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FLEXIBLE PAVEMENT DESIGN SYSTEM FPS 21: USER`S MANUAL

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1. soo foss ASPHCONCPYMT eo foao foss FLEXIBLE BASE ewo fia 020 STABILIZEDSUBGR TAMBILIZED SUBGR 200 00 i 6 0 0 40 SUBGRADE 200 SUBGRADE 200 Figure 17 Modified Texas Triaxial Check Input Screen Three options for supplying the subgrade Texas Triaxial Class TTC are provided for in this version of FPS 21 e Option 1 as selected in Figure 17 requires the designer to input the value based on laboratory tests historic lab data and or experience e Option 2 allows the user to estimate the TTC based on the soil Plasticity Index If this option is selected a field appears and the user inputs the controlling soil PI for the project The TTC is automatically calculated e Option 3 recalls a database of soils information for the applicable Texas County and posts it to the Texas Triaxial Design Check Screen This is shown in Figure 18 When this is selected the Unified Soil Classification System UCS soils type the percentage of the county that is covered by each soil type and the TTC of the each soil are displayed The user clicks on the soil type that best corresponds to the project subgrade for example the CL 5 0 box and that TTC value is used in the Modified Texas Triaxial calculation 15 The Heaviest Wheel Loads Daily ATH LO 000 lb Triaxial Thickness Required finches 22 63 Percentage of Tandem Axles J The FPS Design Thickness inches i 6 00 Modified Cohesiometer Value Cm Allowable Reduct
2. 35 Base Layer ASPHALT TREATED BASE ltem 292 250 400 ksi 0 35 Base Layer EMULSIFIED ASPH TRT BASE ltem 314 50 100 ksi 0 35 Base Layer FLEXIBLE BASE Item 247 407 70ksi 0 35 Base Layer LIME STABILIZED BASE ltem 260 263 60 75ksi 0 30 0 35 Base Layer CEMENT STABILIZED BASE ltem 275 276 80 150ksi 0 20 0 30 Base Layer FLY ASH OR LIME FLY ASH STABI Item 265 307 45 ksi 0 30 SubB ase Layer LIME CEMENT STABILIZED SUBG Item 260 275 30 45 ksi 0 30 _ SubBase Layer EMULSIFIED ASPH TREAT SUBG ltem 314 307 45 ksi 0 35 SubBase Layer SUBGRADE 16 ksi 0 40 0 45 Sub Grade Layer COST MODULUS POISN MIN MAX SALVAGE MATERIAL NAME PERLEY E ksi RATIO DEPTH DEPTH 5 TONE MATRIX ASPHALT Design PERFORMANCE MIX 1 inch SF Type FLEXIBLE BASE SUBGRADE a Inputs to both programs 18 kips 20M TFO 10 years min PSI 3 0 FPS Pavement Design Result Problem 006 District 18 Dalas Section 2 Highway SH 69 Confidence Level Control 1234 County Al ers Job 123 Date 2 7 2011 Wo of Best Designs Design Type PAYEMENT DESIGN TYPE H7 USER DEFINED PAW EMENT Best Design No Design 1 Design 2 Design 3 Design 4 Design 5 Design 6 Material Srrangement GF GFF GF GF GFF GFM F Total Cost 24 08 24 36 24 64 24 92 25 31 26 35 F d No of Layers 3 a 3 a a a Layer Depths finches 2 0 2 5 3 0 3 5 40 25 8 0 v 45 vd ES 6 0 10 0 12 0 12 0 12 0 12 0 12 0 12 0 Nest Page Re Aun FPS Mo of Perf Periods 2 2 2 2 2 1 Fert Time pears 11 24 11 24 11 2
3. Swelling Clay Loss 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 c FPS 19 Design Thicknesses Figure A 3 Design Type 3 Full Depth HMA 22 FS Input Design Data Pavement Structure Const amp Maint Data MIN OVERLAY THICKNESS Inches DETOUR MODEL DURING OVERLAYS OVERLAY CONST TIME HR DAY i TOTAL NUMBER OF LANES for two direction ACP COMP DENSITY TONS CY NUM OPEN LANES OVRLAY DIRECTION ACP PRODUCTION RATE TONS HR NUM OPEN LANES NON OV DIRECTION WIDTH OF EACH LANE Feet i DIST TRAFFIC SLOWED OY DIR FIRST YEAR COST ATN MAINT i DIST TRAFFIC SLOWED NON OV DIR ANN INC INCR IN MAINT COST COST MODULUS POISN MIN MAK SALVAGE MATERIAL NAME PER Cy E ksi RATIO DEPTH DEPTH 4 0 10 0 12 0 A Wh LYR ASPH CONC PYMT Design ASPH STAB BASE Type FPS Pavement Design Result Problem O06 District 18 Dallas Section Z Highway SH 69 Confidence Level C Control 1234 County rl ES Job 123 Date 272011 No of Best Designs Design Type PAVEMENT DESIGN TPE 4 4CP ASPH STAB BASE FLE BASE OVER SUBGRADE Best Design Ho Design 1 Design 2 Design 3 Design 4 Design 5 Design 6 Maternal Arrangement ABC ABC ABC SBC ABC SBC F Total Cost 24 08 24 36 24 64 24 92 25 21 26 35 F A No of Layers 3 3 3 3 a z Layer Depths inches 2 0 2 5 3 0 35 40 as 8 0 P95 z0 6 5 6 0 10 0 12 0 12 0 120 12 0 12 0 12 0 Mo of Pert Periods 2 2 2 z 2 1 Perk Time wears 11 24 11 24 11 24 11 24 11 22 22
4. Type 5 Stabilized Subbase with a Flexible Base Layer 24 S Input Design Data Pavement Structure Const amp Maint Data MIN OVERLAY THICKNESS Inches 2 0 DETOUR MODEL DURING OVERLAYS OVERLAY CONST TIME HR DAY A TOTAL NUMBER OF LANES for two direction ACP COMP DENSITY TONS CY i NUM OPEN LANES OVRLAY DIRECTION ACP PRODUCTION RATE TONS HR NUM OPEN LANES NON O DIRECTION WIDTH OF EACH LANE Feet DIST TRAFFIC SLOWED OV DIF FIRST YEAR COST ATN MAINT DIST TRAFFIC SLOWED NON O DIR ANN INC INCR IN MAINT COST COST MODULUS POISN MIN MAX SALVAGE MATERIAL NAME Benen E ksi RATIO DEPTH DEPTH LYR ACP OVERLAY Iin ASPH CONC PVMT eae BASE SUBGRADE 200 FPS Pavement Design Result a Cad Th d Problem O06 District 18 Dalas Section z Highway SH 63 Confidence Level C Control 1234 County Aeris Job 123 Date a F 2011 No of Best Designs Design Type PAVEMENT DESIGN TYPE 5 USER DEFINED PROBLEM UP TO FIVE LAYERS Best Design No Design 1 Design 2 Maternal Arrangement ABC ABC Total Cost 14 69 18 08 No of Layers 3 a Layer Depths finches 55 5 0 5 0 5 0 10 0 10 0 Re Aun FPS Mo of Perf Pertods 2 q1 z Ferf Time years 11 26 2 Material T able Overlay Policy inches 25 Print Save File b FPS 21 Design Thicknesses FPS Pavement Design Result Problem OE District 14 County 11 Highway SH 6a Confidence Level Control 121 Sechon ai Job 0i 4 Date 27r e201
5. accictednitcascentcursdstieacitdetanedexctnaseeruce ste acieeueet 30 Figure B 5 Mechanistic Design Checks in the User Define Mode cc ceeeeeecseeeeeeeeeeeeeeees 31 Figure B 6 Mechanistic Analysis Following User Define Inputs cc eeccccecceeeeeeeeeeeees 32 1V 1 INTRODUCTION The Flexible Pavement System FPS is a mechanistic empirically M E based design software routinely used by the Texas Department of Transportation TxDOT for 1 pavement structural thickness design 2 structural overlay design 3 stress strain response analysis and 4 pavement life prediction rutting and cracking FPS 21 is the most recent version of this design system developed by the Texas Transportation Institute for TxDOT The program is has several additions to the existing FPS 19 system but it retains much of the familiarity of the previous system FPS 21 is intended to replace FPS 19 which has been implemented since the mid 1990s Both programs incorporate the same performance prediction algorithm and have substantially identical inputs FPS 21 produces identical thickness designs to FPS 19 but it also includes the following new features e Provides the capability of designing pavement structures with up to six layers over the subgrade FPS 19 is restricted to three layers This provides the capability of designing perpetual pavements where multiple hot mix asphalt HMA layers of different moduli values are required e Pr
