scholarly journals Tensile Bending Stresses in Mortar-Grouted Riprap Revetments Due to Wave Loading

2020 ◽  
Vol 8 (11) ◽  
pp. 913
Author(s):  
Moritz Kreyenschulte ◽  
Holger Schüttrumpf
Keyword(s):  
Structural Response ◽  
Model Tests ◽  
Model Parameters ◽  
Sound Design ◽  
Wave Loading ◽  
Technical Standards ◽  
Bending Stresses ◽  
Porosity And Permeability ◽  
Standards And Guidelines ◽  
Dynamic Wave

One of the most common revetment types in Germany is the mortar-grouted riprap revetment (MGRR), which is constructed by placing riprap on a filter or separation layer and subsequent grouting with mortar. Existing technical standards and guidelines for MGRRs do not consider the interaction between dynamic wave loading and structural response. To date, scientifically sound design approaches verified by model tests are missing. Therefore, the aim of this work is to establish a process-based model for the calculation of the acting bending tensile stresses during wave attack for MGRRs to asses crack formation. To this end, MGRRs were modelled as plates on an elastic foundation (PEF). Hydraulic boundary conditions were determined with full-scale hydraulic model tests. Model parameters of the PEF model were established by investigations into the mechanical parameters of the constituents of MGRRs. The results show that tensile bending stresses are particularly dependent on the pressure difference between the top and bottom edge of the top layer, which varies significantly for MGRRs as their porosity and permeability varies significantly depending on the amount of mortar used for grouting. Enveloping functions for maximum relative tensile bending stress σx,max/(ρwgHm0) are given for four configurations of MGRRs that are of great practical relevance.

Effect of buckling-restrained brace model parameters on seismic structural response

2014 ◽  
Vol 98 ◽  
pp. 100-113 ◽  
Author(s):  
Quan Gu ◽  
Alessandro Zona ◽  
Yi Peng ◽  
Andrea Dall'Asta
Keyword(s):  
Structural Response ◽  
Model Parameters ◽  
Buckling Restrained Brace

Simulating and analyzing artificial nonstationary earthquake ground motions

1982 ◽  
Vol 72 (2) ◽  
pp. 615-636
Author(s):  
Robert F. Nau ◽  
Robert M. Oliver ◽  
Karl S. Pister
Keyword(s):  
Difference Equations ◽  
Kalman Filters ◽  
Ground Motions ◽  
Structural Response ◽  
Model Parameters ◽  
Time Varying ◽  
Nonparametric Method ◽  
Linear Difference Equations ◽  
Earthquake Ground Motions ◽  
Earthquake Accelerograms

Abstract This paper describes models used to simulate earthquake accelerograms and analyses of these artificial accelerogram records for use in structural response studies. The artificial accelerogram records are generated by a class of linear linear difference equations which have been previously identified as suitable for describing ground motions. The major contributions of the paper are the use of Kalman filters for estimating time-varying model parameters, and the development of an effective nonparametric method for estimating the variance envelopes of the accelerogram records.

Efficient Derivation of the Probability Distribution of the Extreme Values of Offshore Structural Response: Comparison of Three Different Methods

2013 ◽  
Author(s):  
M. K. Abu Husain ◽  
N. I. Mohd Zaki ◽  
G. Najafian
Keyword(s):  
Probability Distribution ◽  
Extreme Values ◽  
Structural Response ◽  
Offshore Structures ◽  
Simulation Technique ◽  
Random Wave ◽  
Wave Loading ◽  
Sampling Variability ◽  
Time Simulation ◽  
Extreme Responses

Offshore structures are exposed to random wave loading in the ocean environment and hence the probability distribution of the extreme values of their response to wave loading is required for their safe and economical design. To this end, the conventional (Monte Carlo) time simulation technique (CTS) is frequently used for predicting the probability distribution of the extreme values of response. However, this technique suffers from excessive sampling variability and hence a large number of simulated extreme responses (hundreds of simulated response records) are required to reduce the sampling variability to acceptable levels. In this paper, three different versions of a more efficient time simulation technique (ETS) are compared by exposing a test structure to sea states of different intensity. The three different versions of the ETS technique take advantage of the good correlation between extreme responses and their corresponding surface elevation extreme values, or quasi-static and dynamic linear extreme responses.

scholarly journals Addendum: Technical standards and guidelines for spinal muscular atrophy testing

2020 ◽  
Author(s):  
Joshua L. Deignan ◽  
◽  
Caroline Astbury ◽  
Andrea Behlmann ◽  
Saurav Guha ◽  
...  
Keyword(s):  
Spinal Muscular Atrophy ◽  
Muscular Atrophy ◽  
Technical Standards ◽  
Standards And Guidelines

scholarly journals PARTENARIATO TRA PUBBLICO E PRIVATO NELLA TUTELA E NELLA VALORIZZAZIONE DEI BENI CULTURALI

2018 ◽  
Author(s):  
Pietro Petraroia
Keyword(s):  
Cultural Heritage ◽  
Technical Standards ◽  
Public And Private ◽  
Cultural Assets ◽  
Standards And Guidelines ◽  
Italian Legislation

In Italian legislation on cultural heritage, collaboration between publicand private bodies is more important than it is believed. However, the word “private”has many meanings, as well as the word “public”. This essay tells the evolution of therules on public-private cooperation for the enhancement of cultural assets from 1980up today. Unfortunately, still there are no technical standards and guidelines to pro-mote clarity and effectiveness in the collaboration between public and private bodies.

