scholarly journals Finite element simulation and multi-factor stress prediction model for cement concrete pavement considering void under slab

2021 ◽  
Author(s):  
Liu Bangyi ◽  
Huang Xiaoming
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Maximum Tensile Stress ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Void Size ◽  
Tensile Stresses ◽  
The Impact

Uneven support as result of voids beneath concrete slabs can lead to high tensile stresses at the corner of the slab and eventually cause many forms of damage, such as cracking or faulting. Three-dimensional (3D) finite element models of the concrete pavement with void are presented. The accuracy of the model is verified by two methods. The analysis shows that the impact of void size and void depth at the slab corner on the slab stress are similar, which result in the change of the position of the maximum tensile stress. The maximum tensile stresses do not increase with the increase of the void size for relatively small void size. The maximum tensile stress increases rapidly with the enlargement in the void size when the size≥0.4m. The increments of maximum tensile stress can reach 183.7% when the void size are 1.0m. The increase of slab thickness can effectively reduce maximum tensile stress. A function is established to calculate the maximum tensile stress of the concrete slab. The function takes into account the void size and the slab thickness. The reliability of the function was verified by comparing the error between the calculated and simulated results.

scholarly journals Finite Element Simulation and Multi-Factor Stress Prediction Model for Cement Concrete Pavement Considering Void under Slab

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5294
Author(s):  
Bangyi Liu ◽  
Yang Zhou ◽  
Linhao Gu ◽  
Xiaoming Huang
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Mesh Size ◽  
Maximum Tensile Stress ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Void Size ◽  
Tensile Stresses

Uneven support as result of voids beneath concrete slabs can lead to high tensile stresses at the corner of the slab and eventually cause many forms of damage, such as cracking or faulting. Three-dimensional (3D) finite element models of the concrete pavement with void are presented. Mesh convergence analysis was used to determine the element type and mesh size in the model. The accuracy of the model is verified by comparing with the calculation results of the code design standards in China. The reliability of the model is verified by field measurement. The analysis shows that the stresses are more affected at the corner of the slab than at the edge. Impact of void size and void depth at the slab corner on the slab stress are similar, which result in the change of the position of the maximum tensile stress. The maximum tensile stresses do not increase with the increase in the void size for relatively small void size. The maximum tensile stress increases rapidly with the enlargement in the void size when the size is ≥0.4 m. The increments of maximum tensile stress can reach 183.7% when the void size is 1.0 m. The increase in slab thickness can effectively reduce maximum tensile stress. A function is established to calculate the maximum tensile stress of the concrete slab. The function takes into account the void size, the slab thickness and the vehicle load. The reliability of the function was verified by comparing the error between the calculated and simulated results.

Analysis on the Influence of Dowel Bar at Joints on Load Stress of Pavement Slab in the Pumping Area

2011 ◽  
Vol 243-249 ◽  
pp. 4075-4079
Author(s):  
Bin Yang ◽  
Chung Tong Cheng ◽  
Li Fang Huang
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Element Model ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Void Size ◽  
3D Finite Element ◽  
Nonlinear Growth ◽  
Dowel Bar ◽  
The Relationship

A 3D finite element model is used to investigate the state of load stress developed in concrete pavement with dowel bar under the effect of typical pavement damages of pumping area of slab corner and pumping area of transverse joints edge. The results indicate that slab corner stress tends to decrease with the increase of slab thickness and possesses a nonlinear growth as pumping area increases; when the pumping area of slab corner is less than 1.5m×1.5m, the maximum pavement slab tensile stress is less than or close to the load stress in critical loading position. Stress in transverse joints edge also grows in a nonlinear tendency and axle load also grows gradually with the expansion of pumping area, of which the slope of the curve in the relationship between stress and void size is much greater. Whether it is a pumping area of slab corner or pumping area of transverse joints edge, pavement slab deformation and stress are significantly reduced after setting the dowel bar. Therefore, dowel bar can improve the stress state of concrete pavement obviously.

Load Stress Analysis of the Impact of Parameters Variation on Super-Thick Cement Concrete Pavement

2011 ◽  
Vol 255-260 ◽  
pp. 3254-3257 ◽  
Author(s):  
Bin Yang ◽  
Li Jun Suo ◽  
Chun Ren Zhou ◽  
Kai Liang Dong
Keyword(s):  
Concrete Slab ◽  
Element Model ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Structure Parameters ◽  
Cement Concrete ◽  
Obvious Effect ◽  
Cement Concrete Pavement ◽  
Pavement Structure ◽  
The Impact

With the goal of exploring the impact of pavement structure parameters on load stress of super-thick cement concrete pavement, this paper, based on the Quanxing freeway in Guangxi, analyzes the load stress in the situation of the separated type and combined type contact between the cement concrete slab and the lean concrete base by using three-dimensional finite element model. Computational results show that the variation of different pavement structure parameters have various impacts on the load stress of super-thick cement concrete pavement. The load stress σc1 of super-thick cement concrete pavement slab declines with the increase of slab thickness h1 and base thickness h2 and decreases with the reduction of slab length L and the increases of base modulus E2 and subbase modulus Et. Among them, the variation of slab thickness h1 has the greatest impact on the pavement load stress. Thus, there is a quite obvious effect in reducing the pavement load stress by increasing the slab thickness.

