Load Characterization

Rigid Pavement Design Course Traffic Load Considerations Load Groups Lane Wander Load Configuration

Rigid Pavement Design Course Single Axle Load Groups 10 – 12 kips 12 – 14 kips 14 – 16 kips 16 – 18 kips 18 – 20 kips 20 – 22 kips 22 – 24 kips 24 – 26 kips

Rigid Pavement Design Course Pavement Edge Accumulation Fatigue Damage Distribution Traffic Distribution Design Load Position t=10” k=100pci Bituminous ShoulderP.C.C. Pavement Accumulate Fatigue Damage Traffic Distribution (%) Figure 8 Lateral Distribution Fatigue Damage Effects

Rigid Pavement Design Course Dowel Bar Subgrade Critical Stress for Mid Slab Loading Slab Thickness Slab Length (L) Single Axle Loading Agg Subbase hehe w s a Traffic Lane Shoulder Hinge Joint DoDo

Rigid Pavement Design Course Design Load Stress

Rigid Pavement Design Course Load Applications To Failure, N f Stress/Strength ( R ) Mean P f = 0.5 Portland Cement Concrete Flexural Fatigue Hilsdorf Kesler (P f =.05) PCA Z.M. Design P f = 0.24 Figure PCC Flexural Fatigue Data with Various Curves.

Rigid Pavement Design Course d x Edge Interior Single, dual, or dual tandem wheel loads Load Configuration

Rigid Pavement Design Course unbonded or bonded Tandem Dual Tridem Tied or Extended Shoulder DoDo W L slab  = 0 or f

Rigid Pavement Design Course Asphalt Institute - used s/a FAA (based on tire configuration) Effort has always been to transform the actual multiple-wheel load into an equivalent loading system consisting of a single wheel. ESWL: Equivalent Single Wheel Load (Design Position) ESAL: Equivalent Single Axle Load ESAR: Equivalent Single Axle Radius (Design Position)

Rigid Pavement Design Course Lane Wander

Rigid Pavement Design Course Equivalent Damage Ratio (EDR) Damage Ration Shoulder Type Bituminous 10’ Tied 2’ Extended Mean Distance D (in)

Rigid Pavement Design Course Portland Cement Concrete Flexural Fatigue LAB Key: Kesler Raithby and Galloway Ballinger Load Applications To Failure, N f Stress/Strength ( R ) Log N f = 17.61–17.61(R) Se = 1.40 N f = 10 k1+k2r FIELD logN= 2.27(1/R)+0.056

Rigid Pavement Design Course Cracking Slab thickness Subgrade Subbase PCC slab Slab length Single axle Tandem axle STRT Transverse joint

Rigid Pavement Design Course Design Load Stress

Rigid Pavement Design Course Load Equivalency Factors (based on fatigue damage)

Rigid Pavement Design Course Dimensionless Stress Function Edge Condition Axle Type nCoefficients abc FreeSA TA Extended Lane SA x10 -2 TA

Rigid Pavement Design Course Dimensionless Stress Function Int Edge Corner a+bx+cx 2 S

Rigid Pavement Design Course Equivalent Damage Ratio

Rigid Pavement Design Course Equivalent Damage Ratio

Rigid Pavement Design Course Equivalent Damage Ratio

Rigid Pavement Design Course SA, TA, or Tridem Axle Loaded Radius, a i % ADT Less Than a 0 = 1 - % Trucks b 0 = % Legal Axles + a 0 a0a0 b0b0 Maximum Limit Lower Limit Upper Limit aLaL aUaU aMaM % ADT % Trucks % SA % TA % Tridem Also: % Legal Axles = b 0 – a 0 % Illegal Axles = %Trucks – b 0 + a 0 % Trucks % ADT = a + b(a i ) + c(a i ) 2 AjAj Traffic Model

Rigid Pavement Design Course ADT j from P i+1 to P i = per Axle Type (j) per Day ESAL i (N i ) per Load Group (i) per Day % Trucks (A j )ELC j %SA1.0 %TA %Tridem i = Load Group j = Load Configuration (Axle Type) ELC j = Equivalent Load Conversion Factor LEF = Load Equivalency Factor relative to single axle load groups (x) Design ESAL (N) =  ESAL i EDR (Correction for load group, load configuration, and lane wander) Traffic Model

Rigid Pavement Design Course Traffic Model (per load configuration)