期刊文献+
共找到55篇文章
< 1 2 3 >
每页显示 20 50 100
Shear modulus and damping ratio of sand-granulated rubber mixtures 被引量:11
1
作者 M.Ehsani N.Shariatmadari S.M.Mirhosseini 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第8期3159-3167,共9页
Recycled waste tires when mixed with soil can play an important role as lightweight materials in retaining walls and embankments, machine foundations and railroad track beds in seismic zones. Having high damping chara... Recycled waste tires when mixed with soil can play an important role as lightweight materials in retaining walls and embankments, machine foundations and railroad track beds in seismic zones. Having high damping characteristic, rubbers can be used as either soil alternative or mixed with soil to reduce vibration when seismic loads are of great concern. Therefore, the objective of this work was to evaluate the dynamic properties of such mixtures prior to practical applications. To this reason, torsional resonant column and dynamic triaxial experiments were carried out and the effect of the important parameters like rubber content and ratio of mean grain size of rubber solids versus soil solids(D50,r/D50,s) on dynamic response of mixtures in a range of low to high shearing strain amplitude from about 4×10-4% to 2.7% were investigated. Considering engineering applications, specimens were prepared almost at the maximum dry density and optimum moisture content to model a mixture layer above the ground water table and in low precipitation region. The results show that tire inclusion significantly reduces the shear modulus and increases the damping ratio of the mixtures. Also decrease in D50,r/D50,s causes the mixture to exhibit more rubber-like behavior. Finally, normalized shear modulus versus shearing strain amplitude curve was proposed for engineering practice. 展开更多
关键词 sand-rubber mixture shear modulus damping ratio low to high shear strain amplitude cyclic triaxial test torsionalresonant column test granular rubber
下载PDF
Modal parameter identification and damping ratio estimation from the full-scale measurements of a typical Tibetan wooden structure 被引量:6
2
作者 Dai Lu Yang Na +1 位作者 S.S.Law Yang Qingshan 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2016年第4期681-695,共15页
Tibetan heritage buildings have a high historical and cultural value. They have endured adverse environmental loadings over hundreds of years without significant damage. However, there are few reports on their structu... Tibetan heritage buildings have a high historical and cultural value. They have endured adverse environmental loadings over hundreds of years without significant damage. However, there are few reports on their structural characteristics under normal environmental loadings and their behavior under dynamic loadings. In this research, a typical Tibetan wooden wall-frame building is selected to study its dynamic characteristics. Field measurements of the structure were conducted under environmental excitation to collect acceleration responses. The stochastic subspace identification (SSI) method was adopted to calculate the structural modal parameters and obtain the out-of-plane vibration characteristics of the slab and frames. The results indicated that the wall-frame structure had a lower out-of-plane stiffness and greater in-plane stiffness due to the presence of stone walls. Due to poor identified damping ratio estimates from the SSI method, a method based on the variance upper bound was proposed to complement the existing variance lower bound method for estimating the modal damping ratio to address the significant damping variability obtained from different points and measurements. The feasibility of the proposed method was illustrated with the measured data from the floor slab of the structure. The variance lower and upper bound methods both provided consistent results compared to those from the traditional SSI method. 展开更多
关键词 Tibetan wooden structure field test modal parameters damping ratio variance upper/lower bound
下载PDF
Dynamic shear modulus and damping ratio characteristics of undisturbed marine soils in the Bohai Sea,China 被引量:6
3
作者 Zhang Yan Zhao Kai +1 位作者 Peng Yanjv Chen Guoxing 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2022年第2期297-312,共16页
