

An on-site evaluation method for corrosion degradation of in...

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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： Xu, Yang Li, Shunlong Li, Hui Gu, Chenyu Li, Xinbin Chen, Xiaowei Qiao, Weidong Key Lab of Intelligent Disaster Mitigation Ministry of Industrial and Information Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China School of Transportation Science and Engineering Harbin Institute of Technology Harbin150090 China

ISBN: (纸本)9781605953304

This paper proposes a novel non-destructive method by image histogram matching to evaluate the corrosion degradation of cable wires in service quantitatively. Artificial accelerated salt spray test is adopted to simulate the corrosion environment, and adequate RGB images are taken by a consumer-grade camera to cover the whole information of corroded surface for each specimen under different corrosion periods. Histogram distribution analysis is applied to study the concentrated modes of RGB images, and joint Gaussian distribution is fitted to capture location parameters. Timevariant models of the location parameters are regressed and then the mechanical properties are learnt by tensile and fatigue tests. Once the features of RGB corrosion images of steel wires are matched to the proposed time-variant models, the corresponding corrosion degree and mechanical properties can be estimated. The proposed method is meaningful for the on-site evaluation of cable wires in service with no need to carry on corrosion and mechanical degradation tests after replacing cables.

关键词： Graphic methods

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Pseudo-dynamic testing of a fabricated composite frame with steel plate shear walls

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2017年第6期18卷 454-466页

作者： Zheng-gang CAO Peng DU Feng FAN Zhe-ming CHEN Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Shanghai Municipal Engineering Design Institute (Group) Co. Ltd Shanghai 200092 China

A pseudo-dynamic testing program was generated on a fabricated composite frame with steel plate shear walls （SPSWs） to study its seismic perlbrmance. The specimen was a three-storey single-bay frame, which was composed of H- section steel columns and composite beams, and was assembled by bolted height-adjustable steel beam-to-column connections （BHA connections）. Beam-only-connected SPSWs were selected as lateral load resisting members. The specimen was subjected to four ground motions of progressively increasing intensity. The results showed that：（1） beam-only-connected S PSWs provided sufficient lateral load resistance, lateral stiffness, and energy dissipation capacity to the fabricated frame via the tension ficld action developed in their infill panels; （2） the fabricated frame, assembled by BHA connections, exhibited substantial redundancy and good ductility; （3） an undesirable failure mode of the fabricated frame, in huge earthquakes, included severe cracking in composite beams and block shear failure in SPSWs＇ connections; （4） the inter-storey shear force distribution determined by ASCE/SE1 7-10 was verified with experimental data.

关键词： Fabricated frame Composite beam Steel plate shear walls Pseudo-dynamic test

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Mechanical properties of steel fiber-reinforced reactive powder concrete at high temperature and after cooling

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Procedia Engineering 2017年 210卷 597-604页

作者： Muhammad Abid Xiaomeng Hou Wenzhong Zheng Ghulam Qadir Waqar Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin 150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China

Reactive powder concrete (RPC) is advanced cement-based material. It is produced through microstructure enhancement technique. Like other types of concretes, RPC has also been affected by severe environmental conditions such as accidental fire. Up to date, very limited research has been carried out to compare the performance of RPC at fire and after cooling. To address this gap in knowledge, the mechanical properties such as compressive strength, split-tensile strength, flexural strength and elastic modulus have been studied at high temperature and after cooling. 72 cubic specimens and 72 prismatic samples were tested. The hot and residual strength results were plotted as a function of temperature. The results indicated a higher residual strength than hot-strength in the temperature range of 20-300℃. Above 300℃, there was no sizable difference between the hot and residual strength of PRC. A comparison has also been made among the test data with current design codes.

