scholarly journals Efficient time-domain analysis of highly dispersive linear and non-linear metamaterial waveguide and antenna structures operated in the impulse-regime

2010 ◽  
Vol 4 (10) ◽  
pp. 1617 ◽  
Author(s):  
J.S. Gómez-Díaz ◽  
S. Gupta ◽  
A. Álvarez-Melcón ◽  
C. Caloz
Keyword(s):  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Metamaterial Waveguide ◽  
Non Linear

Concrete Modeling for Extreme Wave Slam Events

2017 ◽  
Author(s):  
Kasper Wåsjø ◽  
Terje P. Stavang ◽  
Tore H. Søreide
Keyword(s):  
Time Domain ◽  
Linear Time ◽  
Limit State ◽  
Material Model ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Capacity Control ◽  
Extreme Wave ◽  
Conventional Design ◽  
Non Linear

Experience from model tests has initiated a growing attention towards extreme wave slam as a critical load situation for offshore large volume structures. Most of the problem is related to the local slam pressure, which may go up to several MPa’s for 100-year and 10 000-year waves. The paper deals with modeling techniques for marine concrete structures under extreme slam loading from waves where dynamic effects together with material softening play a major role for the response. Different analysis approaches for ultimate limit state (ULS) and accidental limit state (ALS) controls are discussed in view of reliability philosophy as basis for conventional design approach. The present paper is devoted to the local impact scenario and the alternative approaches for response and capacity control involving non-linear time domain analyses. Conventional design schemes as based on linear elastic models for response calculation together with code specified capacity control often come out more conservative than non-linear approach. The paper demonstrates by case studies how softening of the structure in general reduces the response in terms of section forces. A key issue when going from conventional linear approaches into non-linear techniques is to still keep an acceptable reliability level on the capacity control. Load and material factors are normally based on structures with limited non-linearity where linear response modeling is representative. Implementing non-linear material model in time domain analysis has a major challenge in limiting the sensitivity in response and capacity calculation. The paper demonstrates the way material model of concrete affects the section forces to go into local capacity control, and concludes on needed sensitivity analyses. Practical approaches on the concrete slam problem together with resulting utilizations from the control are demonstrated. The full non-linear technique by response and capacity control in one analysis is also handled, using average material parameters and justifying safety factors for the effect of implementing characteristic lower strength of concrete in the capacity. The paper ends up in a recommendation on non-linear time domain analysis procedure for typically slam problems. A discussion is also given on applicable design codes with attention to non-linear analysis.

Time-Domain Analysis of Wind-Induced Response of a Suspension Bridge in Comparison With the Full-Scale Measurements

2017 ◽  
Author(s):  
Jungao Wang ◽  
Etienne Cheynet ◽  
Jasna Bogunović Jakobsen ◽  
Jónas Snæbjörnsson
Keyword(s):  
Standard Deviation ◽  
Time Domain ◽  
Measurement Data ◽  
Suspension Bridge ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Full Scale ◽  
Buffeting Response ◽  
Non Linear ◽  
The Time Domain

The present study compares the buffeting response of a suspension bridge computed in the time-domain with full-scale measurement data. The in-service Lysefjord Bridge is used as a study case, which allows a unique comparison of the computational results with full-scale buffeting bridge response observed during a one year monitoring period. The time-domain analysis is performed using a finite element approach. Turbulent wind field is simulated according to the governing bridge design standard in Norway for three different terrain categories. The time-domain analysis indicates that the non-linear components of the wind loading are of limited importance in the present case, contributing by less than 5% to the standard deviation of the lateral displacement. The contribution of the buffeting loads on the main cables, hangers and towers to the lateral dynamic response of the bridge girder is about 6%. With the time-domain method, mode coupling as well as the influence of cables and towers are well captured in the simulation results. The buffeting response, estimated in terms of the standard deviation of acceleration, is found to be in good agreement with the field measurement data. Comparison suggests that the proposed numerical method, with the non-linear force model, is able to predict the bridge response reasonably well.

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