Using the Asphalt Pavement Layer Condition Assessment Program: Case Studies

2003 ◽  
Vol 1860 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Bing Xu ◽  
S. Ranji Ranjithan ◽  
Y. Richard Kim
Keyword(s):  
Case Studies ◽  
Asphalt Pavement ◽  
Compressive Strain ◽  
Dynamic Effect ◽  
Field Measurements ◽  
Condition Assessment ◽  
Base Layer ◽  
Element Analysis ◽  
Condition Indicators ◽  
Assessment Program

The Asphalt Pavement Layer Condition Assessment Program (APLCAP) is developed in this research to help highway agencies assess layer conditions of asphalt pavements. APLCAP implements a new integrated procedure for condition assessment from falling-weight deflectometer (FWD) deflections. The main components of this procedure include screening of FWD raw deflections, predictions of condition indicators from FWD measurements, structural adjustments for the predicted condition indicators, and layer condition evaluation based on the adjusted condition indicators. This procedure was developed on the basis of dynamic nonlinear finite element analysis and calibrated using field measurements. The three case studies presented show that the APLCAP algorithms can predict the asphalt concrete modulus, pavement critical strains, and strengths of the base and subgrade quite well, but not the compressive strain in the aggregate base layer. Although the APLCAP procedure includes the complicated dynamic effect of FWD loading and nonlinear behavior of unbound materials, the time to obtain results from this procedure is insignificant and therefore suitable for real-time evaluation of pavement conditions.

Rebuilding of a Large Single Hull Tank Barge into Double Hull

2005 ◽  
Author(s):  
Michael R. Kloesel ◽  
Robert J. Norton ◽  
Thomas R. Hagner
Keyword(s):  
Case Studies ◽  
Condition Assessment ◽  
Interesting Case ◽  
Assessment Program ◽  
Double Hull

This paper presents Maritrans’ groundbreaking experience in rebuilding very large single hull barges into OPA- 90 compliant double hull barges. Details of the process are described along with interesting case studies involving aspects of analysis and construction. The process by which the American Bureau of Shipping certified this barge to be a “Grade 1” under the ABS SafeHull Condition Assessment Program is described in detail. There is a brief discussion of extending this rebuild process to the double hulling of tankers.

scholarly journals Influence of Modulus of Base Layer on The Strain Distribution for Asphalt Pavement

2021 ◽  
Vol 16 (4) ◽  
pp. 126-152
Author(s):  
Kang Yao ◽  
Xin Jiang ◽  
Jin Jiang ◽  
Zhonghao Yang ◽  
Yanjun Qiu
Keyword(s):  
Strain Distribution ◽  
Tensile Strain ◽  
Asphalt Pavement ◽  
Compressive Strain ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Element Model ◽  
Neutral Axis ◽  
Base Layer ◽  
Maximum Tensile Strain

In order to investigate the influence of modulus of the base layer on the strain distribution for asphalt pavement, the modulus ratio of the base layer and the AC layer (Rm) is introduced as a controlled variable when keeping modulus of the AC layer as a constant in this paper. Then, a three-layered pavement structure is selected as an analytical model, which consists of an AC layer with the constant modulus and a base layer with the variable modulus covering the subgrade. A three dimensional (3D) finite element model was established to estimate the strains along the horizontal and vertical direction in the AC layer under different Rm. The results show that Rm will change the distribution of the horizontal strains along the depth in the AC layer; the increase of Rm could reduce the maximum tensile strain in the AC layer, but its effect is limited; the maximum tensile strain in the AC layer does not necessarily occur at the bottom, but gradually rises to the middle with the increase of Rm. Rm could significantly decline the bottom strain in the AC layer, and there is a certain difference between the bottom and the maximum strain when Rm is greater than or equal to one, which will enlarge with increasing Rm. Rm could change the depth of the neutral axis in the AC layer, and the second neutral axis will appear at the bottom of the AC layer under a sufficiently large Rm. The average vertical compressive strain in the AC layer will significantly enlarge with the increase of Rm.

scholarly journals Response Characteristics of Inverted-base Asphalt Pavement Structure in Cold Area under Multi-axle Loads

