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Review of research methods in snow engineering for buildings

Jianzhu Jiegou Xuebao/Journal of Building structures 2019年第6期40卷 1-13页

作者： Fan, Feng Zhang, Borui Zhang, Qingwen Liu, Mengmeng Zhang, Guolong Mo, Huamei Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

Snow engineering for buildings is a new academic discipline, which aims to investigate and forecast the influence of snowfalls on buildings and surroundings as well as the possibility of the disaster such as buildings collapse induced by snow accumulation, based on interdisciplinary researches such as physics, geophysics and catastrophology etc. This paper presents an in-depth review and analysis on the development of three main research methods, namely, field measurement, experimental research and numerical simulation. In terms of the field measurement, the development and theoretical models of several important factors, including snow transport by wind and snow melt by heat transfer, are investigated;the focus of this method in China in the future is also pointed out. Four different research techniques involved in experiments and the establishment of their similarity criterions as well as the selection of relevant parameters are summarized, followed by the necessity of establishing the professional climatic wind tunnel for snow drift research. By reviewing the progress of the computational fluid dynamics (CFD) simulation method, the achievement of existing simulation methods and their potential shortcomings are summarized so as to show the direction of the future improvements in this research method. © 2019, Editorial Office of Journal of Building structures. All right reserved.

关键词： Snow

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Actual measurement research on snow load of heated building roof

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Jianzhu Jiegou Xuebao/Journal of Building structures 2019年第6期40卷 24-31页

作者： Zhang, Borui Zhang, Qingwen Fan, Feng Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

In order to explore the influence of the building thermal environment on the roof snow load, a prefabricated building model for actual measurement was designed based on the requirement of the law of thermal coefficient (Ct) in foreign building load codes (ASCE/SEI 7-10 and ISO 4355:2013). The proposed model can change the heat resistance of roof and indoor temperature. In detail, the actual measurements of apparent density of snow and snow load under natural snow (with low moisture) and artificial snow (with high moisture) conditions in both the snowmelt period (with daily maximum temperature higher than 0℃) and the non-snowmelt period (with daily maximum temperature not higher than 0℃) were completed. The results show that the snow-layer on the building roof in the snowmelt period experiences the stages of the melt of lower surface snow, and then upward movement of melt layer with discharge of the snowmelt water. The apparent density and environmental temperature of snow show a positively correlated relationship while the variation of snow load appears a typical three-stage form, including the melting, the mass-loss and the recrystallization. Besides, the variation of snow-layer on the building roof in the non-snowmelt period is less than that in the snowmelt period, but the trend is highly consistent, where the snow load decreases with the increasing of roof heat loss. Finally, according to GB 50189-2015 and JGJ 134-2010, the thermal coefficient values of all measured conditions were calculated, and the Ct value of the building with the indoor maximum temperature about 0℃ was suggested to be 1.2. © 2019, Editorial Office of Journal of Building structures. All right reserved.

关键词： Roofs

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Jianzhu Jiegou Xuebao/Journal of Building structures 2019年第6期40卷 40-47页

作者： Liu, Mengmeng Zhang, Qingwen Qian, Yiwei Mo, Huamei Fan, Feng Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

Wind-induced snowdrift phenomenon leads to the unbalanced distribution of snow on the building roofs, which could bring a huge safety hazard to the structure. The wind tunnel test is one of the main methods to study wind-induced snowdrift, and similarity theories are the bases of wind tunnel test. In this paper, the similarity theories of Kind, Iversen and Tabler were firstly summarized. After the classification, the main similarity criteria were then summarized, including Froude, Reynold, time similarity criterion and speed similarity criterion, etc. Making use of the wind-snow combined experiment facility, taking artificial snow as the simulating granular material, as well as considering characteristics of different similarity criteria sufficiently, scale experiments on snow distribution around a 0.5 m cube were conducted according to the selected similarity criterion, with the field observation on snow distribution around a 1m cube by Oikawa as the prototypes. Finally, according to the comparison of the prototypes and scale experiments,and with a full consideration of the characteristics of each similarity criterion, the similarity criterion based on the mass transfer rate of saltation process is proved to be the most reliable for the reappearance of snow distribution, and the experimental results show better agreement with the prototype when using the mean wind speed of the prototype. © 2019, Editorial Office of Journal of Building structures. All right reserved.

关键词： Wind tunnels

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Probabilistic Seismic Safety Assessment of Chinese RC Frame structures Using Fragility Curves 2

Probabilistic Seismic Safety Assessment of Chinese RC Frame ...

