https://forum.rubicontoolbox.com/pages/topic73-how-to-use-the-let-multipavement-evaluation-tool.aspx Rubicon Online Help - LET Tools: Standard Axle Design, Axle Spectrum and Stress-Strain Calculator - How to use the LET Multi-Pavement Evaluation Tool - Messages en-us http://blogs.law.harvard.edu/tech/rss Jitbit AspNetForum Mon, 14 Oct 2024 22:38:41 GMT Mon, 14 Oct 2024 22:38:41 GMT https://forum.rubicontoolbox.com/pages/topic73-how-to-use-the-let-multipavement-evaluation-tool.aspx
The LET Multi-Pavement Evaluation is accessed through the Design Tools on the Rubicon Toolbox Online Tools home page. The inputs are defined in an Excel template, and the results downloaded to Excel. All the details are saved in the template, therefore the analyses are not saved in the Tool.

Click on the Design Tools icon and select LET Multi-Pavement Evaluation from the list. The LET Multi-Pavement Evaluation Tool will open.



To start, download the Example Template, enter the relevant data and save the template.




Template Preparation

All input data are entered into the template. Multiple Template sheets can be used in the same Excel template.

Loading

The loading is also specified in the Setup sheet, and the same loading is applicable to all analyses. The load co-ordinates, pressure and load are required. To convert the pavement capacity in million equivalent standard axles (MESA) to years, the Daily Repetitions, and Growth Rate details are required.

Evaluation Key

This number must be unique for each analysis.

Pavement Structure

Each structure must have five layers. The thickness, stiffness and Poisson’s Ratio are specified in the Template sheet. All 5 layers for all the inputs must contain data.

The thickness for Layer 5 must be Semi-Inf.

The Materials and Failure Criteria/Transfer Functions to use in each layer are selected from lists in the Materials and Failure Criteria sheets in the Template. We recommend the names are copied from the lists to the relevant cell in the Template sheet. The Materials and Criteria are limited to those in the Online Tools database as listed in the Template, User Defined Materials cannot be used. The material properties associated with the Materials are their default values, which can be checked in the Standard Axle Tool. Details on the Failure Criteria and their constants can be viewed in the Online Tools main window under Settings, Failure Criteria.

Pavements with two phases can be accommodated. Pavements with two phases are entered in two separate rows of the template, as shown in the example template. Pavements with only one phase use only 1 line. The software will read the template until it reaches a blank row.




Uploading the Template and Running the Analyses

Open the LET Multi-Pavement Tool and click on Select Data.



The Calculate button will become active. Click on Calculate and the analyses will run and the output file will automatically download to your Downloads folder.



Since the template is saved on your PC, the analysis is not saved online. The analysis can be repeated, as and when required.


Output file

The output file contains all the inputs and relevant outputs from the analysis. A similar layout to the input template is used.



The results of the analyses are as follows:

The Design Parameter Value is the stress or strain parameter for the chosen Failure Criteria, for example a horizontal tensile strain, vertical compressive strain, Safety Factor or Stress Ratio. Knowledge of the Failure Criteria is essential to know which stress or strain parameter is used.

The Layer Structural Capacity is the capacity in terms of MESA for each layer in each phase. If “None” was chosen as the Failure Criteria, the layer is not evaluated and n/a is given as the capacity. When the calculated capacity exceeds 100 MESA, a value of 101 is shown. The value given for Phase 2 structures is the effective axle capacity, in line with the guidelines for Mechanistic-Empirical pavement design.

The Critical Layer is the layer with the shortest capacity for each phase.

The Pavement Capacity by Phase is the capacity in MESA and years for the critical layer for each phase.

The Pavement Capacity (all Phases) is the Total Pavement capacity for all Phases in MESA and years. For single phase structures, this capacity is the same as the capacity for the first phase. For two phase structures, the total capacity considers both phases together.




edited by on 10/14/2024
edited by on 10/14/2024
edited by on 10/14/2024
edited by on 10/14/2024]]> Mon, 14 Oct 2024 22:38:41 GMT