scholarly journals Computational Modelling Strategies for Nonlinear Response Prediction of Corroded Circular RC Bridge Piers

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Mohammad M. Kashani ◽  
Laura N. Lowes ◽  
Adam J. Crewe ◽  
Nicholas A. Alexander
Keyword(s):  
Low Cycle Fatigue ◽  
Computational Modelling ◽  
Response Prediction ◽  
Material Model ◽  
Basic Material ◽  
Rc Columns ◽  
Flexural Response ◽  
Modelling Strategies ◽  
The Impact ◽  
Column Element

A numerical model is presented that enables simulation of the nonlinear flexural response of corroded reinforced concrete (RC) components. The model employs a force-based nonlinear fibre beam-column element. A new phenomenological uniaxial material model for corroded reinforcing steel is used. This model accounts for the impact of corrosion on buckling strength, postbuckling behaviour, and low-cycle fatigue degradation of vertical reinforcement under cyclic loading. The basic material model is validated through comparison of simulated and observed responses for uncorroded RC columns. The model is used to explore the impact of corrosion on the inelastic response of corroded RC columns.

scholarly journals Identification of thermal material parameters for thermo-mechanically coupled material models

Meccanica ◽  
2021 ◽  
Vol 56 (2) ◽  
pp. 393-416
Author(s):  
L. Rose ◽  
A. Menzel
Keyword(s):  
Evolution Equations ◽  
Constitutive Relations ◽  
Material Model ◽  
Basic Material ◽  
Dissipated Energy ◽  
Model Formulation ◽  
Material Models ◽  
Material Parameters ◽  
Simple Tension ◽  
The Impact

AbstractThe possibility of accurately identifying thermal material parameters on the basis of a simple tension test is presented, using a parameter identification framework for thermo-mechanically coupled material models on the basis of full field displacement and temperature field measurements. Main objective is to show the impact of the material model formulation on the results of such an identification with respect to accuracy and uniqueness of the result. To do so, and as a proof of concept, the data of two different experiments is used. One experiment including cooling of the specimen, due to ambient temperature, and one without specimen cooling. The main constitutive relations of two basic material models are summarised (associated and non-associated plasticity), whereas both models are extended so as to introduce an additional material parameter for the thermodynamically consistent scaling of dissipated energy. The chosen models are subjected to two parameter identifications each, using the data of either experiment and focusing on the determination of thermal material parameters. The influence of the predicted dissipated energy of the models on the identification process is investigated showing that a specific material model formulation must be chosen carefully. The material model with associated evolution equations used within this work does neither allow a unique identification result, nor is any of the solutions for the underlying material parameters close to literature values. In contrast to that, a stable, that is locally unique, re-identification of the literature values is possible for the boundary problem at hand if the model with non-associated evolution equation is used and if cooling is included in the experimental data.

scholarly journals A multi-mechanical nonlinear fibre beam-column model for corroded columns

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Mehdi Kashani ◽  
Laura N Lowes ◽  
Adam J Crewe ◽  
Nicholas A Alexander
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Design Methodology ◽  
Low Cycle Fatigue ◽  
Nonlinear Behaviour ◽  
Cycle Fatigue ◽  
Rc Columns ◽  
Vertical Bars ◽  
Cyclic Degradation ◽  
The Impact

Purpose A new modelling technique is developed to model the nonlinear behaviour of corrosion damaged reinforced concrete (RC) bridge piers subject to cyclic loading. The model employs a nonlinear beam-column element with multi-mechanical fibre sections using OpenSees. The nonlinear uniaxial material models used in the fibre sections account for the effect of corrosion damage on vertical reinforcing, cracked cover concrete due to corrosion of vertical bars and damaged confined concrete due to corrosion of horizontal tie reinforcement. An advance material model is used to simulate the nonlinear behaviour of the vertical reinforcing bars that accounts for combined impact of inelastic buckling and low-cycle fatigue degradation. The basic uncorroded model is verified by comparison of the computation and observed response of RC columns with uncorroded reinforcement. This model is used in an exploration study of recently tested reinforced concrete components to investigate the impact of different corrosion models on the inelastic response of corrosion damaged RC columns. Design/methodology/approach A series of pushover and cyclic analyses on a hypothetical corroded RC columns are conducted. The impact of corrosion on reinforcing steel and concrete is modelled. The influence of cyclic degradation due to low-cycle fatigue is also modelled. Findings (1) Corrosion has a more significant impact on ductility loss of RC columns than the strength loss (plastic moment capacity). (2) It was found that the flexural failure is initiated by buckling of vertical bars and crushing of core concrete which then followed by fracture of bars in tension. (3) The analyses results showed that for seismic performance and evaluation of existing corroded bridges monotonic pushover analysis is insufficient. The cyclic degradation due to low-cycle fatigue has a significant influence on the response of corroded RC columns. Originality/value The finite element developed in this paper is the most comprehensive model to date that is able to capture the onlinear behaviour of corroded RC columns under cyclic loading up to complete collapse.

