This document discusses fatigue cracking in asphalt pavements. It describes how fatigue cracking can start from the bottom of the pavement layer and work its way up, or can start at the top edges due to tire-pavement interactions. Common fatigue testing methods are described, including flexural beam testing where failure is defined as 50% loss of stiffness. Test results depend on whether constant stress or constant strain is used. Other testing methods like cantilevered beam and diametral are also mentioned. Advanced topics covered include notched beam testing, dissipated energy calculations, and models for predicting fatigue life from binder and mix properties.
This document discusses test methods for characterizing permanent deformation in hot mix asphalt (HMA). It describes loaded wheel testers like the Asphalt Pavement Analyzer (APA), Hamburg Wheel Tracker, and Purdue Wheel Tracker that apply cyclic wheel loads to HMA samples. Terms related to permanent deformation testing like creep, repeated loading, and dynamic loading are defined. Parameters for different loaded wheel testers and typical APA test results are shown. The document also briefly mentions the gyratory shear compactor, simple shear tester, and uniaxial and triaxial testing for HMA characterization.
Stiffness measurements of hot mix asphalt (HMA) mixtures are important for predicting pavement performance and stresses/strains. Various methods exist to measure stiffness through axial, diametral, flexural, or shear testing under repeated or dynamic loading. Stiffness decreases with increasing temperature and air voids, and decreasing asphalt content. Proper characterization of HMA stiffness at different conditions is essential for evaluating fatigue cracking and permanent deformation.
This document discusses thermal cracking in asphalt pavements. Thermal cracking occurs when temperature decreases cause the pavement to contract and develop tensile stresses that can exceed the material strength. Three factors influence thermal cracking: low pavement surface temperature, cooling rate, and pavement age. The Thermal Stress Restrained Specimen Test (TSRST) directly measures the development of thermal stresses during cooling and identifies the fracture temperature and strength. Test results show lower air voids and some aggregate types can increase fracture temperature and strength. Desirable material properties to resist thermal cracking include low-temperature asphalt binder viscosity and aggregate with high abrasion resistance and low freeze-thaw loss. Pavement structure characteristics like thickness, base
The document discusses casing design considerations. It begins by outlining the general criteria considered in casing design, including loading conditions, formation strength, availability/cost of casing strings, and expected deterioration over time. It then describes how casing is designed to withstand burst, collapse, tension, and biaxial stresses using safety factors. Graphical and mathematical methods are presented for designing casing strings to meet differential pressure requirements at varying depths. Considerations like centralizer spacing and stretch are also covered. The document provides a detailed overview of the factors and calculations involved in optimizing casing design.
Evaluation of rigid pavements by deflection approacheSAT Journals
This document discusses using the Benkelman Beam Deflection (BBD) technique to evaluate rigid pavements by measuring load transfer efficiency (LTE) across joints. The BBD technique involves using two Benkelman beams placed on adjacent slabs - one loaded and one unloaded - to measure deflections when a load passes over. LTE is calculated as the ratio of the unloaded slab deflection to loaded slab deflection. The document applies this method to a rigid pavement in Pune, India, finding LTE values ranging from 31-43% across slabs, with a characteristic LTE of 37.11%. It concludes the BBD technique can provide information on dowel bar performance in rigid pavements.
One way slab is designed for an office building room measuring 3.2m x 9.2m. The slab is 150mm thick with 10mm diameter reinforcement bars spaced 230mm centre to centre. It is simply supported on 300mm thick walls and designed to support a 2.5kN/m2 live load. Reinforcement provided meets code requirements for minimum area and spacing. Design checks for cracking, deflection, development length and shear are within code limits.
Initial and routine load tests are conducted on piles to confirm design load calculations. Initial tests apply 2.5 times the safe carrying capacity to piles and routine tests apply 1.5 times. Initial tests establish acceptance limits for routine tests. Routine tests are conducted on 1/2-2% of piles to ensure safe load capacity and detect unusual performance. Vertical, lateral, and pull-out load tests are conducted according to IS standards and involve measuring pile settlement under increasing loads held for durations. Acceptance criteria consider settlement and load levels.
This document summarizes a course on drilling engineering. It discusses hydraulic principles like hydrostatic pressure calculations. It also covers drillstring design, including calculating the length of drill collars and the neutral point. Additional sections describe designing the drillstring to withstand tensile force, torque, burst pressure, and collapse pressure. Specific topics covered include minimum yield strength, tapered drill pipe sections, calculating torque capacity, and safety factors for uncertainties.
This document discusses test methods for characterizing permanent deformation in hot mix asphalt (HMA). It describes loaded wheel testers like the Asphalt Pavement Analyzer (APA), Hamburg Wheel Tracker, and Purdue Wheel Tracker that apply cyclic wheel loads to HMA samples. Terms related to permanent deformation testing like creep, repeated loading, and dynamic loading are defined. Parameters for different loaded wheel testers and typical APA test results are shown. The document also briefly mentions the gyratory shear compactor, simple shear tester, and uniaxial and triaxial testing for HMA characterization.
Stiffness measurements of hot mix asphalt (HMA) mixtures are important for predicting pavement performance and stresses/strains. Various methods exist to measure stiffness through axial, diametral, flexural, or shear testing under repeated or dynamic loading. Stiffness decreases with increasing temperature and air voids, and decreasing asphalt content. Proper characterization of HMA stiffness at different conditions is essential for evaluating fatigue cracking and permanent deformation.
