AN APPROXIMATION METHOD FOR COMPUTING THE DYNAMIC RESPONSES AND EQUIVALENT STATIC WIND LOADS OF LARGE-SPAN ROOF STRUCTURES

2010 ◽  
Vol 10 (05) ◽  
pp. 1141-1165 ◽  
Author(s):  
XUANYI ZHOU ◽  
MING GU
Keyword(s):  
Coupling Effect ◽  
Coupling Factor ◽  
Dynamic Responses ◽  
Wind Loads ◽  
Inertia Force ◽  
Large Span ◽  
Load Distributions ◽  
Modal Coupling ◽  
Vibration Responses ◽  
Equivalent Static Wind Loads

Due to their sensitivity to wind, the design of large-span roofs is generally governed by wind loads. For some flexible large-span roofs with low damping and concentrated modes, the effect of multi-mode coupling should be taken into account in computing the resonant buffeting response and equivalent static wind loads. Such an effect is considered by the modified SRSS method in this paper via the modal coupling factor. Based on the same SRSS method, the equivalent static wind loads combining the mean, background, and resonant components, are computed. Particularly, the background and resonant components are computed by the LRC method and the equivalent inertia force method considering the modal coupling effects by the modified SRSS method, respectively. The method is then applied to the computation of wind-induced vibration responses and equivalent static wind load distributions of a real large-span roof. The results show that the modal coupling effect on the resonant component can be identified by the present method with high accuracy.

Design application and verification of equivalent static wind loads in bridge design

2019 ◽  
Author(s):  
Atte Mikkonen ◽  
Risto Kiviluoma
Keyword(s):  
Wind Load ◽  
Wind Loads ◽  
Wind Tunnel Testing ◽  
Bridge Design ◽  
City Center ◽  
Aeroelastic Model ◽  
Modal Coupling ◽  
Equivalent Static Wind Loads ◽  
Equivalent Static Wind Load ◽  
Turbulence Parameters

<p>Kruunuvuori Bridge is new link to connect Laajasalo area to the Helsinki city center by crossing a Kruunuvuorenselkä bay. It’s a cable stayed bridge with a single pylon and symmetric span arrangement, designed to be built with free cantilever method. For such a structure, wind is a governing load for the construction and for the final stage.</p><p>In the Engineering design of the bridge, equivalent static wind load (ESWL) extraction was used to define the action forces for the structures due to the wind. With the applied method it is possible to include crucial frequency-dependent parameters like statistical wind turbulence parameters; aerodynamic damping; aerodynamic admittances and modal coupling into the design. Skew wind angles could also be defined. Such loads are easy to apply with general commercial software and the workflow for the design is practical. As the method itself is not standardized and includes specialist defined parameters, it requires an additional verification. This paper describes how the static equivalent wind loads were applied in the design and how the results were verified with full-aeroelastic model wind tunnel testing. As a conclusion, static wind load extraction provides reliable results and is a practical approach for bridge design under skew winds.</p>

Constrained Least-Squares Method for Computing Equivalent Static Wind Loads of Large-Span Roofs

2014 ◽  
Vol 17 (10) ◽  
pp. 1497-1515 ◽  
Author(s):  
Xuanyi Zhou ◽  
Ming Gu ◽  
Gang Li
Keyword(s):  
Least Squares ◽  
Large Scale ◽  
Least Squares Method ◽  
Weighting Factor ◽  
Wind Loads ◽  
Specific Response ◽  
Computational Accuracy ◽  
Constrained Least Squares ◽  
Large Span ◽  
Equivalent Static Wind Loads

Equivalent static wind loads (ESWL) are widely used by structural designers to determine a specific response of large-scale structures. However, structural designers usually pay attention to more responses. Thus, this study proposes a constrained least-squares method to compute the ESWL distribution that can simultaneously target multi-responses. The loading distribution is regarded as a linear combination of basic load distributions. Two forms of basic load distribution are presented herein. The magnitude range of ESWLs is limited by controlling the bounds of the participation factor, which can be regarded as a constrained linear least-squares problem. Furthermore, since only a few structural responses are usually emphasized by structural designers, weighting factor is imported to improve the accuracy of these focused responses. To verify its computational accuracy, the method is applied to a real large-span roof structure. The results of calculations show that a reasonable magnitude of ESWL distribution can be achieved. There seems to always be a balance between the number of targeted responses and computational accuracy.

