CHAPTER 7 ASPHALT PAVEMENTS


 Jack Goodwin
 2 years ago
 Views:
Transcription
1 CHAPTER 7 ASPHALT PAVEMENTS 207
2 7.1 Introduction: Flexible pavements consist of one or more asphalt layers and usually also a base. Mostly the base is composed of unbound (granular) materials but also bound bases (obtained by stabilizing the base material with e.g. cement) are applied. In The Netherlands the asphalt layer(s) plus the (un)bound base are normally resting on sand, either the natural sand subgrade or a constructed sand subbase. Figure 7.1 is an example of a flexible pavement structure for a motorway. 50 mm porous asphalt wearing course 210 mm stone asphalt concrete, 4 layers: 3 x 50 mm + 1 x 60 mm 300 mm unbound base of e.g. concrete granulate or mix granulate sand subbase or sand subgrade Figure 7.1: Example of a flexible pavement structure for a heavily loaded motorway. Nowadays the design of the thickness of pavements for roads, airports, industrial yards etc. is based on the calculation of stresses and strains, occurring within the structure due to the traffic loadings, and the comparison with the allowable stresses and strains. In this respect the thickness design of a pavement is essentially the same as for e.g. a concrete beam. Usually the linear elastic multilayer theory is used to calculate the occurring stresses and strains. This however implies that the actual material behavior is simplified to a great extent because most road building materials don t behave linear elastic (see chapter 4). Unbound materials behave strongly stress dependent and asphalt mixes are viscoelastic materials. Nevertheless, the assumption of linear elastic material behavior is in most cases justified and that is certainly the case if the occurring stresses and strains in the structure are rather limited. Of course the traffic loading has to be known to enable the thickness design of the pavement structure. Furthermore the elastic modulus of the various pavement layers must be known as the amount of traffic load spreading strongly depends on the bending stiffness of the subsequent layers. From basic applied mechanics it is known that the bending stiffness is related to the product E.h 3, where E is the elastic modulus and h the layer thickness. 208
3 A pavement structure is a threedimensional structure and for that reason also the Poisson ratio of the various layers is relevant. Finally one should know whether the subsequent pavement layers are fully bonded (which implies that the horizontal displacements just above and just below the interface are equal) or that they can move relatively to each other in the horizontal direction. In this chapter it will be explained how the occurring stresses and strains in a flexible pavement can be calculated. The mathematical backgrounds are however not discussed as they are rather complicated. Instead use will be made of available graphs and computer programs. First the occurring stresses and strains in a halfspace will be discussed. Although Boussinesq s theory already has been explained in the course on Soil Mechanics, in this course it will be demonstrated how this theory can be applied in the structural design of earth and gravel roads. Then the occurring stresses and strains in a twolayer system are discussed. An asphalt pavement laid directly on top of a sand subgrade (so without a base) is an example of a twolayer system. Next attention is paid to threelayer systems and multilayer systems. The occurring stresses and strains in this type of structures can be calculated by means of a computer program that is added to this lecture note. Finally it is demonstrated how all this information can be used in the thickness design of an asphalt pavement structure. 7.2 Stresses in a halfspace: When a load, uniformly distributed over a circular contact area (e.g. a truck wheel load) is placed on a homogeneous soil then normal and shear stresses occur at any soil element. This is schematically shown in figure 7.2. Logically the stresses are dependent on the magnitude of the wheel load, the radius of the circular contact area and the distance to the center of the load. Boussinesq has developed equations to determine the vertical stress and the radial stress on a vertical line through the load center (the shear stresses are zero because of symmetry). These equations are: σ z = p ( 1 z 3 / {( a 2 + z 2 ) 1.5 }) σ r = ( p/2 ) {( 1 + 2ν ) 2 ( 1 + ν ) z / [( a 2 + z 2 ) 1.5 ] + z 3 / [( a 2 + z 3 ) 1.5 ]} σ t = σ r τ rz = τ zr = 0; τ rt = τ tr = 0; τ zt = τ tz = 0 where: p = contact pressure, a = radius of the load contact area, z = depth below the surface, r = radial distance to the load centre, ν = Poisson s ratio. 209
4 Figure 7.2: Stresses in a halfspace due to a circular load (1). Figure 7.3 gives in a graphical way the vertical, radial, tangential and shear stresses as a function of the depth z, the distance to the load center z and Poisson s ratio ν. The use of the graphs is illustrated by means of a practical example that deals with the evaluation of an earth road in a tropical African country. The trucks on the road transport cacao, trees, cement etc. and in general they are overloaded: axle loads of 150 kn frequently occur. The number of trucks is however low, say a few trucks per day. The unpaved road has a top layer of laterite (a redcolored tropical weathered material) and for reason of simplicity it is assumed that this may be considered as a halfspace. The question now is whether damage will occur on this road, while it is known that the cohesion and the angle of internal friction of the applied laterite have the following values. Cohesion c [kpa] Angle of internal friction ϕ [ 0 ] Dry season Wet season
5 Figure 7.3: Stresses in a halfspace due to a circular load (1). Assume that wide base tyres are mounted on all the truck axles; this means that at either side of any axle there is one tyre with a load of 75 kn. It is further assumed that the tyre pressure in all cases is 850 kpa. As stated earlier, as a first approximation the contact pressure between the tyre and the road surface can be taken equal to the tyre pressure. This implies that p = 850 kpa. The radius a of the circular contact area then follows from: a = ( 75 / [ 850 x π ] ) = m The Poisson s ratio is taken as
6 In this specific example only the stresses in the load center (r = 0) are taken into account. It follows from figure 7.3 that the occurring deviatoric stress σ dev is greatest at a depth of m (z = a): σ z = 0.6 x p = 510 kpa, σ r = σ t = 0.1 x p = 85 kpa, σ dev = σ z  σ t = 425 kpa The Mohr s circle of occurring stresses now can be drawn, see figure 7.4. This figure learns that in the dry season the stress circle remains very much below Coulomb s failure envelope. To a smaller extent this is also valid for the (most critical) wet season. The conclusion from this analysis is that the laterite road is strong enough to carry the limited number of 150 kn axle loads. But then another transportfirm starts to use the road and that firm places such a great amount of products on its trucks that it results in extreme heavy axle loads of 225 kn. In such a case also the tyre pressure must increase, say to 1275 kpa. So both the axle load and the tyre pressure increase with a factor of 1.5. This means that the radius of the contact area remains the same: a = m. The occurring stresses at the depth z = m thus also increase with a factor of 1.5. Figure 7.4 shows that the Mohr s circle for these occurring stresses just touches the Coulomb s failure envelope for the wet season. This means that the road immediately fails (shear failure) due to the passage of only one such heavily overloaded truck in the wet season! cirkels van Mohr en faalomhullenden schuifspanning [kpa] faalomhullende natte seizoen cirkel van Mohr 150 kn as cirkel van Mohr 225 kn as faalomhullende droge seizoen spanning [kpa] Figure 7.4: Mohr s circles and Coulomb s failure envelopes for the laterite road. In The Netherlands earth and gravel roads form only a very small part of the road network. However, still today the great majority of the world road network (around 70%) consists of earth and gravel roads! 212
7 In this course emphasis is however laid to flexible pavement structures that are relevant for The Netherlands. As already mentioned these structures nearly always consist of asphalt layers and a base on top of sand (subbase or subgrade). In some cases a base is however not applied and the asphalt layers are directly laid on the subgrade. In such a case a twolayer system is present and in the next paragraph it is discussed how the occurring stresses due to traffic loadings can be calculated in such a system. 7.3 Stresses in a twolayer system: Burmister was the first person that developed mathematical solutions for the calculation of the stresses due to traffic loadings in a twolayer system. These mathematical solutions are also transformed into graphs and the most important ones are presented in the figures 7.5, 7.6 en 7.7. Figure 7.5 enables the determination of the radial stress at the bottom of the toplayer in the load center. The vertical stress at the top of the subgrade in the load centre can be determined with figure 7.6. Finally figure 7.7 allows the determination of the vertical displacement (deflection) at the pavement surface in the load center. It is important to realize that the magnitude of the occurring traffic load stresses is dependent on the magnitude and the geometry of the load, the ratio of the thickness of the toplayer and the radius of the circular contact area, and the ratio of the elastic modulus values of the toplayer and the bottom layer (subgrade). When using the graphs it should be realized that they are all valid for a Poisson s ratio of 0.5 for both layers and that full bond between the toplayer and the subgrade has been assumed. The use of the graphs is illustrated with an example for a motorway pavement structure that consists of 300 mm asphalt (h) directly laid on the sand subgrade. The elastic modulus E 1 of the asphalt amounts 5000 MPa and the elastic modulus E 2 of the sand subgrade is 100 MPa. The pavement structure is subjected to wheel loadings of 50 kn and the tyre pressure (contact pressure) is 700 kpa. We want to know the radial stress at the bottom of the asphalt toplayer in the load center as well as the vertical stress at the top of the sand subgrade in the load center. It can be calculated from the magnitude of the wheel load and the contact pressure that the radius of the circular contact area a = 150 mm. So we find: E 1 / E 2 = 50, h / a = 2, p = 700 kpa. To determine the radial stress at the bottom of the asphalt the bottom graph of figure 7.5 is the easiest one to use. It is read from this graph: σ r / p = 1 213
