New insights in the analysis of the structural response to response-spectrum-compatible accelerograms

Cacciola, Pierfrancesco; D'Amico, Laura; Zentner, Irmela

doi:10.1016/j.engstruct.2014.07.015

Cited by 21 publications

(13 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…in which

β = \frac{9}{T_{s}}

t_{1} = \frac{1.5}{β}

t_{2} = \frac{10.5}{β}

(see, e.g., Cacciola et al) and the length of the stationary part of the time‐history is set to T s = 15 s. An arbitrarily selected artificial ground motion acceleration time‐history (i.e., realization of the considered nonstationary stochastic process) out of the 100 generated is shown in Figure b.…”

Section: Numerical Resultsmentioning

confidence: 99%

An inerter‐equipped vibrating barrier for noninvasive motion control of seismically excited structures

Cacciola

Tombari

Giaralis

2019

Struct Control Health Monit

Self Cite

View full text Add to dashboard Cite

The vibrating barrier (ViBa) is a large-scale oscillating mass-spring-damper unit contained in the ground and tuned to mitigate the motion of surrounding structures under earthquake-induced ground shaking, without being directly in contact to them, through a structure-soil-structure interaction mechanism. Previous research showed that ViBa achieves significant seismic structural response reductions, but in doing so, it requires excessive vibrating mass, equal to the mass of the structure that aims to control or more, which hinders its practical applicability. This paper considers coupling ViBa with a grounded inerter acting as a mass amplifier to reduce ViBa mass/weight in suppressing seismically induced structural response. Attention is focused on structures amenable to modelling as single-degree-of-freedom (SDOF) damped oscillators by establishing equations of motion of a 5-DOF dynamical system of a grounded inerter-equipped ViBa (IViBa) fused with an SDOF structure and accounting for soil-structure interaction effects due to soil compliance. Optimal closed-form H ∞ and numerical H 2 IViBa tuning are addressed minimizing the response of SDOF structure subject to harmonic resonant and to broadband/white base excitation, respectively. Numerical results pertaining to a small-scale physical ViBa prototype specimen are furnished quantifying the trade-off between IViBa mass and inertance considering non-rigid/compliant inerter-to-ground connectivity. Monotonic IViBa mass/weight reduction trend is found for fixed targeted structural performance under white stationary as well as coloured nonstationary seismic excitation for increasing inertance and for sufficiently rigid inerter-to-ground connection. It is concluded that careful engineering design of the inerter-to-ground connection minimizing compliance is most critical in fully exploiting the beneficial effects of grounded inerter for mass/weight IViBa reduction facilitating, thus, its practical implementation. K E Y W O R D Sinerter, nonstationary excitation, optimal design, structure-soil-structure interaction, vibrating barrier

show abstract

“…in which

β = \frac{9}{T_{s}}

t_{1} = \frac{1.5}{β}

t_{2} = \frac{10.5}{β}

Section: Numerical Resultsmentioning

confidence: 99%

An inerter‐equipped vibrating barrier for noninvasive motion control of seismically excited structures

Cacciola

Tombari

Giaralis

2019

Struct Control Health Monit

Self Cite

View full text Add to dashboard Cite

show abstract

“…The spectral characteristics of sea ice crushing damage and bending damage are similar to those of structure under earthquakes, which have abundant frequencies. Referred to as the earthquake response spectrum theory [41][42][43][44][45][46], a similar sea ice response spectrum theory is established in this section. According to Equations (7), (24), and (26), the motion equation of a SDOF system subjected to the ice forces can be expressed as:…”

Section: Response Spectrums For Each Ice Zonementioning

confidence: 99%

Analysis of Offshore Structures Based on Response Spectrum of Ice Force

Liu

Zhang

2019

JMSE

View full text Add to dashboard Cite

With the development of large-scale offshore projects, sea ice is a potential threat to the safety of offshore structures. The main forms of damage to bottom-fixed offshore structures under sea ice are crushing failure and bending failure. Referred to as the concept of seismic response spectrums, the design response spectrum of offshore structures induced by the crushing and bending ice failure is presented. Selecting the Bohai Sea in China as an example, the sea areas were divided into different ice zones due to the different sea ice parameters. Based on the crushing and bending failure power spectral densities of ice force, a large amount of ice force time-history samples are firstly generated for each ice zone. The time-history of the maximum responses of a series of single degree of freedom systems with different natural frequencies under the ice force are calculated and subsequently, a response spectrum curve is obtained. Finally, by fitting all the response spectrum curves from different samples, the design response spectrum is generated for each ice zone. The ice force influence coefficients for crushing and bending failure are obtained, which can be used to estimate the stochastic sea ice force acting on a structure conveniently in a static way. A comparison of the proposed response spectrum method with the Monte Carlo method by a numerical example shows good agreement.