This paper presents results from a series of stress-controlled undrained cyclic triaxial tests on the undisturbed marine silty clay,silt,and fine sand soils obtained from the Bohai Sea,China.Emphasis is placed on the ... This paper presents results from a series of stress-controlled undrained cyclic triaxial tests on the undisturbed marine silty clay,silt,and fine sand soils obtained from the Bohai Sea,China.Emphasis is placed on the major factors for predominating the dynamic shear modulus(G)and damping ratio(λ)in the shear strain amplitude(γ_(a))from 10^(-5) to 10^(-2),involving depth,sedimentary facies types,and water content of marine soils.The empirical equations of the small-strain shear modulus(G_(max))and damping ratio(λ_(min))using a single-variable of depth H are established for the three marine soils.A remarkable finding is that the curves of shear modulus reduction(G/G_(max))and the damping ratio(λ)with increasing γ_(a) of the three marine soils can be simply determined through a set of explicit expressions with the two variables of depth H and water content W.This finding is validated by independent experimental data from the literature.At the similar depths,the G value of the marine soils of terrestrial facies is the largest,followed b_(y) the neritic facies,and the G value of the marine soils of abyssal facies is the smallest.The sedimentary facies types of the marine soils have slight effect on theλvalue.Another significant finding is that the shear modulus reduction curves plotted against the γ_(a) of the three marine soils at the similar depths are significantly below those of the corresponding terrigenous soils,while the damping curves plotted against γ_(a) are just the opposite.The results presented in this paper serve as a worthful reference for the evaluation of seabed seismic site effects in the Bohai Sea due to lack of experimental data. 展开更多
关键词 Bohai Sea marine sediments dynamic shear modulus damping ratio sedimentary facies
下载PDF
Estimation of damping ratio of soil sites using microtremor 被引量:6
4
作者 郭迅 黄玉龙 袁一凡 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2002年第1期45-49,共5页
It is widely known that the seismic response characteristics of a soil site depends heavily on several key dynamic properties of the soil stratum,such as predominant frequency and damping ratio.A widely used method fo... It is widely known that the seismic response characteristics of a soil site depends heavily on several key dynamic properties of the soil stratum,such as predominant frequency and damping ratio.A widely used method for estimating the predominant frequency of a soil site by using microtremor records,proposed by Nakamura,is investigated to determine its effectiveness in estimating the damping ratio.The authors conducted some microtremor measurements of soil sites in Hong Kong and found that Nakamura's method might also be used to estimate the damping ratio of a soil site.Damping ratio data from several typical soil sites were obtained from both Nakamura's ratio curves using the half power point method and resonant column tests.Regression analysis indicates that there is a strong correlation between the damping ratios derived from these two different approaches. 展开更多
关键词 MICROTREMOR predominant frequency damping ratio
下载PDF
Influence of repeated freeze-thaw on dynamic modulus and damping ratio properties of silty sand 被引量:3
5
作者 TianLiang Wang Chao Ma +1 位作者 Han Yan JianKun Liu 《Research in Cold and Arid Regions》 CSCD 2013年第5期572-576,共5页
Under repeated freezing and thawing in deep seasonal frozen regions, the stability and strength of the soil are imposed in the form of large uneven settlement, instability and strength reduction, which affect the norm... Under repeated freezing and thawing in deep seasonal frozen regions, the stability and strength of the soil are imposed in the form of large uneven settlement, instability and strength reduction, which affect the normal operation of railway lines. This study is to obtain the influencing rules of freeze-thaw on the dynamic properties (dynamic strain, confining pressure and compactness) of silty sand. Based on an amount of inner tests, the dynamic modulus and damping ratio properties of silty soil subjected to repeated freeze-thaw cycles were deeply researched and analyzed. The results are as follows: At the same dynamic strain, the relationship of dynamic stress and freeze-thaw cycles presents negative cor- relation, and the relationship of dynamic stress, confining pressure and compactness present positive correlation. The dynamic modulus double decreases while the damping ratio double increases with incremental increase in dynamic strain. The dynamic modulus sharply decreases while the damping ratio increases with incremental increase in freeze-thaw cycles, and then the changes level off after six freeze-thaw cycles. The dynamic modulus increases while the damping ratio decreases as the confining pressure and compactness increase at the same strain level. 展开更多
关键词 freeze-thaw cycles silty sand dynamic modulus damping ratio
下载PDF
Research and Simulation on Weak Signal Detection Based on Duffing Oscillator and Damping Ratio Perturbation 被引量:1
6
作者 张敏 刘志珍 +2 位作者 曹艳 段嗣昊 张连明 《Journal of Measurement Science and Instrumentation》 CAS 2011年第2期161-163,共3页