8 Figure 7.5: Graphs for determination of the radial stress in the load center at the bottom of the toplayer of a twolayer system (1). 214
9 Figure 7.6: Graph for determination of the vertical stress in the load center at the top of the bottom layer of a twolayer system (1). Figure 7.7: Graph for determination of the vertical displacement (deflection) in the load center at the surface of a twolayer system (1). 215
10 The minus sign means that the radial stress is a flexural tensile stress because the contact pressure is a compressive stress. In the remaining part of this calculation example tensile stresses are however given a positive sign and compressive stresses a negative sign, which results in: σ r = 1 x p = 1 x 700 = 700 kpa It appears from figure 7.6 that: σ z / p = In this case σ z and p have the same sign and that means that σ z is a compressive stress. This leads to: σ z = x p = x 700 = 30 kpa In chapter 4 it has been explained that knowledge about the fatigue behavior of asphalt is important because a (truck) wheel load does not pass only one time over the pavement but millions of times. It was also discussed in chapter 4 that usually the occurring strain instead of the stress is used as input in the asphalt fatigue relationship. This implies that the occurring strain at the bottom of the asphalt layer must be known for the determination of the allowable number of load repetitions until fatigue damage (cracking) occurs. This strain cannot be calculated with the equation ε = σ/e because at the bottom of the asphalt layer there is not a onedimensional but a threedimensional stress situation. In the load centre at the bottom of the asphalt layer there is not only a radial stress σ r but also a tangential stress σ t (see also figure 7.2). The vertical line through the load center is the axis of symmetry, therefore is valid σ t = σ r and the shear stresses are zero. Furthermore there is a vertical stress at the bottom of the asphalt layer. Because of the required balance of vertical stresses the vertical stress at the bottom of the asphalt layer is equal to the vertical stress at the top of the subgrade, and this has already been determined above. At the bottom of the asphalt layer in the load center thus the following stresses are present: σ r = σ t = 700 kpa, σ z = 30 kpa The radial strain at the bottom of the asphalt layer can now be calculated with the equation: ε r = [σ r  νσ t  νσ z ] / E 1 = [ x x (0.03)] / 5000 = 7.3 x 105 Be aware of the fact that the stresses were calculated in kpa while the elastic modulus E 1 of the asphalt was given in MPa. For the calculation of the asphalt strain all values are given in MPa. 216
11 To enable the calculation of the vertical strain ε z at the top of the subgrade the radial stress σ r and the tangential stress σ t at that location must be known. These stresses are however absolutely not equal to σ r and σ t at the bottom of the asphalt layer. Another question is whether it is also possible to calculate the stresses σ z, σ r and σ t at the surface of the toplayer in the load center. This is not possible through the given graphs but reasonable estimates can nevertheless be made. Because of the balance of vertical stresses, the vertical stress at the surface of the toplayer must be equal to the contact pressure, so in that point is valid: σ z = 700 kpa. It is furthermore known that the asphalt toplayer behaves as a bending beam under the wheel loading and that its neutral line will be somewhat below the middle of the toplayer. When the ratio E 1 / E 2 increases the neutral line moves into the direction of the middle of the toplayer. The horizontal stresses at the top of the layer therefore will be about equal to the horizontal stresses at the bottom of the layer. The sign is however opposite as through the bending flexural compressive stresses are present in the upper part of the asphalt layer and flexural tensile stresses in the lower part. At the surface of the toplayer in the load center the stresses are thus: σ r = σ t 700 kpa Figure 7.8 presents the radial stresses σ r in a twolayer system. The figure makes clear that the toplayer indeed acts as a bending beam: in the case of a ratio E 1 / E 2 of 10 and higher the neutral line is about in the middle of the toplayer. Figure 7.8: Radial stresses in the load center as a function of depth in a twolayer system (1). 217
12 7.4 Stresses, strains and displacements in multilayer systems: Graphs are also available to determine the occurring stresses, strains and displacements in threelayer systems. The use of these graphs is however rather complicated and therefore no attention is given to them. Another reason to do so is that the analyses can also be done fast and easy with one of the available linearelastic multilayer computer programs. In this paragraph therefore the computer program WESLEA is discussed that is added to these lecture notes on a CDROM. Appendix I gives a short description how the input for this program has to be prepared and how the output is obtained. The use of the WESLEA program is further explained here by discussing a small example problem. The example problem concerns the calculation, for the threelayer system depicted in figure 7.9, of the stresses and strains at the bottom of the asphalt layer and at the top of the subgrade, in both cases in the load centre. The required input parameters are all given in figure 7.9. Full bond between the various layers is assumed. The location at the bottom of the asphalt layer is referred to as position 1 and the location at the top of the subgrade as position 2. After having prepared the input as explained in Appendix I and having done the calculation, the results given in table 7.1 are obtained. Remark! The sign convention used in WESLEA is different from the one used until now. WESLEA uses the socalled soil mechanics convention; in this convention a tensile stress or tensile strain gets the sign, while a compressive stress or compressive strain gets the + sign. 50 kn wheel load tyre pressure 700 kpa 200 mm asphalt, E = 5000 MPa, ν = 0.35 ε r, σ r 300 mm unbound base, E = 400 MPa, ν = 0.35 ε z, σ z subgrade (sand), E = 150 MPa, ν = 0.35 Figure 7.9: Input for the calculation example with WESLEA. 218
13 Position 1 X Y Z Normal stress [kpa] Normal strain [µm/m] Displacement [µm] Position 2 X Y Z Normal stress [kpa] Normal strain [µm/m] Displacement [µm] Table 7.1: The stresses and strains calculated with WESLEA in the two positions indicated in figure 7.9. In figure 7.9 the stress and the strain at the bottom of the asphalt layer are indicated as σ r and ε r respectively, while WESLEA gives the stresses in Cartesian coordinates. However, for an axial symmetric load (such as the one in this example) in the vertical line through the load center is valid: σ r = σ t = σ x = σ y. So it is very easy to calculate the occurring stresses and strains in any point of a certain asphalt pavement structure by means of the WESLEA program. The obtained output allows a pavement life analysis that is discussed in the following paragraph. 7.5 Pavement life calculation: Introduction: In this paragraph the principles of the structural design of an asphalt pavement and the determination of its life are discussed. Prior to that however attention is paid to the various types of damage that may occur on asphalt pavements and that in principle should be taken into account in the structural design. It will appear from the overview of damage types that in this course only a limited number of damage types is addressed and that only a limited number of design criteria is taken into account Damage types on asphalt roads and design criteria to be used: When determining the required thickness of an asphalt pavement structure two design criteria should be taken into account, i.e. cracking and permanent deformation. It already has been explained that horizontal tensile stresses and horizontal tensile strains occur at the bottom of an asphalt layer, laid directly on the subgrade or on an unbound base, due to bending of the structure under the traffic load. After many load repetitions these flexural tensile stresses/strains may lead to fatigue cracking. This fatigue cracking starts at the bottom of the asphalt layer, gradually propagates upward and finally 219
14 appears at the road surface as socalled alligator cracking in the wheel tracks. Figure 7.10 shows an example of this particular type of cracking. An asphalt pavement structure must be designed in such a way that this type of serious damage does not occur too early. Figure 7.10: Example of alligator cracking on an asphalt pavement. Besides of alligator cracking in the wheel tracks also frequently longitudinal cracks are observed. These longitudinal cracks mostly penetrate to a depth of not more than about 50 mm. The cause and propagation of this type of cracking is not yet fully understood. It is however clear that they occur due to the complex distribution of stresses in the contact area between the tyre and the road surface. In the contact area not only vertical stresses occur but also horizontal shear stresses. In regular asphalt pavement design calculations these shear stresses are however not taken into account (in the proceeding examples also a uniform vertical contact pressure over a circular contact area was assumed) and by consequence the development of this surface cracking cannot be analyzed. The propagation of these surface cracks is most probably the result of traffic and climatic influences. To a great extent surface cracking can be prevented by a correct asphalt mix composition. This course 220