This document discusses thermal cracking in asphalt pavements. Thermal cracking occurs when temperature decreases cause the pavement to contract and develop tensile stresses that can exceed the material strength. Three factors influence thermal cracking: low pavement surface temperature, cooling rate, and pavement age. The Thermal Stress Restrained Specimen Test (TSRST) directly measures the development of thermal stresses during cooling and identifies the fracture temperature and strength. Test results show lower air voids and some aggregate types can increase fracture temperature and strength. Desirable material properties to resist thermal cracking include low-temperature asphalt binder viscosity and aggregate with high abrasion resistance and low freeze-thaw loss. Pavement structure characteristics like thickness, base
The document discusses casing design considerations. It begins by outlining the general criteria considered in casing design, including loading conditions, formation strength, availability/cost of casing strings, and expected deterioration over time. It then describes how casing is designed to withstand burst, collapse, tension, and biaxial stresses using safety factors. Graphical and mathematical methods are presented for designing casing strings to meet differential pressure requirements at varying depths. Considerations like centralizer spacing and stretch are also covered. The document provides a detailed overview of the factors and calculations involved in optimizing casing design.
Evaluation of rigid pavements by deflection approacheSAT Journals
This document discusses using the Benkelman Beam Deflection (BBD) technique to evaluate rigid pavements by measuring load transfer efficiency (LTE) across joints. The BBD technique involves using two Benkelman beams placed on adjacent slabs - one loaded and one unloaded - to measure deflections when a load passes over. LTE is calculated as the ratio of the unloaded slab deflection to loaded slab deflection. The document applies this method to a rigid pavement in Pune, India, finding LTE values ranging from 31-43% across slabs, with a characteristic LTE of 37.11%. It concludes the BBD technique can provide information on dowel bar performance in rigid pavements.
One way slab is designed for an office building room measuring 3.2m x 9.2m. The slab is 150mm thick with 10mm diameter reinforcement bars spaced 230mm centre to centre. It is simply supported on 300mm thick walls and designed to support a 2.5kN/m2 live load. Reinforcement provided meets code requirements for minimum area and spacing. Design checks for cracking, deflection, development length and shear are within code limits.
Initial and routine load tests are conducted on piles to confirm design load calculations. Initial tests apply 2.5 times the safe carrying capacity to piles and routine tests apply 1.5 times. Initial tests establish acceptance limits for routine tests. Routine tests are conducted on 1/2-2% of piles to ensure safe load capacity and detect unusual performance. Vertical, lateral, and pull-out load tests are conducted according to IS standards and involve measuring pile settlement under increasing loads held for durations. Acceptance criteria consider settlement and load levels.
This document summarizes a course on drilling engineering. It discusses hydraulic principles like hydrostatic pressure calculations. It also covers drillstring design, including calculating the length of drill collars and the neutral point. Additional sections describe designing the drillstring to withstand tensile force, torque, burst pressure, and collapse pressure. Specific topics covered include minimum yield strength, tapered drill pipe sections, calculating torque capacity, and safety factors for uncertainties.
This document outlines the key considerations for developing an effective casing program. It discusses the different types of casings used, including conductor, surface, intermediate, production casing, and liners. The functions of each casing type are described. Important factors to determine casing setting depths are mentioned, such as formation pressures and stability, as well as factors for the production casing like completion method and expected production. The advantages of smaller hole sizes for cost reduction are balanced with the need for sufficient diameter for completion and production.
Stop criteria for proof load tests verified with field and laboratory testing...Eva Lantsoght
As the existing bridge stock is aging, improved assessment methods such as proof load testing become increasingly important. Proof load testing involves large loads, and as such the risk for the structure and personnel can be significant. To capture the structural response, extensive measurements are applied to proof load tests. Stop criteria, based on the measured quantities, are used to identify when further loading in a proof load test is not permitted. For proof load testing of buildings, stop criteria are available in existing codes. For bridges, recently stop criteria based on laboratory tests on beams reinforced with plain bars have been proposed. Subsequently, improved stop criteria were developed based on theoretical considerations for bending moment and shear. The stop criteria from the codes and the proposed stop criteria are compared to the results from field testing to collapse on the Ruytenschildt Bridge, and to the results from laboratory tests on beams sawn from the Ruytenschildt Bridge. This comparison shows that only a small change to the stop criteria derived from laboratory testing is necessary. The experimental evidence strengthens the recommendation for using the proposed stop criteria in proof load tests on bridges for bending moment, whereas further testing to confirm the stop criteria for shear is necessary.
The document discusses the design of columns. It defines a column as a vertical strut that can fail due to buckling or bending. It notes that failure of a strut can occur due to direct compressive stress, buckling stress, or a combination of the two. The document then discusses key terms used in column design such as radius of gyration, slenderness ratio, effective length, and distinguishes between long columns and short columns based on their slenderness ratios.
Buckling and tension field beam for aerospace structuresMahdi Damghani
This document provides an introduction to column buckling, including:
- Buckling occurs due to high compressive stresses that cause sudden sideways deflection.
- Boundary conditions affect the critical buckling load, with fixed-fixed columns having the highest load.
- Euler's equation is presented for calculating critical buckling loads of columns with various end conditions.
- Examples are provided to demonstrate calculating critical buckling loads and required cross-sectional sizes.
- Buckling of spar webs in aircraft is discussed, along with the concept of complete tension field action to resist buckling through diagonal tensile stresses.
- Equations are given for calculating stresses in spars designed using complete tension field action.
This document discusses buckling of columns. It begins by introducing the concept of buckling as a failure mode distinct from stresses exceeding strength or unacceptable deformations. It then uses an example of two rigid bars joined by a pin to model the mechanics of buckling, defining the critical load as the transition between stable and unstable equilibrium. Finally, it derives equations for the critical buckling load of columns based on their end conditions, noting pinned ends buckle at the lowest load.
