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| Lehman,D. E. | WA-RD 569.1 | Cotton Duck Bearing Pads: Engineering Evaluation and Design Recommendations | 2003 | TRAC/UW |
Abstract:
Cotton duck bearing pads (CDP) are sometimes used to support loads and accommodate movements and rotations at bridge bearings. CDP are preformed elastomeric pads consisting of thin layers of elastomer interlaid with fabric, and they are manufactured under Military Specifications with limited guidance from the AASHTO. The behavior of these CDP bearing pads was experimentally evaluated to establish design models for predicting this behavior, to determine the variation in behavior expected with different bearing pad manufacturers, and to develop design recommendations. This research is a follow-up study of an earlier research program sponsored by Arkansas State University.CDP bearing pads from three different manufacturers were tested, and the test program included dynamic and static (or monotonic) tests of bearings in shear, compression,and rotation. In general, the static tests were used to evaluate strength, stiffness, deformation limits, and general pad behavior. The dynamic tests examined durability and performance under repeated loading and deformation.The results of this test program were used to develop design recommendations, and an appendix includes a draft of proposed wording for modification of the AASHTO LRFD Specifications to include these design recommendations. In addition, a spreadsheet was developed in Microsoft EXCEL to accomplish the calculations necessary to complete the design.
Authors:
Lehman,D. E., Roeder,C. W., Larsen,R., Curtin,K.
Keywords:
cotton duck bearing pads, CDP, bridge bearings, bridge design, loads, bridge, specifications, specification, behavior, design, models, research, program, tests, strength, durability, performance
Cotton duck bearing pads (CDP) are sometimes used to support loads and accommodate movements and rotations at bridge bearings. CDP are preformed elastomeric pads consisting of thin layers of elastomer interlaid with fabric, and they are manufactured under Military Specifications with limited guidance from the AASHTO. The behavior of these CDP bearing pads was experimentally evaluated to establish design models for predicting this behavior, to determine the variation in behavior expected with different bearing pad manufacturers, and to develop design recommendations. This research is a follow-up study of an earlier research program sponsored by Arkansas State University.CDP bearing pads from three different manufacturers were tested, and the test program included dynamic and static (or monotonic) tests of bearings in shear, compression,and rotation. In general, the static tests were used to evaluate strength, stiffness, deformation limits, and general pad behavior. The dynamic tests examined durability and performance under repeated loading and deformation.The results of this test program were used to develop design recommendations, and an appendix includes a draft of proposed wording for modification of the AASHTO LRFD Specifications to include these design recommendations. In addition, a spreadsheet was developed in Microsoft EXCEL to accomplish the calculations necessary to complete the design.
Authors:
Lehman,D. E., Roeder,C. W., Larsen,R., Curtin,K.
Keywords:
cotton duck bearing pads, CDP, bridge bearings, bridge design, loads, bridge, specifications, specification, behavior, design, models, research, program, tests, strength, durability, performance
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http://www.wsdot.wa.gov/research/reports/fullreports/569.1.pdf http://wsdot.wa.gov/Research/Reports/500/569.1.htm |
| Allen,T. M. | WA-RD 522.2 | Prediction of Reinforcement Loads in Reinforced Soil Walls | 2003 | TRAC/UW |
Abstract:
Proper estimation of soil reinforcement loads and strains is key to accurate design of the internal stability of geosynthetic and steel reinfoced soil structures. Current design methodologies use limit equilibrium concepts to estimate reinforcement loads for internal stability design, with empirical modifications to match the prediction to observed reinforcement loads at working stresses. This approach has worked reasonably well for steel reinforced walls but appears to seriously overestimate loads for geosynthetic walls.A large database of full-scale geosynthetic walls (16 fully instrumented, full-scale geosynthetic walls and 14 walls with limited measurements), full-scale steel reinforced wall sections was utilized to develop a new design methodology based on working stress principles, termed the K-Stiffness Method. This new methodology