2020 ◽  
Vol 7 (4) ◽  
pp. 141-146
Author(s):  
Lin Wang ◽  
Chao Shan ◽  
Chuanfeng Zheng
Keyword(s):  
Tensile Stress ◽  
Asphalt Pavement ◽  
Base Layer ◽  
Rigid Base ◽  
Element Analysis ◽  
The Road ◽  
Response Characteristics ◽  
Pavement Structure ◽  
Axle Loads ◽  
Base Course

In cold areas, semi-rigid base asphalt pavement is prone to generate reflection cracks due to thermal contraction and dry shrinkage, and the base layer cracks can cause surface layer cracking and shorten the service life of the pavement. Aiming at understanding the response characteristics of asphalt pavement structure under multi-axle loads in cold areas, this paper took semi-rigid base asphalt pavement and inverted-base asphalt pavement as the research objects, and employed ANSYS to conduct finite element analysis on them to figure out the response characteristics of the asphalt pavement structure under the condition of different multi-axle loads and graded macadam base course. The research results showed that, the action of multi-axal loads increased the tensile stress of the base layer of the asphalt pavement and the tensile stress of the base layer of the semi-rigid base asphalt pavement, and increased the road surface deflection, which had resulted in insufficient bearing capacity of the pavement structure, and thus causing significant damages to the asphalt pavement; analysis of the response characteristics of the two types of asphalt pavement showed that, adding a graded macadam base course as the stress-absorbing layer is conductive to reducing the tensile stress of the base layer of the semi-rigid base asphalt pavement and effectively delaying or inhibiting reflection cracks generating on the pavement. The study of this paper provided a theoretical reference for the design and construction of asphalt pavement.

scholarly journals Comparison of Mechanical Impedance Methods for Vibration Simulation

1996 ◽  
Vol 3 (3) ◽  
pp. 223-232 ◽  
Author(s):  
Jeffrey A. Gatscher ◽  
Grzegorz Kawiecki
Keyword(s):  
Mechanical Impedance ◽  
Field Measurements ◽  
Cumulative Damage ◽  
Vibration Test ◽  
Element Analysis ◽  
Impedance Measurements ◽  
Testing Strategies ◽  
Impedance Testing ◽  
Vibration Simulation ◽  
Test Requirements

The work presented here explored the detrimental consequences that resulted when mechanical impedance effects were not considered in relating vibration test requirements with field measurements. The ways in which these effects can be considered were evaluated, and comparison of three impedance methods was accomplished based on a cumulative damage criterion. A test structure was used to simulate an equipment and support foundation system. Detailed finite element analysis was performed to aid in computation of cumulative damage totals. The results indicate that mechanical impedance methods can be effectively used to reproduce the field vibration environment in a laboratory test. The establishment of validated computer models, coupled with laboratory impedance measurements, can eliminate the overtesting problems inherent with constant motion, infinite impedance testing strategies.

Analysis of Weighting Coefficients of Post-Assessment Indexes for Cold Recycling Engineering of Asphalt Pavement Based on Hierarchy Analytic Procedure

2012 ◽  
Vol 204-208 ◽  
pp. 1857-1863
Author(s):  
Min Jiang Zhang ◽  
Wen Bo Zhang ◽  
Bao Yang Yu
Keyword(s):  
Asphalt Pavement ◽  
Base Layer ◽  
Environmental Benefit ◽  
Analytic Hierarchy ◽  
Analytic Procedure ◽  
The Road ◽  
Technology Project ◽  
Recycling Technology ◽  
Cold Recycling ◽  
Post Assessment

Based on the theory of hierarchy analysis, the post-assessment indexes system of cold recycling technology project have been established, and the hierarchy analytic procedure have been used to determine the weighing coefficients for post-assessment indexes of cold recycling engineering of asphalt pavement, and the weighing values for various levels factors were given for the cold recycling base layer project of highway of Shenyang-Yingkou. Considering the road performance and economic benefit, societal and environmental benefit, the analytic hierarchy procedure (AHP) method can effectively avoid making wrong decisions subjectively and made it more scientific and reasonable to determine the weighing values of post-assessment indexes, and it is an effective method to determine the weighing values for post-assessment indexes of the cold recycling technology project.