Simulation of Rubber-Coated Fabric Material Damage

2011 ◽  
Vol 488-489 ◽  
pp. 585-588 ◽  
Author(s):  
Agnieszka Derewonko ◽  
Pawel Baranowski ◽  
Dariusz Rudnik
Keyword(s):  
Numerical Analysis ◽  
Material Model ◽  
Basic Material ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Simple Method ◽  
Coated Fabric ◽  
Air Cushion ◽  
The Impact ◽  
Fabric Material

The objective of this work is to describe part of the selecting process of a rubber-coated fabric material model. The material is used to construct an air cushion that is a carrying element of the cassette pontoon bridge unit. During operation the air cushion is permanently in contact with a metal component, fresh water and air. Therefore various interactions, such as a contact problem, flow of medium and thermodynamics can occur. The basic material model for numerical simulation was selected based on the uniaxial tensile test. The simple method was used to describe time-dependent material properties for numerical analysis, which allows computation to take a reasonable time. In order to assess the usefulness of the selected material model the impact puncture test was modelled with the same conditions and properties as in the laboratory testing machine called Instron. Moreover, an attempt of simulating the damage process is described. The energy absorbed by the material was registered during the laboratory test which was compared with the results of numerical analysis. An acceptable compatibility of the results is noticed.

Nonlinear Beam-Based Modeling of RC Columns Including the Effect of Reinforcing-Bar Buckling and Rupture

2018 ◽  
Vol 34 (3) ◽  
pp. 1289-1309 ◽  
Author(s):  
Sadik Can Girgin ◽  
Mohammadreza Moharrami ◽  
Ioannis Koutromanos
Keyword(s):  
Low Cycle Fatigue ◽  
Sensitivity Study ◽  
Cyclic Loads ◽  
Reinforcing Steel ◽  
Rc Columns ◽  
Inelastic Buckling ◽  
Modeling Approach ◽  
Strain Penetration ◽  
Bar Buckling ◽  
The Impact

This study presents a beam-based modeling approach for the analysis of reinforced concrete (RC) frame members under cyclic loads that can capture the effect of inelastic buckling and rupture of reinforcing steel bars. The approach uses force-based elements with a fiber-section model and a corotational formulation to account for the geometric nonlinearity effect on the response of columns. A recently proposed phenomenological uniaxial model for steel reinforcement, capable of simulating inelastic buckling and rupture due to low-cycle fatigue, is used for the reinforcing steel fibers. Numerical simulation models also account for strain penetration effects in the analyses. The modeling approach is validated with the results of experimental tests on RC columns under cyclic loads. A sensitivity study is also pursued to elucidate the impact of bar buckling and strain penetration on the analytical results.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Modelling Agricultural Controls for Flooding and Soil Erosion

2018 ◽  
pp. 776-796
Author(s):  
Roger Moussa ◽  
Bruno Cheviron
Keyword(s):  
Spatial Distribution ◽  
Model Structure ◽  
Land Uses ◽  
Research Challenges ◽  
Water And Sediment ◽  
Flow Processes ◽  
Cultivation Practices ◽  
Modelling Strategies ◽  
The Impact ◽  
Significant Factors

Floods are the highest-impact natural disasters. In agricultural basins, anthropogenic features are significant factors in controlling flood and erosion. A hydrological-hydraulic-erosion diagnosis is necessary in order to choose the most relevant action zones and to make recommendations for alternative land uses and cultivation practices in order to control and reduce floods and erosion. This chapter first aims to provide an overview of the flow processes represented in the various possible choices of model structure and refinement. It then focuses on the impact of the spatial distribution and temporal variation of hydrological soil properties in farmed basins, representing their effects on the modelled water and sediment flows. Research challenges and leads are then tackled, trying to identify the conditions in which sufficient adequacy exists between site data and modelling strategies.