15 is not the right place to extensively discuss the occurrence and propagation of surface cracking; reference is made to the course CT4860 Structural design of pavements. One should however realize that surface cracking is a major reason for maintenance of asphalt wearing courses. Asphalt layers are not only applied on an unbound base but also frequently on a cementbound base. For instance, on Amsterdam Airport Schiphol the pavement structure on a runway consists of 200 mm polymermodified asphalt layers on 600 mm lean concrete base. Although a linear elastic multilayer calculation reveals that no tensile stresses or tensile strains occur at the bottom of the asphalt layer, there are however cracks present in the asphalt. The causes of these cracks are the following. Each cementbound material will try to shrink due to the hardening process and due to a decrease of temperature. The shrinkage is however to a great extent obstructed because of the friction with the underlying layer and this results in tensile stresses in the cementbound material. If these tensile stresses become too great (shrinkage) cracks occur. This type of cracking is thus strongly dependent on the climatic conditions and on the properties of the cementbound material. The shrinkage cracks remain not exclusively within the cementbound base but they want to propagate into the bonded asphalt layers. This mechanism is schematically shown in figure 7.11a. The material properties of the cementbound base exhibit quite some variation and as a result also the distance between the (transverse) cracks varies. The greater the strength of the cementbound base material, the greater both the crack distance and the crack width and the movements around the crack due to temperature variations. So the greater the crack distance the greater the movements at the crack and the more heavily loaded the bonded asphalt. asphalt originally closed crack opens because of shrinkage cementbound base a: Shrinkage in the cementbound b: The traffic wheel loadings base results in tensile stresses result in great shear stresses in the bonded asphalt layer in the asphalt layer Figure 7.11: Propagation of cracks from the cementbound base into the bonded asphalt layer. The effects of the temperature movements can be reduced by regulation of the crack distance in the cementbound base. On Amsterdam Airport Schiphol this has been done by creating notches, to a depth of 1/3 of the base 221
16 thickness, at regular distances (about 7 m). Through these notches the base weakens to such an extent that the shrinkage cracks will occur there. The limited crack distance results in smaller movements around the crack and as a result the asphalt layer is less heavily loaded. The principle of a notch is similar to that of a contraction joint in plain concrete pavements (see chapter 5). But even a narrow crack always is a weak point in the pavement structure. At such a crack bending moments cannot be transmitted, load transfer is only possible through crossforces. As indicated in figure 7.11b, during the passage of a wheel load not only substantial shear stresses occur in the asphalt layer above the crack but also an extra large bending moment, and as a result the crack wants to propagate from the base into the asphalt layer. The asphalt layer also has to be designed to resist this type of cracking. This subject is however outside the scope of this course; reference is made to the course CT4860 Structural design of pavements. Permanent deformation of the various pavement layers due to the repeated traffic loadings is another important type of damage that should be taken into account in the structural pavement design. Such permanent deformations manifest themselves as rutting in the wheel tracks. Figure 7.12 is an example of this type of damage. Figure 7.12: Example of rutting on an asphalt pavement. The rutting observed at the road surface results from viscoplastic deformations of the asphalt layers and from plastic deformations of the 222
17 unbound base, subbase and subgrade. In chapter 4 these permanent deformations already have been discussed. It is important to design the asphalt pavement structure in such a way that in all the layers the occurring stress levels remain sufficiently low to prevent these permanent deformations. The various layers also should possess sufficient resistance against permanent deformation. This is directly related with the choice of the type of asphalt mix, the type of base and subbase material and the compaction. In this course not much attention is given to the permanent deformation of the asphalt layers and the unbound base and subbase. Reference is made to the courses CT4850 Road building materials and CT4860 Structural design of pavements. In this course only some rules of thumb are given and used to limit the permanent deformation in the subgrade. In chapter 4 the subgrade criterion already has been introduced. The meaning of that criterion is that the permanent deformation in the subgrade remains limited if the vertical elastic deformation at the top of the subgrade, which is calculated with WESLEA, remains below a certain value. In chapter 4 it also has been explained how, according to the Shell method, the permanent deformation in the asphalt layers can be calculated. All the abovementioned implies that in this course only attention is paid to the structural design of asphalt pavements laid directly on the subgrade or with an unbound (sub)base. Furthermore, the determination of the layer thicknesses is only based on fatigue of the asphalt layer and permanent deformation within the subgrade. The relevant design parameters are thus the occurring horizontal strain at the bottom of the asphalt layer and the vertical compressive strain at the top of the subgrade. A last important type of damage is raveling that frequently occurs in practice, especially on porous asphalt ( zoac ) wearing courses. Raveling is the loss of aggregate at the road surface, resulting in a raw appearance of it. The occurring traffic loading, the climate and the properties of the wearing course asphalt material are the most important factors influencing raveling. Raveling is one of the most important causes of maintenance on motorways. Also this type of damage is not further discussed here, reference again is made to the courses CT4850 Road building materials and CT4860 Structural design of pavements Steps in the structural design of an asphalt pavement: For the structural design of an asphalt pavement the following steps have to be made. Traffic loading A traffic forecast is the basis for the determination of the traffic loading. This traffic forecast should not only describe the growth of the total amount of traffic but also the share of the truck traffic. In chapter 4, table 4.3 is given how the traffic class is determined in The Netherlands; this information is relevant for the structural design of an asphalt pavement. The (truck) traffic loading is usually given as an axle load frequency distribution (see chapter 3, figure 3.3). On the basis of this frequency 223
18 distribution the cumulative number of equivalent standard axle loads can be calculated. The magnitude of the standard axle load is normally taken as 80 or 100 kn. In The Netherlands mostly a standard axle load of 100 kn is used in the structural design of an asphalt pavement. The transformation of the axle load frequency distribution into a number of equivalent standard axle loads is done by means of the load equivalency equation that already has been discussed in chapter 3, paragraph 3.4. For reasons of simplicity the exponent m in the equivalency equation is usually assigned the value of 4. After having calculated the cumulative number of equivalent standard axle loads, it must be determined how the axle load is transmitted to the pavement. Usually dual tyre wheel configurations are taken into account. This means that there are two tyres at either side of the axle. In such a dual tyre wheel the centertocenter distance between the two tyres is some 320 mm. Furthermore a tyre pressure of 700 kpa is normally taken into account. If one wants to analyze the effects of wide base ( super single ) tyres (only one wide tyre at each side of the axle), a tyre pressure of 850 kpa should be used. Material data The strength and stiffness characteristics of the various layers have to be known to enable a structural design calculation with the WESLEA multilayer computer program. At least the following data has to be available:  the CBRvalue of the subgrade,  the composition of the applied asphalt mixes,  the representative (most frequently occurring) speed of the trucks,  the temperature (in The Netherlands an asphalt temperature of 20 0 C is normally used for the structural design of asphalt pavements). The rules of thumb given in chapter 4, paragraph 4.2 then allow to reasonably estimate the Evalue of the subgrade as well as the Evalue of the unbound (sub)base. The stiffness of the bitumen and next the stiffness of the asphalt mix can be determined on the basis of the mix composition by mass, the applied type of bitumen, the asphalt temperature and the loading time. The information given in chapter 4, paragraph enables to determine the asphalt fatigue relationship as well as the healing factor of the asphalt. The obtained Evalues should always be checked on consistency. For instance, it is impossible that an asphalt mix has an Evalue that is greater than that of cement concrete, quality B45. Structural design calculations The occurring strain at the bottom of the asphalt layer and the vertical compressive strain at the top of the subgrade can now be calculated by means of WESLEA. In the calculations you may assume that all the pavement layers are fully bonded to each other. Although the Poisson s ratio is dependent on a number of factors, the following guidelines can be given for it:  asphalt at moderate temperatures and loading times, sand, nonsaturated clay, unbound subbase and base materials: 0.35, 224