scholarly journals Integrating daylighting and lighting in practice: Lessons learned from international case studies

2021 ◽  
Author(s):  
Sergio ALTOMONTE ◽  
Flávia BUKZEM ◽  
Rafael CAMPAMÀ PIZARRO ◽  
Donatienne CARMON ◽  
Giovanni CIAMPI ◽  
...  
Keyword(s):  
Case Studies ◽  
Energy Use ◽  
Real Life ◽  
Field Measurements ◽  
Lessons Learned ◽  
Visual Performance

This report presents lessons learned from twenty-five worldwide real-life case studies implementing the integration of daylighting and electric lighting. The case studies were monitored with respect to energy use for lighting, visual performance, non-visual performance, and users’ satisfaction. The monitoring is largely based on field measurements, but it is also complemented with simulations and calculations where needed.

Field measurements in two tunnels in Edmonton, Alberta

1980 ◽  
Vol 17 (1) ◽  
pp. 20-33 ◽  
Author(s):  
S. Thomson ◽  
F. El-Nahhas
Keyword(s):  
Body Movement ◽  
Small Diameter ◽  
Ground Surface ◽  
Beam Theory ◽  
Field Measurements ◽  
Element Analysis ◽  
Overburden Pressure ◽  
Pressure Cell ◽  
Horizontal Diameter ◽  
Overburden Thickness

Observations of the deformation of the temporary lining of two tunnels are presented. The Whitemud Creek tunnel was 6.05 m in diameter and was bored through Upper Cretaceous clay shale. The 170 Street tunnel was bored through till and had a diameter of 2.56 m.In the Whitemud Creek tunnel, the vertical diameter decreased by 10–15 mm and the horizontal diameter decreased by 6 mm. Movement was essentially complete in about 3 months. There was a rigid body movement upward of the lining system probably due to unloading of the soil in the invert area. Deformation moduli indicate a softening of the soil around the tunnel, which is consistent with the deformation observations. A finite-element analysis suggests that this softened zone is as important with regard to lining deformation as increasing K0 from 0.67 to 1.0In the 170 Street tunnel, the ground surface showed significant movement despite the small diameter and considerable overburden thickness. The vertical and horizontal diameter decreases were about one half of those of the Whitemud Creek tunnel and were essentially complete in 4–5 weeks. Soil pressures calculated from the observations showed a wide variation. Values derived from lagging deflection yielded a maximum of 63% of overburden pressure whereas pressure cell readings were 3.3% of overburden.It appears that the space between the lagging and the moled surface of the soil is an important factor affecting the magnitude of stresses in the temporary lining. Diameter changes are considered to be the easiest and most reliable observation of tunnel linings. The deflection of the lagging is also simple to observe but may not satisfy simple beam theory. Pressure cell results were disappointing and their use is debatable.

Analysis on the Fatigue Life of Asphalt Pavement under Traffic Flow Loads

2013 ◽  
Vol 361-363 ◽  
pp. 1727-1734
Author(s):  
Meng Qi Gao ◽  
Ping Ying Wang ◽  
He Ping Ding
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Fatigue Fracture ◽  
Fatigue Damage ◽  
Asphalt Pavement ◽  
Ansys Software ◽  
Element Analysis ◽  
Damage Area ◽  
Traffic Loads ◽  
Damage Rule

To study the fatigue life of asphalt pavement under traffic loads, a 3-D finite element analysis (FEA) Visio-elastic road model was established on the layered theory with ANSYS software. The fatigue damage was calculated with the maximum horizontal tensile strain of asphalt layer bottom based on the fatigue fracture mechanics, when single axis went across. Then the fatigue life was obtained after the fatigue damage occurred in some degree by the Miners linear cumulative damage rule. The results show that it taken 3.4 years when the damage area reached 10% of wheel path area, and 4.5years when reached 45%; while the calculated result was 5.5 years by axial-load conversion method. The analysis shows that the fatigue life of asphalt pavement calculated by fatigue fracture mechanics rule has more significance in practice.

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