Showing papers by "Qiusheng Li published in 2011"

Dynamic behavior of Taipei 101 tower: Field measurement and numerical analysis

Abstract: This paper presents selected results measured from a monitoring system with 30 accelerometers installed at six floor levels in 508-m high Taipei 101 Tower located in Taipei City, Taiwan where earthquakes and strong typhoons are common occurrences. Emphasis is placed on analyzing the data recorded during three typhoons (Matsa, Talim, and Krosa) and a seismic event (Wenchuan earthquake occurred on May 12, 2008 in Shichuan, China) to investigate the effects of wind and seismic on the supertall building. Dynamic characteristics of the tall building such as natural frequencies, mode shapes, and damping ratios determined from the measured data are presented and compared with those calculated from the finite-element model of the high-rise structure. The seismic performance of this supertall building to a long distance earthquake (Wenchuan earthquake) is assessed based on the field measurements and numerical analysis. The findings of this study are expected to be of considerable interest and practical use to prof...

Integrated wind‐induced response analysis and design optimization of tall steel buildings using Micro‐GA

Abstract: SUMMARY This paper presents an integrated procedure for wind-induced response analysis and design optimization for rectangular steel tall buildings based on the random vibration theory and automatic least cost design optimization technique using Micro-Genetic Algorithm (GA). The developed approach can predict wind-induced drift and acceleration responses for serviceability design of a tall building; the technique can also provide an optimal resizing design of the building under wind loads to achieve cost-efficient design. The empirical formulas of wind force spectra obtained from simultaneous measurements of surface pressures on various rectangular tall building models in wind tunnel tests are verified testified using a published example. Upon the known wind force spectra, the equivalent static wind loads for every storey, such as along-wind, across-wind and torsional loads, are then determined and applied for structural analysis including estimation of wind-induced responses. An improved form of GAs, a Micro-GA, is adopted to minimize the structural cost/weight of steel buildings subject to top acceleration and lateral drifts constraints with respect to the discrete design variables of steel section sizes. The application and effectiveness of the developed integrated wind-induced response analysis and design optimization procedure is illustrated through a 30-storey rectangular steel building example. Copyright © 2009 John Wiley & Sons, Ltd.

Monitoring of typhoons in surface boundary layer and analysis of wind turbulence characteristics

Abstract: Mean wind speed and wind turbulence characteristics of typhoon winds in surface boundary layer were studied based on three-dimensional wind data,which were recorded from ultrasonic anemometers at 10m height at sites near seashore during land falling of Typhoons Damrey,Chunchu and PaipiroonThe relations among turbulence parameters such as power law index,friction velocity,turbulence intensities and gust factor were analyzed under different types of upwind terrains based on the field measurements resultsThe results of the analysis reveal that friction velocity strongly depends on mean wind speed,which increases with increasing wind speedPower law index and turbulence intensities decrease with the increasing of wind speedGust factor increases with the increasing of turbulence intensitiesBy fitting the results of turbulence parameters,the relations among the parameters were proposed which will be useful for the wind resistant design of low rise buildings in typhoon-prone regions

Field monitoring of wind effects on a super-tall building during typhoons

Abstract: This paper presents the field measurement results of wind effects on a super-tall building (CITIC Plaza, 391 m high) located in Guangzhou. The field data such as wind speed, wind direction and acceleration responses were simultaneously and continuously recorded from the tall building by a wind and vibration monitoring system during two typhoons. The typhoon-generated wind characteristics including turbulence intensity, gust factor, peak factor, turbulence integral length scale and power spectral density of fluctuating wind speed were presented and discussed. The dynamic characteristics of the tall building were determined based on the field measurements and compared with those calculated from a 3D finite element model of the building. The measured natural frequencies of the two fundamental sway modes of the building were found to be larger than those calculated. The damping ratios of the building were evaluated by the random decrement technique, which demonstrated amplitude-dependent characteristics. The field measured acceleration responses were compared with wind tunnel test results, which were found to be consistent with the model test data. Finally, the serviceability performance of the super-tall building was assessed based on the field measurement results.

Comparison between wind load by wind tunnel test and in-site measurement of long-span spatial structure

Abstract: The full-scale measurements are compared with the wind tunnel test results for the long-span roof latticed spatial structure of Shenzhen Citizen Center. A direct comparison of model testing results to full-scale measurements is always desirable, not only in validating the experimental data and methods but also in providing better understanding of the physics such as Reynolds numbers and scale effects. Since the quantity and location of full-scale measurements points are different from those of the wind tunnel tests taps, the weighted proper orthogonal decomposition technique is applied to the wind pressure data obtained from the wind tunnel tests to generate a time history of wind load vector, then loads acted on all the internal nodes are obtained by interpolation technique. The nodal mean wind pressure coefficients,root-mean-square of wind pressure coefficients and wind pressure power spectrum are also calculated. The time and frequency domain characteristics of full-scale measurements wind load are analyzed based on filtered data-acquisitions. In the analysis, special attention is paid to the distributions of the mean wind pressure coefficients of center part of Shenzhen Citizen Center long-span roof spatial latticed structure. Furthermore, a brief discussion about difference between the wind pressure power spectrum from the wind tunnel experiments and that from the full-scale in-site measurements is compared. The result is important fundament of wind-induced dynamic response of long-span spatial latticed structures.

Synthesis and growth mechanism of NbC–SiC micro/nanowire by carbothermal reduction

Abstract: NbC–SiC micro/nanowires (MNWs) with NbC content varying from 5 to 20 mol.-% were synthesised at 1600–1800°C via carbothermal reduction utilising silica sol, niobium pentoxide powder and carbon black as starting materials. The synthesis process and growth mechanism of NbC–SiC system were investigated. Results show that the morphology of the synthesised products mainly appears as curve shaped microwires or nanowires. The crystalline consists of both SiC and NbC phases which doped with each other by substitution and interstitial reactions in solid solution. NbC–SiC MNWs were developed by vapour–liquid–solid mechanism according to the existence of liquid droplet phase in the tip at reaction temperature. β-SiC twin crystal growing along [112] direction was formed in the stem, and NbC polycrystal was dissociated from Nb–Si liquid phase. The varied concentration of Nb and Si in the Nb–Si liquid phase could be a significant reason for the curved growth of NbC–SiC MNWs.