6. layer types for this proposed perpetual pavement Design 3 is projected to last longer than the specified minimum time to first overlay 15 years but then requires an overlay to reach the full 20 year design life Design 6 is predicted to last 20 years without requiring an overlay For this example it is proposed to perform a design check on Design 6 so click on the Check Design button under that column The selected design shown in Figure 14 will appear Pavement Plotting Screen DESIGN 6 PAVEMENT PLOTTING Thick irn hak T ype 2 00 STONE MATAIA ASPHALT 3 00 PERFORMANCE Mis 3745F Previous Design Next Design PERFORMANCE Mis 1 inch SF RICH BOTTOM LAYER All Design Plots LIME CEMENT STABILIZED SUBG Mechanistic Check Triaxial Check Stress Analysis E wit SUBGRADE 420 5 years Figure 14 Design Selected for Further Evaluation by Design Checks To perform a check of this structure the designer 1s encouraged to run both the Mechanistic Check and the Modified Triaxial Check Each will be described below 2 4 1 The Mechanistic Checks TxDOT currently recommends the mechanistic design check be run for all for all perpetual pavement designs to verify the limiting strain criteria For all other designs the results are for informational purposes only Once the Mechanistic Check button is selected the screen shown in Figure 15 appears Move click and drag the small green box under the Vary Thickness headin
7. million 200 Check Result The Design is OK for the period 1 which is 20 5 years Jz Trans rtati ransportation AA institute Figure 16 Mechanistic Design Check Results 6D EA 70 to Ea LED 90s aS O SAS Change Thickness in This structure passes all of the mechanistic design checks Details on using this design check are more fully described by accessing the HELP menu See also Appendix B for an example of using the mechanistic design checks to evaluate a non perpetual flexible pavement structure 2 4 2 The Modified Texas Triaxial Check The Modified Triaxial check is mandatory for all pavement designs in Texas although as previously stated the results may be waived with justification by the approving engineer In the screen shown in Figure 16 select Exit then select Triaxial Check in the pavement plotting screen Figure 14 The screen shown in Figure 17 will appear 14 sU Texas Triaxial Design Check for Pavement 1 The Heaviest Wheel Loads Daily ATHLE h 2000 lb Triaxial Thickness Required finches Percentage of Tandem Axles G The FPS Design Thickness inches l 3 Modified Cohesiometer Value Cm 100 Pererence Allowable Reduction inches Modified Triaxial Thickness Inches Input Subgrade Texas Triaxial Clase TTC f option 1 Input TTC based on TEX 117 E f Option 2 Enter soil Pl to estimateTTC f Option 3 Select TTC based on predominate soil type Thick fin Modulus ksi y Material Hame oo
8. 3 We 2S 0 2a 22 Material Table Overlay Policy finches 25 25 25 za 25 Print 75 awe File b FPS 21 Design Thicknesses Identical to Pavement Design Type 4 Figure A 7 Design Type 7 User Defined Pavement Structure 26 APPENDIX B MECHANISTIC CHECKS NON PERPETUAL PAVEMENT CASE This appendix shows an example of using the mechanistic checks on a typical non perpetual pavement design The design type selected was a Type 5 structure ACP surface flex base stabilized subgrade on natural subgrade For purposes of this design the following FPS inputs were used to generate an initial set of feasible designs Cumulative ESALs Initial SI Terminal SI Confidence Level HMAC modulus Flex Base modulus Stab Subgrade modulus Subgrade modulus 2M 4 5 3 0 90 0 B 500 ksi 45 ksi 35 ksi 8 ksi As described in Section 2 paragraph 2 4 of this manual the designer will first run FPS 21 to generate a selection of feasible designs Using the above inputs Figure B 1 shows the Design Results screen for this problem mE i ed ee E a Problem O06 1234 Contral County District 14 Austin FM 373 6 14 2011 Section 2 Highway Confidence Level Job 123 Date No of Best Designs Design Type PAVEMENT DESIGN TYPE 5 ACP FLEX BASE STAB SEGA OVER SUBGRADE Best Design Mo Design 1 Maternal Arrangement ABC Total Cost 16 72 No of Layers a Layer Depths inches 2 0 6 5 6 0 Ho of Perk Periods Per Time
9. 5 inches Currently the mechanistic design check is not required for pavement design approval with the exception of pavements deliberately designed as perpetual but it should be run for informational purposes on all HMA designs 1 2 Modified Texas Triaxial Check The Modified Texas Triaxial criteria was developed to prevent a shear failure in the subgrade soil under the heaviest wheel load anticipated for the pavement section Results of the analysis will recommend the total combined thickness of granular base stabilized materials and HMAC surface to prevent shear failures in the subgrade Currently the Triaxial check is mandated for all flexible pavement designs developed for TxDOT maintained highways however the results can be waived with justification by the approving engineer 1 3 FPS 21 System Requirements and Loading Instructions e Running the FPS 21 requires a Windows 98 or later operating system e Atleast a 1 0 GHz processor speed and minimum of 10 MB disk space are recommended e The software is provided in an executable set up program which loads the software and puts the FPS 21 icon on the desktop The program is supplied in an executable file called FPS21Setupmm dd yyyy exe where the effective date of the current version is included as part of the file name Running the setup program will cause the screen shown in Figure 1 to be displayed Welcome FPS 21 Wer Mayo0s 10 Welcome to the FPS27 Install program
10. COST ATN MAINT DIST TRAFFIC SLOWED NON OY DIR ANN INC INCR IN MAINT COST COST MODULUS POISN MIN MAX SALVAGE MATERIAL NAME PEALE E ksi RATIO DEPTH DEPTH 2 0 12 0 6 0 fal 500 0 26 100 8 fal 2 0 5 d a M m LYR ASPH CONC PVMT Design Type SU FPS Pavement Design Result 00E Tietia 18 Dalas 2 1234 County A EuS Job 123 Date SH 69 Confidence Level C 277r 2011 Problem Section Highway Control Mo of Best Designs Design Type PAVEMENT DESIGN TYPE 5 4CP FLE BASE STAB SEGA OVER SUBGRADE Best Design No Design 1 Design 2 Maternal Arrangement SEC ABC Total Cost 12 12 14 75 Mo of Layers 3 3 Laver Depths inches 2 0 2 0 6 0 12 0 3 0 8 0 ae No of Perk Periods 2 1 Perf Time pears 12 28 21 Material T able Overlay Policy finches 2 5 Print Save File b FPS 21 Design Thicknesses FPS Pavement Design Result Problem a06 D istrict 14 County 11 Highway SH 69 Confidence Level Control 1217 afr eer Section a1 Job gia Date Mo of Best Designs Design Type PAVEMENT DESIGN TYPE 4 ACP FLE BASE STAB SEGRA OVER SUBGAADE Best Design No Design 1 Design 2 Bisterial Aarrangement ABEC ABC Total Cost 12 117 14 754 Ho of Layers E 4 Layer Depths mches 2 00 2 00 6 00 12 00 8 00 8 00 Ho of Fert Periods a 1 Fert Time years 12 28 21 Overlay Policy moches 2 BO Swelling Clay Loss 0 00 0 00 0 00 c FPS 19 Design Thicknesses Figure A 5 Design
11. Date In most cases the user is interested in generating a flexible pavement design and will select the FPS Pavement Design button from the main menu Figure 4 FPS 1 Main Menu TEXAS FLEXIBLE PAVEMENT DESIGN SYSTEM 7 FPS 21 en FPS21 1 2 Released 6 20 2011 x ai Go Stress Analysis Tool Product Disclaimer Figure 4 FPS 21 Main Menu The second button on the Main Menu allows direct access to the Stress Analysis Tool shown in Figure 5 When accessed from the Main Menu this is a stand alone program where the user inputs the pavement structural layers and load format the program predicts stresses strains and deflections within a pavement structure with up to seven layers These predictions can be made for simulated FWD or truck wheel loading configurations Details on using this analysis tool are more fully described by accessing the program HELP menu The HELP menu can be accessed by hitting the F1 button on any of the FPS data entry screens As described later in this report the stress analysis tool can also be activated after an FPS design has been generated to check the induced stresses and strains and make mechanistically based life predictions for the proposed pavement structure Stross amd Strain Analy for Pavyomom l gt Loew Tree Pw met Sage Anaha Aoeuk m Gige Tis Cua Tis E5 PRL ag dmg Lopsiriaorn Pare i gt pu 2 bpa T Ean 7 om i bej i m me 1 E x EE a ee pgmn Paes oats are
