scholarly journals 3D Fiber-Based Frame Element with Multiaxial Stress Interaction for RC Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Alexander Kagermanov ◽  
Paola Ceresa
Keyword(s):  
Reinforced Concrete ◽  
Three Dimensional ◽  
Beam Theory ◽  
Material Model ◽  
Element Formulation ◽  
Multiaxial Stress ◽  
Rc Structures ◽  
Frame Element ◽  
Out Of Plane ◽  
Smeared Crack

A three-dimensional fiber-based frame element accounting for multiaxial stress conditions in reinforced concrete structures is presented. The element formulation relies on the classical Timoshenko beam theory combined with sectional fiber discretization and a triaxial constitutive model for reinforced concrete consisting of an orthotropic, smeared crack material model based on the fixed crack assumption. Torsional effects are included through the Saint-Venant theory of torsion, which accounts for out-of-plane displacements perpendicular to the cross section due to warping effects. The formulation was implemented into a force-based beam-column element and verified against monotonic and cyclic tests of reinforced concrete columns in biaxial bending, beams in combined flexure-torsion, and flexure-torsion-shear.

Numerical simulation of the debonding process in pull-out tests of near-surface mounted FRP rod in concrete

2019 ◽  
Vol 37 (3) ◽  
pp. 1109-1130
Author(s):  
Tie-Lin Chen ◽  
Wenbin Tao ◽  
Wenjun Zhu ◽  
Mozhen Zhou
Keyword(s):  
Three Dimensional ◽  
Crack Model ◽  
Bond Failure ◽  
Near Surface ◽  
Content Type ◽  
Rc Structures ◽  
Pull Out ◽  
Smeared Crack ◽  
Near Surface Mounted ◽  
Debonding Process

Purpose Near-surface mounted (NSM) fiber-reinforced polymer (FRP) rod is extensively applied in reinforced concrete (RC) structures. The mechanical performances of NSM FRP-strengthened RC structures depend on the bond behavior between NSM reinforcement and concrete. This behavior is typically studied by performing pull-out tests; however, the failure behavior, which is crucial to the local debonding process, is not yet sufficiently understood. Design/methodology/approach In this study, a three-dimensional meso-scale finite element method considering the cohesion and adhesion failures is presented to model the debonding failure process in pull-out tests of NSM FRP rod in concrete. The smeared crack model is used to capture the cohesion failures in the adhesive or concrete. The interfacial constitutive model is applied to simulate the adhesion failures on the FRP-adhesive and concrete-adhesive contact interfaces. Findings The present method is first validated by two simple examples and then applied to a practical NSM FRP system. This work studied in detail the debonding process, the bond failure types, the location of peak bond stress, the transmitting deformation in adhesive and the morphology of contact zone. The developed method provides a practical and convenient tool applicable for further investigations on the debonding mechanism for the NSM FRP rod in concrete. Originality/value A three-dimensional meso-scale finite element method considering the cohesion and adhesion failures is presented to model the debonding failure in NSM FRP-strengthened RC structures. The smeared crack model and the interfacial constitutive model are introduced to develop a convenient approach to analyze the failures in adhesive, concrete and related interfaces. The developed numerical method is applicable for studying the debonding process, the bond failure types, the location of peak bond stress, the transmitting deformation in adhesive and the morphology of contact zone in detail.

Computational analysis of reinforced concrete structures subjected to fire using a multilayered finite element formulation

2021 ◽  
pp. 136943322110297
Author(s):  
Batoma Sosso ◽  
Fabian M Paz Gutierrez ◽  
Péter Z Berke
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Low Cost ◽  
Material Behavior ◽  
Element Formulation ◽  
Cross Sectional ◽  
Rc Structures ◽  
Structural Resistance ◽  
Layered Beam ◽  
The Cross