Fatigue Analysis of Structures (Aerospace Application)Mahdi Damghani
This document provides an introduction to fatigue analysis of aerospace structures. It discusses key topics including stress-life analysis methods, S-N curves, stress concentration factors, notch sensitivity, and fatigue failure locations. Examples of fatigue critical locations in aircraft components like flaps, struts, and baffle panels are also shown. The document concludes with examples calculating stresses, stress ratios, and fatigue life based on the stress-life approach.
The document discusses the prestressing of tendons for a 204m long highway bridge in Israel using balanced cantilever construction. It involves prestressing 26 tendons in 8 segments per cantilever using a bonded post-tensioning system. Concrete must reach a minimum strength of 35 MPa before prestressing, which also cannot occur earlier than 2.5 days after casting. Detailed elongation calculations are provided for stressing each tendon in sequential segments as construction progresses outward from the piers.
1. The document discusses the design of one-way reinforced concrete slabs according to Indian code IS 456:2000.
2. It defines one-way slabs as edge supported slabs spanning in one direction with a ratio of long to short span greater than or equal to 2.
3. The main considerations for slab design discussed are effective span, deflection control, reinforcement requirements including minimum area, maximum bar diameter and cover, and load calculations.
The document provides instructions for conducting hardness tests on metal specimens using a hardness tester. It lists mild steel, carbon steel, brass and aluminum as example materials to test. The theory section explains that hardness is the resistance of a material to plastic deformation from an indenter. There are three main types of hardness tests: scratch, rebound, and indentation. The procedure involves securely mounting a specimen, applying a preliminary load and then a major load using a loading lever, allowing the pointer to come to rest, removing the load and recording the hardness reading. Observation tables are included to record readings for each specimen tested.
The document discusses shear design of beams. It covers shear strength, which depends on the web thickness and h/t ratio to prevent shear buckling. Shear strength is calculated as 60% of the tensile yield stress. Block shear failure is also discussed, where the strength is governed by the shear and net tension areas. An example calculates the maximum reaction based on block shear for a coped beam connection.
this slide will clear all the topics and problem related to singly reinforced beam by limit state method, things are explained with diagrams , easy to understand .
This document provides an overview of the design of steel beams. It discusses various beam types and sections, loads on beams, design considerations for restrained and unrestrained beams. For restrained beams, it covers lateral restraint requirements, section classification, shear capacity, moment capacity under low and high shear, web bearing, buckling, and deflection checks. For unrestrained beams, it discusses lateral torsional buckling, moment and buckling resistance checks. Design procedures and equations for determining effective properties and capacities are also presented.
This document discusses fatigue resistance testing. It defines fatigue as failure that occurs in structures subjected to fluctuating stresses over time, usually from repeated stress cycling that causes crack initiation and propagation. There are three types of cyclic stresses: reversed, repeated, and random. Fatigue resistance testing involves subjecting test specimens to these different stress cycles to determine their fatigue life. Two common fatigue testing machines are described: rotating bending and axial loading types. An example fatigue test on LDPE is also mentioned.
The document discusses the design of coupling beams in three categories based on aspect ratio and shear demand:
1) Coupling beams with an aspect ratio greater than 4 are designed as special moment frame beams with conventional reinforcement.
2) Coupling beams with an aspect ratio less than 2 and shear demand greater than a threshold are designed as diagonally reinforced beams.
3) Other coupling beams can be designed as either special moment frame beams or diagonally reinforced beams.
This document discusses shear and diagonal tension in beams. It begins with an introduction to shear forces and shear failure, known as diagonal tension. It then discusses direct shear stresses in beams, shear failure mechanisms, and when shear effects need to be considered in design. The document covers theoretical background on shear stresses and principal stresses. It focuses on diagonal tension failure, including the orientation of principal planes and reinforcement requirements to prevent diagonal cracking. It discusses ACI code provisions for the design of shear reinforcement, including requirements for minimum shear reinforcement.
A two way slab is supported by beams on all four sides and has a ratio of longer to shorter span of less than 2. It has reinforcement in both directions. The design process involves preliminary sizing based on deflection criteria, analysis, sizing of reinforcement in the shorter direction as a singly reinforced section, checking for shear and deflection, and detailing of reinforcement including development length and torsion reinforcement.
This report summarizes a buckling test conducted on a steel column to evaluate the relationship between load and displacement. The test procedure involved securing the column to a buckling test machine and applying a increasing load while measuring deflection. The results showed a linear relationship at first, until buckling occurred, after which increased load did not increase elongation. Calculations determined the critical buckling load and stress on the column based on its material properties and dimensions. In conclusion, buckling tests are important to characterize materials' mechanical properties for engineering applications.
This document discusses the design of drillstrings and bottom hole assemblies (BHAs). It covers the components of drillstrings including drill pipe, drill collars, heavy weight drill pipe, and stabilizers. It also discusses BHA configurations and the purpose and components of BHAs. The document provides information on selecting drill collars and drill pipe grades. It covers criteria for drillstring design including collapse pressure, tension loading, and dogleg severity analysis.
The document discusses the reinforcement requirements and design process for axially loaded columns. It provides guidelines on the minimum longitudinal and transverse reinforcement, including the pitch and diameter of lateral ties. Examples are given to calculate the ultimate load capacity of rectangular and circular columns based on the grade of concrete and steel. Design assumptions and checks for minimum eccentricity are also outlined.
This document outlines the key considerations for developing an effective casing program. It discusses the different types of casings used, including conductor, surface, intermediate, production casing, and liners. The functions of each casing type are described. Important factors to determine casing setting depths are mentioned, such as formation pressures and stability, as well as factors for the production casing like completion method and expected production. The advantages of smaller hole sizes for cost reduction are balanced with the need for sufficient diameter for completion and production.