The chaotic system is sensitive to the initial value, and this can be applied in the weak signal detection. There are periodic, critical and chaotic states in a chaotic system. When the system is in the critical stat... The chaotic system is sensitive to the initial value, and this can be applied in the weak signal detection. There are periodic, critical and chaotic states in a chaotic system. When the system is in the critical state, a small perturbation of system,n parameter may lead to a qualitative change of the system's state. This paper introduces a new method to detect weak signals by the way of disturbing the damping ratio. The authors choose the duffing equation, using MATLAB to carry on the simulation, to study the changes of the system when the signal to be measured is added to the damping ratio. By means of observing the phase loots chart and time damin chart, the weak signal will be detected. 展开更多
关键词 chaotic system duffing oscillator damping ratio signal detection
下载PDF
A new damping ratio identification method based on pattern search
7
作者 刘彦 谭久彬 +1 位作者 谭志波 王雷 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2010年第1期141-144,共4页
In order to improve the effectiveness of traditional time domain identification methods in identifying damping ratios, a new damping ratio identification method based on pattern search is proposed by fluctuating the r... In order to improve the effectiveness of traditional time domain identification methods in identifying damping ratios, a new damping ratio identification method based on pattern search is proposed by fluctuating the reliable natural frequency obtained through traditional time domain identification methods by about 10% to build the boundary conditions, using all the initial identification results to establish the free decay response of the system, and using the pattern search method to correct the initial identification results with the residual sum of squares between the free decay response and the actually measured free-decay signal as the objective function. The proposed method deals with the actually measured free-decay signal with curve fitting and avoids enlarging the identified error caused by intermediate conversion, so it can effectively improve the identified accuracy of damping ratios. Simulations for a room-sized vibration isolation foundation show that the relative errors of analyzed three damping ratios are down to 1.05%, 1.51% and 3.7% by the proposed method from 8.42%, 5.85% and 8.5% by STD method when the noise level is 10%. 展开更多
关键词 modal parameter identification damping ratio pattern search
下载PDF
Influence of Trailing-Edge Wear on the Vibrational Behavior of Wind Turbine Blades
8
作者 Yuanjun Dai Xin Wei +2 位作者 Baohua Li Cong Wang Kunju Shi 《Fluid Dynamics & Materials Processing》 EI 2024年第2期337-348,共12页
To study the impact of the trailing-edge wear on the vibrational behavior of wind-turbine blades,unworn blades and trailing-edge worn blades have been assessed through relevant modal tests.According to these experimen... To study the impact of the trailing-edge wear on the vibrational behavior of wind-turbine blades,unworn blades and trailing-edge worn blades have been assessed through relevant modal tests.According to these experiments,the natural frequencies of trailing-edge worn blades-1,-2,and-3 increase the most in the second to fourth order,thefifth order increases in the middle,and thefirst order increases the least.The damping ratio data indi-cate that,in general,thefirstfive-order damping ratios of trailing-edge worn blades-1 and trailing-edge worn blades-2 are reduced,and thefirstfive-order damping ratios of trailing-edge worn blades-3 are slightly improved.The mode shape diagram shows that the trailing-edge worn blades-1 and-2 have a large swing in the tip and the blade,whereas the second-and third-order vibration shapes of the trailing edge-worn blade-3 tend to be improved.Overall,all these results reveal that the blade’s mass and the wear area are the main fac-tors affecting the vibration characteristics of wind turbine blades. 展开更多
关键词 Wind turbine modal test natural frequency damping ratio mode shape
下载PDF
Measurement of Vibrational Stiffness and Air Damping of Damselfly Wings
9
作者 Rupan Talukder Kunigal N. Shivakumar 《Journal of Biomaterials and Nanobiotechnology》 2016年第3期127-141,共15页
A simple cantilever beam vibration test method made of biomorph and insect wing, were used to measure the vibrational stiffness and the air damping of insect wings. Vibration tests were performed in vacuum pressures t... A simple cantilever beam vibration test method made of biomorph and insect wing, were used to measure the vibrational stiffness and the air damping of insect wings. Vibration tests were performed in vacuum pressures to atmosphere and the wing stiffness and air damping factor were measured. The test method was found to be a viable method for measuring wing stiffness, natural frequencies and mode shapes. The vibrational deformation of the insect wings was found to be combination of bending and torsion because of unsymmetrical geometry of wing. The measured stiffness (K) of damselfly wings varied from 0.18 to 0.31 N/m and the air damping ratio ranged from 0.72 to 0.79. The undamped natural frequency (f<sub>n</sub>) at 13 kPa varied from 249 to 299 Hz and at atmosphere it varied from 168 to 198 Hz. 展开更多
