The deflection under a rigid plate is 79% of that under a flexible plate. A typical cross section of the rigid pavement is shown in figure below compared to flexible pavement, rigid pavements are placed either directly on the prepared subgrade or on a single layer of granular or stabilized material. In rigid pavement, load is distributed by the slab action, rigid pavements are constructed by portland cement concrete pcc and should be analyzed by plate theory instead of layer theory. Stresses in rigid pavements principles of pavement design. Mechanistic analysis of rigid pavement for temperature. Excessive compressive stress causes deterioration in. Rigid pavement rigid pavements have sufficient flexural strength to transmit the wheel load stresses to a wider area below. Material containing subgrade and environment condition are also responsible for stresses in the pavement. Therefore, slab curling calculations seek to find the points of maximum tensile stress as the slab curls due to temperature gradients within figure 1. Different pavement types use different types of joints and reinforcement to control the forces acting on the concrete pavement. Stresses in rigid pavements principles of pavement. Mechanistic analysis of rigid pavement for temperature stresses. The stresses are not transferred from grain to grain to the lower layers as in the ease of flexible pavement layers.
Rigid pavement has sufficient flexural strength to transmit the wheel load stresses to wider below. The loads will distribute to natural soil layer through different layers of rigid pavement. In other words, the foundation reaction or vertical stress. Statistical analysis of stresses in rigid pavement c international journal of civil and environmental engineering 6 2012 265. Effect of tire pressure, total load, and wheel configuration. Introduction to rigid pavement design ced engineering.
Bending of the slab due to wheel load on temperature. These factors tend to result in deformations of the concrete slab. The different types of distresses responsible for failures in rigid pavements are. In the design of a rigid pavement, the flexural strength of concrete is the major factor and not the strength of subgrade. A major functiop of any pavement is to spread the concentrated load delivered to it by the wheel sufficiently so that the stress ultimately transmitted to the underlying soil will not cause shear nor excessive deformation. The mechanisticempirical approach relates calculated pavement stresses to empirically derived failure conditions. There are various types of stresses yields in flexible and rigid pavements under the applied live load. Repair techniques these types of failures in rigid pavements are discussed.
Rigid pavements have sufficient flexural strength to transmit the wheel load stresses to a wider area below. Pdf a rigid pavement is a structure consisting of superimposed layers of processed materials above the natural soilsubgrade, whose primary. A rigid pavement is constructed from cement concrete or reinforced concrete slabs. Pavement design for roads, streets, walks, and open. Nonlinear temperature gradient effect on maximum warping stresses in rigid pavements bouz1d choubane and mang tia the. Failures in rigid pavements are caused by distresses due to various causes. Stresses in layered systems at any point, 9 stresses exist. The following examples illustrate how rigid pavement responses to different stresses are calculated load stress example calculations example 1. Temperature differential between the top and bottom of the slab causes curling warping stress in the pavement. Stresses in flexible pavement rutting engineering intro. The stresses are not transferred from grain to grain to the lower layer as in the case of flexible pavement layers. Stresses are the response of loading on the pavement.
Design, types, flexible and rigid pavement, notes and functions. Design period or design life of a pavement is the period of time for which the initially. Interior loading edge loading corner loading shrinkageexpansion stresses b. Design the length and spacing of tie bars given that the pavement thickness is 20cm and width of the road is 7m with one longitudinal joint. The rigid pavements are made of portland cement concreteeither. Temperature stresses are developed in cement concrete pavement due to variation in slab temperature. He considered rigid pavement slab as a thin elastic plate resting on soil subgrade, which is assumed to be a dense liquid. The rigid pavement design procedure presented herein is based upon the criti cal tensile stresses produced within the slab by the vehicle loading. Download citation stresses in rigid pavements curvature and stresses caused by bending relative stiffness of slabs. Nature of responses under flexible and rigid plates. Pdf mechanistic analysis of rigid pavement for temperature. Twolayer theory burmister topic 3 flexible pavement stress analysis 5. The rigid pavement slab as tensile strength, tensile stresses are developed due to the bending of the slab under the wheel load temperature variations providing a. Correlation between theory, small scale model studies, and fullscale accelerated traf.
This report will be of interest to engineers involved in rigid pavement design and anal ys i s. Rigid pavement analysis and design fhwa us department of. To investigate the influences of roadway roughness on pavement stresses, this study developed a coupled system consisting of a quartercar model and an equivalent lump pavement model. I is a distance of w2 from edge, where w width tire imprint figure 3. This is caused by i daily variation resulting in a. Pavement design for roads, streets, walks, and open storage areas. Analysis of rigid pavement stresses by finite element method. Oct 12, 2019 rigid pavements are those which posses note worthy flexural strength or flexural rigidity. Modulus of subgrade reaction, k, is the constant that defines the subgrade in classical works of rigid pavements as shown in figure 214 and defined as. Mechanistic analysis of rigid pavement for wheel load. A project description form pdf was prepared for state agencies interested in.
The rigid pavement does this by beam or slab action. The high flexural strength is predominant and the subgrade strength does not have much importance as in case of flexible pavement. Foster and ahlvin 1954 developed charts for computing vertical, tangential and radial stresses. Rigid pavements are those which posses note worthy flexural strength or flexural rigidity. Rigid pavements support loads through rigidity and high modulus of elasticity of concrete slab. Analysis of rigid pavement stresses by finite element. National academies of sciences, engineering, and medicine. The flexible pavement system action is more complexthe load is spread. Rigid pavements are made up of portland cement concreteeither plain, reinforced or prestressed concrete. Principal stress represents the extreme normal stress ales florian, lenka s evelova, and rudolf hela statistical analysis of stresses in rigid pavement c international journal of civil and environmental engineering 6 2012 265. Of course, the stresses at any point in the subgrade consist of combinations of shear and normal stress. However, the dynamic effects were not taken into account in most pavement design and studies. Poor subgradesubbase preparation can not be overcome with thickness.
