scholarly journals An Improved Equation for Predicting Compressive Stress in Posttensioned Anchorage Zone

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Young-Ha Park ◽  
Moon-Young Kim ◽  
Jong-Myen Park ◽  
Se-Jin Jeon
Keyword(s):  
Finite Element Method ◽  
Compressive Stress ◽  
Prestressed Concrete ◽  
Approximate Equation ◽  
The Finite Element Method ◽  
Concrete Member ◽  
Design Specifications ◽  
Compressive Stresses ◽  
Aashto Lrfd ◽  
Accurate Stress

Validity of the approximate equation for predicting compressive stress in the posttensioned anchorage zone presented in the AASHTO LRFD Bridge Design Specifications was investigated in this study. Numerical analysis based on the finite element method (FEM) and theoretical analysis showed that the AASHTO formula gives relatively accurate stress values when the effect of duct holes is neglected. However, it was found that the formula can significantly overestimate the stresses in the actual prestressed concrete member with spaces occupied by ducts. Therefore, an improved equation was proposed for the existing AASHTO equation to consider the effect of the duct holes on the stress distribution. This resulted in relatively accurate prediction of the distribution and magnitude of the compressive stresses even with the presence of the duct holes. The proposed equation was also validated by comparing with the stresses measured in the test of a posttensioned full-scale specimen. This study is expected to contribute to the design of the anchorage zone in prestressed concrete structures by suggesting a more reasonable way to assess the appropriateness of anchorage devices.

Effect Review of the Strengthening Technique by Use of the External Prestressing

2011 ◽  
Vol 121-126 ◽  
pp. 3258-3262
Author(s):  
Long Sheng Bao ◽  
Dan Yang ◽  
Ling Yu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cross Section ◽  
Prestressed Concrete ◽  
Measured Data ◽  
The Finite Element Method ◽  
Construction Monitoring ◽  
External Prestressing ◽  
Monitoring Result ◽  
Strengthening Technique

The grand bridge of Fu Feng is prestressed concrete cross-section continuous girder, which is reinforced with external prestressing. Construction monitoring is based on the measured data, and using the finite element method to calculate, it need to analyze the control of the stress and deflection in the construction to ensure to make the construction could be completed on schedule and to reach an ideal type. The field monitoring result indicates that the type of bridge did improve and reach the requirement of design after reinforcement.

scholarly journals A Parameter Sensitivity Analysis of the Effect of Rebar Corrosion on the Stress Field in the Surrounding Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Fangyuan Li ◽  
Wenya Ye
Keyword(s):  
Finite Element Method ◽  
Stress Field ◽  
Prestressed Concrete ◽  
Radial Displacement ◽  
Protective Layer ◽  
Fem Analysis ◽  
The Finite Element Method ◽  
Parameter Sensitivity Analysis ◽  
Ordinary Concrete ◽  
Rebar Corrosion

Rebar corrosion results in a change in the stress field in the surrounding concrete, which in turn accelerates the deterioration of the concrete structure. In addition to the protective layer, the compressive stress under which concrete is prestressed also affects the effect of corrosion-induced rebar expansion on the stress field in the concrete. The present study simulates the effect of corrosion-induced rebar expansion on the stress field in the concrete using the finite element method (FEM) by applying a virtual radial displacement to the product of corrosion-induced rebar expansion. Based on an analysis of the effect of multiple rebars on the stress field in ordinary concrete, stress distribution in the protective layer of the concrete is determined. Afterward, the locations where there is damage to the surface concrete caused by rebar corrosion are determined. After verifying the feasibility of the FEM analysis, the effect of corrosion-induced ordinary rebar expansion in a typical prestressed concrete segment is determined by analyzing the characteristics of corrosion-induced rebar expansion occurring in various prestressed concrete specimens.

scholarly journals Prediction and optimization of thinning in automotive sealing cover using Genetic Algorithm

2015 ◽  
Vol 3 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Ganesh M. Kakandikar ◽  
Vilas M. Nandedkar
Keyword(s):  
Genetic Algorithm ◽  
Finite Element Method ◽  
Finite Element ◽  
Process Parameters ◽  
Deep Drawing ◽  
Drawing Process ◽  
The Finite Element Method ◽  
Deep Drawing Process ◽  
Compressive Stresses ◽  
Element Method