Stop criteria for proof load tests verified with field and laboratory testing...Eva Lantsoght
As the existing bridge stock is aging, improved assessment methods such as proof load testing become increasingly important. Proof load testing involves large loads, and as such the risk for the structure and personnel can be significant. To capture the structural response, extensive measurements are applied to proof load tests. Stop criteria, based on the measured quantities, are used to identify when further loading in a proof load test is not permitted. For proof load testing of buildings, stop criteria are available in existing codes. For bridges, recently stop criteria based on laboratory tests on beams reinforced with plain bars have been proposed. Subsequently, improved stop criteria were developed based on theoretical considerations for bending moment and shear. The stop criteria from the codes and the proposed stop criteria are compared to the results from field testing to collapse on the Ruytenschildt Bridge, and to the results from laboratory tests on beams sawn from the Ruytenschildt Bridge. This comparison shows that only a small change to the stop criteria derived from laboratory testing is necessary. The experimental evidence strengthens the recommendation for using the proposed stop criteria in proof load tests on bridges for bending moment, whereas further testing to confirm the stop criteria for shear is necessary.
The document discusses the design of columns. It defines a column as a vertical strut that can fail due to buckling or bending. It notes that failure of a strut can occur due to direct compressive stress, buckling stress, or a combination of the two. The document then discusses key terms used in column design such as radius of gyration, slenderness ratio, effective length, and distinguishes between long columns and short columns based on their slenderness ratios.
Buckling and tension field beam for aerospace structuresMahdi Damghani
This document provides an introduction to column buckling, including:
- Buckling occurs due to high compressive stresses that cause sudden sideways deflection.
- Boundary conditions affect the critical buckling load, with fixed-fixed columns having the highest load.
- Euler's equation is presented for calculating critical buckling loads of columns with various end conditions.
- Examples are provided to demonstrate calculating critical buckling loads and required cross-sectional sizes.
- Buckling of spar webs in aircraft is discussed, along with the concept of complete tension field action to resist buckling through diagonal tensile stresses.
- Equations are given for calculating stresses in spars designed using complete tension field action.
This document discusses buckling of columns. It begins by introducing the concept of buckling as a failure mode distinct from stresses exceeding strength or unacceptable deformations. It then uses an example of two rigid bars joined by a pin to model the mechanics of buckling, defining the critical load as the transition between stable and unstable equilibrium. Finally, it derives equations for the critical buckling load of columns based on their end conditions, noting pinned ends buckle at the lowest load.
Fatigue Analysis of Structures (Aerospace Application)Mahdi Damghani
This document provides an introduction to fatigue analysis of aerospace structures. It discusses key topics including stress-life analysis methods, S-N curves, stress concentration factors, notch sensitivity, and fatigue failure locations. Examples of fatigue critical locations in aircraft components like flaps, struts, and baffle panels are also shown. The document concludes with examples calculating stresses, stress ratios, and fatigue life based on the stress-life approach.
The document discusses the prestressing of tendons for a 204m long highway bridge in Israel using balanced cantilever construction. It involves prestressing 26 tendons in 8 segments per cantilever using a bonded post-tensioning system. Concrete must reach a minimum strength of 35 MPa before prestressing, which also cannot occur earlier than 2.5 days after casting. Detailed elongation calculations are provided for stressing each tendon in sequential segments as construction progresses outward from the piers.
1. The document discusses the design of one-way reinforced concrete slabs according to Indian code IS 456:2000.
2. It defines one-way slabs as edge supported slabs spanning in one direction with a ratio of long to short span greater than or equal to 2.
3. The main considerations for slab design discussed are effective span, deflection control, reinforcement requirements including minimum area, maximum bar diameter and cover, and load calculations.
The document provides instructions for conducting hardness tests on metal specimens using a hardness tester. It lists mild steel, carbon steel, brass and aluminum as example materials to test. The theory section explains that hardness is the resistance of a material to plastic deformation from an indenter. There are three main types of hardness tests: scratch, rebound, and indentation. The procedure involves securely mounting a specimen, applying a preliminary load and then a major load using a loading lever, allowing the pointer to come to rest, removing the load and recording the hardness reading. Observation tables are included to record readings for each specimen tested.
The document discusses shear design of beams. It covers shear strength, which depends on the web thickness and h/t ratio to prevent shear buckling. Shear strength is calculated as 60% of the tensile yield stress. Block shear failure is also discussed, where the strength is governed by the shear and net tension areas. An example calculates the maximum reaction based on block shear for a coped beam connection.
this slide will clear all the topics and problem related to singly reinforced beam by limit state method, things are explained with diagrams , easy to understand .
This document provides an overview of the design of steel beams. It discusses various beam types and sections, loads on beams, design considerations for restrained and unrestrained beams. For restrained beams, it covers lateral restraint requirements, section classification, shear capacity, moment capacity under low and high shear, web bearing, buckling, and deflection checks. For unrestrained beams, it discusses lateral torsional buckling, moment and buckling resistance checks. Design procedures and equations for determining effective properties and capacities are also presented.
This document discusses fatigue resistance testing. It defines fatigue as failure that occurs in structures subjected to fluctuating stresses over time, usually from repeated stress cycling that causes crack initiation and propagation. There are three types of cyclic stresses: reversed, repeated, and random. Fatigue resistance testing involves subjecting test specimens to these different stress cycles to determine their fatigue life. Two common fatigue testing machines are described: rotating bending and axial loading types. An example fatigue test on LDPE is also mentioned.
