Center of Excellence for Airport Technology, CEAT Analysis of NAPTF Trafficking Dynamic Response Data For Pavement Deformation Behavior Center of Excellence for Airport Technology, CEAT Research Progress and FY07 Tasks – January 30, 2007 PI: Erol Tutumluer RA: Phillip Donovan

Introduction NAPTF designed to investigate NGA/pavement system interaction Previous analysis found disturbing trends -- Wander caused downward deformation to be offset by upward deformation (shuffling of system elements) May need improvements in our aggregate lab testing and modeling for permanent deformation National Airport Pavement Test Facility (NAPTF) constructed to generate full-scale tests to investigate the performance of airport pavements subjected to complex gear loading configurations of new generation aircraft. Previous analysis of NAPTF data by Hayhoe et al. (2004) found that the downward residual deformation from one pass seemed to be offset by upward residual deformation from another. One consequence of this observation is that typical repeated load laboratory tests of permanent deformation in unbound pavement materials may not represent behavior under traffic

Research Objectives Detailed analysis of deformation trends Goals (1) Investigate deformation trends based on load magnitudes and loading sequences (stress history and application effects) trafficking speeds (load duration effects) traffic directions (shear stress reversals) gear spacing and gear/wheel interaction wander positions and wander sequence effects (2) Validate rutting models for unbound base and subbase Objective This research project is aimed to utilize the NAPTF trafficking dynamic response database, as well as the response tests conducted in association with the trafficking tests, for a detailed analysis and better understanding of the CC1 and CC3 flexible pavement test section deformation trends (both recovered and unrecovered deformations). Goals (1) Investigate deformation trends with respect to the various combinations of applied load magnitudes and loading sequences (application order and stress history effects); trafficking speeds (load duration effects); traffic directions (shear stress reversals); gear spacing and gear/wheel interaction; wander positions and wander sequences (order of 66 loadings); and (2) Based on the previously proposed test procedure (Kim and Tutumluer, 2005), fully develop and validate models to evaluate and predict potential rutting in variable thickness unbound base/subbase courses due to realistic full scale aircraft gear loading.

Work Plan Status Task I: Acquire NAPTF trafficking response data for the CC1 and CC3 test sections Most data have been obtained Some data not compiled yet No data at all from LFC MDD sensors CC3 trench data Most sensors have limited amount of sensor records Example: MFC 777 path sensor 1537, 16,000 events recorded only events 2800-4000 have sensor records

Work Plan Status Too much data in other cases LFS sensor records 400+ data points Cannot analyze in Excel (only 256 columns) Only last 200 data points required Access to NAPTF database during FAA meeting in April would be extremely helpful Data download and verification of sensors

Work Plan Status Task II: Analyze NAPTF Trafficking Response Data for Individual Gear/Wheel Passes Analysis of MFC 777 path data showing: Effect of wander positions and wander Effect of traffic direction

Task II: Progress Made In 2006 Just to give you an idea of what I’m talking about when I talk about sensors and sensor location and wander.

Task II: Progress Made In 2006 Line graph of Peak Responses

Task II: Progress Made In 2006 Scatter Graph of Peak Responses

Task II: Progress Made In 2006 4 4 3 3 2 2 -3 -3 -2 -2 -4 -1 -4 -1 1 1 Peak Response with wander I was able to separate out the wander rows thanks to the master event to wander row file provided. This is a 25pt moving average so the peaks are lower than what you saw on the last screen.

Task II: Progress Made In 2006 0 W-E 2 W-E 2 E-W -3 E-W -3 W-E 0 E-W 4 W-E 4 E-W Directional Response of MDD Surface Sensor For the directional response I was able to separate the rows by using the starting and ending position of the carriage.

Task II: Progress Made In 2006 -2 4 -3 -4,4 -1 3 3 -3 2 1 -2 -1 -4 1 Time History Average of all available sensor records up to 16,000 events Normalized means I averaged the first 1.5 seconds of data and subtracted that out from each data point Then I averaged each time step data point for each wander pattern to produce the graph. 16,000 events

Task II: Progress Made In 2006 -3,-2,2 4 4 3 -1 -4 1 3 2 -2 -3 -4 -1 4000 events 1 Looking at the other surface sensor No. 1537 we see something slightly different; dilative peaks of wander pattern 4. These did not show up in sensor 1544, or did they?

Task II: Progress Made In 2006 4 -3,-2,2 4 3 -1, -4 3 1 2 -2 -3 -4 -1 1 If we only look at the sensor records for sensor 1544 from the same set of data for sensor 1537 we see the exact same dilative peaks at the surface from wander row 4.

Work Plan Status Task II: continued Analysis of other sensors progressing MFC - 747 MFS – 747 (no 777 MDD data) LFx – 777 and 747 Individual layer residual and rebound response

Work Plan Status Task III: Analyze NAPTF trafficking response data for pavement loading until failure To be evaluated after rutting analysis Task IV: Identify and evaluate deformation trends in the CC1 and CC3 test sections Progressing with Task II Task V: Develop and Validate Realistic Granular Base/Subbase Deformation Models To be evaluated after Tasks II-IV

Future Research

Future Research Task II: Continue analysis of NAPTF trafficking response data for individual gear/wheel passes Reduce data to actual sensor movement --Must subtract sensor readings from the exact same sensor reading of the anchors Issue 1: matching the sensor records from the anchor to the other sensors Issue 2: limited capabilities of Excel

NAPTF trafficking dynamic response Base/Subbase Contractive & Dilative Behavior

Future Research Task IV: Identify and evaluate deformation trends in the CC1 and CC3 test sections Based on Task II results, identify and quantify the trends Task III: Analyze NAPTF trafficking response data for pavement loading until failure Based on Task IV results, analyze data for failure

Future Research Task V: Develop and Validate Realistic Granular Base/Subbase Deformation Models Update Rutting model to include “normal” trafficking effects

Any Questions?