An hourglass-type electromagnetic isolator with negative resistance electromagnetic shunt circuit

2020 ◽  
Vol 64 (1-4) ◽  
pp. 549-556
Author(s):  
Yajun Luo ◽  
Linwei Ji ◽  
Yahong Zhang ◽  
Minglong Xu ◽  
Xinong Zhang
Keyword(s):  
Vibration Isolation ◽  
Electromechanical Coupling ◽  
Coupling Effect ◽  
Negative Resistance ◽  
Isolation System ◽  
Amplitude Vibration ◽  
Vibration Responses ◽  
The Stability ◽  
Isolation Performance ◽  
Shunt Circuit

The present work proposed an hourglass-type electromagnetic isolator with negative resistance (NR) shunt circuit to achieve the effective suppression of the micro-amplitude vibration response in various advanced instruments and equipment. By innovatively design of combining the displacement amplifier and the NR electromagnetic shunt circuit, the current new type of vibration isolator not only can effectively solve the problem of micro-amplitude vibration control, but also has significant electromechanical coupling effect, to obtain excellent vibration isolation performance. The design of the isolator and motion relationship is presented firstly. The electromechanical coupling dynamic model of the isolator is also given. Moreover, the optimal design of the NR electromagnetic shunt circuit and the stability analysis of the vibration isolation system are carried out. Finally, the simulation results about the transfer function and vibration responses demonstrated that the isolator has a significant isolation performance.

Nonlinear Dynamics Behavior of Tethered Submerged Buoy under Wave Loadings

2020 ◽  
Vol 21 (1) ◽  
pp. 11-21
Author(s):  
Lin Zhao ◽  
Weihao Meng ◽  
Zhongqiang Zheng ◽  
Zongyu Chang
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Behavior ◽  
Coupling Factor ◽  
Dynamic Responses ◽  
Mooring Line ◽  
Second Law ◽  
Largest Lyapunov Exponent ◽  
Nonlinear Characteristic ◽  
Runge Kutta Method ◽  
Marine Engineering

AbstractTethered submerged buoy is used extensively in the field of marine engineering. In this paper considering the effect of wave, the nonlinear dynamics behavior of tethered submerged buoy is debated under wave loadings. According to Newton’s second law, the dynamic of the system is built. The coupling factor of the system is neglected, the natural frequency is calculated. The dynamic responses of the system are analyzed using Runge–Kutta method. Considering the variety of the steepness kA, the phenomenon of dynamic behavior can be periodic, double periodic and quasi-periodic and so on. The bifurcation diagram and the largest Lyapunov exponent are applied to judge the nonlinear characteristic. It is helpful to understand the dynamic behavior of tethered submerged buoy and design the mooring line of tethered submerge buoy.

scholarly journals Dynamic Study of a Rooftop Vertical Axis Wind Turbine Tower Based on an Automated Vibration Data Processing Algorithm

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3135 ◽  
Author(s):  
Ying Wang ◽  
Wensheng Lu ◽  
Kaoshan Dai ◽  
Miaomiao Yuan ◽  
Shen-En Chen
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Dynamic Responses ◽  
Ambient Vibration ◽  
Structural Vibration ◽  
Vertical Axis Wind Turbine ◽  
Mode Identification ◽  
Stochastic Subspace Identification ◽  
Vibration Data ◽  
Vibration Responses

When constructed on tall building rooftops, the vertical axis wind turbine (VAWT) has the potential of power generation in highly urbanized areas. In this paper, the ambient dynamic responses of a rooftop VAWT were investigated. The dynamic analysis was based on ambient measurements of the structural vibration of the VAWT (including the supporting structure), which resides on the top of a 24-story building. To help process the ambient vibration data, an automated algorithm based on stochastic subspace identification (SSI) with a fast clustering procedure was developed. The algorithm was applied to the vibration data for mode identification, and the results indicate interesting modal responses that may be affected by the building vibration, which have significant implications for the condition monitoring strategy for the VAWT. The environmental effects on the ambient vibration data were also investigated. It was found that the blade rotation speed contributes the most to the vibration responses.

Sign in / Sign up

Export Citation Format

Share Document