The document discusses the design of coupling beams in three categories based on aspect ratio and shear demand:
1) Coupling beams with an aspect ratio greater than 4 are designed as special moment frame beams with conventional reinforcement.
2) Coupling beams with an aspect ratio less than 2 and shear demand greater than a threshold are designed as diagonally reinforced beams.
3) Other coupling beams can be designed as either special moment frame beams or diagonally reinforced beams.
This document discusses shear and diagonal tension in beams. It begins with an introduction to shear forces and shear failure, known as diagonal tension. It then discusses direct shear stresses in beams, shear failure mechanisms, and when shear effects need to be considered in design. The document covers theoretical background on shear stresses and principal stresses. It focuses on diagonal tension failure, including the orientation of principal planes and reinforcement requirements to prevent diagonal cracking. It discusses ACI code provisions for the design of shear reinforcement, including requirements for minimum shear reinforcement.
A two way slab is supported by beams on all four sides and has a ratio of longer to shorter span of less than 2. It has reinforcement in both directions. The design process involves preliminary sizing based on deflection criteria, analysis, sizing of reinforcement in the shorter direction as a singly reinforced section, checking for shear and deflection, and detailing of reinforcement including development length and torsion reinforcement.
This report summarizes a buckling test conducted on a steel column to evaluate the relationship between load and displacement. The test procedure involved securing the column to a buckling test machine and applying a increasing load while measuring deflection. The results showed a linear relationship at first, until buckling occurred, after which increased load did not increase elongation. Calculations determined the critical buckling load and stress on the column based on its material properties and dimensions. In conclusion, buckling tests are important to characterize materials' mechanical properties for engineering applications.
This document discusses the design of drillstrings and bottom hole assemblies (BHAs). It covers the components of drillstrings including drill pipe, drill collars, heavy weight drill pipe, and stabilizers. It also discusses BHA configurations and the purpose and components of BHAs. The document provides information on selecting drill collars and drill pipe grades. It covers criteria for drillstring design including collapse pressure, tension loading, and dogleg severity analysis.
The document discusses the reinforcement requirements and design process for axially loaded columns. It provides guidelines on the minimum longitudinal and transverse reinforcement, including the pitch and diameter of lateral ties. Examples are given to calculate the ultimate load capacity of rectangular and circular columns based on the grade of concrete and steel. Design assumptions and checks for minimum eccentricity are also outlined.
Soil and rock for geoscientist and engineersAinun Fatihah
This document summarizes key information about soils and rocks for geoscientists and engineers. It defines soil as unconsolidated mineral and organic material that forms in place and supports plant life, while rock is a solid aggregate of minerals. It describes the three main types of rocks - igneous, sedimentary, and metamorphic - and their formation processes. Several important properties of soils and rocks are also outlined, including particle size, density, porosity, plasticity, compressibility, shear strength, deformation, discontinuities, and methods for evaluating rock mass quality.
تجربة الضغط على نقطة Point load test 2013 full copyAli A. Alzahrani
تجربة الضغط على نقطة Point load test 2013 full copy
هذه التجربة من اكثر التجارب سهولة واقلها تكلفة , وتستخدم في الوصف والتصنيف بعيدا تماما عن كل مايتعلق بالتصميم الهندسي وذلك كله يعود الى نتائجها المعيارية وغير المباشرة.
Schmidt's Hammer Rebound Value Analysis for finding Uniaxial Compressive Stre...Jasmeet Singh Saluja
An innovative & easy way of establishing a relationship ship between Schmidt's Hammer Rebound value & Uniaxial Compressive Strength, Point Load Index & Density of rocks to obtain the value of UCS on site.
This method helps in eliminating the need of laboratory analysis of rock for UCS, Point Load Index & density determination.
It,s all about Index properties of Rocks.
It can help those students who want to give presentation about this topic.
Also it can give you information about Pocks and very helpful in Geo mechanics.
This contains methods of exploration in rock. How the rock samplers are taken. Quality of rock samples and its reporting. Along with the laboratory tests conducting on these rock samples.
This document discusses several index tests used by engineers and geologists to determine the strength and deformation properties of soils and rocks in the field. It describes the Brazilian test, point load index test, impact test, and Schmidt hammer rebound test. The Brazilian test measures tensile strength. The point load index test uses a handheld device to apply a compressive force and induce tensile cracking. The impact test evaluates coal degradation. The Schmidt hammer rebound test measures surface hardness in a non-destructive manner using rebound value correlations. These index tests provide immediate preliminary results without extensive preparation and can be correlated to laboratory strength tests.
This document discusses the fundamentals of rheology and describes various types of rheometers used to measure the rheological properties of asphalt binders. It explains that rheology is the study of flow and deformation and introduces constitutive relationships between force and deformation. It then describes different types of rheometers, including shear rheometers that apply drag or pressure-driven flows, and other rheometers that measure stiffness and strength through bending beam or direct tension tests. Specific examples of equipment are also shown, such as concentric cylinder and parallel plate shear rheometers, a bending beam rheometer, and a direct tension testing device.
The document discusses Superpave asphalt binder specifications. It provides sources of information on Superpave specifications and describes how the performance grade specification system works based on climate. The performance grade takes into account the average 7-day maximum pavement temperature and the 1-day minimum pavement temperature. It then outlines how the Superpave specification addresses key distresses like permanent deformation, fatigue cracking, and low temperature cracking through test requirements on properties like stiffness and viscosity.