Due to this property of pavement, when the subgrade deflects. Rigid pavementrigid pavement 20 deflection is very small hence the name rigid pavement. Highwaytransportation lec 18u4pavement design part a1 flexible pavement by bk mahawar duration. Types of pavement flexible pavements and rigid pavements. Westergaards theory is considered good to design the rigid pavements. Utility structures that are not isolated from the rigid pavement lanes, develop higher stresses in the pavement. Rigid pavement response calculations pavement interactive. The behavior of rigid pavement on loose sand by nonlinear. This pressure deformation characteristics of rigid pavement lead westergaard to the define the term radius of relative stiffness in cm is given by the equation. Through the use of reinforcement, the location and spacing of cracks can also be controlled.
Pavement design is governed by a number of considerationsfactors, as given below. Since pcc is much stronger in compression than tension, tensile stresses tend to control pcc pavement design. Rigid pavements respond to loading in a variety of ways that affect performance both initial and longterm. The top most paved surface of such type of pavement is flexible, that is extremely dependent on the underlying layers. Stresses in rigid pavements stresses in rigid pavements result from variety of sources, of which the applied vehicle loads, changes in temperature of the slab, friction between the slab and the subgrade or base course are the most important. Joints may be thought of as controlled cracks that will reduce the stresses the concrete will experience during its life and greatly increase the life of the concrete pavement. Friction stresses l l2 h friction between concrete slab and its foundations induces internal tensile stresses in the concrete.
The stresses are not transferred from grain to grain to the lower layers as in the case of flexible pavement layers. Mar 06, 2019 highwaytransportation lec 18u4pavement design part a1 flexible pavement by bk mahawar duration. The deflection that occurs within the pavement layers d p is neglected and. This is a textbook on the structural analysis and design of highway pavements. Effects of pavement roughness on rigid pavement stress. The rigid pavement has rigidity and high modulus of. Types of failures in rigid pavements causes and repair. Stresses due to environment warping or curling stresses stresses due to temperature differential or change in humidity temperature or moisture gradient location. Vertical stresses in subgrades beneath statically loaded. It also adds another loadspreading layer to the pavement system. With respect to asphalt concrete pavements, the current failure criteria used are the horizontal tensile strain at the bottom of the asphalt concrete layer and the vertical strain at the top of the subgrade layer. The rigid pavement undergoes temperature, wheel load and frictional stresses. Section 5 rigid pavement construction standard specification for urban infrastructure works 51 edition 1, revision 0 september 2002 contents 5 rigid pavement construction 53 5.
The compostion and structure of rigid pavement tells us about the function of each layer of rigid pavement as explained below. Onelayer theory can be applied as an approximation for a conventional flexible pavement with granular basesubbase with a thin asphaltic layer on a stiff. Friction stresses l l2 h friction between concrete slab and its foundations induces internal tensile stresses in. Computed tensile stresses across bottom of pcc slab at midpoint. The design of rigid pavement is based on providing a structural cement concrete slab of sufficient strength to resists the loads from traffic. When there is variation in temperature due to which curling of slab with different temperature will be different and hence tdc and buc factors has to be considered. Calculate the three critical stresses for 9 inch thick slabs. The pavement structure model and traffic load were determined for the calculations. Mechanistic analysis of rigid pavement for temperature stresses using ansys article pdf available january 2014 with 154 reads how we measure reads.
Nonlinear temperature gradient effect on maximum warping. Stresses from loading on rigid pavement courses abstract key words in this paper stresses are presented which are deduced from a traffic load performed on the middle, edge and the corner of a slab. Contract stresses are non uniform under a rigid plate. The reaction of the subgrade is vertical only and is proportional to the. In rigid pavements, due to difference in temperatures of top and bottom of slab, temperature stresses or frictional stresses are developed. The rigid pavements are made of portland cement concreteeither plain, reinforced or prestressed concrete. Christos drakos university of florida topic 8 rigid pavement stress analysis cause of stresses in rigid pavements. In a rigid pavement, load is distributed by the slab action rigid pavements are constructed by portable cement concrete and should be analyzed by plat theory instead of layer theory. Guide to using existing pavement in place and achieving long life. Rigid pavement crosssection minor variations in subgrade strength have little influence on the structural capacity of a rigid pavement. Engineeringsciencetechnology civilgette effects of. Any concrete pavement, built of any thickness, will have problems on a poorly designed and constructed subgrade or subbase. Effect of modulus of subgrade reaction on thickness.
Nov 05, 2016 rigid pavementrigid pavement 21 rigid pavements, though costly in initial investment, are cheap in long run because of low maintenance costs, the cost of construction of single lane rigid pavement varies from 35 to 50 lakhs per km in plain area, rigid pavement have deformation in the sub grade is not transferred to subsequent layers. Topic 3 flexible pavement stress analysis developed solutions for. Pdf rigid pavement stress analysis topic 8 rigid pavement. The rigid pavement has a slab action and is capable of transmitting the wheel load stresses through a wider area below. Jun 04, 2016 rigid pavement rigid pavements have sufficient flexural strength to transmit the wheel load stresses to a wider area below. The stresses were calculated using several methods.
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