scholarly journals COMPUTER TECHNOLOGIES FOR CONCRETE AIRFIELD PAVEMENT DESIGN

Aviation ◽  
2018 ◽  
Vol 21 (3) ◽  
pp. 111-117 ◽  
Author(s):  
Oleksandr RODCHENKO
Keyword(s):  
Tensile Stress ◽  
Computer Program ◽  
Concrete Slab ◽  
Pavement Design ◽  
Empirical Formulas ◽  
Design Factor ◽  
Tensile Stresses ◽  
Pavement Thickness ◽  
Analysis Models ◽  
The Impact

The purpose of the research is to develop formulas, expressions and a computer program for concrete airfield pavement design under the impact of all Airbus 380 main landing gears taking into consideration the design factor of tensile stresses at the top and bottom of a concrete slab. The top-down cracking in concrete slabs has not been directly simulated in structural analysis models used for one- and two-layer concrete airfield pavement design by the Ukrainian Standard. Empirical formulas for the calculation of top tensile stress and the coverages to failure using the criterion of top tensile stress are obtained. Computer program “Aerodrom 380” has been developed for the design of concrete airfield pavement thickness. It provides the required thickness of a concrete slab needed to support an Airbus 380 over a particular subgrade and uses the bottom and top tensile stresses as design factors. “Aerodrom 380” contains a fatigue function for determining the number of coverages to failure permissible for a concrete slab before it has top-bottom and bottom-up cracks. The results obtained with this program are compared to other solutions using the Ukrainian Standard SNiP 2.05.08–85, “LIRA-SAPR”, software and the FAARFIELD computer program. The anticipated life of a concrete airfield pavement calculated using computer program “Aerodrom 380” is about 70% of the FAARFIELD pavement life.

Spreadsheet Tool for Quick-Turn 3D Numerical Modeling of Package Thermal Performance With Non-Uniform Die Heating

2001 ◽  
Author(s):  
Abhay A. Watwe ◽  
Ravi S. Prasher
Keyword(s):  
Finite Element ◽  
Numerical Modeling ◽  
Finite Volume ◽  
Thermal Performance ◽  
Three Dimensional ◽  
3D Numerical Modeling ◽  
Conventional Analysis ◽  
Time Required ◽  
The Impact ◽  
Fourier Equation

Abstract Traditional methods of estimating package thermal performance employ numerical modeling using commercially available finite-volume or finite-element tools. Use of these tools requires training and experience in thermal modeling. This methodology restricts the ability of die designers to quickly evaluate the thermal impact of their die architecture due to the added throughput time required to enlist the services of a thermal analyst. This paper describes the development of an easy to use spreadsheet tool, which performs quick-turn numerical evaluations of the impact of non-uniform die heating. The tool employs well-established finite-volume numerical techniques to solve the steady-state, three-dimensional Fourier equation of conduction in the package geometry. Minimal input data is required and the inputs are customized using visual basic pull-down menus to assist die designers who may not be thermal experts. Data showing comparison of the estimates from the spreadsheet tool with that obtained from a conventional analysis using the commercially available finite element code ANSYS™ is also presented.

Backcalculation of Thermally Deformed Concrete Pavements

2000 ◽  
Vol 1716 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Samir N. Shoukry
Keyword(s):  
Thermal Gradient ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Plain Concrete ◽  
Slab Thickness ◽  
Fe Model ◽  
Concrete Pavements ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Falling Weight

Nonlinear explicit three-dimensional finite element (3-D FE) modeling is used to investigate the performance of the falling weight deflectometer (FWD) test in the evaluation of layer moduli of jointed plain concrete pavements (JPCP) subjected to nonlinear thermal gradient through the slab thickness. Concrete slab separation from the base, in-plane friction at the concrete-base interface, the gravitational forces, and the interface characteristics between dowel bars and surrounding concrete are all represented in the 3-D FE model. Experimental verification of the model is obtained through comparison of the 3-D FE generated response to ( a) the FWD measured deflection basin and ( b) the measured response of an instrumented rigid pavement section located in Ohio to a loaded truck moving at 21.8 m/s (48 mph). Several cases of linear and nonlinear thermal gradients are applied to the model, and deflection basins are obtained. Two backcalculation programs, MODULUS 5.0 and EVERCALC 4.0, are used for prediction of the layer moduli in each case, and the values are compared. The results indicate that thermal curling of the slab due to negative thermal gradient has little effect on the accuracy of backcalculated moduli. Warping of the slab due to positive thermal gradient greatly influences the measured FWD deflection basin and leads to significant errors in the backcalculated moduli. These errors may be minimized if the time an FWD test is conducted falls between the late afternoon and midmorning (from 5:30 p.m. to 9:30 a.m. during summer in West Virginia).