关键词 VIBratioN Natural Frequency STIFFNESS Damselfly Wing damping ratio Biomorph
下载PDF
Feasibility study of a large-scale tuned mass damper with eddy current damping mechanism 被引量:19
10
作者 Wang Zhihao Chen Zhengqing Wang Jianhui 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2012年第3期391-401,共11页
Tuned mass dampers (TMDs) have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-kno... Tuned mass dampers (TMDs) have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-known disadvantages, such as oil leakage and difficult adjustment of damping ratio for an operating TMD. Alternatively, eddy current damping (ECD) that does not require any contact with the main structure is a potential solution. This paper discusses the design, analysis, manufacture and testing of a large-scale horizontal TMD based on ECD. First, the theoretical model of ECD is formulated, then one large-scale horizontal TMD using ECD is constructed, and finally performance tests of the TMD are conducted. The test results show that the proposed TMD has a very low intrinsic damping ratio, while the damping ratio due to ECD is the dominant damping source, which can be as large as 15% in a proper configuration. In addition, the damping ratios estimated with the theoretical model are roughly consistent with those identified from the test results, and the source of this error is investigated. Moreover, it is demonstrated that the damping ratio in the proposed TMD can be easily adjusted by varying the air gap between permanent magnets and conductive plates. In view of practical applications, possible improvements and feasibility considerations for the proposed TMD are then discussed. It is confirmed that the proposed TMD with ECD is reliable and feasible for use in structural vibration control. 展开更多
关键词 tuned mass damper eddy current damping permanent magnets conductive plate modal damping ratio
下载PDF
Structural vibration passive control and economic analysis of a high-rise building in Beijing 被引量:6
11
作者 Chen Yongqi Cao Tiezhu +1 位作者 Ma Liangzhe Luo Chaoying 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2009年第4期561-568,共8页
Performance analysis of the Pangu Plaza under earthquake and wind loads is described in this paper. The plaza is a 39-story steel high-rise building, 191 m high, located in Beijing close to the 2008 Olympic main stadi... Performance analysis of the Pangu Plaza under earthquake and wind loads is described in this paper. The plaza is a 39-story steel high-rise building, 191 m high, located in Beijing close to the 2008 Olympic main stadium. It has both fluid viscous dampers (FVDs) and buckling restrained braces or unbonded brace (BRB or UBB) installed. A repeated iteration procedure in its design and analysis was adopted for optimization. Results from the seismic response analysis in the horizontal and vertical directions show that the FVDs are highly effective in reducing the response of both the main structure and the secondary system. A comparative analysis of structural seismic performance and economic impact was conducted using traditional methods, i.e., increased size of steel columns and beams and/or use of an increased number of seismic braces versus using FVD. Both the structural response and economic analysis show that using FVD to absorb seismic energy not only satisfies the Chinese seismic design code for a "rare" earthquake, but is also the most economical way to improve seismic performance both for one-time direct investment and long term maintenance. 展开更多
关键词 fluid viscous dampers (FVD) damping ratio secondary system One-time investment maintenance factor
下载PDF
Accuracy of the half-power bandwidth method with a third-order correction for estimating damping in multi-DOF systems 被引量:3
12
作者 Wang Jinting Lü Dandan +1 位作者 Jin Feng Zhang Chuhan 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2013年第1期33-38,共6页
A third-order correction was recently suggested to improve the accuracy of the half-power bandwidth method in estimating the damping of single DOF systems.This paper analyzes the accuracy of the half-power bandwidth m... A third-order correction was recently suggested to improve the accuracy of the half-power bandwidth method in estimating the damping of single DOF systems.This paper analyzes the accuracy of the half-power bandwidth method with the third-order correction in damping estimation for multi-DOF linear systems.Damping ratios in a two-DOF linear system are estimated using its displacement and acceleration frequency response curves,respectively.A wide range of important parameters that characterize the shape of these response curves are taken into account.Results show that the third-order correction may greatly improve the accuracy of the half-power bandwidth method in estimating damping in a two-DOF system.In spite of this,the half-power bandwidth method may significantly overestimate the damping ratios of two-DOF systems in some cases. 展开更多