关键词： Reactive powder concrete high temperature hot behavior residual behavior mechanical properties

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Evaluation of residual mechanical properties of steel fiber-reinforced reactive powder concrete after exposure to high temperature using nondestructive testing

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Procedia Engineering 2017年 210卷 588-596页

作者： Xiaomeng Hou Muhammad Abid Wenzhong Zheng Ghulam Qadir Waqar Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin 150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China

Reactive powder concrete (RPC) is classified as ultra-high performance concrete, owing to its superior strength, excellent durability and high fracture energy. However, RPC may also be severely affected by devastating fire exposures. This paper presents the variations in residual mechanical properties of RPC after exposure to high temperature. The strength of RPC after cooling was also assessed by nondestructive tests (NDTs). The ultrasonic pulse velocity (UPV) method and resonance frequency (RF) method were used. The samples were subjected to the target temperature of 120℃, 300℃, 500℃, 700℃ and 900℃. The heating was continued for further 3 hours so that steady state condition was achieved. The available equations have been used for determination of dynamic elastic modulus of RPC using UPV and RF measurements. The residual mechanical properties, RF and UPV were plotted as a function of temperature. The result shows that the residual strength increases from room temperature to 300℃. However, above 300℃, it’s decreasing gradually. Various comparisons have been made between residual mechanical strength versus UPV and RF measurements. Relationships have been proposed among residual mechanical properties versus NDTs values. These relationships can be employed for post-fire strength assessment of RPC structures.

关键词： Reactive powder concrete high temperature residual mechanical properties ultrasonic pulse velocity resonance frequency

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Early Age Deformation of Mortar Under Sub-zero Temperature

Early Age Deformation of Mortar Under Sub-zero Temperature

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第九届水泥混凝土国际会议

作者： Ge ZHANG Haiyang Yu Yingzi YANG Key Lab of Structures Dynamic Behavior and Control Harbin Institute of TechnologyMinistry of Education School of Civil Engineering Harbin Institute of Technology

Early defonnation of mortars exposed to sub-zero temperature was *** measure the deformation precisely,a self-made defonnation test device which can be used under sub-zero temperature was *** addition,the compressive strength and dynamic modulus of elasticity of mortars exposed to sub-zero temperature were *** results showed that the deformation of mortars exposed to the sub-zero temperature at early age can be considered as 6 *** were plastic settlement stage,frost heaving stage,deformation stabilization stage,positive temperature settlement stage,positive temperature expansion stage,and re-stabilization stage,*** early compressive strength of mortars would be seriously affected by the sub-zero *** once the curing temperature was transformed to the positive temperature,it would develop *** results of the dynamic modulus of elasticity showed that the internal structure can be developed even at the sub-zero temperature,but the early internal structure of mortar would be damaged by the low temperature.

关键词： Sub-zero temperature deformation early age mortar

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Multi-species ionic transport model for concrete coupling ion-cement hydrate interactions into Nernst-Planck equation

Multi-species ionic transport model for concrete coupling io...

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第三届中国国际复合材料科技大会

作者： Bingbing Guo Yi Hong Guofu Qiao Jinping Ou Key Lab of Structures Dynamic Behavior and Control (Harbin Institute of Technology) Ministry of Education School of Civil Engineering Harbin Institute of Technology Centre for Composite Material and Structure Harbin Institute of Technology

Reinforced concrete(RC) structures are widely used in civil engineering, but the ingress of chloride ions is one of the major factors that deteriorate the durability of RC structures. Thus, many numerical models have been reported to study the mass transport of cement-based material in the previous papers. However, most of these models did not consider the interactions between ions in the pore solution and the cement hydrate or considered the interactions by modifying the diffusion coefficients. This research presents a multi-species ionic transport model for concrete that couples ion-cement hydrate interactions into Nernst-Planck equation. Firstly, a two-phase FEM concrete geometric model that included mortar phase and coarse aggregate phase was built. Moreover, the surface complexation model and the phase-equilibrium model were used to simulate the ion-cement hydrate interactions, and Nernst-Planck equation was used to simulate the effect of the driving forces of the concentration and electric field gradients in the concrete, which were conducted by using PHREEQC code and COMSOL, respectively. Then, the interactive interface that coupled the ion-cement hydrate interactions and Nernst-Planck equation was established by using MATlab language. Finally, the results of the numerical multi-species ionic transport model for concrete were verified by the experimental data published in the previous paper.