19  asphalt at high temperatures and long loading times, saturated clay: 0.5,  cementbound base materials: 0.2,  concrete: In the calculations much care must be taken that the correct units are used because nonsense in = nonsense out. Also realistic layer thicknesses should be used! The minimum thickness of a layer is about 2.5 to 3 times the maximum grain size. Probably a number of calculations, with different layer thicknesses, are required to obtain the desired pavement life. Adapting the layer thicknesses has to be done in a systematic way and care must be taken that the stresses and strains are calculated at the correct positions within the (modified) pavement structure. It is recalled that WESLEA uses the soil mechanics sign convention, so the sign means tension and the + sign means compression. Pavement life The fatigue life of the asphalt can be determined on the basis of the calculated strain at the bottom of the asphalt layer. The fatigue life resulting from the (laboratory) fatigue relationship has to be multiplied with the factors for healing (see chapter 4, paragraph ) and for lateral wander (as stated earlier, a value of 2.5 is a reasonable assumption for the lateral wander factor). The pavement life based on the subgrade criterion is found by inputting the calculated vertical compressive strain in the subgrade criterion given in chapter 4, paragraph 4.3. This found pavement life of course should not be multiplied with the healing factor and the lateral wander factor (you should be able to explain why this should not be done). 7.6 References: 1. Meier, H.; Eisenmann, J.; Koroneos, E. Effects of traffic loadings on pavement structures (in German) Forschungsarbeiten aus dem Strassenwesen. Kirschbaum Verlag; Bonn/Bad Godesberg
20 APPENDIX I MANUAL FOR THE PROGRAM WESLEA 226
21 Introduction: The WESLEA program has been developed for the American Waterways Experiment Station (WES) of the US Army Corps of Engineers. It is a linear elastic multilayer program that enables the analysis of a pavement structure consisting of maximum 5 layers (the subgrade counts as one layer). The number of circular loads is maximum 20. This is a very useful option because it enables to analyze the effects of complex load systems such as the landing gears of a Boeing 747 aircraft. There are two options with respect to the bond between the layers: a. the subsequent layers are fully bonded to each other (this is the most commonly used option), b. the subsequent layers are not bonded to each other, so they can slip along each other without any friction (this option is only used for very special cases). The starting point in the following description of the input and output of the program is the example given in figure 7.9. The input: On the main screen you first click units and then SI. You have to realize that the WESLEA program has originally been developed for the American system of units. Your input in SIunits therefore is converted into American units and then of course some roundoff errors occur. Also in the output you will notice this. Next you click input and then structure. You input that the number of layers is 3. The next step is the input of the properties of the various pavement layers. As material for layer 1 you chose asphalt and for the elastic modulus you fill in 5000 MPa. As material for the layers 2 and 3 you chose other. The reason for doing so is that the choice for GB (= granular base) yields a confrontation with a maximum value for the elastic modulus that is hidden in the program. This limitation is bypassed through the choice of the material other. Next you input the values for the elastic modulus of the unbound base and the subgrade in MPa. Also the values of the Poisson s ratio have to be input but you will observe that the value 0.35 is set as default value. Next the thickness (in cm!) of the asphalt layer and the base has to be input. Then you have to input whether the asphalt layer is fully bonded to the base and whether the base is fully bonded to the subgrade. As stated earlier this is a very reasonable assumption for most of the cases. You now click the button ok. You click again on input and then on loads. There is the possibility to analyze various load configurations, which are: a. a single axle with dual tyre wheels, b. a tandem axle with dual tyre wheels, c. a triple axle with dual tyre wheels, d. a single axle with wide base tyre wheels ( steer ), 227
22 e. your own load configuration. Because we want to simulate the effects of a wide base tyre we click steer. You may wonder if the combined effect of both wide base tyres (at both sides of the axle) is now analyzed. This is not the case, only the effects of one wheel at one side of the axle are analyzed; this is also the case for the other axle configurations. The reason to do so is that the wheel at the other side of the axle has hardly any effect on the stresses and strains under the wheel under consideration. The program now asks for the number of load repetitions. Here you can input any number. The program only uses this number of load repetitions if you want to analyze the standard locations (see next step evaluation ). In the program fatigue relations for the asphalt and the subgrade have been built in that are based on the greatest occurring horizontal tensile strain in the asphalt and the greatest occurring vertical compressive strain in the subgrade. These relations are however not universal applicable. When using the standard locations the pavement life is calculated on the basis of these calculated strain values. Because as a matter of fact we are interested in such a fatigue calculation we input as number of load repetitions the expected number of repetitions of the considered wheel load, e.g For load (wheel load) you fill in 50 kn and for pressure (tyre pressure) 700 kpa. You now click the ok button. Next you click again input and then evaluation. You see a grey screen with a v on standard locations. You observe that there are two locations. By means of clicking on next location or previous location you can see which locations they are. The first location appears to be in the load center at the bottom of the asphalt layer (z = cm) and the second location is also in the load center at the top of layer 3, the subgrade (z = cm). Of course it is strange that the program yields the depth z = cm while the top of the subgrade is on the depth z = 50 cm, but this is the result of roundingoffs. Therefore check whether the locations are in the correct layer. If you remove the v on standard locations you can input your own locations but the program then does not perform a pavement life calculation. If you have completed this part of the input you click on ok. The output: You have prepared all the required input and now you click on the main screen first output and then view output. You now see a grey table containing the stresses, strains and displacements that already have been given in table 7.1. You also get the pavement life based on fatigue (fatigue of the asphalt) and rutting (permanent deformation of the subgrade). However, the program calculates these pavement lifes on the basis of the greatest horizontal tensile strain and the vertical compressive strain that have been calculated. So you have to be very careful in interpreting these numbers! For example, the rutting life is completely irrelevant for position 1, at the bottom of the asphalt, and the fatigue life is completely irrelevant for position 3, the top of the subgrade. 228
23 The calculated damage factor is the ratio between the applied (the occurring) and the allowable number of load repetitions. Finally you can have a look to the fatigue relationship for the asphalt ( fatigue ) and the criterion for the allowable permanent deformation in the subgrade ( rutting ) by means of the button view transferfunctions. It is stressed again that these functions are not universal applicable. The relations that normally used in The Netherlands already have been given in chapter 4. Final remark: The WESLEA program generates numerical solutions. The accuracy of the obtained calculation results depends among other things on the magnitude of the integration steps. In this calculation process errors may be introduced. Simple checks are possible to investigate whether these errors have occurred and whether the program has functioned well. This is however beyond the scope of this course; reference is made to the course CT4860 Structural design of pavements. In that course also other programs will be discussed. 229
24 229a
Lecture Notes CT 4860 Structural Pavement Design. Design of Flexible Pavements
Lecture Notes CT 4860 Structural Pavement Design Design of Flexible Pavements Prof.dr.ir. A.A.A. Molenaar Delft, March 2007 Table of contents Preface 3 1. Introduction 4 2. Major defect types in flexible
More informationPavement Design for Rural Low Volume Roads Using Cement and Lime Treatment Base
Pavement Design for Rural Low Volume Roads Using Cement and Lime Treatment Base General Manager, Pavement, Material and Geotechnical Division, Intercontinental Consultants and Technocrats Private Limited,
More informationTesting and appraisal of Lucobit polymer effect as an additive on asphalt mixture performance
Abstract Testing and appraisal of polymer effect as an additive on asphalt mixture performance Hamid Sabbagh mollahosseini*,golazin Yadollahi**, Ershad Amoosoltani*** *, ***Executive of Engineering and
More informationUsing Accelerated Pavement Testing to Evaluate Permeable Interlocking Concrete Pavement Performance
Using Accelerated Pavement Testing to Evaluate Permeable Interlocking Concrete Pavement Performance Rongzong Wu, David Jones, Hui Li and John Harvey University of California Pavement Research Center Prepared
More informationPERFORMANCE TESTING OF BITUMINOUS MIXES USING FALLING WEIGHT DEFLECTOMETER
ABSTRACT NO. 6 PERFORMANCE TESTING OF BITUMINOUS MIXES USING FALLING WEIGHT DEFLECTOMETER Prof Praveen Kumar Dr G D Ransinchung Lt. Col. Mayank Mehta Nikhil Saboo IIT Roorkee IIT Roorkee IIT Roorkee IIT
More informationPERFORMANCE EVALUATION SYSTEM FOR BITUMINOUS BINDERS
PERFORMANCE EVALUATION SYSTEM FOR BITUMINOUS BINDERS A. Vanelstraete, W. Teugels, Belgian Road Research Centre, Belgium, Nynas Bitumen, Belgium Abstract Understanding the behaviour and performance of bituminous
More informationThe AASHO Road Test site (which eventually became part of I80) at Ottawa, Illinois, was typical of northern climates (see Table 1).
