A finite element model to simulate long-term behavior of prestressed concrete girders

2014 ◽  
Vol 81 ◽  
pp. 48-56 ◽  
Author(s):  
Tiejiong Lou ◽  
Sergio M.R. Lopes ◽  
Adelino V. Lopes
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Prestressed Concrete ◽  
Element Model ◽  
Concrete Girders ◽  
Prestressed Concrete Girders ◽  
Long Term Behavior

Nachweis der Kippstabilität schlanker Stahlbeton- und Spannbetonträger komplexer Geometrie mit der nicht-linearen FEM/Design of slender free formed reinforced and prestressed concrete girders against lateral instability

Bauingenieur ◽  
2017 ◽  
Vol 92 (05) ◽  
pp. 212-222
Author(s):  
A. Kolodziejczyk ◽  
R. Maurer
Keyword(s):  
Finite Element ◽  
Prestressed Concrete ◽  
Lateral Instability ◽  
Concrete Girders ◽  
Prestressed Concrete Girders

Oft erfüllen sehr schlanken Binder für weit gespannte Dachflächen im Fertigteilbau nicht das in DIN EN 1992–1–1 enthaltene geometrische Grenzkriterium für den vereinfachten Nachweis ausreichender Kippsicherheit. In der Praxis kommen in diesen Fällen häufig in der einschlägigen Fachliteratur beschriebene Näherungsverfahren zum Einsatz. Deren Anwendungsbereich beschränkt sich allerdings auf die für den Hallenbau typischen Parallelgurt- und Satteldachbinder. Ist die Kippsicherheit von freigeformten schlanken Trägergeometrien zu untersuchen, kann der Nachweis auf Grundlage nicht-linearer Finite-Element-Berechnungen erfolgen. Neben einer realitätsnahen Simulation des Tragverhaltens ist hierbei ein angepasstes Sicherheitskonzept für die Einhaltung des geforderten Sicherheitsniveaus bei nicht-linearen Verfahren nach DIN EN 1990 erforderlich. Dabei ist zu beachten, dass die derzeit in den Regelwerken enthaltenen vereinfachten Sicherheitskonzepte für nicht-lineare Verfahren ausschließlich für reine Biegeprobleme kalibriert wurden. Im Rahmen des Beitrags wird der Nachweis der Kippsicherheit mit der nicht-linearen FEM behandelt. Dabei stehen die wesentlichen Anforderungen an die Modellierung der Werkstoffeigenschaften, die Tragmechanismen bei Kippproblemen sowie ein angepasstes Sicherheitskonzept für nicht-lineare Berechnungsverfahren im Vordergrund.

Comparison of femur strain under different loading scenarios: Experimental testing

2020 ◽  
Vol 235 (1) ◽  
pp. 17-27
Author(s):  
Ievgen Levadnyi ◽  
Jan Awrejcewicz ◽  
Yan Zhang ◽  
Yaodong Gu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Strain Distribution ◽  
Element Model ◽  
Surface Strain ◽  
Image Correlation ◽  
Loading Conditions ◽  
Bone Implant ◽  
Bone Stiffness

Bone fracture, formation and adaptation are related to mechanical strains in bone. Assessing bone stiffness and strain distribution under different loading conditions may help predict diseases and improve surgical results by determining the best conditions for long-term functioning of bone-implant systems. In this study, an experimentally wide range of loading conditions (56) was used to cover the directional range spanned by the hip joint force. Loads for different stance configurations were applied to composite femurs and assessed in a material testing machine. The experimental analysis provides a better understanding of the influence of the bone inclination angle in the frontal and sagittal planes on strain distribution and stiffness. The results show that the surface strain magnitude and stiffness vary significantly under different loading conditions. For the axial compression, maximal bending is observed at the mid-shaft, and bone stiffness is also maximal. The increased inclination leads to decreased stiffness and increased magnitude of maximum strain at the distal end of the femur. For comparative analysis of results, a three-dimensional, finite element model of the femur was used. To validate the finite element model, strain gauges and digital image correlation system were employed. During validation of the model, regression analysis indicated robust agreement between the measured and predicted strains, with high correlation coefficient and low root-mean-square error of the estimate. The results of stiffnesses obtained from multi-loading conditions experiments were qualitatively compared with results obtained from a finite element analysis of the validated model of femur with the same multi-loading conditions. When the obtained numerical results are qualitatively compared with experimental ones, similarities can be noted. The developed finite element model of femur may be used as a promising tool to estimate proximal femur strength and identify the best conditions for long-term functioning of the bone-implant system in future study.

