Three-dimensional nonlinear response of utility tunnels under single and multiple earthquakes

2021 ◽  
Vol 143 ◽  
pp. 106607
Author(s):  
F.D. Konstandakopoulou ◽  
N.D. Beskou ◽  
G.D. Hatzigeorgiou
Keyword(s):  
Nonlinear Response ◽  
Three Dimensional ◽  
Multiple Earthquakes

scholarly journals Significance of Rotating Ground Motions on Behavior of Symmetric- and Asymmetric-Plan Structures: Part II. Multi-Story Structures

2015 ◽  
Vol 31 (3) ◽  
pp. 1613-1628 ◽  
Author(s):  
Erol Kalkan ◽  
Juan C. Reyes
Keyword(s):  
Ground Motion ◽  
Nonlinear Response ◽  
Rotation Angle ◽  
Ground Motions ◽  
Three Dimensional ◽  
Companion Paper ◽  
Apparent Velocity ◽  
Near Fault ◽  
Design Values ◽  
Linear And Nonlinear

The influence of the ground motion rotation angle on engineering demand parameters (EDPs) is examined in the companion paper based on three-dimensional (3-D) computer models of single-story structures. Further validations are performed here using 3-D models of nine-story buildings that have symmetric and asymmetric layouts subjected to a suite of bi-directional near-fault records with and without apparent velocity-pulses. The linear and nonlinear response-history analyses (RHAs) are used for evaluating the use of fault-normal and fault-parallel (FN/FP) directions and maximum-direction (MD) to rotate ground motions. This study suggests that individual ground motions rotated to MD or FN/FP directions not always provide conservative EDPs in nonlinear range, but often produce larger EDPs than as-recorded motions. In practice, when a suite of ground motions is used, nonlinear RHAs should be performed by rotating them to the MD and FN/FP directions, and maximum response values should be taken from these analyses as design values.

Forced Wave Propagation in Elastic Cables With Small Curvature

1995 ◽  
Author(s):  
M. Behbahani-Nejad ◽  
N. C. Perkins
Keyword(s):  
Nonlinear Response ◽  
Asymptotic Form ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Harmonic Excitation ◽  
Forced Response ◽  
Transverse Waves ◽  
Propagating Waves ◽  
Distinct Frequency ◽  
Elastic Cables

Abstract This study presents an investigation of the coupled longitudinal-transverse waves that propagate along an elastic cable. The coupling considered derives from the equilibrium curvature (sag) of the cable. A mathematical model is presented that describes the three-dimensional nonlinear response of a long elastic cable. An asymptotic form of this model is derived for the linear response of cables having small equilibrium curvature. Linear in-plane response is described by coupled longitudinal-transverse partial differential equations of motion, which are comprehensively evaluated herein. The spectral relation governing propagating waves is derived using transform methods. In the spectral relation, three qualitatively distinct frequency regimes exist that are separated by two cut-off frequencies. This relation is employed in deriving a Green’s function which is then used to construct solutions for in-plane response under arbitrarily distributed harmonic excitation. Analysis of forced response reveals the existence of two types of periodic waves which propagate through the cable, one characterizing extension-compressive deformations (rod-type) and the other characterizing transverse deformations (string-type). These waves may propagate or attenuate depending on wave frequency. The propagation and attenuation of both wave types are highlighted through solutions for an infinite cable subjected to a concentrated harmonic excitation source.

Harmonically Forced Wave Propagation in Elastic Cables With Small Curvature

1997 ◽  
Vol 119 (3) ◽  
pp. 390-397 ◽  
Author(s):  
M. Behbahani-Nejad ◽  
N. C. Perkins
Keyword(s):  
Nonlinear Response ◽  
Asymptotic Form ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Harmonic Excitation ◽  
Forced Response ◽  
Periodic Waves ◽  
Transverse Waves ◽  
Propagating Waves ◽  
Elastic Cables

This study presents an investigation of coupled longitudinal-transverse waves that propagate along an elastic cable. The coupling considered derives from the equilibrium curvature (sag) of the cable. A mathematical model is presented that describes the three-dimensional nonlinear response of an extended elastic cable. An asymptotic form of this model is derived for the linear response of cables having small equilibrium curvature. Linear, in-plane response is described by coupled longitudinal-transverse partial differential equations of motion, which are comprehensively evaluated herein. The spectral relation governing propagating waves is derived using transform methods. In the spectral relation, three qualitatively distinct regimes exist that are separated by two cut-off frequencies which are strongly influenced by cable curvature. This relation is employed in deriving a Green’s function which is then used to construct solutions for in-plane response under arbitrarily distributed harmonic excitation. Analysis of forced response reveals the existence of two types of periodic waves which propagate through the cable, one characterizing extension-compressive deformations (rod-type) and the other characterizing transverse deformations (string-type). These waves may propagate or attenuate depending on wave frequency. The propagation and attenuation of both wave types are highlighted through solutions for an infinite cable subjected to a concentrated harmonic excitation source.

Closed Crack Detection with Nonlinear Instantaneous Baseline

2013 ◽  
Vol 577-578 ◽  
pp. 633-636
Author(s):  
Wei Liang Wu ◽  
Wen Zhong Qu ◽  
Li Xiao
Keyword(s):  
Nonlinear Response ◽  
Crack Detection ◽  
Three Dimensional ◽  
Element Model ◽  
Closed Crack ◽  
Nonlinear Part ◽  
Nonlinear Springs ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Low Amplitude

Closed cracks, which stay in contact unless the excitation exceeds a certain threshold, exist as great menace to structures. Since nonlinear response is more sensitive to micro damage than conventional linear approaches, analyzing the nonlinear part of the collected response of structures to an input ultrasonic excitation is more promising in damage detection. In this paper, in order to image the location of a closed crack, an instantaneous baseline measurement is adopted and the nonlinear response is extracted by using scaling subtraction method. A three-dimensional finite element model of a plate with a closed crack is developed and the behavior of the closed crack is simulated with nonlinear springs at the crack interfaces. A network of actuators and sensors which constitutes of two arrays of surface-bonded piezoelectric transducers is built. The instantaneous baselines of each path are collected when the model is excited with low amplitude excitation. To diagnose the closed crack, a higher amplitude excitation over the threshold is applied to the model and the response signals of each path are recorded. The result shows that the differences caused by the crack can be observed from the scaling subtraction of these two recorded responses and the location of closed crack can be accurately imaged.

scholarly journals Ultrafast Nonlinear Response of Gold Gyroid Three-Dimensional Metamaterials

2014 ◽  
Vol 2 (4) ◽  
Author(s):  
Petros Farah ◽  
Angela Demetriadou ◽  
Stefano Salvatore ◽  
Silvia Vignolini ◽  
Morgan Stefik ◽  
...  
Keyword(s):  
Nonlinear Response ◽  
Three Dimensional
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