UFC 3-260-02
30 June 2001
The transverse joint must be capable of withstanding the sum of the temperature and moisture change in
length. Figure 16-4 shows typical sections of two general methods of construction of the transverse
joints. Type A consists of having the transition slab rest directly on the subbase. The transition slab will
be constructed to the thickness requirements of either plain or reinforced concrete pavements and
connected to the prestressed slabs with dowel bars to provide load transfer through the joint. The size
and spacing of the dowel bars will be determined from Chapter 12 based upon the plain or reinforced
concrete thickness requirements. Type B consists of a grade slab underlying the ends of the
prestressed concrete pavement and transition slab. The transition slab will be reinforced concrete of the
same thickness as the prestressed concrete pavement. The grade slab will also be reinforced concrete.
The thickness of the grade slab and the percent of reinforcing steel in both the transition slab and grade
slab will be determined in accordance with overlay design procedures if the transition slab is a reinforced
concrete overlay of the reinforced grade slab.
c. Joint Seals. Longitudinal joints in prestressed concrete pavements, except where longitudinal
transition lanes will be required to permit prestressing operations of wide paved areas, need not be
sealed since they will be held tightly closed by the prestressing. However, if these joints are sealed,
materials meeting the requirements for plain concrete pavements should be used. When longitudinal
transition lanes are required, the longitudinal joint should be treated in the same manner as a transverse
joint. Several types of sealants have been used for the transverse joints, but no standardized seals have
been established. Poured-in-place materials have not been satisfactory to accommodate the large
movements that occur. Preformed and mechanical seals, such as shown in Figure 16-5 are
recommended. The final selection of a sealant will be a matter of engineering judgment that must be
approved by HQUSACE (CEMP-ET), the appropriate Air Force Major Command, or the Naval Facilities
Engineering Command.
9. EXAMPLES OF PRESTRESSED CONCRETE PAVEMENT DESIGN.
a. General. A 75-foot-wide by 10,000-foot-long taxiway pavement is to be designed for
100,000 passes of the C-141 aircraft at 320,000 pounds gross weight using prestressed concrete.
Laboratory and field test programs have yielded the following pertinent physical property data for the
foundation and concrete: modulus of soil reaction, k = 200 pci; 90-day flexural strength of concrete, R =
700 psi; density of concrete = 150 lb/ft3; modulus of elasticity in flexure of concrete, E = 4 106 psi;
Poisson's ratio of concrete, < = 0.15; and coefficient of thermal expansion of concrete, ,c = 4 10-6 inch
per inch per degree Fahrenheit.
b. Determination of Design Prestress Level. Prestress loads will be determined for preselected
thicknesses hp of 6, 7, and 8 inches. Following the procedures described in paragraph 5, the load-
repetition factor N is 2.46 (Figure 16-1) and the load-moment factor B is 0.0523, 0.0544, and 0.0565 for
thicknesses of 6, 7, and 8 inches, respectively. The ratio of multiple-wheel gear load to single-wheel
gear load, w is 2.22, 2.23, and 2.335 for thickness of 6, 7, and 8 inches, respectively. A polyethylene
sheet bond-breaking medium will be used between the foundation and prestressed slab, and the
coefficient of sliding friction Cf will be 0.60. A slab length L of 400 feet will be used; therefore, the
subgrade restraint stress in the longitudinal direction will be
(
(16-8)
In the transverse direction, the subgrade restraint stress will be
16-7
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