关键词 half-power bandwidth method third-order correction damping ratio estimation error two-DOF system
下载PDF
The damping model for sea waves covered by oil films of a finite thickness 被引量:3
13
作者 ZHANG Yanmin ZHANG Jie +2 位作者 WANG Yunhua MENG Junmin ZHANG Xi 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2015年第9期71-77,共7页
In combination with a wave action balance equation, a damping model for sea waves covered by oil films of a finite thickness is proposed. The damping model is not only related to the physical parameters of the oil fil... In combination with a wave action balance equation, a damping model for sea waves covered by oil films of a finite thickness is proposed. The damping model is not only related to the physical parameters of the oil film, but also related to environment parameters. Meanwhile, the parametric analyses have been also conducted to understand the sensitivity of the damping model to these parameters. And numerical simulations demonstrate that a kinematic viscosity, a surface/interfacial elasticity, a thickness, and a fractional filling factor cause more significant effects on a damping ratio than the other physical parameters of the oil film. From the simulation it is also found that the influences induced by a wind speed and a wind direction are also remarkable. On the other hand, for a thick emulsified oil film, the damping effect on the radar signal induced by the reduction of an effective dielectric constant should also be taken into account. The simulated results are compared with the damping ratio evaluated by the 15 ENVISAT ASAR images acquired during the Gulf of Mexico oil spill accident. 展开更多
关键词 sea surface wave oil film of finite thickness damping ratio
下载PDF
Research on Influence of Damping Material on Structure Performance of Torpedo
14
作者 曹银萍 石秀华 孙青岩 《Defence Technology(防务技术)》 SCIE EI CAS 2010年第2期100-103,共4页
Reducing the self-noise and radiated noise of torpedo is an effective way to enhance its detection and concealment capabilities.After discussing the basic principle on noise and vibration control and main noise source... Reducing the self-noise and radiated noise of torpedo is an effective way to enhance its detection and concealment capabilities.After discussing the basic principle on noise and vibration control and main noise sources in torpedo,the application of damping treatment for noise and vibration absorption was proposed in this paper.Compared composite materials(damping and metal materials)used as segment joint,their different contributions to the damping performance of base structure were investigated.The results show that the damping material can be used as segment joint effectively in vibration control.Taking cantilever beam as an example,four different damping treatments were compared in natural frequency and damping loss factor,the results show the influences of different damping layer layouts on the structure damping performance,and offer a reference for the torpedo shell design. 展开更多
关键词 composite materials noise and vibration control TORPEDO damping treatment damping ratio
下载PDF
Operational Mode Identification Based on Sliding Time Window Method and Eigensystem Realization Algorithm
15
作者 WANG Liang ZHANG Yan +1 位作者 CAI Yipeng NANGONG Zijun 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2019年第5期838-844,共7页
The identification result of operational mode is eurychoric while operational mode identification is investigated under ambient excitation,which is influenced by the signal size and the time interval.The operational m... The identification result of operational mode is eurychoric while operational mode identification is investigated under ambient excitation,which is influenced by the signal size and the time interval.The operational mode identification method,which is based on the sliding time window method and the eigensystem realization algorithm(ERA),is investigated to improve the identification accuracy and stability.Firstly,the theory of the ERA method is introduced.Secondly,the strategy for decomposition and implementation is put forward,including the sliding time window method and the filtration method of modes.At last,an example is studied,where the model of a cantilever beam is built and the white noise exciting is input.Results show that the operational mode identification method can realize the modes,and has high robustness to the signal to noise ratio and signal size. 展开更多
