Papers by Keyword: Non-Proportional Damping

Abstract: The structural resonance properties of damped structures can be exploited to obtain a required dynamic response with relatively low input power requirements. Practical applications often demand temporary modifications of this response. This paper presents a systematic approach to modify the response of harmonically driven, non-proportionally damped resonating structures using local structural property changes and excitation adjustments. The complex response is written in polar form (i.e., modulus and argument) to enhance insights. Sensitivity analysis is used to approximate the influence of the control variables on the response. A projection is proposed to determine the locations at which a specific structural change scores maximum effect to reach the desired response modifications. The introduced response normalization separates amplitude and shape modifications in a clear way. This work shows response modifications of non-proportionally damped resonating structures due to control variables in an intuitive manner.

Abstract: Today, the structures constituted by different materials, increase more and more, especially the lower part is concrete, the upper is steel. For this type of structural system, modal damping matrix is non-diagonal matrix, the earthquake response equation is coupled on the modal damping matrix, the modal coupling of the non-proportional damping system leads to the traditional real modal analysis methods not be directly applied. For such structure, the changes of the damping ratio are analyzed in this article. Finally, the equivalent damping ratio of Shenzhen Airport is obtained using the energy theory.

Abstract: In recent years, on the one hand destructive earthquakes frequently occur, and vibration control devices such as dampers and isolation become increasingly application in actual large-scale structures, on the other hand modern structures with complex styles and diversified materials possess significant non-proportional damping characteristics, and traditional methods based on Rayleigh damping assumption no longer meet seismic calculation requirement. According to this situation, firstly multiple degree of freedom modal equation and pseudo excitation method are both utilized to establish a new efficient calculation method system which is suitable for stochastic analysis of non-proportionally damped structure, and the new method can achieve adjustive calculation efficiency and accuracy. Furthermore, advantages and features of established method are analyzed, and guidance suggestions for appropriate method use are also proposed. Finally, numerical study is carried out to verify conclusions proposed by theoretical derivation, and efficiency and accuracy of established method system used in stochastic response calculation of non-proportionally damped structure is confirmed.

Abstract: The damping makeup of large span cable-stayed bridges is complicated. The damping matrices of such structures cannot be easily accurately determined. On assumption of the damping coefficients of substructures in cable-stayed bridge (such as girder, tower, cable and support et al) are constants, a method to estimate the damping coefficients and damping matrices of such structures is presented. The method is based on several known modal damping ratios and the calculation of complex eigenvalue and eigenvector utilizing the state-space methodology. Numerical simulation was carried out by the example of Tatara Bridge. Through comparison between the calculated damping ratios utilizing the approximated damping matrices and the field test data, the method is proved valid.