Showing papers by "Qiusheng Li published in 2005"
TL;DR: In this article, the authors present the field measurement results of wind characteristics and structural responses of two super tall buildings, Central Plaza Tower (374m, 78 floors) in Hong Kong and Di Wang Tower (384 m, 78 feet) in Shenzhen during the passage of Typhoon Sally.
89 citations
TL;DR: In this article, the authors investigated the probability distributions of extreme wind speed and its occurrence interval and found that although the three distributions are all suitable for describing the probability distribution of the Extreme Wind Speed data, the Type I and the three-parameter Weibull distributions are more appropriate than the two-dimensional Weibell distribution.
53 citations
TL;DR: In this article, a seismic analysis of the powerhouse monolith of the Three Gorges dam is performed through model testing at a geometric scale of 1:100 on a shaking table and numerical simulation using a three-dimensional finite element model of the structure.
29 citations
17 May 2005
TL;DR: The proposed wireless sensor networks based health monitoring system for tall buildings has been explored integrated with wireless sensing communication, computation, data management and data remote access via Internet and is shown to be effective for structural health monitoring.
Abstract: Health Monitoring is very important for large structures like suspension- and cable-stayed bridges, offshore platforms, tall buildings and so on. Due to recent developments in new sensor systems, wireless communication systems, Internet-based data sharing and monitoring, advanced technologies for structure health monitoring (SHM) have been caused much more attentions, in which the wireless sensor network is recently received special interests. Wireless sensor networks (WSNs) consist of large populations of wirelessly connected nodes, capable of computation, communication, and sensing. In this paper, a wireless sensor networks based health monitoring system for tall buildings has been explored integrated with wireless sensing communication, computation, data management and data remote access via Internet.
Firstly, a laboratory prototype was designed and developed to demonstrate the feasibility and validity of the proposed system. Wireless sensor nodes were deployed on a test structure, the data being sensed by the sensor nodes in the network is eventually transmitted to a base station, where the information can be accessed. Through a Wireless Local Area Network (WLAN, IEEE802.11b), the simulated data was transferred among personal computers and wireless sensor nodes peripherals without cables. And then, a Wireless Sensor Network (WSN) includes eight sensor nodes and one base station was installed on Di Wang Tower to verify the performance of the present system in-depth. Finally, comparisons between WSN and cable-based monitoring analytical acceleration responses of field measurement have been performed. The proposed system is shown to be effective for structural health monitoring.
17 citations
17 citations
TL;DR: In this paper, a lever-type multiple tuned mass dampers (LT-MTMD) was proposed for the vibration control of long-span bridges, and the performance of the LT-MTD with identical stiffness and damping coefficients but unequal masses for mitigating harmonically forced vibrations was evaluated.
Abstract: The lever-type multiple tuned mass dampers (LT-MTMD), consisting of several lever-type tuned mass dampers (LT-TMDs) with a uniform distribution of natural frequencies, are proposed for the vibration control of long-span bridges. Using the analytical expressions for the dynamic magnification factors (DMF) of the LT-MTMD structure system, an evaluation, with inclusion of the LT-MTMD stroke, is conducted on the performance of the LT-MTMD with identical stiffness and damping coefficients but unequal masses for mitigating harmonically forced vibrations. The LT-MTMD is found to possess the near-zero optimum average damping ratio regimen when the total number of dampers exceeds a certain value. In comparison, the LT-MTMD without the near-zero optimum average damping ratio and the traditional hanging-type multiple tuned mass dampers (HT-MTMD) without the near-zero optimum average damping ratio can achieve approximately the same optimum frequency spacing (an indicator for robustness), effectiveness, and stroke. Compared with the HT-MTMD, the LT-MTMD needs lesser optimum average damping ratio but significantly higher optimum tuning frequency ratio. Its main advantage is that the static stretching of the spring may be adjusted to meet the practical requirements through the support movement, while maintaining the same robustness, effectiveness, and stroke. Consequently, the LT-MTMD is a better choice for suppressing the vibration of long-span bridges as the static stretching of the spring required is not large.