12. Design Check Input Screen ccccccecccceccccceceeeeeeeeeeeeseseeeeeeeeeeeeeees 13 Figure 16 Mechanistic Design Check Results c cc cessssssssseseeeeeeccececcceeaaeeeeaeseceeeeeeeeeeeeeeees 14 Figure 17 Modified Texas Triaxial Check Input Screen 2 0 0 0 cccccccnnennteeseesseeeeeeeeeeeeeeeees 15 Figure 18 Option 3 for Selecting the Soil TTC from Soils Database eeeeeeeceeeeeeeeeeeees 16 Figure 19 Stress Analysis Tool as Accessed from the Pavement Plotting Screen 17 Figure A 1 Design Type 1 Surface Treated Pavement ccccccccccccccceeeeeeeeesseeeeeeeeeeeeeeeeeees 20 Fieure A 2 Design Type 2 Thm TINA SU di Cerere pen ssasnsiavtaceqteavatel senncea Ea 21 Fieure AS Desien Type S Pull Depth HMA ereraa R 22 Figure A 4 Design Type 4 Full Depth HMA with a Flexible Subbase Layet 000 23 Figure A 5 Design Type 5 Stabilized Subbase with a Flexible Base Layet ee 24 Figure A 6 Design Type 6 Overlay Thickness DeSIgn ec ccceececccccccccceceeeeeeeessesseeeeeeeeeeeeees 25 Figure A 7 Design Type 7 User Defined Pavement Structure eeessssessssssssseeseeeerrereesssssssss 26 Proure Bi JPeas tole QOS in RESU o a E E E AA 21 Figure B 2 Design 3 Selected for Further Evaluation by Mechanistic Checks ee 28 Figure B 3 Mechanistic Design Check Input SCreen ccc ccccccccccccssssseeeeeceeeeeeeaeeeeeseeeeeeeenaas 28 Figure BA Mechanisic Desie Check RESUS
13. ES This appendix shows examples of comparable design types run in both FPS 19 and FPS 21 In all cases the generated thickness designs are identical In the following figures Figure a shows the identical inputs supplied to both programs Figure b shows the FPS 21 thickness design results and Figure c shows the FPS 19 comparable thickness design results 19 Input Design Data Pavement Structure Const amp Maint Data MIN OVERLAY THICKNESS Inches 2 OVERLAY CONST TIME HR DAY 12 0 ACP COMP DENSITY TONS CY 1 90 ACP PRODUCTION RATE TONS HR 200 0 WIDTH OF EACH LANE Feet 12 0 FIRST YEAR COST ATN MAINT 100 ANN INC INCR IN MAINT COST 200 MATERIAL NAME SURFACE TREATMENT FLEXIBLE BASE SUBGRADE 200 LYR 1 Design Type 3 Detour Design for Overlays DETOUR MODEL DURING OVERLAYS f TOTAL NUMBER OF LANES for two direction o NUM OPEN LANES OVRLAY DIRECTION Save Input File NUM OPEN LANES NON OV DIRECTION F DIST TRAFFIC SLOWED OV DIR 06 DIST TRAFFIC SLOWED NON O DIR 06 COST MODULUS POISN MIN SALVAGE PERCY E ksi RATIO DEPTH DEPTH 2 200 0 0 35 30 0 35 44 0 35 75 0 0 40 E 2000 90 0 a Inputs to both programs 18 kips 0 5M TFO 10 years min PSI 2 5 at FPS Pavement Design Result O06 1234 14 SH 69 2 6 2011 Section 2 Highway Confidence Level Job 123 Problem District Control County Date Mo of Best Designs Design Type PAVEMENT DESIGN TPE 1 SUR
14. FACE TREATED FLE BASE OVER SUBGRADE Best Design Mo Material Arrangement Total Cost Mo of Layers Layer Depths inches Mo of Perf Periods Perk Time years Overlay Policy finches Check Design Design 1 AB 12 34 2 0 5 12 5 Material T able Print Save File Detail Cost TO Main Menu b FPS 21 Design Thicknesses FPS Pavement Design Result 006 Problem Control 121 District 14 County 11 Highway SH 63 Confidence Level Section 01 Job 014 Date 2 6 2011 No of Best Designs Design Type PaVEMENT DESIGN TPE 17 ACF FLEs BASE OVER SUBGAADE Best Design Ho Material Aucrangerment Total Cost Ho of Layers Layer Depths mehes Ho ot Fert Periods Fert Time wears Overlay Policy mehes Swelltig Clay Loss Design 1 AB 12 244 2 50 12 50 2 10 36 2 50 0 00 0 00 c FPS 19 Design Thicknesses Figure A 1 Design Type 1 Surface Treated Pavement 20 Input Design Data Pavement Structure Const amp Maint Data MIN OVERLAY THICKNESS Inches 2 0 OVERLAY CONST TIME HR DAY Detour Design for Overlays DETOUR MODEL DURING OVERLAYS TOTAL NUMBER OF LANES for two direction e ACP COMP DENSITY TONS CY NUM OPEN LANES OVALAY DIRECTION 0 ACP PRODUCTION RATE TONS HR NUM OPEN LANES NON O Y DIRECTION 1 WIDTH OF EACH LANE Feet DIST TRAFFIC SLOWED OY DIR 0 6 FIRST YEAR COST ATN MAINT DIST TRAFFIC SLOWED NO
15. FLEXIBLE PAVEMENT DESIGN SYSTEM FPS 21 USER S MANUAL FLEXIBLE PAVEMENT DESIGN SYSTEM FPS 21 USER S MANUAL by Wenting Liu Assistant Research Scientist Texas Transportation Institute and Tom Scullion Associate Research Engineer Texas Transportation Institute Published August 2011 TEXAS DEPARTMENT OF TRANSPORTATION 125 E 11 Street Austin Texas 78701 2483 With TEXAS TRANSPORTATION INSTITUTE The Texas A amp M University System College Station Texas 77843 3135 DISCLAIMER The contents of this manual reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein The contents do not necessarily reflect the official view or policies of the Federal Highway Administration FHWA or the Texas Department of Transportation TxDOT This manual does not constitute a standard specification or regulation The manual is intended to give rudimentary guidance in the operational features of the design program FPS 21 only and should be used in conjunction with the TxDOT online Pavement Design Guide District SOP and sound engineering judgment The engineer in charge of this project was Tom Scullion P E 62683 1i TABLE OF CONTENTS 11S Isidro eel ay OOE ara ee t nMmOerc rs eer maT teen ene sre r a Teen er tener Tn 1V S B06 96 400 BG D EAE A em E A cer E E E I S E I S E E E A E l tI Mechanistic Desem Chet Kosena a a E E E 2 t2 Modtied Texas Tiaia CHECK cacy tices oci
16. Figure B 6 Again the designer evaluates the Pavement Life section and notes the following e The estimated cumulative ESALs to the end of the first performance period at 10 8 years 1s 0 965M e The estimated number of 18 kip repetitions to failure in fatigue is 1 00M 104 percent of the projected ESALs by the end of the 1 performance period e The estimated number of 18 kip repetitions to failure in subgrade rutting is 1 58M 164 percent of the projected ESALs by the end of the 1 performance period e Repetitions to failure of 18 kip ESALs in both of these modes exceed the cumulative ESALs predicted by FPS by time to first overlay and the Check Result message validates this This adjusted FPS option is in better balance with these checks 31 By looking at the left hand side of the screen the designer can evaluate the effect on the performance for these two failure criteria by increasing or decreasing the HMAC layer thickness in 1 0 inch increments For both fatigue cracking and protecting the subgrade from rutting an increase in the HMAC thickness by small amounts is relatively beneficial The user is advised that the mechanistic models used in this program are rather unsophisticated by current state of the art practice as they do not consider material specific behavior the effects of the environment variable axle loading traffic wander etc and should not rely solely on the outcome of this check However due consideration for