The document discusses the Superpave performance graded specification for asphalt binders. The specification grades asphalt binders based on the climate and expected pavement temperatures. A variety of tests are used to evaluate the binder properties related to different distresses at different temperatures. The rotational viscosity test evaluates workability at construction temperatures. The dynamic shear rheometer test evaluates rutting resistance at high in-service temperatures after both short-term aging from mixing and long-term aging. The bending beam rheometer and direct tension tests evaluate stiffness and strength respectively at low in-service temperatures. Conditioning such as short-term aging with the rolling thin film oven test and long-term aging with the pressure aging vessel better simulate
The document discusses the history and evolution of asphalt binder specifications. Early specifications focused on consistency and graded binders based on penetration testing. Later, specifications incorporated viscosity grading which characterizes binders across a range of temperatures relevant to mixing and compaction. Current performance-based specifications further consider aging characteristics by testing rolled thin film oven aged residues. Viscosity grading provides more information on asphalt properties and performance compared to penetration grading. Specifications have evolved with technological advances to better ensure desirable asphalt characteristics for pavement performance.
The document discusses different types and uses of asphalt binders. It describes how asphalt binder is produced from petroleum crude oil through refining processes like solvent deasphalting and residuum oil supercritical extraction. These processes break down the crude oil into components that are blended to produce asphalt binders of desired properties. The asphalt binders are then used to manufacture hot mix asphalt for paving roads through batch and continuous mix drum plants. Other asphalt products discussed include cutback asphalts and emulsions, along with their compositions and uses.
This document discusses modified asphalt binders, which are used to improve the performance of asphalt pavements. Modifiers such as polymers and fillers are added to asphalt binders to increase rutting resistance at warm temperatures and inhibit cracking from traffic and environmental stresses. The document describes different types of modifiers and provides examples of polymeric modifiers. It also discusses traditional testing methods for modified binders and uses microscopy images to illustrate how polymers interact within asphalt binders.
This document discusses techniques for rehabilitating and maintaining asphalt overlays on concrete pavements, including crack and seat, break and seat, rubblization, and saw and seal. Crack and seat and break and seat involve fracturing concrete slabs to shorten their length and allow for interlocking of pieces. Rubblization involves fracturing concrete into pieces smaller than 9 inches to prevent reflection cracking in overlays. Saw and sealing joints is used to control the rate of deterioration of reflection cracks.
The document discusses various aspects of asphalt pavement rehabilitation and maintenance using hot mix asphalt overlays. It covers topics such as bituminous patching, surface leveling, cold milling, crack sealing, subsurface drainage, reflection cracking control methods, recycling existing pavement, pavement widening, shoulder rehabilitation, and design of overlays along projects. The key steps for an effective overlay project involve examining preoverlay repairs, subsurface drainage improvements, and methods for controlling reflection cracking from the existing pavement.
This document discusses hot mix asphalt (HMA) overlays for rehabilitating flexible and rigid pavements. It defines functional and structural overlays, and describes how they are used to address surface defects versus structural defects. The rehabilitation process and factors considered for overlay design like pre-overlay repair, materials selection, and traffic loads are also summarized. Thick and thin overlays as well as reconstruction are presented as options to correct deficiencies.
This document discusses moisture sensitivity in HMA (hot mix asphalt). It describes several reasons for moisture damage including loss of cohesion in the asphalt binder, loss of adhesion between the binder and aggregate, and degradation of the aggregate. It also discusses factors that influence moisture sensitivity related to the aggregate properties, asphalt binder properties, HMA mix properties, and weather conditions during construction. Methods for adding antistripping additives like liquid antistrips or lime are presented, as well as several tests for evaluating moisture sensitivity like the boiling water test or freeze-thaw pedestal test.
This document discusses typical distresses that can occur in flexible asphalt pavements and their causes. It describes various types of cracking like fatigue cracking, thermal cracking, block cracking, longitudinal cracking, reflection cracking, as well as other distresses such as rutting, corrugations, slippage, stripping, raveling, reduced skid resistance, roughness, and swelling from frost. Each distress is explained in terms of how it manifests visually and what factors can contribute to its development, such as heavy traffic loads, inadequate drainage, mix design issues, or temperature susceptibility of the asphalt binder. The document provides an overview of the main distresses that can affect flexible pavements and their underlying mechanisms.
This document discusses quality control and quality assurance control charts. It explains that control charts can be used to monitor processes and detect variation, including chance causes and assignable causes. Control charts have benefits like early detection of issues, establishing process capability, and providing a permanent record of quality. Examples are provided of how to construct X-bar and R control charts and interpret the results to determine whether a process is in statistical control.
This document discusses quality control and quality assurance procedures for obtaining representative samples of asphalt mixtures and their components. It describes how to properly sample materials at different stages, including at plants, trucks, and roadways. The key aspects covered are sampling locations and techniques, sample size requirements, handling and storage of samples, and potential issues that can arise from improper sampling procedures like segregation. Maintaining representative samples is important for ensuring accurate test results and mixture quality.
This document discusses quality control and quality assurance sampling procedures for construction projects. It addresses requirements for a sampling program, including frequency, location, and size of samples. Different types of sampling are described, such as judgment, quota, systematic, stratified, and random sampling. Random sampling is preferable to avoid bias, and it is best to use random number tables to select sample locations. Stratified random sampling involves dividing a construction site into sublots for sampling. The document provides an example of how to use random numbers to select sample locations within sublots for both roadway and hot mix asphalt plant sampling.