Fire is a critical risk in reinforced concrete (RC) structures and appropriate structural resistance against it has to be ensured. In this contribution, an approach using corotational layered beam finite elements is employed in which the cross-section temperature is derived from a low-cost closed form model, as opposed to the more commonly used fully computational thermal analysis. The effect of geometrical and material nonlinearities (constitutive behavior fitted to experimental data for concrete and steel), material degradation as a function of temperature rise, and the contributions of thermal, transient, and creep strains are incorporated in the structural analysis. The computational results are favorably compared to experimental data from the literature for an RC beam and for a larger RC frame. Taking benefit of the layered beam formulation offering local insight into the cross-sectional and material behavior, the relationship between the structural degradation and data extracted from the cross-sectional behavior is successfully established. Noteworthy originalities of the contribution are the use of ultimate strain and its evolution as a function of temperature for both materials and the explanation of the observed structural response in fire conditions from cross-sectional data.

Pontoon Torsional Strength Analysis Related to Ships with Large Deck Openings

1991 ◽  
Vol 35 (04) ◽  
pp. 339-351
Author(s):  
Ivo Senjanovic ◽  
Ying Fan
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Beam Theory ◽  
Element Model ◽  
Middle Part ◽  
Strength Analysis ◽  
Element Formulation ◽  
Dimensional Finite Element ◽  
Torsional Analysis ◽  
Three Dimensional Finite Element

The torsional problem of a pontoon, consisting of channel middle part and rectangular tube peaks, isconsidered within the higher-order beam theory. The cross section and the contour compatibility conditions for assembling of the pontoon parts are investigated. The acceptability of the introduced assumptions is checked by three-dimensional finite-element model analysis. Some deficiencies of the classical beam theory regarding the girder stiffness are noticed. The finite-element formulation to be used for the torsional analysis of the ship's hull with large hatch openings is given.

Dynamic Modelling of Blades Based on a Novel Curved Thin Walled Beam Theory

2018 ◽  
Author(s):  
Juan C. Jauregui ◽  
Diego Cardenas ◽  
Hugo Elizalde ◽  
Oliver Probst
Keyword(s):  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Dynamic Modelling ◽  
Beam Theory ◽  
General Description ◽  
B Splines ◽  
Out Of Plane ◽  
Thin Walled ◽  
Aided Design

There are several Thin-Walled Beam models for straight beams, but few TWB models consider beams with arbitrary curvatures. Although, a curved beam can be modelled using finite elements, the number of degrees of freedom is too large and a nonlinear dynamic solution is very cumbersome, if not impossible. In this work, a general description of arbitrary three-dimensional curves, based on the Frenet-Serret field frame, is applied to determine the dynamic stresses in wing turbines blades. The dynamic model is developed using the Isogeometric Analysis (IGA) and the in plane and out-of-plane curvature’s gradients are found in an Euler-type formulation, allowing the treatment of cases with highly-curved geometry. An Isogeometrical (IGA) formulation relies on a linear combination of Non-Uniform Rational B-Splines (NURBS) to represent not just the model’s geometry, a standard practice in most Computer-Aided Design (CAD) platforms, but also the unknown solution field of each sought variable. For the unified model hitherto described, these variables are represented by a NURBS curve.

Simulation of Impact Tests With Hard, Soft and Liquid Filled Missiles on Reinforced Concrete Structures

2013 ◽  
Vol 80 (3) ◽  
Author(s):  
Christian Heckötter ◽  
Jürgen Sievers
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Failure Mechanisms ◽  
Material Model ◽  
Nuclear Facilities ◽  
Bending Vibration ◽  
Rc Structures ◽  
Rc Slab ◽  
Scale Test ◽  
Punching Failure