16 citations
TL;DR: In this paper, the authors investigated the seismic random responses due to the wave passage effect by using the pseudo excitation method (PEM) and showed that the seismic responses vary significantly with wave speed, especially for low velocity or large span.
Abstract: Seismic random responses due to the wave passage effect are extensively investigated by using the pseudo excitation method (PEM). Two examples are used. The first is very simple but also very informative, while the second is a realistic suspension bridge. Numerical results show that the seismic responses vary significantly with wave speed, especially for low velocity or large span. Such variations are not monotonic, especially for flexible structures. The contributions of the dynamic and quasi-static components depend heavily on the seismic wave velocity and the natural frequencies of structures. For the lower natural frequency cases, the dynamic component has significant effects on the dynamic responses of the structure, whereas the quasi-static component dominates for higher natural frequencies unless the wave speed is also high. It is concluded that if insufficient data on local seismic wave velocity is available, it is advisable to select several possible velocity values in the seismic analysis and to choose the most conservative of the results thus obtained as the basis for design.
15 citations
TL;DR: In this article, simplified empirical formulas for estimating across-wind and torsional response of rectangular tall buildings are presented, based on simultaneous pressure measurements from a series of tall building models with various side and aspect ratios in a boundary layer wind tunnel.
Abstract: Tall buildings under wind action usually oscillate simultaneously in the along-wind and across-wind directions as well as in torsional modes. While several procedures have been developed for predicting wind-induced loads and responses in along-wind direction, accurate analytical methods for estimating across-wind and torsional response have not been possible yet. Simplified empirical formulas for estimation of the across-wind dynamic responses of rectangular tall buildings are presented in this paper. Unlike established empirical formulas in codifications, the formulas proposed in this paper are developed based on simultaneous pressure measurements from a series of tall building models with various side and aspect ratios in a boundary layer wind tunnel. Comparisons of the across-wind responses determined by the proposed formulas and the results obtained from the wind tunnel tests as well as those estimated by two well-known wind loading codes are made to examine the applicability and accuracy of the proposed simplified formulas. It is shown through the comparisons that the proposed simplified formulas can be served as an alternative and useful tool for the design and analysis of wind effects on rectangular tall buildings.
12 citations
TL;DR: In this paper, a time-dependent reliability procedure is proposed for glass cladding design under wind loading in a statistical way, which differs from conventional reliability approaches for glass-cladding design.
7 citations
TL;DR: In this article, the authors measured mean and extreme pressure distributions on a large cantilevered flat roof model in a boundary layer wind tunnel, and the largest peak suction values were observed from pressure taps beneath conical "delta-wing type" corner vortices that occur for oblique winds, then the characteristics and causes of local peak suctions were discussed in detail.
Abstract: Mean and extreme pressure distributions on a large cantilevered flat roof model are measured in a boundary layer wind tunnel. The largest peak suction values are observed from pressure taps beneath conical "delta-wing type" corner vortices that occur for oblique winds, then the characteristics and causes of the local peak suctions are discussed in detail. Power spectra of fluctuating wind pressures measured from some typical taps located at the roof edges under different wind directions are presented, and coherence functions of fluctuating pressures are also obtained. Based on these results, it is verified that the peak suctions are highly correlated with the conical vortices. Furthermore, according to the characteristics of wind loads on the roof, an aerodynamic solution to minimize the peak suctions by venting the leading edges and the corners of the roof is recommended. The experimental results show that the suggested strategy can effectively control the generation of the conical vortices and make a reduction of 50% in mean pressures and 25% in extreme local pressures at wind sensitive locations on the roof.
7 citations
TL;DR: An efficient finite segment method for the analysis of curved box girders with corner stiffeners is presented in this article, which simplifies a three dimensional structure into a one dimensional structure, which results in significant saving in computational efforts.
