Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

LecturerDr. Eng. Omar Osman

Asst. Professor of Highway & Airport EngineeringFaculty of Engineering, Cairo University

CAIRO UNIVERSITY FACULTY OF ENGINEERINGPUBLIC WORKS DEPARTMENT

Structural Design of Pavements

4th Year Civil Engineering Highway Engineering Course2008-2009

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

Structural Design of Pavements

II- Rigid Pavements

- Materials

- Stresses

- Design Methods

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

Pavement Types

- Flexible

- Rigid

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

Factors Influencing Pavement Design/Performance

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

Cracks

Corner Breaks Joint Failure

Faulting

Critical Concrete Pavement Responses: Distresses

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

RIGID PAVEMENT TYPES

a) Simply Reinforced

b) doweled

c) plain

d) skewed joints

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

JOINT TYPES

• Expansion:

• Doweled Contraction:

• Keyed Construction:

• Doweled Construction:

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

JOINT TYPES

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

STRUCTURAL SYSTEM

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

• SUBGRADE SUPPORT

• Modulus of Subgrade Reaction: k (pci)

STRUCTURAL SYSTEM

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

• Radius of Relative Stiffness

STRUCTURAL SYSTEM

[50~500 pci][0.15]

[4,000,000 psi][8~24 inch]

[25~98 inch]

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

STRESSES IN RIGID PAVEMENTS –Temperature: Warping Stresses

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

Temperature: Warping Stresses

[2~3 ºF/inch][0.000005]

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

Temperature: Warping Stresses

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

STRESSES IN RIGID PAVEMENTS –Temperature: Friction Stresses

[1.5]

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

Temperature: Friction Stresses –Slab Length

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

STRESSES IN RIGID PAVEMENTS –Loading

Wheel Loads& Stresses

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

STRESSES IN RIGID PAVEMENTS –Loading Cases

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

STRESSES IN RIGID PAVEMENTS –Loading Stresses

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

STRESSES IN RIGID PAVEMENTS –Loading Stresses

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Design Method

• Design Considerations:• Flextural Strength of Concrete• Subgrade & Subbase Support• Traffic Load

• Design Procedure:• Finite-element analysis: Stresses & Deflections• Fatigue analysis (crack initiation)• Erosion analysis (Pumping, Faulting)

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Design Method

• Flextural Strength of Concrete (modulus of rupture)

ASTM C78 – Third-point methodP × L / (w d2)

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Design Method

• Subgrade Characterization

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Design Method•Subbase Support: Correction of Modulus of sub grade reaction (K)

associated with agg. subbase thickness.

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Design Method• Traffic

• Load factors• Interstate: 1.2• Arterial: 1.1• Local access: 1.0

• Axle configuration and loads: Classes & Counts

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Design Method• Fatigue analysis

• To limit fatigue cracking (initiation of first crack)• Determine equivalent stress associate with sub grade reaction and

pavement thickness• Determine stress ratio = equivalent stress/MOR • Determine allowable number of stress application at the given axel

load and stress ratio• Repeat for all axel loads• Calculate the % fatigue life used for each applied load. The sum

for all loads must be less then 100%.

• Erosion analysis• Basically the same method is used as in the fatigue analysis.

Limiting corner deflections is the target.

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Fatigue Analysis, Equiv. Stress; No Shoulder

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Fatigue Analysis, Equiv. Stress; With Shoulder

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Fatigue Analysis, Allowable Repetitions

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Erosion Analysis, Erosion Factor; Doweled No Shoulder

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Erosion Analysis, Erosion Factor; Agg Interlock No Shldr

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Erosion Analysis, Erosion Factor; Doweled & Shoulder

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Erosion Analysis, Erosion Factor; Agg Interlock & Shldr

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Erosion Analysis, Allowable Repetitions –No Shoulder

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method – Erosion Analysis, Allowable Repetitions –With Shoulder

Highway Engineering - Structure Design of Pavements

Lecture Notes - Dr. Omar Osman

PCA Method –Thickness Design Example