The Characteristic of Prestressed Concrete Pier Seismic Crack

2014 ◽  
Vol 501-504 ◽  
pp. 1628-1632
Author(s):  
Hui Li Wang ◽  
Hong Wang ◽  
Si Feng Qin
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Prestressed Concrete ◽  
Three Dimensional ◽  
Element Model ◽  
Dimensional Finite Element ◽  
Tensile Zone ◽  
Three Dimensional Finite Element ◽  
Prestressed Reinforcement

Through three dimensional finite element analyzes, overall cast-in-place prestressed concrete pier seismic crack characteristic is researched. The separation formula finite element model is established by means of bilinear reinforce model and Kent-R.Park concretes model, without considering slip between concretes and. reinforce. It compares and analyzes the seismic crack characteristic between prestressed concrete pier and reinforcement concretes pier. The results show that the prestressed reinforcement can reduce the tensile zone of concrete, put off the appearance of cracks, improved the stiffness of pier, and reduced the top displacement.

Prestressed Time-Limited Aging Analyses of Concrete Containment Structure

2017 ◽  
Author(s):  
Dahua Cai ◽  
Yonghuan Wang ◽  
Jiangtao Zhang ◽  
Lin Yang ◽  
Hua Rong ◽  
...  
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Finite Element Model ◽  
Prestressed Concrete ◽  
Element Model ◽  
Test Results ◽  
Prestress Loss ◽  
Pressure Test ◽  
Key Factor ◽  
Over Time

For prestressed concrete containment structure, prestress loss is a key factor that affects the performance of containment structure. Therefore, prestressed time-limited aging analysis (TLAA) is essential for containment structures. The main objective of prestressed TLAA is to assess the safety of containment structures after prestress loss occurred over time. This paper takes the in-service containment structure as an example to investigate the method of TLAA for grounted prestressed containment structure. Firstly, it introduces methods for prestressed TLAA. Secondly, a finite element model of containment structure is established to calculate the minimum required value (MRV) of prestress. The numerical model is verified by the pressure test results. Thirdly, prestress loss of tendons is calculated. Finally, the residual prestress of tendons are compared with the MRV of prestress to confirm whether the containment can service in a certain period. This study can provide guidance for goouted prestressed TLAA of containment structures.

Finite Element Model for Analysis of Time-Dependent Behaviour of Concrete-Filled Steel Tubular Arches

2014 ◽  
Vol 553 ◽  
pp. 606-611
Author(s):  
Kai Luo ◽  
Yong Lin Pi ◽  
Wei Gao ◽  
Mark A. Bradford
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Nonlinear Analysis ◽  
Element Model ◽  
Time Dependent ◽  
Concrete Core ◽  
Time Dependent Behaviour ◽  
Linear And Nonlinear ◽  
Dependent Behaviour

This paper presents a finite element model for the linear and nonlinear analysis of time-dependent behaviour of concrete-filled steel tubular (CFST) arches. It is known when a CFST arch is subjected to a sustained load, the visco-elastic effects of creep in the concrete core will result in significant increases of the deformations and internal forces in the long-term. In this paper, a finite element model is developed using the age-adjusted effective modulus method to describe the creep behaviour of the concrete core. The finite element results of long-term displacement and stress redistribution agree very well with their analytical counterparts. The finite element model is then used to compare the linear and nonlinear results for the long-term behaviour of shallow CFST arches. It is demonstrated that the linear analysis underestimates the long-term deformations and internal force significantly and that to predict the time-dependent behaviour shallow CFST arches accurately, the nonlinear analysis is essential.

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