Página 1 de 12 AASHO Road Test The AASHO Road Test, a $27 million (1960 dollars) investment and the largest road experiment of its time, was conceived and sponsored by the American Association of State
More informationStress and Deformation Analysis. Representing Stresses on a Stress Element. Representing Stresses on a Stress Element con t
Stress and Deformation Analysis Material in this lecture was taken from chapter 3 of Representing Stresses on a Stress Element One main goals of stress analysis is to determine the point within a loadcarrying
More informationStep 1: Launch KENPAVE. Step 2: Select LAYERINP
Step 1: Launch KENPAVE Step 2: Select LAYERINP Step 3: Click on File on the toolbar To set up a new data file click 'File' and 'New' and the filename 'Untitled' will appear on the label beneath 'File'.
More informationPavement Thickness. esign and RCCPave Software. RollerCompacted Concrete Pavement: Design and Construction. October 24, 2006 Atlanta, Georgia
RollerCompacted Concrete Pavement: Design and Construction Pavement Thickness esign and RCCPave Software Gregory E. Halsted, P.E. Pavements Engineer Portland Cement Association October 24, 2006 Atlanta,
More informationRMS Guide for design of concrete pavements in areas of settlement. Version 1.0. Roads and Maritime Services www.rms.nsw.gov.au
Guide for design of concrete pavements in areas of settlement Version 1.0 RMS Guide for design of concrete pavements in areas of settlement Version 1.0 Roads and Maritime Services www.rms.nsw.gov.au Title:
More informationBending, Forming and Flexing Printed Circuits
Bending, Forming and Flexing Printed Circuits John Coonrod Rogers Corporation Introduction: In the printed circuit board industry there are generally two main types of circuit boards; there are rigid printed
More informationReinforcement HUESKER. HaTelit. Engineering with geosynthetics
HUESKER Engineering with geosynthetics rhuesker HUESKER HUESKER HUESKER HUESKER HUESKERr SKER HUESKER HUESKER Asphalt HUESKER HUESKER HUESKERHUES Reinforcement  the answer to reflective cracking in asphalt
More informationProgram COLANY Stone Columns Settlement Analysis. User Manual
User Manual 1 CONTENTS SYNOPSIS 3 1. INTRODUCTION 4 2. PROBLEM DEFINITION 4 2.1 Material Properties 2.2 Dimensions 2.3 Units 6 7 7 3. EXAMPLE PROBLEM 8 3.1 Description 3.2 Hand Calculation 8 8 4. COLANY
More informationMETHODS FOR ACHIEVEMENT UNIFORM STRESSES DISTRIBUTION UNDER THE FOUNDATION
International Journal of Civil Engineering and Technology (IJCIET) Volume 7, Issue 2, MarchApril 2016, pp. 4566, Article ID: IJCIET_07_02_004 Available online at http://www.iaeme.com/ijciet/issues.asp?jtype=ijciet&vtype=7&itype=2
More informationWhat is design ESALs?
TEXAS DEPARTMENT OF TRANSPORTATION What is ESAL? ESAL is the acronym for equivalent single axle load. ESAL is a concept developed from data collected at the American Association of State Highway Officials
More informationCHAPTER 8 ROAD SURFACE PROPERTIES
CHAPTER 8 ROAD SURFACE PROPERTIES 230 8.1 Introduction: The road user desires a road surface where he can drive safe and comfortable. This requires a pavement structure with enough stiffness, a fast runoff
More informationRehabilitation by cracking and seating of concrete pavement optimized by FWD analysis
Rehabilitation by cracking and seating of concrete pavement optimized by FWD analysis H. C. Korsgaard & J. P. Pedersen Carl Bro Pavement Consultants, Kokbjerg 5, DK6000 Kolding M. Rasmussen Copenhagen
More informationTECHNISCHE UNIVERSITÄT MÜNCHEN München, 05.07.2007 Lehrstuhl und Prüfamt für Bau von Landverkehrswegen. Research Report No. 2362
TECHNISCHE UNIVERSITÄT MÜNCHEN München, 5.7.27 Lehrstuhl und Prüfamt für Bau von Landverkehrswegen MUNICH TECHNICAL UNIVERSITY Chair and Institute for Road, Railway and Airfield Construction Research Report
More informationMECHANICS OF SOLIDS  BEAMS TUTORIAL 1 STRESSES IN BEAMS DUE TO BENDING. On completion of this tutorial you should be able to do the following.
MECHANICS OF SOLIDS  BEAMS TUTOIAL 1 STESSES IN BEAMS DUE TO BENDING This is the first tutorial on bending of beams designed for anyone wishing to study it at a fairly advanced level. You should judge
More informationCOMPUTATIONAL ENGINEERING OF FINITE ELEMENT MODELLING FOR AUTOMOTIVE APPLICATION USING ABAQUS
International Journal of Advanced Research in Engineering and Technology (IJARET) Volume 7, Issue 2, MarchApril 2016, pp. 30 52, Article ID: IJARET_07_02_004 Available online at http://www.iaeme.com/ijaret/issues.asp?jtype=ijaret&vtype=7&itype=2
More informationTechnical Notes 3B  Brick Masonry Section Properties May 1993
Technical Notes 3B  Brick Masonry Section Properties May 1993 Abstract: This Technical Notes is a design aid for the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 40292) and Specifications
More informationApplying a circular load. Immediate and consolidation settlement. Deformed contours. Query points and query lines. Graph query.
Quick Start Tutorial 11 Quick Start Tutorial This quick start tutorial will cover some of the basic features of Settle3D. A circular load is applied to a single soil layer and settlements are examined.
