New real‐value modal combination rules for non‐classically damped structures

Falsone, G.; Muscolino, G.

doi:10.1002/eqe.394

Cited by 18 publications

(4 citation statements)

References 25 publications

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“…For non-classically damped systems, the matrix is not diagonal. The relative maximum magnitude of the offdiagonal elements of with respect to the diagonal elements can be expressed by the following coupling index [34,35], which measures the degree of non-proportionality of the damping.…”

Section: Dynamic Equilibrium Equation Of Motion and Characteristic Eqmentioning

confidence: 99%

Exploring damping characteristics of composite tower of cable-stayed bridges

Raheem

2016

Sādhanā

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The damping characterization is important in making accurate predictions of the seismic response of the hybrid structures dominated by different damping mechanisms. Different damping characteristics arise from the construction of the tower with different materials: steel for the upper part; reinforced concrete for the lower main part and interaction with supporting soil. The process of modeling damping matrices and experimental verification is challenging because damping cannot be determined via static tests as mass and stiffness can be. The assumption of classical damping is not appropriate if the system to be analyzed consists of two or more parts with significantly different levels of damping. The dynamic response of structures is critically determined by the damping mechanisms, and its value is very important for the design and analysis of vibrating structures. An analytical approach that is capable of evaluating the equivalent modal damping ratio from structural components is desirable for improving seismic design. Two approaches are considered to define and investigate dynamic characteristics of a composite tower of cable-stayed bridges: The first approach makes use of a simplified approximation of two lumped masses to investigate the structure irregularity effects including damping of different material, mass ratio, frequency ratio on dynamic characteristics and modal damping. The second approach employs a detailed numerical step-by-step integration procedure.

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Section: Dynamic Equilibrium Equation Of Motion and Characteristic Eqmentioning

confidence: 99%

Exploring damping characteristics of composite tower of cable-stayed bridges

Raheem

2016

Sādhanā

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“…Firstly, the largest values of the modal responses is determined in terms of the given response spectrum of the considered input. Then, these maximum values are combined through an appropriate combination rule, whose coefficients are connected to the cross-correlation coefficients [8] .…”

Section: Load Conditions Criteria Level Load Combinationsmentioning

confidence: 99%

Seismic Analysis for Axial Fan Used in Nuclear Power Plant

Xiang

et al. 2014

AMM

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The seismic performance of the axial fan used in nuclear power plants (NPP) is investigated by using the commercial FEM software ANSYS. In the modal analysis, the first five orders of the natural frequencies of the axial fan is obtained, as well as the corresponding vibration modes. And in the spectrum analysis, the complete quadratic mode combination method is applied to determine the dynamic response of the axial fan under a random seismic excitation. The simulation results show that the seismic performance of the axial fan satisfies the requirement of the RCC-M 2007 design codes.

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“…Therefore, the modal damping ratio cannot be obtained from conventional modal analysis. Researchers have developed modal combination rules for nonproportionally damped systems to compute the seismic demand (Gupta and Jaw 1986;Villaverde 1988;Yang et al 1990;Sinha and Igusa 1995;Falsone and Muscolino 2004;Palmeri 2006); however, those methods are complicated and difficult to integrate into the current spectrum-based design practice.…”

Section: Introductionmentioning

confidence: 99%

Equivalent Modal Damping of Short-Span Bridges Subjected to Strong Motion

et al. 2011

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In this paper four different methods are investigated for estimating the equivalent modal damping ratios of a short-span bridge under strong ground motion by considering the energy dissipation at the boundary. The Painter Street Overcrossing (PSO) is investigated because of seismic data availability. Computed responses using the response-spectrum method with the equivalent damping ratios estimates are compared with the recorded responses. The results show that the four methods provide reasonable estimation of equivalent modal damping ratios and that neglecting off-diagonal elements in the damping matrix is the most efficient and practical method. The equivalent damping ratio of the PSO was nearly 25% under an earthquake with peak ground acceleration of 0:55g, which is much higher than the conventional assumption of 5%.

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New real‐value modal combination rules for non‐classically damped structures

Cited by 18 publications

References 25 publications

Exploring damping characteristics of composite tower of cable-stayed bridges

Exploring damping characteristics of composite tower of cable-stayed bridges

Seismic Analysis for Axial Fan Used in Nuclear Power Plant

Equivalent Modal Damping of Short-Span Bridges Subjected to Strong Motion

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