Abstract Deep drawing is a forming process in which a blank of sheet metal is radially drawn into a forming die by the mechanical action of a punch and converted to required shape. Deep drawing involves complex material flow conditions and force distributions. Radial drawing stresses and tangential compressive stresses are induced in flange region due to the material retention property. These compressive stresses result in wrinkling phenomenon in flange region. Normally blank holder is applied for restricting wrinkles. Tensile stresses in radial direction initiate thinning in the wall region of cup. The thinning results into cracking or fracture. The finite element method is widely applied worldwide to simulate the deep drawing process. For real-life simulations of deep drawing process an accurate numerical model, as well as an accurate description of material behavior and contact conditions, is necessary. The finite element method is a powerful tool to predict material thinning deformations before prototypes are made. The proposed innovative methodology combines two techniques for prediction and optimization of thinning in automotive sealing cover. Taguchi design of experiments and analysis of variance has been applied to analyze the influencing process parameters on Thinning. Mathematical relations have been developed to correlate input process parameters and Thinning. Optimization problem has been formulated for thinning and Genetic Algorithm has been applied for optimization. Experimental validation of results proves the applicability of newly proposed approach. The optimized component when manufactured is observed to be safe, no thinning or fracture is observed.

scholarly journals Distribution of stress on TMJ disc induced by use of chincup therapy: assessment by the finite element method

2017 ◽  
Vol 22 (5) ◽  
pp. 83-89
Author(s):  
Flávio Siqueira Calçada ◽  
Antônio Sérgio Guimarães ◽  
Marcelo Lucchesi Teixeira ◽  
Flávio Atsushi Takamatsu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Inferior Surface ◽  
Compressive Stresses ◽  
Mandibular Plane ◽  
Tmj Disc ◽  
Distribution Of Stress ◽  
Element Method

ABSTRACT Objective: To assess the distribution of stress produced on TMJ disc by chincup therapy, by means of the finite element method. Methods: a simplified three-dimensional TMJ disc model was developed by using Rhinoceros 3D software, and exported to ANSYS software. A 4.9N load was applied on the inferior surface of the model at inclinations of 30, 40, and 50 degrees to the mandibular plane (GoMe). ANSYS was used to analyze stress distribution on the TMJ disc for the different angulations, by means of finite element method. Results: The results showed that the tensile and compressive stresses concentrations were higher on the inferior surface of the model. More presence of tensile stress was found in the middle-anterior region of the model and its location was not altered in the three directions of load application. There was more presence of compressive stress in the middle and mid-posterior regions, but when a 50o inclined load was applied, concentration in the middle region was prevalent. Tensile and compressive stresses intensities progressively diminished as the load was more vertically applied. Conclusions: stress induced by the chincup therapy is mainly located on the inferior surface of the model. Loads at greater angles to the mandibular plane produced distribution of stresses with lower intensity and a concentration of compressive stresses in the middle region. The simplified three-dimensional model proved useful for assessing the distribution of stresses on the TMJ disc induced by the chincup therapy.

Test and Design of Tensile-Compression Prestressed Concrete Beam

2011 ◽  
Vol 71-78 ◽  
pp. 722-727 ◽  
Author(s):  
Jing Bo An
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Prestressed Concrete ◽  
Concrete Structure ◽  
Concrete Beam ◽  
Steel Tube ◽  
The Finite Element Method ◽  
Ansys Software ◽  
Prestressed Concrete Beam ◽  
Pressure Area

In this paper, the tensile-compression prestressed concrete beam was researched, and gets deflection of the beam subjected to load. Then, the beam was analyzed by the finite element method of ANSYS software. The test and analysis results show that the beam has a good flexibility and the phenomenon of stress concentration were appeared in ends concrete of pre-compressed steel tube. The pre-compressed steel tube control stress is 0.5 times the nominal value of steel tube, the concrete pre-tensile stress can be obtained effectively by relaxes pre-compressed steel tube. This paper further optimizes the dosage of pre-tensile tendon (Ap), pre-compressed steel tube (AT), tensile reinforcements (As)and compression reinforcements (A`s).The results from example show that the concrete structure of tensile-compression prestressed can reduce the pressure area height of the beam effectively and solving conventional prestressed concrete structure excessive or cannot reinforcement in pressure area.

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