Salman bin Abdulaziz University
College of Engineering
Dept. of Civil Engineering
‫جامعة سلمان بن عبدالعزيز‬
‫كلية الهندسة‬
‫قسم الهندسة المدنية‬
Homework n°2 (Semester II -2015)
CE 1341 : Pavement Materials and Design
12/05/1436 H )03/03/1045 G)
Time allowed : Free
Instructor : Dr. Khaled KHEDER
Student Name
ID
Exercises and Questions
Marks
Exercise n° 1
4
Exercise n° 2
3
Exercise n° 3
3
Total
10
1
Exercise n° 1 (4 marks) :
Referring to Fig. 1 below, three-layer pavement structure has the following
characteristics :
● The thickness of layer 1 is h1 =3 in;
● The thickness of layer 2 is h2 =12 in;
● The Young modulus of layer 1 is E1 = 600,000 psi;
● The Young modulus of layer 2 is E2 = 30,000 psi;
● The Young modulus of layer 3 is E3 = 15,000 psi;
For p = 80 psi and a = 6 in, calculate the following :
● The vertical stress at the interface 1;
● The vertical stress at the interface 2;
● The horizontal stress at the bottom of layer 1;
● The horizontal stress at the bottom of layer 2;
● The horizontal stress at the top of layer 3;
● The horizontal strain at the bottom of layer 1;
● The vertical strain at the top of layer 3.
Fig. 1 : Three-layer pavement system showing location of stress.
2
Exercise n° 2 (3 marks) :
Design size and spacing of dowel bars at an expansion joint of concrete
pavement of thickness 20 cm. Given the radius of relative stiffness of 90 cm. Design
wheel load 4000 kg. Load capacity of the dowel system is 40 percent of design wheel
load. Joint width is 3.0 cm and the permissible stress in shear, bending and bearing
stress in dowel bars are 1000, 1500 and 100 kg/cm2 respectively.
Exercise n° 3 (3 marks) :
Design the length and spacing of tie bars given that the pavement thickness is
20 cm and width of the road is 7 m with one longitudinal joint. The unit weight of
concrete is 2400 kg/m3, the coefficient of friction is 1.5, allowable working tensile
stress in steel is 1750 kg/cm2, and bond stress of deformed bars is 24.6 kg/cm2.
.‫باهلل‬
3
‫إستعن‬