关键词： concrete multi-species transport model ion-cement hydrate interactions Nernst-Planck equation

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LQD-RKHS-based distribution-to-distribution regression methodology for restoring the probability distributions of missing SHM data

arXiv

引用

arXiv 2018年

作者： Chen, Zhicheng Bao, Yuequan Li, Hui Spencer, Billie F. Key Lab of Intelligent Disaster Mitigation of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin China Key Lab of Structures Dynamic Behaviour and Control of the Ministry of Education Harbin Institute of Technology Harbin China School of Civil Engineering Harbin Institute of Technology Harbin China Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign UrbanaIL United States Department of Civil and Environmental Engineering University of Illinois at Urbana - Champaign UrbanaIL United States

Data loss is a critical problem in structural health monitoring (SHM). Probability distributions play a highly important role in many applications. Improving the quality of distribution estimations made using incomplete samples is highly important. Missing samples can be compensated for by applying conventional missing data restoration methods;however, ensuring that restored samples roughly follow underlying distributions of true missing data remains a challenge. Another strategy involves directly restoring the probability density function (PDF) for a sensor when samples are missing by leveraging distribution information from another sensor with complete data using distribution regression techniques;existing methods include the conventional distribution-to-distribution regression (DDR) and distribution-to-warping function regression (DWR) methods. Due to constraints on PDFs and warping functions, the regression functions of both methods are estimated from the Nadaraya-Watson kernel estimator with relatively low degrees of precision. This article proposes a new indirect distribution-to-distribution regression method in the context of functional data analysis for restoring distributions of missing SHM data. PDFs are transformed to ordinary functions residing in a Hilbert space via the newly proposed log-quantile-density (LQD) transformation;the regression for distributions is realized in the transformed space via a functional regression model constructed based on the theory of Reproducing Kernel Hilbert Space (RKHS), corresponding result is subsequently mapped back to the density space through the inverse LQD transformation. Test results using field monitoring data indicate that the new method significantly outperforms conventional methods in general cases;however, in extrapolation cases, the new method is inferior to the distribution-to-warping function regression method. Copyright © 2018, The Authors. All rights reserved.

关键词： Probability distributions

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Study on the effect of ground motion direction on the response of engineering structure

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Earthquake Engineering and Engineering Vibration 2016年第4期15卷 649-656页

作者： Sun Menghan Fan Feng Sun Baitao 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 Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration

Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on a structure are studied herein. Ground motion records usually contain three vertical ground motion data, which are obtained by sensors arranged in accordance with the EW （East -West） direction, NS （South- North） direction and perpendicular to the surface （z） direction, referring to the construction standard of seismic stations. The seismic records in the EW and NS directions are converted to Cartesian coordinates in accordance with the rotation of θ = 0°-180°, and consequently, a countless group of new ground motion time histories are obtained. Then, the characteristics of the ground motion time history and response spectrum of each group were studied, resulting in the following observations：（1） the peak and phase of ground motion are changed with the rotation of direction θ, so that the direction θ of the maximum peak ground motion can be determined; （2） response spectrum values of each group of ground motions change along with the direction θ, and their peak, predominant period and declining curve are also different as the changes occur; then, the angle θ in the direction of the maximum peak value or the widest predominant period can be determined; and （3） the seismic response of structures with different directions of ground motion inputs has been analyzed under the same earthquake record, and the results show the difference. For some ground motion records, such as the Taft seismic wave, these differences are significant. Next, the Lushan middle school gymnasium structure was analyzed and the calculation was checked using the proposed method, where the internal force of the upper space truss varied from 25% to 28%. The research results presented herein can be used for reference in choosing the ground motion when checking the actual damage to struct

关键词： direction of grotmd motion structure effect coordinate transformation response spectrum

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