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3. 3HMA Charaterization Fatigue Cracking
Mechanisms
• Traditionally considered to start at the
bottom and work up to the top
• Crack starts when tensile strain exceeds
tensile strength of mix
• When cracks visible on top, full layer
cracked
Subgrade
Base
AC Mix εt
Longitudinal pavement profile
4. 4HMA Charaterization Fatigue Cracking
Mechanisms
• Recent observations of fatigue
cracking that starts from the top at the
outside edges of the wheel path
• Tensile stresses due to tire-pavement
interactions at surface
Subgrade
Base
AC Mix
εt
Transverse pavement profile
Transverse pavement profile
6. 6HMA Charaterization Fatigue Cracking
General Terms
• Dynamic load
• Load applied using a sinusoidal wave form
• Repeated load
• Load pulse applied then removed
• Rest period between loads
Load
Load
Time
Time
7. 7HMA Charaterization Fatigue Cracking
Flexural Beam Fatigue Testing
• Repeated load preferred to sinusoidal to
permit stress relaxation
• Loading can be either constant stress or
constant strain
• Failure = 50% loss of stiffness (controlled
strain)
8. 8HMA Charaterization Fatigue Cracking
Determining Failure for Constant Strain
0
0.2
0.4
0.6
0.8
1
1.2
100 1,000 10,000 100,000
Numbers of Cycles
StiffnessRatio
Failure = 0.5 Stiffness Ratio
10. Test Results
Strain, ε
• Results dependent upon how test run
• Constant stress means stiffer asphalt
binders perform better
Stress, σ
Soft
Stiff
11. Test Results
Strain, ε
• Results dependent upon how test run
• Constant strain means softer asphalt
binders perform better
Stress, σ
Soft
Stiff
12. Constant Stress vs. Constant Strain
Subgrade
Base
HMA 100 mm or less
Subgrade
Base
HMA
150 mm or more
Strain at bottom of
AC layer controls
Stress controls
14. Cantilevered Beam Testing
• Trapezoid beam
configuration
• Requires concrete beam
be fabricated then sawn
• Fixed at bottom, loaded in
a cantilever fashion at top
15. Diametral Fatigue Testing
• Repeated load (usually)
• Considered less sensitive to mix
properties than flexural
16. 16HMA Charaterization Fatigue Cracking
Example of Test Results
0
15,000
30,000
45,000
Cycles to
Failure
20C
Test Temperature
Flexural
Trapezoid
Diametral
Reported in SHRP A-404, 1994
17. 17HMA Charaterization Fatigue Cracking
Advanced Fatigue Topics
• Notched-beam test (C* line integral)
• Dissipated Energy
• Models for Predicting Fatigue Life
19. 19HMA Charaterization Fatigue Cracking
Dissipated Energy
• Dissipated energy is the amount of energy
lost for each loading cycle
• Calculated from the changes in stresses
and strains for each cycle of testing
20. 20HMA Charaterization Fatigue Cracking
Difficulties
• Research showed that dissipated energy
equations are dependent on mix variables
and conditions of testing
21. 21HMA Charaterization Fatigue Cracking
Predicting Fatigue from
Binder and Mix Properties
• SHRP strain-dependent model
• Asphalt Institute’s DAMA Program
• University of Nottingham
• Shell
22. 22HMA Charaterization Fatigue Cracking
SHRP Strain-Dependent Model
• Low air voids and crushed, rough-textured
aggregates
• Increase stiffness
• Increase fatigue life (constant strain)
• Indicate that asphalt binder property
information not sufficient for predicting
fatigue life
References: Asphalt Institute. Computer Program DAMA: Pavement Structural Analysis Using Multi-Layered Elastic Theory Users Manual. 1984. Asphalt Research Program, Institute of Transportation Studies, University of California, Berkeley. Fatigue Response of Asphalt-Aggregate Mixes. Strategic Highway Research Program Report SHRP-A-404, National Research Council, Washington, D.C. 1994. Judycki, J. Comparison of Fatigue Criteria for Flexible and Semi-Rigid Pavements. Proceedings, Eighth International Conference on Asphalt Pavements, Seattle Washington. Aug. 10-14, 1997.) Myers, L.A., Roque, R., and Ruth, B.R. Mechanisms of Surface-Initiated Longitudinal Wheel Path Cracks in High-Type Bituminous Pavements. Journal for the Association of Asphalt Paving Technologists. Vol. 67. 1998 pp 401-432.
Historically, fatigue cracking has been considered to start at the bottom of the HMA layer. Fatigue cracks are initiated when the tensile strength of the asphalt concrete is exceeded as the pavement deflects under repeated traffic loads. These cracks continue to grow with increasing numbers of loads. When the cracks are visible on the surface of the pavement, the crack extends the full depth of the HMA layer. Once about 10% of the wheel path exhibits fatigue cracking, it will only be short time before the cracking increases to 45% in the wheel paths.
(Ref: Myers, L.A., Roque, R., and Ruth, B.R. Mechanisms of Surface-Initiated Longitudinal Wheel Path Cracks in High-Type Bituminous Pavements. Journal for the Association of Asphalt Paving Technologists. Vol. 67. 1998 pp 401-432.) This type of fatigue cracking is characterized by longitudinal cracks on one or both sides of the wheel paths. The increase in the use of radial tires (from 80% in 1985 to 98% in 1996) and a corresponding increase in tire pressures of about 20 psi represent a significant change in the surface loading conditions (Florida data). It is these changes in surface conditions that appear to be responsible for increase transverse surface tensions needed to initiate tensile cracking at the tire-pavement interface. This type of fatigue cracking is relatively independent of the type of pavement structure. This indicates that a material’s solution is needed to mitigate this type of cracking.
The most common fatigue test uses a simply supported beam. Dynamic loading is applied to achieve either a constant bending stress or constant bending strain over a number of loading cycles. A cantilevered trapezoidal beam has been used extensively in testing by the University of Nottingham. Similar methods of loading and analysis are used for this testing. Diametral loading can also be used to evaluate fatigue testing since this type of failure is related to the tensile properties of the HMA. However, this method is considered to be less sensitive to mixture variables than beam testing. A notched beam concept has been used with in order to fix the location of the sample failure.