关键词 mode identification ROBUST eigensystem realization algorithm(ERA) operational mode damping ratio
下载PDF
Research of Magnesium Alloy Wheel Vibration Performance Based on Finite Element Method
16
作者 Xin Jiang 《材料科学与工程(中英文B版)》 2021年第2期59-63,共5页
As the automotive industry is increasingly demanding on energy saving and environmental protection,people are taking more attention on the lightweight design and comfort of automobiles.Wheel vibration is one of the mo... As the automotive industry is increasingly demanding on energy saving and environmental protection,people are taking more attention on the lightweight design and comfort of automobiles.Wheel vibration is one of the most important parts of a vehicle performance.The dynamic characteristics of the vehicle are determined by the modal parameters of the vehicle system.The wheel also has a great influence on the vibration.Based on finite element method,we analyze wheel vibration performance.This research studies the effect of different damping properties on wheel frequency.By comparing of acceleration and speed of the wheel,we can improve the vibration performance of the vehicle. 展开更多
关键词 Magnesium alloy wheel VIBratioN damping ratio finite element method
下载PDF
Analysis of vibration attenuation characteristics of large thickness carbon fiber composite laminates
17
作者 Yi-Qi WANG Chaoqun WANG +2 位作者 Pengxiao YANG Ziao WANG Tete CAO 《Mechanical Engineering Science》 2022年第1期22-26,共5页
The vibration attenuation and damping characteristics of carbon fiber reinforced composite laminates with different thicknesses were investigated by hammering experiments under free boundary constraints in different d... The vibration attenuation and damping characteristics of carbon fiber reinforced composite laminates with different thicknesses were investigated by hammering experiments under free boundary constraints in different directions.The dynamic signal testing and analysis system is applied to collect and analyze the vibration signals of the composite specimens,and combine the self-spectrum analysis and logarithmic decay method to identify the fundamental frequencies of different specimens and calculate the damping ratios of different directions of the specimens.The results showed that the overall stiffness of the specimen increased with the increase of the specimen thickness,and when the thickness of the sample increases from 24mm to 32mm,the fundamental frequency increases by 35.1%,the vibration showed the same vibration attenuation and energy dissipation characteristics in the 0°and 90°directions of the specimen,compared with the specimen in the 45°direction,which was less likely to be excited and had poorer vibration attenuation ability,while the upper and lower surfaces of the same specimen showed slightly different attenuation characteristics to the vibration,the maximum difference of damping capacity between top and bottom surfaces of CFRP plates is about 70%. 展开更多
关键词 Carbon fiber composite laminates Logarithmic decay method damping ratio Natural frequency
下载PDF
Test and numerical investigations on static and dynamic characteristics of extra-wide concrete self-anchored suspension bridge under vehicle loads 被引量:8
18
作者 ZHOU Guang-pan LI Ai-qun +1 位作者 LI Jian-hui DUAN Mao-jun 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第10期2382-2395,共14页
The present work is aimed at studying the mechanic properties of the extra-wide concrete self-anchored suspension bridge under static and dynamic vehicle loads. Based on the field test using 12 heavy trucks and finite... The present work is aimed at studying the mechanic properties of the extra-wide concrete self-anchored suspension bridge under static and dynamic vehicle loads. Based on the field test using 12 heavy trucks and finite element simulations, the static deformations of different components, stress increments and distributions of the girder, as well as the vibration characteristics and damping ratio of the Hunan Road Bridge were analyzed, which is the widest self-anchored suspension bridge in China at present. The dynamic responses were calculated using the Newmark-β integration method assisted by the simulation models of bridge and vehicles, the influences on the dynamic impact coefficient(DIC) brought by the vehicle parameters, girder width, eccentricity travel and deck flatness were also researched. The spatial effect of the girder is obvious due to the extra width, which performs as the stress increments distribute unevenly along the transverse direction, and the girder deflections and stress increments of the upper plate change as a "V" and "M" shape respectively under the symmetrical vehicle loads affected by the shear lag effect, cross slope and local effect of the wheels, the maximum of stress increments are located in the junctions with the inner webs. The obvious girder torsional deformation and the apparent unevenness of the hanger