Vital parts of nuclear facilities are commonly protected by reinforced concrete (rc-) structures. In order to assess the barrier effectiveness of these structures, different internal and external loads have to be considered. Among others, external missile impacts, for instance due to an airplane crash, are assumed to be relevant loading cases. In this context, impacts of nondeformable (“hard”), deformable (“soft”) as well as liquid filled (“wet”) missiles are considered. Major rc-target failure mechanisms are global bending, punching and perforation. This paper presents simulations with the computer program AUTODYN (ANSYS INC., 2010, ANSYS AUTODYN, Version 13.0 & Theory Manual) on intermediate- and large-scale impact experiments dealing with the aforementioned failure mechanisms. Missile velocities are in the range of 110 to 250 m/s. In particular, two different intermediate scale test series are considered. One test deals with predominant punching failure and perforation of a rc-slab (target) hit by a hard missile. Further, bending vibration of slabs impacted by soft missiles is analyzed, whereupon the influence of liquid infill on loading and target response is pointed out. Finally, a large scaled test with combined bending and punching failure of a rc-slab due to soft missile impact is considered. Results of numerical simulation and tests are compared. It is found, that the used concret material model developed by Riedel, Hiermaier, and Thoma (RHT) (Riedel, 2004, “Beton Unter Dynamischen Lasten: Meso-Und Makromechanische Modelle Und Ihre Parameter, Fraunhofer–Ernst-Mach-Institut, Freiburg/Br., ISBN 3-8167-6340-5) is suitable to reproduce the responses of rc-structures subjected to various kinds of impact conditions. Sensitivities of simulation results on modeling parameters are discussed.

scholarly journals Numerical investigation of reinforced-concrete beam-column joints retrofitted using external superelastic shape memory alloy bars

2021 ◽  
Vol 8 (5) ◽  
pp. 716-738
Author(s):  
Yamen Ibrahim Elbahy ◽  
◽  
Maged A. Youssef ◽  
M. Meshaly ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Shape Memory ◽  
Parametric Study ◽  
Linear Regression Analysis ◽  
Three Dimensional ◽  
Element Model ◽  
Multiple Linear Regression Analysis ◽  
Reinforced Concrete Beam ◽  
Rc Structures ◽  
Three Dimensional Finite Element

<abstract> <p>The unique properties of Shape Memory Alloys (SMAs) have motivated researchers to use them as primary reinforcement in reinforced concrete (RC) structures. In this study, the applicability of using external unbonded SMA bars to retrofit RC beam-column joints (BCJs) is investigated. A three-dimensional finite element model, which simulates the suggested retrofitting technique, is first developed, and validated using ABAQUS software. The model is then further simplified and utilized to conduct a parametric study to investigate the behaviour of SMA retrofitted RC BCJs. Results of the parametric study are used to perform multiple linear regression analysis. Simple equations, which can be used to calculate the length and amount of SMA bars required to retrofit a RC BCJ, are then developed.</p> </abstract>

Finite element modelling of plain and reinforced concrete specimens with the Kotsovos and Pavlovic material model, smeared crack approach and fine meshes

2021 ◽  
pp. 105678952098660
Author(s):  
George Markou ◽  
Wynand Roeloffze
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Research Work ◽  
Plain Concrete ◽  
Material Model ◽  
Ultimate Limit State ◽  
Material Models ◽  
Concrete Material ◽  
Smeared Crack Approach ◽  
Smeared Crack

Modelling of concrete through 3 D constitutive material models is a challenging subject due to the numerous nonlinearities that occur during the monotonic and cyclic analysis of reinforced concrete structures. Additionally, the ultimate limit state modelling of plain concrete can lead to numerical instabilities given the lack of steel rebars that usually provide with the required tensile strength inducing numerical stability that is required during the nonlinear solution procedure. One of the commonly used 3 D concrete material models is that of the Kotsovos and Pavlovic, which until recently it was believed that when integrated with the smeared crack approach, it can only be used in combination with relatively larger in size finite elements. The objective of this study is to investigate into this misconception by developing different numerical models that foresee the use of fine meshes to simulate plain concrete and reinforced concrete specimens. For the needs of this research work, additional experiments were performed on cylindrical high strength concrete specimens that were used for additional validation purposes, whereas results on a reinforced concrete beam found in the international literature were used as well. A discussion on the numerical findings will be presented herein by comparing the different experimental data with the numerically predicted mechanical response of the under study concrete material model.

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