More informationWalter Gerritsen, Jacob Groenendijk, Christ van Gurp KOAC NPC pavement research & consultancy, The Netherlands
Monitoring of primary road network Walter Gerritsen, Jacob Groenendijk, Christ van Gurp KOAC NPC pavement research & consultancy, The Netherlands The Netherlands Mainport to EU 41.526 km² area 17 million
More informationPavement Design. Guest Lecturer Dr. Sirous Alavi, P.E. SIERRA TRANSPORTATION. 1005 Terminal Way, Suite 125 Reno, Nevada 89502
Pavement Design Guest Lecturer Dr. Sirous Alavi, P.E. SIERRA TRANSPORTATION ENGINEERS,, INC. I 1005 Terminal Way, Suite 125 Reno, Nevada 89502 Topics Introduction Design Factors Pavement Types Fundamentals
More informationAPPENDIX B. I. Background Information
APPENDIX B GUIDELINES FOR IDENTIFYING AND REPAIRING LOCALIZED AREAS OF DISTRESS IN AC PAVEMENTS PRIOR TO CAPITAL PREVENTIVE MAINTENANCE OR REHABILITATION REPAIRS I. Background Information A. AC Pavement
More informationDrained and Undrained Conditions. Undrained and Drained Shear Strength
Drained and Undrained Conditions Undrained and Drained Shear Strength Lecture No. October, 00 Drained condition occurs when there is no change in pore water pressure due to external loading. In a drained
More informationLEAB: sustainable lowtemperature production of asphalt Maarten Jacobs and Rémy van den Beemt, BAM Wegen bv
LEAB: sustainable lowtemperature production of asphalt Maarten Jacobs and Rémy van den Beemt, BAM Wegen bv Introduction Climate and sustainability issues are increasingly being given priority by government
More informationImpacts of Increased Loading Due to Heavy Construction Traffic on Thin Pavements
Impacts of Increased Loading Due to Heavy Construction Traffic on Thin Pavements Author: Harry Sturm, P. Eng. Stantec Consulting Ltd. 1677 Mississauga Road Mississauga, ON L5N 7G2 Phone: (95) 817296
More informationNumerical modelling of shear connection between concrete slab and sheeting deck
7th fib International PhD Symposium in Civil Engineering 2008 September 1013, Universität Stuttgart, Germany Numerical modelling of shear connection between concrete slab and sheeting deck Noémi Seres
More informationOptimum proportions for the design of suspension bridge
Journal of Civil Engineering (IEB), 34 (1) (26) 114 Optimum proportions for the design of suspension bridge Tanvir Manzur and Alamgir Habib Department of Civil Engineering Bangladesh University of Engineering
More informationFlexural Strength of Concrete (The Modulus of Rupture Test)
Revised 09063, WKS Datasheet No. 7.6a & 7.6b MOHAWK COLLEGE OF APPLIED ARTS AND TECHNOLOGY BUILDING AND CONSTRUCTION SCIENCES DEPARTMENT Flexural Strength of Concrete (The Modulus of Rupture Test) INTRODUCTION
More information4.3 Results... 27 4.3.1 Drained Conditions... 27 4.3.2 Undrained Conditions... 28 4.4 References... 30 4.5 Data Files... 30 5 Undrained Analysis of
Table of Contents 1 One Dimensional Compression of a Finite Layer... 3 1.1 Problem Description... 3 1.1.1 Uniform Mesh... 3 1.1.2 Graded Mesh... 5 1.2 Analytical Solution... 6 1.3 Results... 6 1.3.1 Uniform
More informationConstruction Specifications for Keyhole Pavement Coring and Reinstatement
F I N A L Construction Specifications for Keyhole Pavement Coring and Reinstatement Gas Technology Institute 1700 S. Mount Prospect Rd. Des Plaines, Illinois 60018 www.gastechnology.org Version 13 October
More informationField Damage Inspection and Static Load Test Analysis of Jiamusi Highway Prestressed Concrete Bridge in China
Advanced Materials Research Vols. 163167 (2011) pp 11471156 Online available since 2010/Dec/06 at www.scientific.net (2011) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/amr.163167.1147
More information1. Introduction 2. 2. Different types of asphalt pavement interlayers 3. 3. Fibrerovings for asphalt pavement interlayers 5
1 Contents 1. Introduction 2 2. Different types of asphalt pavement interlayers 3 3. Fibrerovings for asphalt pavement interlayers 5 4. Reinforced asphalt pavement as a composite building material 6 5.
More informationEVALUATION OF SEISMIC RESPONSE  FACULTY OF LAND RECLAMATION AND ENVIRONMENTAL ENGINEERING BUCHAREST
EVALUATION OF SEISMIC RESPONSE  FACULTY OF LAND RECLAMATION AND ENVIRONMENTAL ENGINEERING BUCHAREST Abstract Camelia SLAVE University of Agronomic Sciences and Veterinary Medicine of Bucharest, 59 Marasti
More informationHIGHWAYS DEPARTMENT GUIDANCE NOTES ON THE USE OF WATERPROOFING MEMBRANES ON CONCRETE BRIDGE DECKS
HIGHWAYS DEPARTMENT GUIDANCE NOTES ON THE USE OF WATERPROOFING MEMBRANES ON CONCRETE BRIDGE DECKS Research & Development Division RD/GN/033 June 2008 THE USE OF WATERPROOFING MEMBRANES ON CONCRETE BRIDGE
More informationReinforced Concrete Design
FALL 2013 C C Reinforced Concrete Design CIVL 4135 ii 1 Chapter 1. Introduction 1.1. Reading Assignment Chapter 1 Sections 1.1 through 1.8 of text. 1.2. Introduction In the design and analysis of reinforced
More informationproduct manual HS4210 HS4210_MAN_09.08 Digital Static Cone Penetrometer
HS4210_MAN_09.08 product manual HS4210 Digital Static Cone Penetrometer Introduction This Manual covers the measurement of bearing capacity using the Humboldt Digital Static Cone Penetrometer (DSCP).
More informationA transverse strip of the deck is assumed to support the truck axle loads. Shear and fatigue of the reinforcement need not be investigated.
Design Step 4 Design Step 4.1 DECK SLAB DESIGN In addition to designing the deck for dead and live loads at the strength limit state, the AASHTOLRFD specifications require checking the deck for vehicular
More informationPAVEMENT REHABILITATION using BITUMEN STABILISATION STATE OF THE ART
PAVEMENT REHABILITATION using BITUMEN STABILISATION STATE OF THE ART 23 rd Road Pavement Forum Fern Hill Hotel, Tweedie, KZN Wednesday 9 th May 2012 Dave Collings UCD Technology LOUDON INTERNATIONAL THE
More informationNumerical Analysis of Independent Wire Strand Core (IWSC) Wire Rope
Numerical Analysis of Independent Wire Strand Core (IWSC) Wire Rope Rakesh Sidharthan 1 Gnanavel B K 2 Assistant professor Mechanical, Department Professor, Mechanical Department, Gojan engineering college,
More informationGUIDELINE ON IN SITU RECYCLING WITH CEMENT GUIDELINE ON IN SITU RECYCLING WITH CEMENT GUIDELINE ON IN SITU RECYCLING WITH CEMENT INTRODUCTION
International Seminar on Recycling Warsaw, 1011 October 2002 GUIDELINE ON IN SITU RECYCLING WITH CEMENT Carlos Jofré IECA, Spain GUIDELINE ON IN SITU RECYCLING WITH CEMENT Working group Australia Austria
More informationAsphalt Pavement Association Of Michigan Selecting the Right Mix. 2937 Atrium Drive, Suite 202 Okemos, MI 48864 5173237800 www.apami.
2937 Atrium Drive, Suite 202 Okemos, MI 48864 5173237800 www.apami.org History Performance Graded Binders MDOT Local Agency Guide NAPA Guide Outline Other Considerations For each there are: Right
More informationANALYSIS FOR BEHAVIOR AND ULTIMATE STRENGTH OF CONCRETE CORBELS WITH HYBRID REINFORCEMENT
International Journal of Civil Engineering and Technology (IJCIET) Volume 6, Issue 10, Oct 2015, pp. 2535 Article ID: IJCIET_06_10_003 Available online at http://www.iaeme.com/ijciet/issues.asp?jtype=ijciet&vtype=6&itype=10
More informationINTRODUCTION TO SOIL MODULI. JeanLouis BRIAUD 1
INTRODUCTION TO SOIL MODULI By JeanLouis BRIAUD 1 The modulus of a soil is one of the most difficult soil parameters to estimate because it depends on so many factors. Therefore when one says for example:
More informationTraffic volumes adopted for pavement designs are based on the parameters contained in Section 7 of this report.
11. Pavements 11.1 Pavement design Preliminary pavement designs have been developed for the highway travel lanes (through carriageways), the inner and outer shoulders, on and off ramps and service roads.