TL;DR: In this article, a semi-active control device for structural control implementations is presented and discussed, which is more suitable for structures with ordinary height or the magnitude of earthquake excitations is not very large (because the control force provided by the semiactive control is limited).
Abstract: A semi-active control device for structural control implementations is presented and discussed in this paper. Based on two passive control devices, the mass pump and the hydraulic mass system, a new passive control system, the mass damper pump (MDP), is introduced. It is found that the MDP system is more effective in vibration control than the other two passive control systems. It is then shown that the passive control MDP can be modified to be a semi-active control device and is very effective in structural control. Through theoretical analysis and numerical simulations, it is found that the proposed semi-active control device MDP is more suitable for structures with ordinary height or the magnitude of earthquake excitations is not very large (because the control force provided by the semi-active control is limited). Under these situations, the maximum response of a controlled structure can be reduced by one-third to one-half. Also, it is found that multiple MDP is more effective in reducing structural response than a single MDP when they are placed in appropriate locations. Copyright © 2005 John Wiley & Sons, Ltd.
TL;DR: In this article, the suboptimal control rule is introduced in structural control implementation as an alternative over the optimal control because the optimal Control may require large amount of processing time when applied to complex structural control problems.
Abstract: The suboptimal control rule is introduced in structural control implementation as an alternative over the optimal control because the optimal control may require large amount of processing time when applied to complex structural control problems. It is well known that any time delay in structural control implementation will cause un-synchronized application of the control forces, which not only reduce the effectiveness of an active control system, but also cause instability of the control system. The effect of time delay on the displacement and acceleration responses of building structures is studied when the suboptimal control rule is adopted. Two examples are given to show the effectiveness of the suboptimal control rule. It is shown through the examples that the present method is easy in implementation and high in efficiency and it can significantly reduce the time delay in structural control implementation without significant loss of performance.
TL;DR: In this paper, the effect of the lateral boundary in homogenous soil on the seismic response of a superstructure was investigated and several influencing factors were presented and discussed, and several parameters are identified to be important for conducting soil-structure interaction experiments on shaking tables.
Abstract: In this paper, the finite element method is applied to investigate the effect of the lateral boundary in homogenous soil on the seismic response of a superstructure. Some influencing factors are presented and discussed, and several parameters are identified to be important for conducting soil-structure interaction experiments on shaking tables. Numerical results show that the cross-section width L, thickness H, wave propagation velocity and lateral boundaries of soil layer have certain influences on the computational accuracy. The dimensionless parameter L/H is the most significant one among the influencing factors. In other words, a greater depth of soil layer near the foundation should be considered in shaking table tests as the thickness of the soil layer increases, which can be regarded as a linear relationship approximately. It is also found that the wave propagation velocity in soil layer affects the numerical accuracy and it is suggested to consider a greater depth of the soil layer as the wave propagation velocity increases. A numerical study on a soil-structure experimental model with a rubber ring surrounding the soil on a shaking table is also conducted. It is found the rubber ring has great effect on the soil-structure interaction experiments on shaking table. The experimental precision can be improved by reasonably choosing the elastic parameter and width of the rubber ring.
TL;DR: In this paper, a combined approach of the incremental load transfer matrix method and the approximate differential equation solution method is presented for the nonlinear analysis of interaction between flexible pile group and soil.
Abstract: Using the nonlinear load transfer function for pile side soil and the linear load transfer function for pile end soil, a combined approach of the incremental load transfer matrix method and the approximate differential equation solution method is presented for the nonlinear analysis of interaction between flexible pile group and soil. The proposed method provides an effective approach for the solution of the nonlinear interaction between flexible pile group under rigid platform and surrounding soil. To verify the accuracy of the proposed method, a static load test for a nine-pile group under a rigid platform is carried out. The finite element analysis is also conducted for comparison purposes. It is found that the results from the proposed method match very well with those from the experimental test and are better in comparison with the finite element method.