17. Mo of Best Designs Design Type PAVEMENT DESIGN TYPE 5 USER DEFINED PROBLEM UP TO FIVE LAYERS Re Run FPS Material T able Print Save File Detail Cost TO Main Menu Best Design Ho Design 1 Design 2 PMaterial srrangerment AEC ABC Total Cost 14 686 16 081 Ho of Lavers a a Layer Depths moches 5 50 2 00 5 00 5 00 10 00 10 00 Ho of Pert Periods a 1 Feri Tire years 11 26 z2 Overlay Folicy mches gt 50 Swelling Clay Loss 0 00 0 00 0 00 c FPS 19 Design Thicknesses Figure A 6 Design Type 6 Overlay Thickness Design 25 This problem is identical to Design Type 4 presented earlier this time the pavement structure was built under the User Defined type 7 option td a User Define Pavement Go Back Material Type 2004 TREA Design Modulus Paisson Ratio Layer Type SURFACE TREATMENT Item 316 318 200 ksi 0 35 AC Layer DENSE GRADED HMA Thin ltem 340 341 500 ksi 0 35 AC Layer DENSE GRADED HMA Thick Item 340 341 650 ksi 0 35 AC Layer PERMEABLE FRICTION COURSE ltem 342 500 ksi 0 30 AC Layer PERFORMANCE MIX 3 45F ltem 344 650 950 ksi 0 35 AC Layer PERFORMANCE MIX 1 inch SF tem 344 650 950 ksi 0 35 AC Layer STONE MATRIX ASPHALT Item 346 _ 650 850 ksi 0 35 AC Layer LIMESTONE ROCK ASPH PYMT ltem 330 200 350 ksi 0 35 AC Layer HOT MIx COLD LAID ACP tem 334 300 400 ksi 0 35 AC Layer RICH BOTTOM LAYER ltem 344 400 600 ksi 0 35 AC Layer FA or LFA STABILIZED ltem 265 50 150 ksi 0
18. N O DIR ANN INC INCR IN MAINT COST LYR kd Design 2 Type E a Inputs to both programs 18 kips 1M TFO 10 years min PSI 2 5 COST REREN 70 0 28 0 MODULUS E ksi 500 0 2 ea Ie 10 0 POISN RATIO 0 35 0 35 0 40 MIN MAX DEPTH DEPTH 6 15 0 SALVAGE 30 0 75 0 90 0 MATERIAL NAME SURFACE TREATMENT FLEXIBLE BASE SUBGRADE 200 200 0 FPS Pavement Design Result Problem 006 District 14 Austin Section 2 Highway SH 69 Confidence Level C Control 1234 County 11 BASTROP Job 123 Date 2 6 2011 No of Best Designs 16 Design Type PAVEMENT DESIGN TYPE 1 SURFACE TREATED FLEX BASE OVER SUBGRADE Best Design No Design 1 Design 2 Design 3 Design 4 Design 5 Design 6 Material Arrangement AB AB AB AB AB AB Total Cost 14 15 14 19 14 24 14 40 14 50 14 76 No of Layers 2 2 2 2 2 2 Layer Depths finches ois 29 1 5 4 0 TS 3 0 6 0 7 0 13 0 6 0 125 8 5 Next Page No of Perf Periods 2 2 2 2 2 2 Perf Time years 10 21 11 20 lee l2 2z 10 21 10 21 Material T able Overlay Policy finches 3 0 25 25 25 3 0 3 0 Print Save File Design Type PAVEMENT DESIGN TYPE 2 ACP FLE BASE OVER SUBGRADE b FPS 21 Design Thicknesses W FPS Pavement Design Result Problem O06 District 14 County 11 Highway SH 69 Confidence Level Control 1217 Section di Job o14 Date 2 6 2011 No of Best Designs Design Type PaVEMENT DESIGN TYPE 17 ACP FLE BASE OVER SUBGRADE Best De
19. Overlay Policy inches 2 15 2s 2 5 a 25 Print S ave File b FPS 21 Design Thicknesses FPS Pavement Design Result Problem a06 District 14 County 11 Highway SH 69 Confidence Lewel Control 1217 Section on Job o14 Date 2 7 F207 1 Mo of Best Designs Design Type P VEMENT DESIGN TYPE 3 ACP ASPH STAB BASE FLE BASE OVER SUBGRADE Eest Design Ho Design 1 Design 2 Design 3 Design 4 Design 5 Design 6 Material Arrangement ABC ABC ABEC ABC ABC ABC Total Cost 4 078 24 360 24 642 24 924 25 206 26 346 Mo of Layers 3 3 3 3 a a Layer Depths mches z2 00 2 50 3 00 3 50 4 00 2 50 2 00 7 50 7 00 6 50 6 00 10 00 12 00 12 00 12 00 12 00 12 00 12 00 Ho of Fert Periods 2 2 a 2 2 1 Feri Time years 11 24 11 24 11 24 11 24 11 23 oe Overlay Policy mches 2 50 2 50 2 50 2 50 z2 50 Swelling Clay Loss 0 00 0 00 0 00 0 00 0 00 0 00 0 000 00 0 00 0 00 0 00 c FPS 19 Design Thicknesses Figure A 4 Design Type 4 Full Depth HMA with a Flexible Subbase Layer 23 Input Design Data Pavement Structure Const amp Maint Data MIN OVERLAY THICKNESS Inches 2 0 OVERLAY CONST TIME HR DAY ACP COMP DENSITY TONS CY ACP PRODUCTION RATE TONS HR WIDTH OF EACH LANE Feet Detour Design for Overlays DETOUR MODEL DURING OVERLAYS 2 uae TOTAL NUMBER OF LANES for two direction 2 NUM OPEN LANES OVRLAY DIRECTION 0 NUM OPEN LANES NON OY DIRECTION 1 DIST TRAFFIC SLOWED OY DIF 0 6 FIRST YEAR
20. SLOWED OV DIR DIST TRAFFIC SLOWED NON OV DIR DETOUR DISTANCE OVERLAY ZONE SALVAGE POISN PCT RATIO MODULUS E ksi MIN DEPTH MAX DEPTH Figure 12 Accessing the Layer Material Parameters Table 2 4 Running FPS 21 and Interpreting the Results The program is run by selecting the red arrow button shown in Figure 12 For the inputs provided the six possible designs shown in Figure 13 will be generated These are ranked according to lowest cost per square yard SU FPS Pavement Design Result 2 Fort Worth 249 Wie Section Job Problem District 2 123 Control County Design Type PAVEMENT DESIGN TYFE 7 USER DEFINED PAVEMENT Design GEFJA 50 11 5 Design 2 GEFJ 49 66 4 2 0 3 0 pS 20 Best Design Mo Design 1 GEF 46 94 3 20 3 0 2 5 Material Arrangement Total Cost No of Layers Layer Depths inches No of Perk Periods Perf Time years Overlay Policy inches Swelling Clay Loss Check Design 2 Check Design SH 114 Highway Confidence Level Date 262008 Mo of Best Designs 3 Design 6 GEFIR Fez 5 Design 5 GEFJ 51 76 4 20 3 0 3 0 20 Design 4 GEF 50 42 3 20 0 3 0 D s 0 TO Main Menu Check Design Check Design Check Design Figure 13 Feasible Design Results Options 11 The designer must select one of these feasible designs for follow up structural checking Designs 3 and 6 include all the required
21. This program allows pou to install FPS217 on your hard drive lk is strongly recommended that before proceeding you ensure that no other windows programs are running IF vou do not wich to install FPS217 click Exit now othenwise click Mext to continue imnspertiehan Ineeiitiehe Figure 1 Opening Screen of FPS 21 Setup Program The user selects the Next button and then specifies the folder location where the FPS 21 program is to be stored After that the screen shown in Figure 2 is displayed To load the program select the Start button Confirmation Thiz program will install FPS27 into CNFPS21 Click Start to install FPS 21 A 5 m AE iiie Figure 2 Setup Program Screen Following Selection of Drive Storage Location In most computers the program will display the message shown in Figure 3 asking 1f the user wants to overwrite existing DLLs In all cases reply NO as the system is trying load an older version of the DLL FPS21 Install Program Cw INDO wW Sisvstemsetasycrilt dll This file exists and is a more recent version than the file to install Do you want to overwrite the installed version anyway Figure 3 Overwrite DLL Dialogue Box Once this is complete the FPS 21 icon will be installed onto the desktop 2 NEW FEATURES IN THE FPS 21 SOFTWARE 2 1 Initiating the FPS 21 Design Software Click on the FPS 21 icon to run the program S Fps21 exe 2 2 Main Menu with Version Number
22. XIBLE BASE LIME CEMENT STAB SUBG SUBGRADE Draw User Design Pavement Detour Design for Overlays DETOUR MODEL DURING OVERLAYS TOTAL NUMBER OF LANES for two direction 2 4 NUM OPEN LANES OVRLAY DIRECTION 0 NUM OPEN LANES NON O DIRECTION 1 DIST TRAFFIC SLOWED OV DIR 0 6 DIST TRAFFIC SLOWED NON OV DIR 06 COST MODULUS POISN MIN Max SALVAGE PER CY E ksi RATIO DEPTH DEPTH 2 Figure 8 Final FPS 21 Input Screen Initial View 2 3 3 Selecting a Traffic Detour Model To Main Menu Save to Default Save Input File Detour models are the same as used in FPS 19 The designer is assisted in selecting the correct model by means of a graphical display Enter the detour model anticipated for future overlays for this project by entering the appropriate number in the first field under Detour Design for Overlays A graphic will appear that displays the anticipated mode of handling traffic for the future overlay Figure 9 Const amp Maint Data MIN OVERLAY THICKNESS IN 2 OVERLAY CONST TIME HR DAY 12 0 ACP COMP DENSITY TONS CY 1 90 ACP PRODUCTION RATE TONS HR WIDTH OF EACH LANE FT 12 0 FIRST YEAR COST ATN MAINT 0 0 ANN INC INCR IN MAINT COST 0 0 Detour Design for Overlays DETOUR MODEL DURING OVERLAYS 3 4 TOTAL NUMBER OF LANES NUM OPEN LANES OVRLAY DIRECTION NUM OPEN LANES NON OY DIRECTION DIST TRAFFIC SLOWED OV DIR DIST TRAFFIC SLOWED NON OY DIR DETOUR DISTANCE OVERLAY