More informationStructural Integrity Analysis
Structural Integrity Analysis 1. STRESS CONCENTRATION Igor Kokcharov 1.1 STRESSES AND CONCENTRATORS 1.1.1 Stress An applied external force F causes inner forces in the carrying structure. Inner forces
More informationExpected Service Life and Performance Characteristics of HMA Pavements in LTPP
Expected Service Life and Performance Characteristics of HMA Pavements in LTPP Expected Service Life and Performance Characteristics of HMA Pavements in LTPP Submitted to: Asphalt Pavement Alliance Prepared
More informationImpacts of Tunnelling on Ground and Groundwater and Control Measures Part 1: Estimation Methods
Impacts of Tunnelling on Ground and Groundwater and Control Measures Part 1: Estimation Methods Steve Macklin Principal Engineering Geologist GHD Melbourne 1. Introduction, scope of Part 1 2. Terminology
More informationHardened Concrete. Lecture No. 14
Hardened Concrete Lecture No. 14 Strength of Concrete Strength of concrete is commonly considered its most valuable property, although in many practical cases, other characteristics, such as durability
More information8.2 Elastic Strain Energy
Section 8. 8. Elastic Strain Energy The strain energy stored in an elastic material upon deformation is calculated below for a number of different geometries and loading conditions. These expressions for
More informationCRITERIA FOR PRELOADED BOLTS
National Aeronautics and Space Administration Lyndon B. Johnson Space Center Houston, Texas 77058 REVISION A JULY 6, 1998 REPLACES BASELINE SPACE SHUTTLE CRITERIA FOR PRELOADED BOLTS CONTENTS 1.0 INTRODUCTION..............................................
More informationPrecision Miniature Load Cell. Models 8431, 8432 with Overload Protection
w Technical Product Information Precision Miniature Load Cell with Overload Protection 1. Introduction The load cells in the model 8431 and 8432 series are primarily designed for the measurement of force
More informationDetailing of Reinforcment in Concrete Structures
Chapter 8 Detailing of Reinforcment in Concrete Structures 8.1 Scope Provisions of Sec. 8.1 and 8.2 of Chapter 8 shall apply for detailing of reinforcement in reinforced concrete members, in general. For
More informationMETHOD OF STATEMENT FOR STATIC LOADING TEST
Compression Test, METHOD OF STATEMENT FOR STATIC LOADING TEST Tension Test and Lateral Test According to the American Standards ASTM D1143 07, ASTM D3689 07, ASTM D3966 07 and Euro Codes EC7 Table of Contents
More informationTechnical Presentation: Follow up on HVS testing of Roller Compacted Concrete and Ultrathin reinforced concrete test sections
Technical Presentation: Follow up on HVS testing of Roller Compacted Concrete and Ultrathin reinforced concrete test sections Louw du Plessis 12 Febuary 2015 Objectives UTRCP Previous round of HVS testing
More informationSTUDY OF THE BEHAVIOUR OF BITUMINOUS MIXTURES RESISTANT TO FUEL
STUDY OF THE BEHAVIOUR OF BITUMINOUS MIXTURES RESISTANT TO FUEL INTRODUCTION Evaluation of the performance of asphalt mixtures applied on wearing courses of road and airport pavements when subjected to
More informationFLEXIBLE PAVEMENT DESIGN Examples of design with different systems.
FLEXIBLE PAVEMENT DESIGN Examples of design with different systems. Design three types of highways, all main roads but with different traffic loads. The roads shall all be designed on the same subgrade.
More informationDesign of pile foundations following Eurocode 7Section 7
Brussels, 1820 February 2008 Dissemination of information workshop 1 Workshop Eurocodes: background and applications Brussels, 1820 Februray 2008 Design of pile foundations following Eurocode 7Section
More informationSKER HUESKER HUESKER HUESKER HUESKER HUESKERHUES
rhuesker HUESKER HaTelit HUESKER HUESKER HUESKER HUESKERr SKER HUESKER HUESKER Asphalt HUESKER HUESKER HUESKERHUES SKER HUESKERHUES HUESKERr SKER HUESKERHUES rhueskerreinforcement HUESKERr Longterm retardation
More informationThe full range of Kilsaran products are manufactured to fully meet all requirements of all current British and European Standards.
The extensive range of paving products available from Kilsaran will provide a full range of solutions for any project whether commercial, civic, industrial or a residential scheme. appraisal purposes Generally
More informationMATERIALS AND MECHANICS OF BENDING
HAPTER Reinforced oncrete Design Fifth Edition MATERIALS AND MEHANIS OF BENDING A. J. lark School of Engineering Department of ivil and Environmental Engineering Part I oncrete Design and Analysis b FALL
More informationStructural Axial, Shear and Bending Moments
Structural Axial, Shear and Bending Moments Positive Internal Forces Acting Recall from mechanics of materials that the internal forces P (generic axial), V (shear) and M (moment) represent resultants
More informationCH 6: Fatigue Failure Resulting from Variable Loading
CH 6: Fatigue Failure Resulting from Variable Loading Some machine elements are subjected to static loads and for such elements static failure theories are used to predict failure (yielding or fracture).
More informationSoil Mechanics SOIL STRENGTH page 1
Soil Mechanics SOIL STRENGTH page 1 Contents of this chapter : CHAPITRE 6. SOIL STRENGTH...1 6.1 PRINCIPAL PLANES AND PRINCIPAL STRESSES...1 6.2 MOHR CIRCLE...1 6.2.1 POLE METHOD OF FINDING STRESSES ON
More informationSolid Mechanics. Stress. What you ll learn: Motivation
Solid Mechanics Stress What you ll learn: What is stress? Why stress is important? What are normal and shear stresses? What is strain? Hooke s law (relationship between stress and strain) Stress strain
More informationSEISMIC UPGRADE OF OAK STREET BRIDGE WITH GFRP
13 th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 16, 2004 Paper No. 3279 SEISMIC UPGRADE OF OAK STREET BRIDGE WITH GFRP Yuming DING 1, Bruce HAMERSLEY 2 SUMMARY Vancouver
More informationHIGHWAYS DEPARTMENT GUIDANCE NOTES ON ROAD SURFACE REQUIREMENTS FOR EXPRESSWAYS AND HIGH SPEED ROADS
HIGHWAYS DEPARTMENT GUIDANCE NOTES ON ROAD SURFACE REQUIREMENTS FOR EXPRESSWAYS AND HIGH SPEED ROADS Research & Development Division RD/GN/032 June 2007 1. Purpose ROAD SURFACE REQUIREMENTS FOR EXPRESSWAYS
More informationEstimation of Adjacent Building Settlement During Drilling of Urban Tunnels
Estimation of Adjacent Building During Drilling of Urban Tunnels Shahram Pourakbar 1, Mohammad Azadi 2, Bujang B. K. Huat 1, Afshin Asadi 1 1 Department of Civil Engineering, University Putra Malaysia
More informationSECTION 3 DESIGN OF POST TENSIONED COMPONENTS FOR FLEXURE
SECTION 3 DESIGN OF POST TENSIONED COMPONENTS FOR FLEXURE DEVELOPED BY THE PTI EDC130 EDUCATION COMMITTEE LEAD AUTHOR: TREY HAMILTON, UNIVERSITY OF FLORIDA NOTE: MOMENT DIAGRAM CONVENTION In PT design,
More informationINTRODUCTION TO CONCRETE PAVEMENTS
INTRODUCTION TO CONCRETE PAVEMENTS Abstract Arvo Tinni Tinni Management Consulting February 2013 This paper describes the experiences and design methodologies for concrete pavements in Australia. It is
More information5. Report Date GUIDELINES FOR EVALUATING ROUTINE OVERWEIGHT TRUCK ROUTES. 8. Performing Organization Report No. Emmanuel G. Fernando and JeongHo Oh
1. Report No. FHWA/TX04/04184P2 2. Government Accession No. 3. Recipient's Catalog No. 4. Title and Subtitle 5. Report Date GUIDELINES FOR EVALUATING ROUTINE OVERWEIGHT TRUCK ROUTES May 2004 6. Performing
More informationTorsion Testing. Objectives
Laboratory 4 Torsion Testing Objectives Students are required to understand the principles of torsion testing, practice their testing skills and interpreting the experimental results of the provided materials
More informationMechanically stabilized layers in road construction
Mechanically stabilized layers in road construction Zikmund Rakowski, Jacek Kawalec Tensar International, UK, Technical University of Silesia, Poland Abstract: Effective and economical technologies are
More informationModeling Beams on Elastic Foundations Using Plate Elements in Finite Element Method
Modeling Beams on Elastic Foundations Using Plate Elements in Finite Element Method Yungang Zhan School of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang,
More informationSEISMIC RETROFITTING TECHNIQUE USING CARBON FIBERS FOR REINFORCED CONCRETE BUILDINGS
Fracture Mechanics of Concrete Structures Proceedings FRAMCOS3 AEDIFICA TIO Publishers, D79104 Freiburg, Germany SEISMIC RETROFITTING TECHNIQUE USING CARBON FIBERS FOR REINFORCED CONCRETE BUILDINGS H.