Probabilistic Modelling of Extreme Offshore Structural Response due to Random Wave Loading

2013 ◽  
Author(s):  
Y. Wang ◽  
H. Mallahzadeh ◽  
M. K. Abu Husain ◽  
N. I. Mohd Zaki ◽  
G. Najafian
Keyword(s):  
Extreme Values ◽  
Structural Response ◽  
Offshore Structures ◽  
Random Wave ◽  
Wave Loading ◽  
Empirical Distributions ◽  
Generalized Pareto ◽  
Economical Design ◽  
Ocean Environment ◽  
Extreme Responses

Offshore structures are exposed to random wave loading in the ocean environment and hence the probability distribution of the extreme values of their response to wave loading is required for their safe and economical design. This paper investigates the suitability of the Gumbel, the Generalized Extreme Value (GEV), and the Generalized Pareto (GP) distributions for modelling of extreme responses by comparing them with empirical distributions derived from extensive Monte Carlo time simulations. It will be shown that none of these distributions can model the extreme values adequately but that a mixed distribution consisting of both GEV and GP distributions seems to be capable of modelling the extreme responses with very good accuracy.

Structural Response of Pipeline Free Spans Based on Beam Theory

2002 ◽  
Author(s):  
Olav Fyrileiv ◽  
Kim Mo̸rk
Keyword(s):  
Natural Frequencies ◽  
Structural Response ◽  
Beam Theory ◽  
Vertical Vibration ◽  
Mode Shapes ◽  
Ocean Current ◽  
Vibration Modes ◽  
Wave Loading ◽  
Vortex Induced Vibrations ◽  
Subsea Pipelines

One of the main risk factors for subsea pipelines exposed on the seabed is fatigue failure of free spans due to ocean current or wave loading. This paper describes how the structural response of a free span, as input to the fatigue analyses, can be assessed in a simple and still accurate way by using improved beam theory formulations. In connection with the release of the DNV Recommended Practice, DNV-RP-F105 “Free Spanning Pipelines”, the simplified structural response quantities have been improved compared to previous codes. The boundary condition coefficients for the beam theory formulations have been updated based an effective span length concept. This concept is partly based on theoretical studies and partly on a large number of FE analyses. The updated expressions are general and fit all types of soil and pipe dimensions for lower lateral and vertical vibration modes. The present paper focus on estimation of simplified response quantities such as lower natural frequencies and associated mode shapes. Hydrodynamical aspects of Vortex Induced Vibrations (VIV) are outside the scope of this paper.

An Efficient Monte Carlo Simulation Technique for Derivation of the Probability Distribution of the Extreme Values of Offshore Structural Response

2010 ◽  
Author(s):  
M. K. Abu Husain ◽  
G. Najafian
Keyword(s):  
Probability Distribution ◽  
Extreme Values ◽  
Structural Response ◽  
Offshore Structures ◽  
Simulation Technique ◽  
Random Wave ◽  
Wave Loading ◽  
Sampling Variability ◽  
Monte Carlo Simulation Technique ◽  
Ocean Environment

Offshore structures are exposed to random wave loading in the ocean environment and hence the probability distribution of the extreme values of their response to wave loading is required for their safe and economical design. To this end, the conventional simulation technique (CTS) is frequently used for predicting the probability distribution of the extreme values of response. However, this technique suffers from excessive sampling variability and hence a large number of simulated response extreme values (hundreds of simulated response records) are required to reduce the sampling variability to acceptable levels. In this paper, a more efficient version of the time simulation technique (ETS) is introduced to derive the probability distribution of response extreme values from a much smaller sample of simulated extreme values.

scholarly journals A METHODOLOGY TO PRIORITIZE INVESTMENTS TO REDUCE RISKS IN PORTS

2018 ◽  
pp. 65
Author(s):  
Carmen Castillo ◽  
Álvaro Galán ◽  
Raquel Balmaseda ◽  
Ana María Díaz ◽  
Elena Calcerrada
Keyword(s):  
Climate Change ◽  
Decision Making ◽  
Risk Management ◽  
Structural Response ◽  
Coastal Engineering ◽  
Risk Level ◽  
Decision Making Process ◽  
Wave Loading ◽  
Coastal Structures ◽  
Stochastic Nature

In many countries worldwide, a strong economical effort in the construction of coastal infrastructures has already been faced. Nowadays, due to the financial crisis, most of the efforts are devoted to the conservation and maintenance of coastal structures instead of building new ones. Furthermore, the expected variations in sea level and met-ocean conditions due to climate change modify the stochastic nature of both wave loading and structural response which is different nowadays from that at the time the structures were designed. These facts encourage the coastal engineering community towards the development of reliable risk management and decision-making tools. A key point in the decision-making process is how to prioritize investments when deciding about adaptation or mitigation alternatives. This paper aims at providing a proposal including tips to select among the possible alternatives based on risk analysis and how each alternative modifies the risk level compared to the do-nothing alternative. An example on a Spanish port will be provided for better understanding.

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