scholarly journals Finite Element Modeling of FRP-Strengthened RC Beam under Sustained Load

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Shiyong Jiang ◽  
Weilai Yao ◽  
Jin Chen ◽  
Tao Cai
Keyword(s):  
Finite Element ◽  
Field Performance ◽  
Adhesive Layer ◽  
Aging Effect ◽  
Time Dependent ◽  
Sustained Load ◽  
Fe Model ◽  
Rc Beam ◽  
Long Term Behavior

External bonding of FRP laminates to the tension soffit of concrete members has become a popular method for flexural strengthening. However, the long-term field performance of FRP-strengthened RC members under service conditions is still a concern, and more work needs to be done. Based on concrete smeared-crack approach, this paper presents a finite-element (FE) model for predicting long-term behavior of FRP-strengthened RC beam, which considers the time-dependent properties of all components including the aging effect of concrete. According to the comparison between theoretical predictions and test results, the validity of the FE model is verified. The interfacial edge stresses in adhesive layer were determined through appropriate mesh refinement near the plate end, and their time-dependent characteristics were investigated. The results show that creep of concrete and epoxy resin cause significant variations of the edge stresses with time. According to the research in this paper, the FE approach is found to be able to properly simulate the long-term behavior of the FRP-strengthened beam and help us better understand the complex changes in the stress state occurring over time.

Modeling of the Long-Term Behavior of Glassy Polymers

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Sami Holopainen ◽  
Mathias Wallin
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Glassy Polymers ◽  
Integration Scheme ◽  
Element Formulation ◽  
Algebraic Equations ◽  
Plastic Spin ◽  
Backward Euler ◽  
Long Term Behavior

The constitutive model for glassy polymers proposed by Arruda and Boyce (BPA model) is reviewed and compared to experimental data for long-term loading. The BPA model has previously been shown to capture monotonic loading accurately, but for unloading and long-term behavior, the response of the BPA model is found to deviate from experimental data. In the present paper, we suggest an efficient extension that significantly improves the predictive capability of the BPA model during unloading and long-term recovery. The new, extended BPA model (EBPA model) is calibrated to experimental data of polycarbonate (PC) in various loading–unloading situations and deformation states. The numerical treatment of the BPA model associated with the finite element analysis is also discussed. As a consequence of the anisotropic hardening, the plastic spin enters the model. In order to handle the plastic spin in a finite element formulation, an algorithmic plastic spin is introduced. In conjunction with the backward Euler integration scheme use of the algorithmic plastic spin leads to a set of algebraic equations that provides the updated state. Numerical examples reveal that the proposed numerical algorithm is robust and well suited for finite element simulations.

Viscoelastic Finite Element Modeling of Bimodal High Density Polyethylene (HDPE) Piping Materials for Nuclear Safety-Related Applications

2010 ◽  
Author(s):  
Do-Jun Shim ◽  
Prabhat Krishnaswamy ◽  
Yunior Hioe ◽  
Sureshkumar Kalyanam
Keyword(s):  
Finite Element ◽  
Service Life ◽  
High Density Polyethylene ◽  
Viscoelastic Behavior ◽  
Time Dependent ◽  
Tensile Creep ◽  
Uniaxial Tensile ◽  
Fe Model ◽  
Creep Tests ◽  
Uniaxial Tensile Creep

The U.S. Nuclear Regulatory Commission (USNRC) has recently approved Relief Requests for the use of high density polyethylene (HDPE) piping in safety-related applications. The ASME Boiler and Pressure Vessel Code, meanwhile, has developed Code Case N-755 that defines the design and service life requirements for PE piping in nuclear plants though it has not as yet been approved by the USNRC. One of the issues of concern is premature failure of PE piping due to slow crack growth (SCG) that can initiate due to a combination of sustained loads, elevated temperatures, and a pre-existing defect. Understanding and predicting the SCG behavior is an essential step in developing a methodology for predicting the service life of PE piping. The first step in studying the failure process in a polymer under a constant sustained load is the selection of a suitable constitutive model to represent the time-dependent behavior of the material. In this paper, uniaxial tensile creep tests were performed for a bimodal HDPE (PE4710) piping material. This creep data was used to determine the viscoelastic material constants for this bimodal HDPE using a power-law creep model. These material constants were used in finite element (FE) analyses to study the viscoelastic behavior of the bimodal HDPE. As a first step, the FE model was verified by comparing the results from numerical simulations and experiments for a set of uniaxial tensile creep tests. The FE model was then applied to study the viscoelastic behavior of a SCG specimen. The time dependent stress and strain fields were investigated.

Long term behavior of FRC flexural beams under sustained load

2013 ◽  
Vol 56 ◽  
pp. 1858-1867 ◽  
Author(s):  
Emilia Vasanelli ◽  
Francesco Micelli ◽  
Maria Antonietta Aiello ◽  
Giovanni Plizzari
Keyword(s):  
Sustained Load ◽  
Long Term Behavior

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.

