检索结果-内蒙古大学图书馆

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

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

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

Water transport properties for unsaturated cement-based materials

Water transport properties for unsaturated cement-based mate...

引用

第三届中国国际复合材料科技大会

作者： Chunsheng Zhou Wei Wang Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry and Information Technology Harbin Institute of Technology

The durability performance of cement-based material is actually and mostly determined by the penetration process of deleterious agents and possible chemical and physical reactions between them, where water always plays an important role. In addition, the transport properties of other agents also depend seriously on the water content. It is rather essential to understand the distribution of water and its transport in partially saturated cement-based materials, which are facilitated herein through low-field nuclear magnetic resonance(NMR) technique and gas permeability testing on partially saturated white cement mortar specimens. It is found that most water is stored in inter-layer pores when it is equilibrated with relative humidity below 75%. Due to the marked contraction or swelling of interlayer pores during drying or wetting, the gel pores and inter-hydrate pores are greatly changed while the overall porosity is little altered. At totally drying state, the pore structure of cement-based material becomes obviously coarser, making the gas permeability remarkably larger than water permeability by as large as 2-3 orders of magnitudes. The intrinsic gas permeability obtained on partially saturated specimens reveals that, both the permeability to water and gas depend nonlinearly on the water content, which are well characterized by the models we suggested. Not only the water saturation degree but also the induced pore structure evolution should be incorporated when modelling the transport of water.

关键词： Durability permeability pore structure saturation degree low-field NMR

来源：评论

学校读者我要写书评

暂无评论

Investigation on mapping relationship between deflection and cable tension by artificial neural networks 11

Investigation on mapping relationship between deflection and...

引用

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

作者： Tian, Yadi Li, Hui Key Laboratory of Intelligent Disaster Prevention and Mitigation for Civil Infrastructure Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology Key Laboratory of Structural Dynamic Behavior and Control School of Civil Engineering Harbin Institute of Technology Harbin150090 China

ISBN: (纸本)9781605953304

Cables usually serve as critical load-bearing structural components in cable-stayed bridges. Vertical deflection is an important overall indicator that directly reflects the health status of bridge. The relationship between cable tension and vertical deflection also reflects the underlying mechanism of structures. In this context, a machine learning-based approach is proposed. Cable tension and vertical deflection are caused by prestress, temperature and vehicle loads. In this study, we focus on the cable force and vertical deflection caused by vehicle loads. Artificial neural network (ANN) is employed as the supervised learning method to learn the relationship between cable tension and vertical deflection. Field monitored data of Jintang Bridge are used to test the validity of the proposed method. The results show that ANN is capable of modelling vertical deflection from cable tension data in the case of arbitrary vehicle distribution. The proposed method which integrates the local and global variables by using two different kinds of monitoring data, avoids the complicated mechanical derivations, and is proved to be environment-insensitive.

关键词： Neural networks

来源：评论

学校读者我要写书评

暂无评论

Experimental study on pore structure and chloride ion diffusion of negative temperature cement-based materials

Experimental study on pore structure and chloride ion diffus...

引用

第三届中国国际复合材料科技大会

作者： Guan Xinchun Bai Shuai Li Hui Ou Jinping Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology

The early frost may cause serious injury to the internal pore structure of concrete, and hence has a strong influence on the impermeability and mechanical properties of concrete. In this paper, the chloride ion diffusion coefficient of different frozen level and different kind negative temperature cement-based materials was studied. The pore structures of those negative temperature cement-based materials was studied by fractal theory. The correlation between chloride ion diffusion coefficient and fractal dimension was discussed. Experimental results show that the pore structure of negative temperature cement-based materials possesses fractal characteristics and fractal dimension has good correlation with chloride ion diffusion coefficient. The results can provide a reference to application of negative temperature concrete.

关键词： Cement-based materials Negative temperature concrete Pore structure Fractal Chloride diffusion

来源：评论

学校读者我要写书评

暂无评论

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...

引用

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

来源：评论

学校读者我要写书评

暂无评论

Long term mechanical properties of alkali activated slag

引用

IOP Conference Series: Materials Science and Engineering 2018年第1期292卷

作者： J Zhu W Z Zheng Z Z Xu Y F Leng C Z Qin College of Civil Engineering and Architecture Harbin University of Science and Technology Harbin 150080 Key Lab of Structures Dynamic Behavior and Control of the Ministry Education Harbin Institute of Technology Harbin 150090

This article reports a study on the microstructural and long-term mechanical properties of the alkali activated slag up to 180 days, and cement paste is studied as the comparison. The mechanical properties including compressive strength, flexural strength, axis tensile strength and splitting tensile strength are analyzed. The results showed that the alkali activated slag had higher compressive and tensile strength, Slag is activated by potassium silicate (K2SiO3) and sodium hydroxide (NaOH) solutions for attaining silicate modulus of 1 using 12 potassium silicate and 5.35% sodium hydroxide. The volume dosage of water is 35% and 42%. The results indicate that alkali activated slag is a kind of rapid hardening and early strength cementitious material with excellent long-term mechanical properties. Single row of holes block compressive strength, single-hole block compressive strength and standard solid brick compressive strength basically meet engineering requirements. The microstructures of alkali activated slag are studied by X-ray diffraction (XRD). The hydration products of alkali-activated slag are assured as hydrated calcium silicate and hydrated calcium aluminate.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Effect of different fibers on mechanical properties and ductility of alkali-activated slag cementitious material

引用

IOP Conference Series: Materials Science and Engineering 2018年第1期292卷

作者： J Zhu W Z Zheng C Z Qin Z Z Xu Y Q Wu College of Civil Engineering and Architecture Harbin University of Science and Technology Harbin 150080 Key Lab of Structures Dynamic Behavior and Control of the Ministry Education Harbin Institute of Technology Harbin 150090

The effect of different fibers on mechanical properties and ductility of alkali-activated slag cementitious material (AASCM) is studied. The research contents include: fiber type (plant fiber, polypropylene fiber), fiber content, mechanical property index, tensile stress-strain relationship curve, treating time. The test results showed that the compressive strength of two fibers reinforced AASCM was about 90 ~ 110MPa, and the tensile strength was about 3 ~ 5MPa. The reinforcement effect of polypropylene fiber is superior to that of plant fiber, and the mechanical properties of polypropylene fiber reinforced AASCM are superior to those of plant fiber, According to the comparison of SEM pictures, the plant fiber and polypropylene fiber are both closely bound with the matrix, and the transition zones are complete and close. Thus, it is proved that plant fiber and polypropylene fiber delay the crack extension and enhance the ductility of AASCM.

关键词：

来源：评论

学校读者我要写书评

暂无评论

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...

引用

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

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：