show abstract

“…This is defined through evolutionary one‐sided PSD:

G_{A_{g}} ((),, ω, t) = {|φ (t)|}^{2} G_{A_{g}} ((), ω),

where φ ( t ) is a time‐dependent modulating function modeling the temporal nonstationarity, while

G_{A_{g}} ((), ω)

is the one‐sided PSD of the stationary counterpart. This representation is adopted in this paper using the model proposed in Cacciola et al, which provides the following recursive expression to determine the one‐sided PSD compatible with the chosen response spectrum:

({, \begin{matrix} G_{A_{g}} ((), ω_{i}) = 0 & 0 \leq ω \leq ω_{a} \\ G_{A_{g}} ((), ω_{i}) = \frac{4 ζ_{0}}{π ω_{i} - 4 ζ_{0} ω_{i - 1}} (\frac{RSA {((),, ω_{i}, ζ_{0})}^{2}}{{\overset{η}{true}}_{U}^{2} (ω_{i}, ζ_{0})} - Δ ω \sum_{k = 1}^{i - 1} G_{A_{g}} (ω_{k})) & ω > ω_{a} \end{matrix}),

where RSA ( ω i , ζ 0 ) is the pseudo‐acceleration response spectrum obtained from Equation for given damping ratio ζ 0 and circular frequency ω i = (2 π )/ T i , and

{\overset{true¯}{η}}_{U} ((),, ω_{i}, ζ_{0})

is the peak factor under the assumption of the following barrier outcrossing in clumps:

{\overset{true¯}{η}}_{U} ((),, ω_{i}, ζ_{0}) = \sqrt{2 normalln ({}, 2 N_{U} ([], 1 - normalexp ([], -)))}

…”

Section: Numerical Applicationsmentioning

confidence: 99%

Kernel density maximum entropy method with generalized moments for evaluating probability distributions, including tails, from a small sample of data

Alibrandi

Mosalam

2017

Numerical Meth Engineering

View full text Add to dashboard Cite

In this paper, a novel method to determine the distribution of a random variable from a sample of data is presented. The approach is called generalized kernel density maximum entropy method, because it adopts a kernel density representation of the target distribution, while its free parameters are determined through the principle of maximum entropy (ME). Here, the ME solution is determined by assuming that the available information is represented from generalized moments, which include as their subsets the power and the fractional ones. The proposed method has several important features: (1) applicable to distributions with any kind of support, (2) computational efficiency because the ME solution is simply obtained as a set of systems of linear equations, (3) good tradeoff between bias and variance, and (4) good estimates of the tails of the distribution, in the presence of samples of small size. Moreover, the joint application of generalized kernel density maximum entropy with a bootstrap resampling allows to define credible bounds of the target distribution. The method is first benchmarked through an example of stochastic dynamic analysis. Subsequently, it is used to evaluate the seismic fragility functions of a reinforced concrete frame, from the knowledge of a small set of available ground motions. /journal/nme other quantities derived from the data. The first general representations for a PDF have adopted Hermite polynomials, eg, A-type and C-type Gram Charlier series and the Edgeworth series expansion. 3,4 An improvement is represented by the model proposed by Winterstein, 5 and it is largely applied in engineering.The choice of the distribution type is an open issue, from a conceptual and practical point of view. In the presence of limited information (sample of small size and/or lower-order moments), in the most general case, there is no theoretical justification to prefer one distribution over another. In such case, an attractive technique is based on the principle of maximum entropy (ME). [6][7][8] The ME distribution represents the least biased distribution given the available information. However, the application of the ME principle, as typically adopted in literature, has some practical and theoretical limitations.If the power moments represent the available information, then the ME PDF f ME (x) may require a large number M of moments (M ≥ 4) to accurately describe the tails of the distribution. However, the moment problem is an ill-posed problem. 9 Thus, for large M, the entropy maximization algorithm experiences numerical instability. Moreover, at the tails, the ME distribution oscillates because of the nonmonotonic nature of the polynomial embedded in the f ME (x). Thus, only the lower-order moments are typically considered, but in such case, f ME (x) hardly models tails fatter than the Gaussian. Therefore, the tails of many distributions cannot be well fitted by the ME distribution with M ≤ 4. 10 Furthermore, from a practical point of view, we do not have the true moments, but samples of data, f...

show abstract

New insights in the analysis of the structural response to response-spectrum-compatible accelerograms

Cited by 21 publications

References 18 publications

An inerter‐equipped vibrating barrier for noninvasive motion control of seismically excited structures

An inerter‐equipped vibrating barrier for noninvasive motion control of seismically excited structures

Analysis of Offshore Structures Based on Response Spectrum of Ice Force

Kernel density maximum entropy method with generalized moments for evaluating probability distributions, including tails, from a small sample of data

Contact Info

Product

Resources

About