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2nd International Conference on Vulnerability and Risk Analysis and Management, ICVRAM 2014 and the 6th International Symposium on Uncertainty Modeling and Analysis, ISUMA 2014

作者： Yu, Xiaohui Lu, Dagang Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education P.O. Box 2546 Harbin150090 China School of Civil Engineering Harbin Institute of Technology P.O. Box 2546 Harbin150090 China

ISBN: (纸本)9780784413609

A simulation-based procedure was adopted to generate fragility curves for five Chinese code-conforming reinforced concrete (RC) frame structures with increasing design-based earthquake (DBE) intensities. Two important elements, namely probabilistic seismic demand analysis (PSDA) and probabilistic seismic capacity analysis (PSCA), were involved in the procedure. In PSDA, 100 real ground motion records were selected to perform nonlinear time history analyses for representing the influence of earthquake uncertainties on structural demands. In PSCA, a group of ten structural parameters were considered as random, and then the conventional (deterministic) pushover analysis was extended by introducing 100 building samples according to the principle of the Latin hypercube sampling technique. From the derived pushover curves, the thresholds corresponding to the limit states -namely, "slight damage", "moderate damage", "extensive damage" and "complete damage" -were obtained for statistics. Finally, fragility curves were generated through combining the results of PSDA and PSCA, and the exceeding probabilities of the example frames conditioned on the three mostly concerned earthquake levels, i.e. frequent earthquake (FE), DBE and maximum considered earthquake (MCE), were consequently calculated. The results show that the increase of fortification earthquake intensity cannot correspondingly promote the probabilistic safety level. © 2014 American Society of Civil Engineers.

关键词： Uncertainty analysis

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Effect of trigger system on experimental dispersion characteristics of active surface wave testing

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 311-318页

作者： Lin Shibin Jeramy C.Ashlock Zhu Liming Qin Zexiang Li Bo Zhu Xingji Zhai Changhai State Key Laboratory of Precision Blasting Jianghan UniversityWuhan 430056China Hubei Key Laboratory of Blasting Engineering Jianghan UniversityWuhan 430056China Department of Civil Construction&Environmental EngineeringIowa State UniversityAmesIA 50010USA Wuhan Airport Road Development Co. Ltd.Wuhan 430065China School of Civil and Environmental Engineering Harbin Institute of TechnologyShenzhen 518055China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disaster of the Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin 150090China

A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data *** effect of the trigger system on the dispersion image of surface waves is empirically known to be negligible,however,theoretical explanation regarding the effect of the trigger system is *** study systematically examines the theory for surface wave dispersion analysis and proves that the effect of the trigger system on a dispersion image is negligible via a solid theoretical ***,based on the new theoretical explanation,an alternative method that uses only the relative phase difference between sensors to extract dispersion characteristics with better conceptual clarity is *** active surface wave testing cases are considered to validate the theory and *** results indicate that(1)an accurate trigger system is not necessary for surface wave data acquisition,and(2)it is unnecessary to assume that the impact point is the generation point of the surface waves for the experimental dispersion analysis.

关键词： site investigation surface waves data acquisition dispersion

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Experimental research on the seismic performance of reinforced reactive powder concrete frame joints

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Zhendong yu Chongji/Journal of Vibration and Shock 2018年第6期37卷 149-156页

作者： Wang, Dehong Ju, Yanzhong Zheng, Wenzhong Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering and Architecture Northeast Electric Power University Jilin132012 China

To study the seismic behavior of frame joints made of reactive powder concrete with ultrahigh strength, toughness and durability, 4 reinforced reactive powder concrete beam-column joints were tested under cyclic loads simulated seismic load conditions. The failure patterns, seismic bearing capacity, hysteretic characteristics, ductility, energy dissipating, strength and rigidity degeneration of the reactive powder concrete frame joints were analyzed. The test results show that, the shear-cracking strength of the reactive powder concrete specimens is higher, and the development of surface crack exhibits the characteristics of multiple fine cracking and a little concrete spalling, and the specimens remain as an integral whole as the loading *** strength and rigidity degeneration rates are small. The deformation capacity and energy dissipation are well. When the failure is occurring, the shear deformation is the double of that under the peak load, and the averaging equivalent viscous damping coefficient of specimens is 0.137, which is higher than the equivalent viscous damping coefficient of normal and high-strength concrete joints. The use of reactive powder concrete can improve the seismic performances of frame joints, including the shear ductility, energy dissipation capacity and so on, and reduce the stirrup ratio in joint core, which is conducive to the construction. © 2018, Editorial Office of Journal of Vibration and Shock. All right reserved.