Concrete and Fiber Reinforced Concrete Subjected to Impact Loading

1985 ◽  
Vol 64 ◽  
Author(s):  
Surendra P. Shah
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Basic Material ◽  
Strain History ◽  
Moderate Increase ◽  
Fiber Reinforced ◽  
The Impact

ABSTRACTDespite its extensive use, low tensile strength has been recognized as one of the major drawbacks of concrete. Although one has learned to avoid exposing concrete structures to adverse static tensile load, these cannot be shielded from short duration dynamic tensile stresses. Such loads originate from sources such as impact from missiles and projectiles, wind gusts, earthquakes and machine vibrations. The need to accurately predict the structural response and reserve capacity under such loading has led to an interest in the mechanical properties of the component materials at high rates of straining.One method to improve the resistance of concrete when subjected to impact and/or impulsive loading is by the incorporation of randomly distributed short fibers. Concrete (or Mortar) so reinforced is termed fiber reinforced concrete (FRC). Moderate increase in tensile strength and significant increases in energy absorption (toughness or impact-resistance) have been reported by several investigators in static tests on concrete reinforced with randomly distributed short steel fibers. A theoretical model to predict fracture toughness of FRC is proposed. This model is based on the concept of nonlinear elastic fracture mechanics.As yet no standard test methods are available to quantify the impact resistance of such composites, although several investigators have employed a variety of tests including drop weight, swinging pendulums and the detonation of explosives. These tests though useful in ascertaining the relative merits of different composites do not yield basic material characteristics which can be used for design.The author has recently developed an instrumented Charpy type of impact test to obtain basic information such as load-deflection relationship, fracture toughness, crack velocity and load-strain history during an impact event. From this information, a damage based constitutive model was proposed. Relative improvements in performance due to the addition of fibers as observed in the instrumented tests are also compared with other conventional methods.

Influence of Phase Transformations on Residual Stresses in Welded Structures

2013 ◽  
Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Numerical Models ◽  
Material Model ◽  
Transformation Model ◽  
Austenitic Steels ◽  
Beam Specimen ◽  
Welded Structures ◽  
The Impact

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.

Material Modeling of Concrete for the Numerical Simulation of Steel Plate Reinforced Concrete Panels Subjected to Impacting Loading

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Huiyun Li ◽  
Guangyu Shi
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Steel Plate ◽  
Material Model ◽  
Tensile Failure ◽  
Scale Model ◽  
Flow Rule ◽  
Plastic Damage ◽  
The Impact ◽  
Concrete Model

The steel plate reinforced concrete (SC) walls and roofs are effective protective structures in nuclear power plants against aircraft attacks. The mechanical behavior of the concrete in SC panels is very complicated when SC panels are under the action of impacting loading. This paper presents a dynamic material model for concrete subjected to high-velocity impact, in which pressure hardening, strain rate effect, plastic damage, and tensile failure are taken into account. The loading surface of the concrete undergoing plastic deformation is defined based on the extended Drucker–Prager strength criterion and the Johnson–Cook material model. The associated plastic flow rule is utilized to evaluate plastic strains. Two damage parameters are introduced to characterize, respectively, the plastic damage and tensile failure of concrete. The proposed concrete model is implemented into the transient nonlinear dynamic analysis code ls-dyna. The reliability and accuracy of the present concrete material model are verified by the numerical simulations of standard compression and tension tests with different confining pressures and strain rates. The numerical simulation of the impact test of a 1/7.5-scale model of an aircraft penetrating into a half steel plate reinforced concrete (HSC) panel is carried out by using ls-dyna with the present concrete model. The resulting damage pattern of concrete slab and the predicted deformation of steel plate in the HSC panel are in good agreement with the experimental results. The numerical results illustrate that the proposed concrete model is capable of properly charactering the tensile damage and failure of concrete.

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