Any of these types of fatigue tests have been used with either dynamic loading or repeated loading methods. The most commonly used is the repeated load.
For controlled-stress testing, failure is defined as the numbers of cycles needed to visibly crack the beam. Failure for the constant strain mode of testing is defined as a 50% loss of initial stiffness. Stiffness at any given cycle is computed from the tensile stress and strain at that specific cycle. The loss of stiffness with numbers of cycles is usually presented as the stiffness ratio (initial stiffness divided by the stiffness at a given cycle). When the ratio is plotted for the test results, it is easy to see when the sample fails (next slide).
The first sample failed after 10,000 loading cycles while the second sample is still above the 50% reduction in stiffness limit at 100,000 cycles.
The Australian fatigue unit is a small, table top device that can test beams using either dynamic or repeated loading. The picture shows a beam loaded in the frame. The clamps at either end hold the beam but are on pivot points that allow the beam to deflect. The two center clamps apply the load and are used to provide a constant moment region in the bottom of the beam (i.e., tensile stress region).
Materials behave differently between constant stress and constant strain loading conditions. When constant stress is used, a stiff asphalt binder will deform very little while a softer asphalt binder will show a much greater deformation (i.e., strain). As conceptually shown in this figure, the strain induced in the softer asphalt binder mix may be very close to the failure strain and would therefore fail faster than the stiffer HMA that is being tested as strains well below failure. This would lead to the conclusion that softer asphalt binders fatigue more quickly.
However, when the same test is conducted with constant strain, the stiffer asphalt binder will be tested at much higher stresses, in some cases close to the failure stress. At the same time the softer asphalt binder mixes have significantly lower stresses at the same strain level. Under these testing conditions, the softer asphalt binder mixes would appear to be the best choice to resist fatigue cracking.
The selection of either constant stress or constant strain should be based on the pavement structure in which the mix will be used. When the HMA layer is less than about 100 mm (4 inches), the mode of failure will be controlled by the large strains at the bottom of the asphalt binder layer. This thickness is typical of low volume roads. When the HMA layer is more than about 150 mm (6 inches) thick, then stress will control the occurrence of fatigue cracking. This thickness is typical of high volume roadways or older pavements that are being overlayed.
Beam and trapezoid beam fatigue testing are similar in many ways. Both simulate flexural stresses seen in pavements but apply uniaxial rather than triaxial stresses. Both reverse stresses (tension-compression) and neither permits the accumulation of permanent deformation with increasing numbers of loading cycles. The only reason for choosing trapezoid rather than beam fatigue testing is the researcher’s preference or local customs. Beam fatigue is typically used in the United States while trapezoid fatigue is popular in the United Kingdom.
This test is simple to perform and uses typical cylindrical specimens. The state of stresses induced in the sample during testing are complex, however, the critical stresses and strains can be calculated assuming linear elastic behavior. A biaxial state of stress is present along the vertical axis with the tensile stress being reasonably constant with significantly more variability in the compressive stress. The main differences between the diametral and beam fatigue tests are that permanent deformation occurs and stress reversal is not practical in diametral testing. Diametral fatigue testing also consistently underestimates the fatigue life relative to other fatigue tests.
This figure gives the student a feel for how the results from each of the fatigue tests compare for the same mix and test method variables.
Laboratory determination of HMA fatigue characteristics takes a considerable amount of time before results can be obtained. Typical testing time for flexural beam fatigue for a set of three samples at each of only two stress (or strain) levels take as long as 3 weeks. In order to obtain estimates of fatigue characteristics quickly, a number of researchers have developed prediction equations for estimating the fatigue life. This section briefly presents some of these predictive equations.
While used on a limited basis for some fatigue studies, researchers at the University of California, Berkeley found that the fracture mechanics approach was excessively complex and difficult. This test, while initially included in the original SHRP research, was eliminated from further study for this reason.
Some of the early research indicated that there may be a unique relationship between the numbers of cycles to failure and the cumulative dissipated energy to failure. That is, the results might be independent of mix variables. Later work indicated that the results were dependent upon mix properties but independent of test methods (two- and three-point bending), temperature (10 to 40 o C [50 to 104 o F]), modes of loading (controlled stress or controlled strain), and the frequency 10 to 50 Hz) (UC Berkeley, 1994).
Conclusions of the testing during the original SHRP program indicated that results were not, as previously thought, independent of the testing variables. Dissipated energy is influenced by the choice of test temperature and the mode of loading. It was found that dissipated energy is highly correlated with incremental decreases in stiffness during fatigue testing which helps explain the effects of mode of loading on mix behavior.
Because of the extensive time required to obtain fatigue results, a number of researchers have developed mathematical models for predicting fatigue from more easily obtainable (in most cases) mix information. This section presents several of the more commonly used equations. The SHRP research resulted in the formulation of an equation for predicting fatigue for actual pavements. The equation constants were calibrated using both field and laboratory data. An evaluation of the SHRP model with a range of mixes indicated that fatigue life, in constant strain, was dependent on aggregate properties such as percent crushing and surface texture. Results indicated that information on the binder alone was not sufficient for predicting actual fatigue life of a pavement. The accumulation of damage is calculated in increments by month. This allows for differences in fatigue cracking due to changing combinations of temperature and traffic loadings.
An evaluation of the SHRP model with a range of mixes indicated that fatigue life, in constant strain, was dependent on aggregate properties such as percent crushing and surface texture. Results indicated that information on the binder alone was not sufficient for predicting actual fatigue life of a pavement.