What are the considerations for design of rigid pavement?
Design of rigid pavements is based on Westergaard’s analysis, where modulus of subgrade reaction, radius of relative stiffness, radius of wheel load distribution are used. For critical design, a combination of load stress, frictional stress and warping stress is considered.
What are the factors to be considered in design of pavement?
Factors Affecting Pavement Design
- Wheel load.
- Axle configuration.
- Contact pressure.
- Vehicle speed.
- Repetition of loads.
- Subgrade type.
- Temperature.
- Precipitation.
What is meant by radius of relative stiffness?
The radius of relative stiffness is a useful term describing the relative stiffness of the slab compared to its foundation. In Westergaard’s equations the distance from the centre of the slab to the point of contraflexure is equal to the radius of relative stiffness for the interior loading condition.
What would be the Centre to Centre distance between the wheels if the clear gap between them is 60 mm and the radius of contact area is 150 mm?
Explanation: The equation relating the clear gap (d), centre to centre spacing (S) and radius of contact area (r) is given by S=(d+2a). So, d can be found out as d=S-2a=280-2×110=60 mm. 12. What is the original shape of the contact area?
Which is the most essential requirements in highway pavement design?
Which of the following requirement is given most importance in highway design? Explanation: The structural design like highway speed, geometric design is given the most importance in design. Explanation: The surface of the pavement should be sufficient enough to resist the skid of vehicles by using friction.
What are the requirements of highway pavement?
Requirements of a pavement
- Sufficient thickness to distribute the wheel load stresses to a safe value on the sub-grade soil,
- Structurally strong to withstand all types of stresses imposed upon it,
- Adequate coefficient of friction to prevent skidding of vehicles,
What are four factors to be considered in the design of a road or highway?
The setting and character of the area, the values of the community, the needs of the highway users, and the challenges and opportunities are unique factors that designers must consider with each highway project.
Which one is very important factor for design and analysis of pavement?
Traffic is the most important factor in the pavement design. The key factors include contact pressure, wheel load, axle configuration, moving loads, load, and load repetitions.
What is relative stiffness?
Relative stiffness can also be defined as ratio of second moment of area and member length. It can be said that the relative stiffness is ratio of stiffness of a member to total stiffness of the all members that are meeting at joint.
What would be the Centre to Centre distance between the wheels if the clear gap between them is 70 mm and the radius of the contact area is 150?
Clarification: The equation relating the clear gap (d), centre to centre spacing (S) and radius of contact area (r) is given by S=(d+2a). So, S can be found out as S=70+2×150=370 mm.
What is the formula for the Centre to Centre spacing between wheels?
P is the wheel load (single wheel load) = 5500/2 = 2750 Kg. S is the centre to centre distance between the two wheels = 30 cm. d is the clear distance between two wheels = 10 cm. Z is the thickness of the pavement.
What is the Westergaard’s analysis used for?
Arora (2003) has reported that the Westergaard’s analysis is used for design of rigid pavements. The stresses in the concrete slab are determined using Westergaard’s theory. Westergaard considered the rigid pavement as a thin elastic plate resting on soil subgrade.
What is Westergaard analysis of rigid pavement design technique?
The Westergaard analysis of rigid pavement design technique involves simplification of the problem of wheel loading on a slab by assuming that the contact area is circular. This forms a circular patch load with stress distributed evenly across the patch.
What is the relationship between Westergaard’s equation and the resisting section?
Westergaard’s gives a relation for equivalent radius of the resisting section in cm in the equation . The cement concrete slab is assumed to be homogeneous and to have uniform elastic properties with vertical sub-grade reaction being proportional to the deflection.
What is the Westergaard analysis of slab deflection?
The Westergaard analysis interior loading condition leads to a slab deflection as illustrated in the below diagram. The point of contraflexure is equal to the radius of relative stiffness and the maximum tensile stresses occur at the bottom of the slab directly beneath the load.