Lessons Learned From Operational Integrity of HP/HT Deepwater Pipelines

2019 ◽  
Author(s):  
Carlos O. Cardoso ◽  
Rafael F. Solano ◽  
Bruno R. Antunes
Keyword(s):  
Finite Element ◽  
High Pressures ◽  
Compressive Load ◽  
Lessons Learned ◽  
Fe Model ◽  
Special Device ◽  
Original Design ◽  
Element Analysis ◽  
Lateral Displacements

Abstract This paper addresses the results from a monitoring inspection as part of Petrobras regular plane of inspection of rigid pipelines (PIDR) and numerical Finite Element analysis (FEA) of two parallel HP/HT subsea pipelines operating in Brazilian deepwater subjected to lateral buckling and walking behaviors. The results obtained from inspection and numerical reanalysis furnishes important feedback for the integrity management of the two pipelines, reducing potential risks and lessons learned for future projects. Deepwater pipelines submitted to high pressures and temperatures (HP/HT) are susceptible to global buckling due to axial compressive load. To guarantee pipeline and equipment’s integrity frequently is necessary to relieve high stresses and strains at buckle apex as well as to mitigate end expansion. Thus, the two parallel HP/HT pipelines were designed with single and double sleepers to trigger buckles at pre-determined locations and an anchoring system to prevent pipeline walking. Another important design aspect was to avoid undesirable buckles at the several crossings along the pipeline route applying a special device with stoppers to lock lateral displacements. During a programmed inspection as part of regular Petrobras pipeline integrity program of rigid pipelines (PIDR), it has been verified that some double sleepers didn’t work as foreseen in design. Otherwise, some unplanned buckles on soil have been formed along the two pipelines changing the buckle apex stress levels and end expansions foreseen in detailed design. In order to understand buckle formation behavior and guarantee long-term integrity of the HP/HT pipelines a Multi-Beam Echosounder Survey (MBES) was conducted in 2016 to build a representative Finite Element (FE) model. The temperature and pressure gradients from steady state and transient conditions were obtained from flow assurance simulations based on monitored platform operational historic data. The FE model was calibrated with buckle shapes and end displacements to assess pipeline behavior and its long-term integrity for load scenarios different from original design.

A SLOT-CUTTING TECHNIQUE FOR REPAIR AND REHABILIATION OF CONCRETE DAMS AFFECTED BY ALKALI-SILICA REACTION

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Mohammad S. Pourbehi ◽  
Breda Strasheim
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Economic Consequences ◽  
Structural Safety ◽  
Alkali Silica Reaction ◽  
Fe Model ◽  
Concrete Dams ◽  
Before And After ◽  
Slot Cutting

The combined impacts of earthquake damage and aging of concrete material on vulnerable aged dam systems have been typical causes of structural failure. The possible malfunction or loss of these vital systems and components can have serious socio-economic consequences and impacts on potable water resource availability, crop irrigation, and electric power generation. Worldwide extensive work has been done to evaluate the structural safety of aged concrete dam system components and to develop suitable remedial action and rehabilitation strategies. This paper reports a Chemo-Thermo-Mechanical Finite Element model developed by the authors which was used to demonstrate the use of the Finite Element Method (FEM) to model the behavior of a synthetic dam if the concrete is affected by Alkali-Silica Reaction (ASR), applying the slot cutting rehabilitation technique. ASR is a destructive chemical reaction between the cement paste and siliceous aggregate components in concrete materials that causes long-term expansion and degradation of concrete structures, including dams. Slot cutting is recognized as one of the promising techniques suitable to repair concrete dams suffering from ASR. The results show that the FE model could predict the stress and displacement field before and after the sawing of the slot in an assumed dam affected by ASR and demonstrate a promising capability for modeling the repair strategies in real dams suffering from ASR.

Long-Term Investigations of Metal Seals for Storage Casks of Radioactive Materials

2016 ◽  
Author(s):  
Sven Nagelschmidt ◽  
Ulrich Probst ◽  
Holger Völzke ◽  
Dietmar Wolff
Keyword(s):  
Numerical Models ◽  
Safety Evaluation ◽  
Aging Effect ◽  
Experimental Investigations ◽  
Radioactive Materials ◽  
Federal Institute ◽  
Materials Research ◽  
Long Term Behavior ◽  
Analytical Approaches

The Bundesanstalt für Materialforschung und –prüfung (BAM) is a federal institute for materials research and testing in Germany and has been involved in the qualification and safety evaluation procedures of metal seals from the early beginning of the interim storage licensing procedures for radioactive materials, stored in dual purpose casks. Regarding this subject, BAM investigates the long-term behavior of metal seals under the influence of temperature using experimental data and analytical approaches. The development of numerical models is in progress as well. Systematic experimental investigations performed by BAM indicate a continuous decrease of the remaining seal force and the usable resilience considering the leak tightness. Hence, there is a fundamental interest of describing time and temperature dependency to gain predictable values for the long-term behavior and to achieve reliable results with help of short-term tests. The paper gives an overview about the sealing principle, test program and test results of metal seals of the type HELICOFLEX® HN200. The aging effect, respectively the long-term behavior in dependency of time and temperature, are introduced for two different outer liner materials, aluminum and silver.

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