关键词： High performance concrete

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Review and analysis on spalling critical temperature of concrete and fibers dosage to prevent spalling at elevated temperatures

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Jianzhu Jiegou Xuebao/Journal of Building structures 2017年第1期38卷 161-170页

作者： Chen, Mingyang Hou, Xiaomeng Zheng, Wenzhong Wu, Bo Key Lab of Structures Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China State Key Laboratory of Subtropical Building Science South China University of Technology Guangzhou510640 China

The principle of fire safety design is to ensure that concrete structures will not collapse or spall during fire and can be repaired after fire. There is important significance to research the spalling critical temperature of concrete without fibers or with lower fibers and rational fibers dosage to prevent spalling at elevated temperatures. The test results on fire-induced concrete spalling were analyzed. The relationship of spalling critical temperature and concrete cube compressive strength was obtained. Results show that the spalling critical temperature decreases with the increase of concrete compressive *** relationship of volume dosage of polypropylene (PP) fibers and steel fibers to prevent spalling and concrete compressive strength was obtained. The dosage of PP fibers increases linearly with the increase of concrete compressive strength, while the dosage of steel fibers increases with the increase of concrete compressive strength and the relationship can be expressed as an exponent *** is not safe to apply the recommendation in EN 1992-1-2: 2004 'Design of concrete structures: part 1-2: general rules: structural fire design' that the volume dosage 0.22% of PP fibers in concrete to prevent spalling. The proposed formula for fibers dosage will reduce the fire-induced spalling of concrete effectively. © 2017, Editorial Office of Journal of Building structures. All right reserved.

关键词： Steel fibers

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Ultrasonic guided waves sensing using optical fiber sensor 7

Ultrasonic guided waves sensing using optical fiber sensor

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7th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2015

作者： Zhou, W. Li, H. Dong, Y. Wang, A. Key Lab. of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China National Key Laboratory of Science and Technology on Tunable Laser Harbin Institute of Technology Harbin150001 China

Optical fiber sensors have been proven that they have potential as ultrasonic guided waves sensor for structural health monitoring and damage detection. They can be used to receive acoustic emission signals from dynamic structural damages or guided waves propagating in waveguide and excited by ultrasonic actuators. Optical fiber sensors based on Mach-Zehnder interferometer were investigated in this work. Their sensing properties were explored experimentally using Lamb waves excited by a piezoelectric wafer in an aluminum plate. Spiral shape with different size was selected to increase their sensitivity. Experiments were also conducted to examine the voltage responses received by this type of sensor, and investigate results of tuning frequency. © 2015, International Society for Structural Health Monitoring of Intelligent Infrastructure, ISHMII. All rights reserved.

关键词： Structural health monitoring

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Passive Perforated Pipe control Method for Wind?Induced Vibration of a High?Rise Chemical Tower

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Transactions of Nanjing University of Aeronautics and Astronautics 2020年第1期37卷 99-107页

作者： LU Shanshan ZHANG Zhifu ZHANG Runtao CHEN Wenli Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin 150090P.R.China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090P.R.China

Vortex-induced vibration is likely to occur when subjected to wind loads because of low horizontal stiffness,resulting in internal force and large lateral ***-term wind-induced vibration can not only affect the normal service and durability performance of chemical towers,but also seriously endanger the safety of towers in service periods,and cause property *** this study,a passive control method for suppressing wind-induced vibration of chemical towers is *** flow around the flow field is guided by a pre-set air-blowing channel,thus destroying the unsteady vortex shedding in the wake region of the flow field and achieving the purpose of flow *** accelerometers are used to measure the vibration signal of the chemical tower model with and without the perforated *** control effects of the spacing and the installation position of the perforated pipe are then *** results show that the passive perforated pipe control method can effectively reduce the vibration amplitude of the chemical tower under wind loads,and decrease the potential wind-induced vibration.

关键词： chemical tower wind-induced vibration pneumatic control

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Analysis of measured data of snow loads on roof with parapets based on comparison of foreign codes

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Jianzhu Jiegou Xuebao/Journal of Building structures 2019年第6期40卷 32-39页

作者： Zhang, Guolong Zhang, Qingwen Mo, Huamei Fan, Feng Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Laboratory of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

In the calculation of the snow load on the roof with parapets, standards of Japan, America, and Europe have given full consideration to the erosion effect on the snow load of the fully exposed roof caused by wind field, the movement of snow induced by wind, the supplementation of upstream snow to snow heaped up around downstream obstruction. In addition, factors such as the indoor heating and the combined effect of rain and snow are introduced to realize an accurate estimation of snow load on building roofs. By contrast, the Chinese code only considers the influence of the parapet height. Therefore, based on the measured snow distribution on an actual parapet roof on ages and the influencing factors in foreign codes introduced above, the snow distribution characteristics on the parapet roof were analyzed. The results show that: more snow is blown downstream towards the parapet;the peak snow depth close to the downstream parapet is proportional to the upstream roof width, and with an increasing wind velocity, the drifting effect is enhanced;the upstream roof width and the ground snow load have a great influence on the peak snow depth at the parapet, and the influence of wind velocity depends on the ground snow load;the larger the ground snow load is, the greater influence the wind velocity has;the ratio of the snowdrift length to the parapet height is around 3.75, and it is suggested to adopt a value of 4.0 in Chinese code. © 2019, Editorial Office of Journal of Building structures. All right reserved.

关键词： Roofs

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