Maximum Stress at Intersecting Bores of Pressurized Blocks

1994 ◽  
Author(s):  
Ajay Garg
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Stress ◽  
Element Model ◽  
Maximum Tensile Stress ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Empirical Methods ◽  
Element Analysis ◽  
Matched Design

Abstract In high pressure applications, rectangular blocks of steel are used instead of cylinders as pressure vessels. Bores are drilled in these blocks for fluid flow. Intersecting bores with axes normal to each other and of almost equal diameters, produce stresses which can be many times higher than the internal pressure. Experimental results for the magnitude of maximum tensile stress along the intersection contour were available. A parametric finite element model simulated the experimental set up, followed by correlation between finite element analysis and experimental results. Finally, empirical methods are applied to generate models for the maximum tensile stress σ11 at cross bores of open and close ended blocks. Results from finite element analysis and empirical methods are further matched. Design optimization of cross bores is discussed.

scholarly journals New Design Procedure of Transtibial ProsthesisBed Stump Using Topological Optimization Method

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1837 ◽  
Author(s):  
Martin Sotola ◽  
David Stareczek ◽  
David Rybansky ◽  
Jiri Prokop ◽  
Pavel Marsalek
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Design Procedure ◽  
Optimization Method ◽  
Topological Optimization ◽  
Element Analysis ◽  
Current Application ◽  
Transtibial Prosthesis ◽  
Walking Biomechanics ◽  
The Impact

This paper presents a new design procedure for production of a transtibial prosthesis bed stump by three-dimensional (3D) printing with topological optimization. The suggested procedure combines the medical perspective with finite element analysis and facilitates regaining the symmetry in patients with transtibial prosthesis, which leads to life improvement. The particular focus of the study is the weight reduction of the lower part of the bed stump, while taking into account its stiffness and load-bearing capacity. The first part of the work deals with the analysis of the subject geometry of the bed stump, which is usually oversized in terms of the weight and stiffness that are necessary for the current application. In the second part, an analysis of walking biomechanics with a focus on the impact and rebound phases is presented. Based on the obtained information, a spatial model of the lower part of the bed stump is proposed in the third phase, in which the finite element method is described. In the fourth part, the topological optimization method is used for reducing the structure weight. In the last part, the results of the designed model are analyzed. Finally, the recommendations for the settings of the method are presented. The work is based on the practical industry requirements, and the obtained results will be reflected in the design of new types of transtibial prosthesis.

Finite-element analysis of multi-body contacts for pile driving using a hydraulic pile hammer

2011 ◽  
Vol 225 (5) ◽  
pp. 1153-1161 ◽  
Author(s):  
Y Guo ◽  
J P Hu ◽  
L Y Zhang
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Test Point ◽  
Pile Driving ◽  
Penalty Function Method ◽  
Three Dimensional Model ◽  
Element Analysis ◽  
Material Choice ◽  
Multi Body ◽  
The Impact

This article treats the pile driving as multi-body dynamic contacts. By using the penalty function method and three-dimensional model of finite-element method, the dynamic process of pile driving is acquired and a method for choosing the cushion material of the hydraulic pile hammer to improve driving efficiency is proposed. The process of pile driving in the real situation of an industrial experiment is simulated. The results of stress on test point are consistent with the test point. By analysing the stress distributed along the direction of pile radius and pile axis, the rule of the stress distribution on the pile is concluded. The rule for cushion material choice is obtained by comparing the influence for the impact stress with different elastic modulus ratio of the hammer cushion to the pile and the pile cushion to the pile.

Probabilistic Analysis of Highway Pavement Life for Illinois

2003 ◽  
Vol 1823 (1) ◽  
pp. 111-120 ◽  
Author(s):  
Nasir G. Gharaibeh ◽  
Michael I. Darter
Keyword(s):  
Reinforced Concrete ◽  
Probabilistic Analysis ◽  
Asphalt Concrete ◽  
Geographic Location ◽  
Concrete Pavement ◽  
Pavement Management ◽  
Slab Thickness ◽  
Probability Of Survival ◽  
Load Carrying ◽  
The Impact

The Illinois Department of Transportation has periodically conducted pavement longevity studies to assess the longevities and the traffic loadcarrying capacities of these new and rehabilitated pavements so that any needed improvements to design, construction, or rehabilitation could be identified and implemented in a timely manner. The results of the latest round of pavement longevity studies in Illinois provide performance data updated through 2000 for new hot-mix asphalt concrete (HMAC), jointed reinforced concrete pavement (JRCP), and continuously reinforced concrete pavement (CRCP) construction as well as the asphalt concrete (AC) overlays (first, second, and third overlays) of these original pavements. These studies were conducted on more than 2,000 centerline miles of Interstate and other freeways that were constructed beginning in the 1950s in Illinois. Significant findings on the performance of the original pavements and overlays were obtained, and these findings will be of value to designers and managers to improve pavement cost-effectiveness and life. Survival curves have an economic impact on the agency. Key findings show the impact of pavement type (HMAC, JRCP, or CRCP), slab thickness, geographic location (north or south), durability cracking (D-cracking), and AC overlay thickness (coupled with preoverlay condition) on longevity and load-carrying capacity. The results of the probabilistic analysis illustrate the wide variation in pavement life and traffic carried. The study also provides models for predicting the probability of survival for various designs of original pavements and AC overlays in Illinois for use in pavement management.

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