23. ZONE Model Ill Two lane merge non overlay direc not affected Design Type Draw User Design Pavement Click inside figure to close Figure 9 Graphic Corresponding to Selected Detour Model To Main Menu Save to Default Save Input File Click inside the model graphic to hide the graphic and return to the original screen 2 3 4 Selecting a Pavement Design Type Click on Design Type to view the design type options screen shown in Figure 10 By selecting any design type option a template will be revealed for that type of structure at Page 3 Const amp Maint Data Detour Design for Overlays MIN OVERLAY THICKNESS IN 2 DETOUR MODEL DURING OVERLAYS To Main Menu Save to Default OVERLAY CONST TIME HR DAY 12 0 TOTAL NUMBER OF LANES Save Input File LEE ACP COMP DENSITY TONS CY 1 90 NUM OPEN LANES OVRLAY DIRECTION ACP PRODUCTION RATE TONS HR NUM OPEN LANES NON OV DIRECTION WIDTH OF EACH LANE FT DIST TRAFFIC SLOWED OV DIR FIRST YEAR COST ATN MAINT DIST TRAFFIC SLOWED NON OY DIR ANN INC INCR IN MAINT COST DETOUR DISTANCE OVERLAY ZONE Select Pavement Design Type C 1 SURFACE TREATED FLEX BASE OVER SUBGRADE C 2 ACP FLEX BASE OVER SUBGRADE C 3 ACP ASPH STAB BASE OVER SUBGRADE t C 4 ACP ASPH STAB BASE FLEX BASE OVER SUBGRADE C 5 ACP FLEXIBLE BASE STAB SBGR OVER SUBGRADE C 6 OVERLAY DESIGN j S TETTE Exit Pavement Design Type Selection gt Figure 10 D
24. c performance of a design using slightly thicker HMAC and base layers without having to re run FPS for the time being for documentation purposes a final run of FPS should be run after any follow on mechanistic evaluation if the designer chooses to alter the layer thicknesses moduli etc Select the Exit button to return to the Mechanistic Checks input screen Now the designer decides to select the User Define option in the Analysis Mode section at the center of the screen Figure B 5 The designer overwrites the FPS generated design thicknesses for the HMAC surface by inserting 3 5 inches and the Flexible Base thickness by inserting 8 0 inches Note that this combination of layer thicknesses was not offered in the original feasible design options given in Figure B 1 Also the designer would now like to evaluate the sensitivity of increasing the HMAC thickness in 1 0 inch increments so the green box under the Vary Thickness heading is dragged to the surface layer x Thick n Modulus ksi Material Hame Vary Thickness ooo ps CRSPHEONCeT mho M50 0350s FLERIBLEBASE O00 jso foso STABILIZED SUBGR Bo foso SUBGRADE 200 OOO pen m p 200 O0 Analysis Mode A SUBGRADELZOC C Design f User Define os a Neke a N a i Ja Ak Figure B 5 Mechanistic Design Checks in the User Define Mode Once all desired changes are made the designer again selects Run and the mechanistic analysis output is re displayed as in
25. dix B Mechanistic Checks Non Perpetual Pavement Case cccccccsesseeeeeeeeeeeeeeees 27 111 LIST OF FIGURES Figure Opening Screen of FPS 21 Setup Prosram cess sivesediee cee caries hase viene 3 Figure 2 Setup Program Screen Following Selection of Drive Storage Location 0 3 Figure 5 Overwrite DLE Dido ou BOK ena E A sd aciaersedbesarieueaauen ss 4 Fome t PRS 20 Mati Menina E eaieewsin ee ilenausuciers 5 Figure 5 Stress Analysis Tool as Accessed from Main Menu ccccccccsssssseeeeeseeeeeeeeeeeeeeees 6 Figure 6 FPS 21 Project Administrative Data Input Screen cccnnnneeeeseeeeeeeeeeeeeeeeeees 6 Figure 7 FPS 21 Basic Design and Traffic Inputs c00ssssssessesesscccescnsececsesensecesseeseecctenes 7 Figure 8 Final FPS 21 Input Screen Initial View c ccs ssesssesseseeeceeeeceeceeeeeesaassseseeeeeeeeeeeeeeees 8 Figure 9 Graphic Corresponding to Selected Detour Model 0 0 cceccssseseeeeeeeeeeeeeeeeeeeees 8 Figure 10 Desioen Type Options arcicaustatienacceoias tiskincaietamen a a E 9 Figure 11 Building a Structure in the User Defined Pavement Option cccseeeeeeeees 10 Figure 12 Accessing the Layer Material Parameters Table ccseseeeeeeeeeeeeeeeeeeeeeees 11 Fig re 13 Feasible Desiei Results OPONS sssri ne i E E aa 11 Figure 14 Design Selected for Further Evaluation by Design Checks cccccceseeeeeeeeeeees IZ Figure 15 Mechanistic
26. er Sub Grade Layer Figure 11 Building a Structure in the User Defined Pavement Option 2 3 5 Editing the Material Parameters Table After clicking on the Go back button the screen shown in Figure 12 will appear that allows access to the layer material parameters table Edit the material type description layer moduli and thickness ranges as desired The default layer moduli are those currently recommended by TxDOT for design but should be overwritten when district experience dictates In this design example the only layer that is to be designed is the 1 inch SF Item 344 performance designed mixture layer It has a user defined thickness ranging from 4 to 12 inches all other layers have fixed thicknesses The goal is to determine the thickness of this layer to carry the cumulative design traffic loads 10 Const amp Maint Data MIN OVERLAY THICKNESS IN OVERLAY CONST TIME HR DAY ACP COMP DENSITY TONS CY ACP PRODUCTION RATE TONS HR WIDTH OF EACH LANE FT FIRST YEAR COST ATN MAINT ANN INC INCR IN MAINT COST MATERIAL NAME STONE MATRIX ASPHALT PERFORMANCE MIX 3 45F PERFORMANCE Mix 1 inch SF RICH BOTTOM LAYER LUIME CEMENT STABILIZED SUBG SUBGRADE Draw User Design Pavement COST PER Cy Detour Design for Overlays I To Main Menu DETOUR MODEL DURING OVERLAYS Save to Default TOTAL NUMBER OF LANES NUM OPEN LANES OVRLAY DIRECTION Save Input File NUM OPEN LANES NON OV DIRECTION DIST TRAFFIC
27. eriod the estimated traffic is 44 6 million ESALs The mechanistic check is performed to check that this traffic level passes the fatigue and subgrade rutting criteria built into FPS 21 In both cases with the proposed pavement structure the cracking and fatigue lives are close to 200 million ESALs which is the maximum value predicted by program For this case the designer must also verify that the perpetual pavement limiting strain criteria are not exceeded These criteria are e Tensile strain at the bottom of the HMA less than 70 micro strain the computed value is 40 9 e Vertical compressive strain at the top of the subgrade less than 200 micro strain computed value 108 13 at Formi Eg Cracking Life vs Changed thickness Design Parameters 400 Cracking Life in million ESAL se 2 00 650 0 lo ISTONE MATRIX ASPHALT 35 05 PERFORMANCE MIK 3745F os AICHBOTTOMLAYER SSS 30 0 Q3 o Oo mn oO oOo o Oo nm Mm co oS oa oi ea oo om oO a ofl a e oOo fo LIME CEMENT STABILIZED SUBG 0 4 SUBGRADE hs o fm 5 L w 60 BS 20 Sto Ssh Ses A r IUD AUS EO TS Change Thickness in m Pavement Life Based on design period 20 5 years the design life is million 44 688 Rutting Life vs Changed thickness B Rutting Life in million ESAL HMA Tensile Strain 40 9 Crack Life million 190 11 2000 1800 1600 1400 1200 1000 Subgrade Compressive Strain 108 0 Rut Life
28. esign Type Options All design type options except options 1 and 7 were available in FPS 19 Design option 1 is a variant of the ACP Flex Base over Subgrade option in FPS 19 now option 2 in FPS 21 where the final surface is a surface treatment The same performance model is used for both pavement types The important new feature of FPS 21 is Pavement Design Type 7 user defined pavement for this example select 7 and click on the Exit Pavement Design Type Selection button This option is intended to be used for multi layered pavement systems where four or more layers are to be designed This option will not permit designs of less than four layers including the subgrade When you first enter the screen shown in Figure 11 a tentative pavement structure is shown with four dummy layers There are 20 material types from which the designer can build a pavement structure To build the pavement structure shown in Figure 11 a Press the button to increase the number of layers in the pavement to 6 b Use the drag and drop feature Go to the material type select the material type by clicking it with the left mouse button Hold the button down and drag the layer into the proposed pavement structure Start with the subgrade click it and drag it to layer 6 then insert the lime treated subgrade and complete the pavement structure as shown c Press the Go back button to view the layer material parameters table and modify entries if desired a Use