forces between the two cable planes under the eccentric vehicle loads, together with the mode shapes such as the girder transverse bending and torsion which appear relatively earlier, all reflect the weakened torsional rigidity of the extra-wide girder. The transverse displacements of towers are more obvious than the longitudinal ones. As for the influences on the DIC, the static effect of the heavier vehicles plays a major role when pass through with a higher speed and the changes of vehicle suspension stiffness generate greater impacts than the suspension damp. The values of DIC in the vehicle-running side during the eccentric travel, affected by the restricts from the static effects of the eccentric moving trucks, are significantly smaller than the vehicle-free side, the increase in the road roughness is the most sensitive one among the above influential factors. The results could provide references for the design, static and dynamic response analysis of the similar extra-wide suspension bridges. 展开更多
关键词 self-anchored suspension bridge extra-wide girder field test simulation vehicle loads increments distribution damping ratio mode shape dynamic impact coefficient
下载PDF
Analysis of the dynamic characteristics and stochastic simulation on variations of beach volumes 被引量:8
19
作者 Chen Zishen(Institute of Estuarine and Coastal Research of Zhongshan University, Guangzhou 510275, China) 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1995年第3期393-403,共11页
This paper analyzes the dynamic characteristics of the variations of the beach volumes for three level zonesof the Yanjing Beach in the Shuidong Bay of the western Guangdong Province by using the methods of dynamic sy... This paper analyzes the dynamic characteristics of the variations of the beach volumes for three level zonesof the Yanjing Beach in the Shuidong Bay of the western Guangdong Province by using the methods of dynamic systemanalysis and the multi-dimensional spectral estimation. The results show that the variations of the beach volume arecharaCterized by the multiband oscillations with a dominant semimonth period. Upwards the low tide level, the beachtends to be stable. The estimates of the partial coherences and the partial phases indicate that the variations of thebeach volumes are mainly the results of the direct actions of the waves which are influenced by the tidal level changesand driven by the wind stress. The simulation results of the beach volume series for different beach heart zones bythreshold mixed regressive models indicate that the influence of the tide on the variations of the beach volumes is weakened and the direct actions of the wave energy and the wind stress are apparently enhanced with the increase of thebeach height.(This project was supported by the National Natural Science Foundation of China.) 展开更多
关键词 Beach volume variations natural frequency damping ratio multi-dimensional spectral estimation stochastic simulation
下载PDF
Experimental studies on behavior of fully grouted reinforced-concrete masonry shear walls 被引量:3
20
作者 Zhao Yan Wang Fenglai 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2015年第4期743-757,共15页
An experimental study is conducted on fully grouted reinforced masonry shear walls (RMSWs) made from concrete blocks with a new configuration. Ten RMSWs are tested under reversed cyclic lateral load to investigate the... An experimental study is conducted on fully grouted reinforced masonry shear walls (RMSWs) made from concrete blocks with a new configuration. Ten RMSWs are tested under reversed cyclic lateral load to investigate the influence of different reinforcements and applied axial stress values on their seismic behavior. The results show that flexural strength increases with the applied axial stress, and shear strength dominated by diagonal cracking increases with both the amount of horizontal reinforcement and applied axial stress. Yield displacement, ductility, and energy dissipation capability can be improved substantially by increasing the amount of horizontal reinforcement. The critical parameters for the walls are derived from the experiment: displacement ductility values corresponding to 15% strength degradation of the walls reach up to 2.6 and 4.5 in the shear and flexure failure modes, respectively; stiffness values of flexure- and shear-dominated walls rapidly degrade to 17%–19% and 48%–57% of initial stiffness at 0.50 D<sub>max</sub> (displacement at peak load). The experiment suggests that RMSWs could be assigned a higher damping ratio (~14%) for collapse prevention design and a lower damping value (~7%) for a fully operational limit state or serviceability limit state. 展开更多
关键词 reinforced-concrete masonry shear wall shear strength DUCTILITY stiffness degradation energy dissipation equivalent viscous damping ratio
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部