More informationREVISED INTERIM REPORT: CHAPTERS 1 AND 2 NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM (NCHRP)
REVISED INTERIM REPORT: CHAPTERS 1 AND 2 Submitted to the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM (NCHRP) For Project NCHRP 142: TopDown Fatigue Cracking of HotMix Asphalt Layers LIMITED USE DOCUMENT
More information1.054/1.541 Mechanics and Design of Concrete Structures (309) Outline 1 Introduction / Design Criteria for Reinforced Concrete Structures
Prof. Oral Buyukozturk Massachusetts Institute of Technology Outline 1 1.054/1.541 Mechanics and Design of Concrete Structures (309) Outline 1 Introduction / Design Criteria for Reinforced Concrete Structures
More informationENGINEERING SCIENCE H1 OUTCOME 1  TUTORIAL 3 BENDING MOMENTS EDEXCEL HNC/D ENGINEERING SCIENCE LEVEL 4 H1 FORMERLY UNIT 21718P
ENGINEERING SCIENCE H1 OUTCOME 1  TUTORIAL 3 BENDING MOMENTS EDEXCEL HNC/D ENGINEERING SCIENCE LEVEL 4 H1 FORMERLY UNIT 21718P This material is duplicated in the Mechanical Principles module H2 and those
More informationSECTION 3.3  PAVEMENT DESIGN
SECTION 3.33.3.1 GENERAL 3.3.2 SUBSURFACE DRAINAGE 3.3.3 DETERMINATION OF DESIGN TRAFFIC 3.3.4 SUBGRADE EVALUATION 3.3.5 PAVEMENT THICKNESS 3.3.5.1 GRANULAR PAVEMENTS WITH THIN BITUMINOUS SURFACING 3.3.5.2
More informationUnit 48: Structural Behaviour and Detailing for Construction. Chapter 13. Reinforced Concrete Beams
Chapter 13 Reinforced Concrete Beams Concrete is a material strong in its resistance to compression, but very weak indeed in tension. good concrete will safely take a stress upwards of 7 N/mm 2 in compression,
More informationMunicipal Pavement Design with StreetPave Software
Municipal Pavement Design with StreetPave Software March 5, 2009 Scott Haislip Senior VP Pavement Engineering Presentation Overview Background / history of the design procedure Concrete pavement design
More informationReinforced Concrete Design SHEAR IN BEAMS
CHAPTER Reinforced Concrete Design Fifth Edition SHEAR IN BEAMS A. J. Clark School of Engineering Department of Civil and Environmental Engineering Part I Concrete Design and Analysis 4a FALL 2002 By Dr.
More informationFinite Element Method (FEM) Introduction
Engineering manual No. 20 Updated: 06/2016 Finite Element Method (FEM) Introduction The objective of this engineering manual is to explain the basic terms of a particular field of problems and the practical
More informationSEISMIC DESIGN. Various building codes consider the following categories for the analysis and design for earthquake loading:
SEISMIC DESIGN Various building codes consider the following categories for the analysis and design for earthquake loading: 1. Seismic Performance Category (SPC), varies from A to E, depending on how the
More informationDeflection Calculation of RC Beams: Finite Element Software Versus Design Code Methods
Deflection Calculation of RC Beams: Finite Element Software Versus Design Code Methods G. Kaklauskas, Vilnius Gediminas Technical University, 1223 Vilnius, Lithuania (gintaris.kaklauskas@st.vtu.lt) V.
More informationSoftware Development (PAKPAVE) for Flexible Pavement Design
Software Development (PAKPAVE) for Flexible Pavement Design Rafi Ullah Khan, Muhammad Imran Khan and Afed Ullah Khan Abstract In today s world, the road and surface failure of the flexible pavement has
More informationbi directional loading). Prototype ten story
NEESR SG: Behavior, Analysis and Design of Complex Wall Systems The laboratory testing presented here was conducted as part of a larger effort that employed laboratory testing and numerical simulation
More informationOverview of Topics. StressStrain Behavior in Concrete. Elastic Behavior. NonLinear Inelastic Behavior. Stress Distribution.
StressStrain Behavior in Concrete Overview of Topics EARLY AGE CONCRETE Plastic shrinkage shrinkage strain associated with early moisture loss Thermal shrinkage shrinkage strain associated with cooling
More informationAppendix A Investigation of Suitable Soil Constitutive Models for 3D Finite Element Studies of Live Load Distribution Through Fills Onto Culverts
Appendix A Investigation of Suitable Soil Constitutive Models for 3D Finite Element Studies of Live Load Distribution Through Fills Onto Culverts National Cooperative Highway Research Program Project
More informationChapter Outline. Mechanical Properties of Metals How do metals respond to external loads?
Mechanical Properties of Metals How do metals respond to external loads? Stress and Strain Tension Compression Shear Torsion Elastic deformation Plastic Deformation Yield Strength Tensile Strength Ductility
More informationStress Analysis Verification Manual
Settle3D 3D settlement for foundations Stress Analysis Verification Manual 00701 Rocscience Inc. Table of Contents Settle3D Stress Verification Problems 1 Vertical Stresses underneath Rectangular Footings
More informationENGI 8673 Subsea Pipeline Engineering Faculty of Engineering and Applied Science
GUIDANCE NOTE LECTURE 12 THERMAL EXPANSION ANALYSIS OVERVIEW The calculation procedure for determining the longitudinal pipeline response can be formulated on the basis of strain. The longitudinal strain
More informationSECTION 3 DESIGN OF POST TENSIONED COMPONENTS FOR FLEXURE
SECTION 3 DESIGN OF POST TENSIONED COMPONENTS FOR FLEXURE DEVELOPED BY THE PTI EDC130 EDUCATION COMMITTEE LEAD AUTHOR: TREY HAMILTON, UNIVERSITY OF FLORIDA NOTE: MOMENT DIAGRAM CONVENTION In PT design,
More informationThe following sketches show the plans of the two cases of oneway slabs. The spanning direction in each case is shown by the double headed arrow.
9.2 Oneway Slabs This section covers the following topics. Introduction Analysis and Design 9.2.1 Introduction Slabs are an important structural component where prestressing is applied. With increase
More informationPerformance Tests for Road Aggregates and Alternative Materials
Performance Tests for Road Aggregates and Alternative Materials Dr Greg Arnold, Pavespec Ltd Dr Sabine Werkmeister, University of Canterbury David Alabaster, Transit New Zealand Land Transport New Zealand
More informationEngineering Road Note 9 May 2012
Engineering Road Note 9 May 2012 PROCEDURE FOR THE DESIGN OF ROAD PAVEMENTS 1. INTRODUCTION This Note outlines the procedure to be used for the design of road pavements under the control of the Commissioner
More informationMECHANICS OF SOLIDS  BEAMS TUTORIAL 2 SHEAR FORCE AND BENDING MOMENTS IN BEAMS
MECHANICS OF SOLIDS  BEAMS TUTORIAL 2 SHEAR FORCE AND BENDING MOMENTS IN BEAMS This is the second tutorial on bending of beams. You should judge your progress by completing the self assessment exercises.
More information