29. g to the layer being designed in this case only the l inch SF layer Also move the tensile strain indicator ME to the bottom of the lowest HMA layer in this case the RBL Note that the compressive strain indicator t cannot be moved since the evaluation location is always at the top of the subgrade Then select Run 12 Thick ir Modulus kei Material Name Var Thickness 2 00 STONE MATRIX ASPHALT J 3 01 m PERFORMANCE MIs 3745F z A l PERFORMANCE Mi 1 inch SF PERFORMANCE MIX 1 inch SF E 0 50 RICH BOTTOM LAYER LIMEICEMENT STABILIZED SUBG SUBGRADE M Analysis blode Design C User Define Figure 15 Mechanistic Design Check Input Screen In the Design analysis mode shown in Figure 15 the user cannot change the pavement structure However by selecting the User Define mode the thickness and layer moduli values can be changed This allows some flexibility in evaluating alternate materials and or thicknesses without re running FPS The results of the mechanistic analysis are shown in Figure 16 There is one change to this procedure as provided in FPS 19 In FPS 21 the mechanistic check is performed on the traffic loads accumulated over the FPS computed time to first overlay as opposed to the 20 year cumulative loading For most flexible pavement designs this period will be less than the standard 20 year analysis period In the example given below the computed time to first overlay is 20 5 years for that p
30. igner looks at the Pavement Life section and notes the following e The estimated cumulative ESALs to the end of the first performance period at 10 8 years 1s 0 965M e The estimated number of 18 kip repetitions to failure in fatigue is 0 55M 57 percent of the projected ESALs by the end of the 1 performance period e The estimated number of 18 kip repetitions to failure in subgrade rutting is 0 44M 46 percent of the projected ESALs by the end of the 1 performance period e Both of these failure modes are likely to occur before the FPS predicted time to first overlay and the Check Result message accentuates this This FPS option could be under designed By looking at the left hand side of the screen the designer can evaluate the effect on the performance for these two failure criteria by increasing or decreasing the flexible base layer thickness in 0 inch increments Projected ESALs to failure are given on the vertical axis versus the flexible base layer thickness Also data labels are given for the estimated ESALs to failure on the trend line In the case of fatigue cracking increasing the base thickness has little benefit whereas for protecting the subgrade from rutting small increases in flexible base thickness are relatively beneficial 30 The structural parameters given in the table at the upper right are for reference purposes only and cannot be edited from this location The designer now wishes to evaluate the mechanisti
31. ike lala ares Ppa ald ase Ete gabe cial a Lod festa a Sh 1 m FF in Pieck i wal tas ad sn EmO kri dual t ot fpe a a a ya O15 Tas 7 i eee E THe ricde 7 Fer i Ena Loo ao w 10 0 ame Tamar L ee te irta Figure 5 Stress Analysis Tool as Accessed from the Main Menu 2 3 Setting up a Design Problem in the FPS 21 System Select the Main Menu FPS Pavement Design Option 2 3 1 Project Administrative Data Inputs The project administrative data input screen appears Figure 6 By clicking on the District input box a map is provided where the user can select a new District and County Updated default subgrade support values are provided within FPS 21 for every county in Texas Also a database of county soil types with average Texas Triaxial Class values is uploaded Use the blue arrow in the bottom right corner to go to the next input page FPS 21 FLEXIBLE PAVEMENT DESIGN Texas Departmenti of Transportation PAOBLEM oos DISTRICT E Enri Wom CONTROL 2 GATE 5 26 2008 HIG Hiii SH EE counts Z423 Pioi SECTION E JOB fiz3 COMMENTS This is a demo wersion otihe FPS 21 pragram Figure 6 FPS 21 Project Administrative Data Input Screen 2 3 2 Basic Design and Traffic Inputs In this version of FPS 21 all of the basic design criteria and traffic data are entered on the second input screen Figure 7 A HELP menu is provided click on any field select F1 and a description of the variable and allowable values w
32. ill be displayed These details are not provided in this report and the user is advised to consult the HELP menu within the program directly a Page 2 Input Data Basic Design Criteria H rafic Data LENGTH OF ANALYSIS PERIOD VAS 20 ADT BEGINNING WEH DAY 18000 MIN TIME TO FIRST OVERLAY YAS 15 ADT END 20 YA WEH DA 43000 MIN TIME BETWEEN OVERLAYS YRS 10 18 kip ESAL 20 YRA 1 DIR millions 43 2 DESIGN CONFIDENCE LEVEL 95 04 C AVG APP SPEED TO OW ZOME 70 INITIAL SERYVICEABILITY IND Ers 4 5 AVG SPEED OV DIRECTION 45 FINAL SERVICEABILITY IND Es a AMG SPEED HON OW DIRECTION fale SERY YICEABILITY INDE AFTER OVERLAY 4 PERCENT ADT HA CONSTRUCTION 6 0 DISTRICT TEMPERATURE CONSTANT 31 PERCENT TRUCKS IN ADT INTEREST RATE 70 Program Controls MA FUNDS SG YD INIT CONST 99 0 Max THICKNESS INIT CONST 69 0 Max THICKNESS ALL OVERLAYS 60 To Main Menu a Figure 7 FPS 21 Basic Design and Traffic Inputs The blue arrows are for moving between pages Using the right hand arrow advances you to the final design input page that appears as shown in Figure 8 input Design Data Pavement structure Const amp Maint Data MIN OVERLAY THICKNESS Inches OVERLAY CONST TIME HR DAY ACP COMP DENSITY TONS CY ACP PRODUCTION RATE TONS HR WIDTH OF EACH LANE Feet FIRST YEAR COST ATN MAINT ANN INC INCR IN MAINT COST MATERIAL NAME STONE MATRIX ASPHALT Design DENSE GRADED HMA Thin Type FLE
33. ion inches 492 Modified Traxzial Thickness inches 1 77 Input Subqrade Texas Triaxial Class TTC Option 1 Input TTC based on TEs 11 E f potion 2 Enter soil Pl to estimateTTC Soil type f Dption 3 Select TTC based on predominate soil type These soil types and TTC values are inthe KAUFMAN county database Modulus kst Y Material Hame 2 00 500 0 0 35 ASPH CONC PVMT 6 00 50 0 0 35 FLEXIBLE BASE 2 00 125 0 0 20 STABILIZED SUBGR CTARILI ED SUBGE 200 00 20 0 0 40 SUEGRADE 200 SUBGRADE 200 Figure 18 Option 3 for Selecting the Soil TTC from Soils Database In the example shown above the selected soil type is the CL clay which is reported to cover 54 percent of the selected county This soil in this county corresponds to a TTC value of 5 00 which is entered as the input to the calculation For this particular pavement design a cement stabilized layer was used using the Reference button a drop down table of materials is presented Selecting the Cement stabilized option the modified Cohesiometer value was set at 1000 This pavement structure fails the Triaxial check The FPS 21 design consists of 16 inches of cover over the subgrade For this check the total amount of cover required was 17 7 inches To meet the Modified Triaxial requirement one option would be to increase the base thickness by 2 inches Details on using this design check are more fully described by accessing the program HELP menu 2 4 3 Stress A
34. large differences in the projected ESALs to the FPS generated first performance period versus that estimated for failure in the two mechanistic modes appears to be prudent As always local experience may show better performance than indicated by these checks Cracking Life vs Changed thickness Cracking Life in million ESAL Design Parameters Thick Modulus Y Material Name oss ESPR CONCPyMT ps Feee 030 STABILI EDSUBGR 040 SUBGRADE 0 400 500 600 7 00 9 00 10 00 Change Thickness in Pavement Life Based on design period 10 8 years the traffic to first overlay is million 0 965 Rutting Life vs Changed thickness Rutting Life in million ESAL HMA Tensile Strain 231 0 Crack Life million 1 00 Subgrade Compressive Strain 432 0 Rut Life million 1 58 Check Result The Design is OK for the period 1 which is 10 8 years sA Trans nat ransportation A institute Figure B 6 Mechanistic Analysis Following User Define Inputs 300 400 500 600 700 800 92 00 Change Thicknesslin 32
35. lated for the first performance period as determined by the FPS run under Design 3 shown in Figure B 1 The designer wishes to evaluate the sensitivity of the flexible base layer thickness so the green box beneath the Vary Thickness heading is dragged to this layer level and the thickness increment is set to 1 0 inches The designer verifies that the tensile strain indicator ME is located at the bottom of the asphalt concrete layer The designer decides to use the default fatigue cracking and subgrade rutting equations Asphalt Institute The Asphalt Institute AI equations as used in FPS date back to the early 1980s In the case of the fatigue cracking performance equation the parameters apply to a typical dense graded HMAC mixture with 5 percent air voids using an unmodified binder at 11 percent by mixture volume roughly 4 8 to 5 0 percent asphalt content by weight The AI failure criterion is 20 percent of the highway surface is cracked In the case of subgrade rutting the AI performance equation does not evaluate the susceptibility of the flexible base or HMAC layers to rutting and failure is defined as 0 5 inch rutting as evaluated at the surface of the pavement The fatigue and rutting performance equation fields are active links to several other fatigue or rutting performance equations that the designer can select for alternate evaluations Also the designer can directly input alternate coefficient values f through fs to any of these
36. ment Design Result Problem O06 District 14 Austin Sechon 2 Highway 3H BY Conhidence Level C Control 1234 Coutu T1 SASTROF Job 123 Date 2 6 2011 Mo of Best Designs B Design Type PAVEMENT DESIGN TYRE 3 ACF ASPH STAB BASE OVER SUBGRADE Best Design No Design 1 Design 2 Design 3 Design 4 Design 5 Design 6 Material 4rrangement AB AB AB AB 4B AB Total Cost 14 65 il svat 15 41 15 62 15 23 15 52 No of Layers 2 Z 2 2 2 2 Layer Depths inches 1 5 2 0 2 5 3 0 14 2 0 7 0 6 5 6 0 5 5 9 0 8 5 No of Perk Periods 2 2 2 2 1 1 Fer Time years Wil 28 11 28 12 28 14 23 21 21 Material T able Overlay Policy inches 25 2 2 5 2 5 Print Gave File W FPS Pavement O06 Problem Control 1217 b FPS 21 Design Thicknesses Design Result District 14 County Ti Highway SH 69 Confidence Level Section aT Job 014 Date 2 77 2011 Mo of Best Designs Design Type PAVEMENT DESIGN TYFE 2 ACF ASPH STAB BASE OVER SUBGAADE Mert Page Re Aun FPS Material T able Print Save File Detail Cost TO Main Menu Best Design No Design 1 Design 2 Design 3 Design 4 Design 5 Design 6 Material Arrcarngerrnerit AB AB AB AB AB AB Total Cost 14 647 16 129 15 411 15 619 16 234 16 516 Ho of Layers 2 z 2 2 2 2 Layer Depths mchez 1 50 2 00 2 50 3 00 1 50 2 00 00 6 50 6 00 5 50 3 00 5 50 Ho ot Pert Periods 2 2 2 2 1 1 Pert Time Wears 11 28 11 28 12 28 12 29 2 21 Overlay Policy mchez 2 50 2 50 2 50 2 50
37. mmended values also available in TxDOT s online pavement design guide The FPS design process is comprised of the following two steps 1 generate a trial pavement structure with proposed FPS design thicknesses and 2 check this design with additional analysis routines which include mechanistic performance prediction The FPS system has an embedded design equation relating the computed surface curvature index difference of the W and W deflections of the pavement to the loss in serviceability as defined in the original AASHO Road Test As described below the design checks are principally based on either mechanistic design concepts which computed fatigue life and subgrade rutting potential or the Modified Texas Triaxial criteria which evaluates the impact of the anticipated heaviest load on the proposed pavement structure 1 1 Mechanistic Design Check The mechanistic design check computes and checks the sufficiency of the mechanistic responses in terms of the maximum induced horizontal tensile strain at the bottom of the lowest HMA layer and the maximum vertical compressive strain at the top of the subgrade Standard models are available to convert these values into the number of standard 18 kip load applications until either cracking or subgrade rutting failure occurs The mechanistic design check is recommended for all pavements with HMA surfaces The fatigue analysis is restricted to all pavements where the HMA thickness is greater than 1
38. nalysis Tool Post FPS Design Analysis Another user option in FPS 21 is to perform a stress analysis of the designed structure This Stress Analysis option is also accessed from the Pavement Plotting screen Figure 14 In the example shown below the simulated FWD deflection bowl for the proposed pavement design can be generated This information could be used post construction as a construction check to verify design requirements were achieved or it could be used during design to determine structures that might return a deflection deemed suitable for project requirements 16 Load Tpm Pavernart Blreas Anah nia Pia DO 5ra The DOO Jus Tae E ETI Ld Shey Er Ey L si j resin ees fl Pisco pel Wari l Tho Eke Peesen aon ff cxf aon 035 CE PEA ann A RE PES ESEE i aso eon cs TPE ENE T Cate aed os LE es D Erb Hode w Degi 0 Um ss en Figure 19 Stress Analysis Tool as Accessed from the Pavement Plotting Scre In this example the temperature corrected design maximum deflection for this highway at the 9000 Ib load level would be 6 5 mils and the value for the outer sensor subgrade strength would be 1 9 mils Field FWD deflections significantly higher than this would be a cause for concern Details on using this tool are more fully described by accessing the program HELP menu 17 APPENDIX A THICKNESS DESIGN COMPARISON FPS 19 VERSUS FPS 21 FOR COMPARABLE PAVEMENT DESIGN TYP
39. ovides the capability of generating user defined pavement structures in addition to the fixed design options currently available in FPS 19 The user defined option is recommended for thick HMA structures when more than three layers are to be built on top of the subgrade The designer can select layer materials based on specification item numbers and a recommended design modulus value is also supplied e Provides additional procedures for obtaining estimated Texas Triaxial Class values for the subgrade soils either based on county specific soil types or from basic soil properties such as plasticity index e Provides extended stress analysis capabilities where for example the allowable deflections for the as proposed pavement structure can be computed These values could be used for structural strength verification after construction e Incorporates the findings from recently completed research studies and also the recommendations from TxDOT s Pavement Design Guide The FPS design approach is based on a linear elastic analysis system and the key material inputs are the backcalculated modulus values of the pavement layers For in place materials these are obtained from testing with the Falling Weight Deflectometer and processing the data with backcalculation software such as MODULUS 6 For newly placed materials realistic average moduli values for the main structural layers in typical Texas pavements are supplied based on user experience with reco
40. performance equations by overwriting the defaults For example Craus et al concluded that for HMAC surfaces thinner than 4 0 inches f 0 0636 for the AI fatigue performance model which effectively reduces the number of repetitions to failure for thinner HMAC surfaces Craus J R Yuce and C L Monismith 1984 Fatigue Behavior of Thin Asphalt Concrete Layers in Flexible Pavement Structures Proceedings Association of Asphalt Paving Technologies Vol 53 pp 559 582 29 Once the designer has made all desired inputs the Run button is selected and the mechanistic analysis output is displayed as shown in Figure B 4 SEOnm Cracking Life vs Changed thickness hep Cracking Life in million ESAL Design Parameters x Material Name 0 55 pas 0 35 ASPH CONC PVMT eben nati 1 Wes AEE EE E SEMEN E E E E E e eae Se ae 0 35 FLEXIBLE BASE a u a 030 STABIUZED SUBGR 0 40 SUBGRADE 200 2 00 300 400 500 600 700 800 900 1000 11 00 Change Thickness in Pavement Life Based on design period 10 8 years the traffic to first overlay is million 0 965 Rutting Life vs Changed thickness Rutting Life in million ESAL HMA Tensile Strain 278 0 Crack Life million 0 55 Subgrade Compressive Strain 575 0 Rut Life million 0 44 sA rans niati ransportation A institute Figure B 4 Mechanistic Design Check Results Change Thickness in Looking at the center right hand part of the screen the des
41. r Define Pavement Go Back No _ Material Type 2004 Speciicati Design Moduius Poisson Ratio Layer Type 35 Item 316 318 Item 340 341 item 340 341 SURFACE TREATMENT DENSE GRADED HMA Thin DENSE GRADED HMA Thick 200 ksi 500 ksi 650 ksi 0 0 35 0 35 AC Layer AC Layer AC Layer Item 342 Item 344 Item 344 Item 346 Item 330 Item 334 Item 344 Item 265 Item 292 ltem 314 ltem 247 500 ksi 0 30 B50 950 ksi 0 35 B50 950 ksi 0 35 650 850ksi 0 35 200 350ksi 0 35 300 400ksi 0 35 4007 600ksi 0 35 50 150ksi 0 35 250 400ksi 50 100ksi 0 35 40 70ksi 0 35 Item 260 263 60 75ksi 0 30 0 35 ltem 275 276 80 150ksi 0 20 0 30 Item 265 807 ksi 030 LIME CEMENT STABILIZED SUBG Item 260 275 30 45ksi 0 30 EMULSIFIED ASPH TREAT SUBG Item 314 15 Bksi 03 SUBGRADE 16ksi 0 40 0 45 PERMEABLE FRICTION COURSE PERFORMANCE MIx 3 4SF PERFORMANCE MIX 1 inch SF AC Layer AC Layer AC Layer AC Layer AC Layer AC Layer AC Layer LIMESTONE ROCK ASPH PVMT HOT MIx COLD LAID ACP RICH BOTTOM LAYER FA or LFA STABILIZED ASPHALT TREATED BASE EMULSIFIED ASPH TRT BASE FLEXIBLE BASE LIME STABILIZED BASE CEMENT STABILIZED BASE FLY ASH OR LIME FLY ASH STABI 1 2 3 4 5 6 td 8 9 RICH BOTTOM LAYER Modulus 500 0 ksi Thickness from 2 0 to 2 0 inches Base Layer Base Layer Base Layer Base Layer Base Layer Base Layer _ SubBase Layer _ SubBase Layer _ SubBase Lay
42. sign Ho Design 1 Design 2 Design 3 Design 4 Design 5 Design 6 Material Arrangernent AB AB AB AB AB AB Total Cost 14 148 14 185 14 237 14 404 14 499 14 757 Ho of Layers 2 2 2 2 2 Layer Depths mchez 3 50 3 501 1 50 4 00 1 50 3 00 6 00 700 13 00 6 00 12 50 5 50 Mo of Fert Periods 2 Z 2 2 2 Fert Time years 10 21 11 20 11 21 12 22 10 21 10 21 Overlay Policy mchez 3 00 2 50 2 50 2 50 3 00 3 00 Swelling Clay Loss 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 c FPS 19 Design Thicknesses Figure A 2 Design Type 2 Thin HMA Surface 21 Input Design Data Pavement Structure Const amp Maint Data MIN OVERLAY THICKNESS Inches 2 0 OVERLAY CONST TIME HR DAY ACP COMP DENSITY TONS CY ACP PRODUCTION RATE TONS HR WIDTH OF EACH LANE Feet FIRST YEAR COST ATN MAINT ANN INC INCR IN MAINT COST Detour Design for Overlays a 255 NUM OPEN LANES OVALAY DIRECTION 0 DETOUR MODEL DURING OVERLAYS TOTAL NUMBER OF LANES for two direction NUM OPEN LANES NON O DIRECTION 1 DIST TRAFFIC SLOWED OV DIR 0 6 DIST TRAFFIC SLOWED NON OY DIR LYR 1 Design 2 Type 3 COST MODULUS POISN MIN MAX SALVAGE MATERIAL NAME PERG E ksi RATIO DEPTH DEPTH 4 ASPH CONC PVMT 70 0 500 0 0 35 30 0 ASPH STAB BASE 60 0 450 0 0 35 10 0 90 0 SUBGRADE 200 12 0 0 40 200 0 90 0 a Inputs to both programs 18 kips 5M TFO 10 years min PSI 2 5 SW FPS Pave
43. ts euccutasennaas ais maaaucetubeduetaateavaserneiaie maanceiuoediataaeantanan 2 1 3 FPS 21 System Requirements and Loading Instructions esessssooeessssssssoerrssssssserrrssss 2 2 New Features 1n the PPS ZL S0Wai enar e E E E E 5 2A Jnitatine the PPS 2 1 Design SoftWare senera E eesurivedseowes 5 2 2 Main Menu with Version Number Date ccc ccc cescccsecceeccceeccesscesceesseessseeseeseseeeess 5 2 3 Setting up a Design Problem in the FPS 21 System cc cccccccessseeeeeceeeeeeaeeseeeeeeees 6 2 3 1 Project Administrative Data Inputs cc ccesseseecccccceeeaeeeeeeececeeeeeeaeeeeeceeeeeeeeaeeeeees 6 Zo Basic Desienvand Prarie Inputs renin E A 7 2 3 0 SeleCUne AL Parlic Detour Mode crsscissepern achuccaccmsrendaticlennenmseede aces 8 Zoe Selecting a Pavement estan Type sessir icra he icone ioriame cena 9 2 5 Editing the Material Parameters 1 ables c sisiiwsateccinataneatiedivaiutinasiiuniedialitinsious 10 2 4 Running FPS 21 and Interpreting the Results i eecccsecccccceceeeseeeeeeeceeeeaaaeeeeeeeeees 11 Zk Ehe Mechanistic Cheek Sursee E A E 12 242 1 ne Moditied Texas Mriak tal Ce eresi 14 2 4 3 Stress Analysis Tool Post FPS Design AnalySis ccccccccccccceccesesseeeeceeeeeeeeeeeeees 16 Appendix A Thickness Design Comparison FPS 19 versus FPS 21 for Comparable Pavement Desioen Types lt sxscucssnseaiainsexstydnsntesdatntuaczncmansansthenssaveunsoediaiaswiaandniyiosdaiaweaaioweeiatas 19 Appen
44. years Overlay Policy inches Check Design Design 2 Design 3 Design 4 Design 5 ABC ABC ABC ABC 16 93 17 56 20 73 23 05 3 3 3 3 20 20 45 40 6 0 6 0 6 0 10 5 2 0 an 2 0 a0 Check Design Check Design Check Design Figure B 1 Feasible Design Results 2i Based on the design options given the designer would like to investigate design 3 further Clicking on the Check Design button beneath these results will display the pavement plot with design check options as shown in Figure B 2 Best Pavement Design Drawing 3 DESIGN 3 PAVEMENT PLOTTING Period 1 Period 2 Thick fin Mat Type First Overlay ASPH CONC PYMT FLESIELE BASE STABILIZED SUBGR SUBGRADE 200 10 8 years 21 7 years Print Previous Design Mest Design All Design Plots Mechanistic Check Triazial Check Stress Analysis Figure B 2 Design 3 Selected for Further Evaluation by Mechanistic Checks By selecting the Mechanistic Check button the screen shown in Figure B 3 will appear Mechanistic Design Check for Pavement 3 cr Ti Fy Thick in Modulus ksi Maternal Hame Vary Thickness 6 00 s0 fis PEBE Mho ao o fpa premos ooo psen a m ra NAE ENA 1376 09 aar Nn Fale Figure B 3 Mechanistic Design Check Input Screen 28 Note in the upper left of the screen are all the structural layer material parameters as originally entered by the designer in FPS and layer thicknesses calcu

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