considers the stiffness of the various wall components and their influence on reinforcement loads. Results of simple statistical analyses to evaluate the ratio of predicted to measured peak reinforcement loads in geosynthetic walls were telling: the AASHTO Simplified Method results to an average ratio of measured to predicted loads of 0.45 with a coefficient of variation (COV) of 91 percent, whereas the proposed method results in an average of 0.99 and a COV of 36 percent. The proposed method remains accurate up until the point at which the soil begins to fail (approximaely 3 to 5 percent strain). For steel reinforced MSE walls, the improvement was more modest: AASHTO's Simplified Method results in an average ratio of predicted to measured loads of 1.12 with a (COV) of 45 percent, whereas the new K-Stiffness Method results in an average of 0.95 and a COV of 32 percent. The objective of the method is to design the wall reinforcement so that the soil within the wall backfill will not reach a state of failure consistent with the notion of working stress conditions. This soil failure limit state is not considered in the design methods currently available, yet, given the research results presented herein, is likely to be a controlling limit state for geosynthetic structures.The fruit of this research is a more accurate method for estimating reinforcement loads, thereby reducing reinforcement needs and improving the economy of reinforced soil walls. The scope of this research was limited to reinforced soil walls that utilize granular (non-cohesive, relatively low silt content) backfill.
Authors:
Allen,T. M., Bathurst,R. J.
Keywords:
reinforcement, walls, loads, strains, creep, design, research
Proper estimation of soil reinforcement loads and strains is key to accurate design of the internal stability of geosynthetic and steel reinfoced soil structures. Current design methodologies use limit equilibrium concepts to estimate reinforcement loads for internal stability design, with empirical modifications to match the prediction to observed reinforcement loads at working stresses. This approach has worked reasonably well for steel reinforced walls but appears to seriously overestimate loads for geosynthetic walls.A large database of full-scale geosynthetic walls (16 fully instrumented, full-scale geosynthetic walls and 14 walls with limited measurements), full-scale steel reinforced wall sections was utilized to develop a new design methodology based on working stress principles, termed the K-Stiffness Method. This new methodology considers the stiffness of the various wall components and their influence on reinforcement loads. Results of simple statistical analyses to evaluate the ratio of predicted to measured peak reinforcement loads in geosynthetic walls were telling: the AASHTO Simplified Method results to an average ratio of measured to predicted loads of 0.45 with a coefficient of variation (COV) of 91 percent, whereas the proposed method results in an average of 0.99 and a COV of 36 percent. The proposed method remains accurate up until the point at which the soil begins to fail (approximaely 3 to 5 percent strain). For steel reinforced MSE walls, the improvement was more modest: AASHTO's Simplified Method results in an average ratio of predicted to measured loads of 1.12 with a (COV) of 45 percent, whereas the new K-Stiffness Method results in an average of 0.95 and a COV of 32 percent. The objective of the method is to design the wall reinforcement so that the soil within the wall backfill will not reach a state of failure consistent with the notion of working stress conditions. This soil failure limit state is not considered in the design methods currently available, yet, given the research results presented herein, is likely to be a controlling limit state for geosynthetic structures.The fruit of this research is a more accurate method for estimating reinforcement loads, thereby reducing reinforcement needs and improving the economy of reinforced soil walls. The scope of this research was limited to reinforced soil walls that utilize granular (non-cohesive, relatively low silt content) backfill.
Authors:
Allen,T. M., Bathurst,R. J.
Keywords:
reinforcement, walls, loads, strains, creep, design, research
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http://www.wsdot.wa.gov/research/reports/fullreports/522.2.pdf http://wsdot.wa.gov/Research/Reports/500/522.2.htm |
| Allen,T. M. | WA-RD 513.1 | Development of the Simplified Method for Internal Stability Design of Mechanically Stabilized Earth Walls | 2001 | Washington State Dept. of Transportation |
Abstract:
In 1994, a technical working group under the auspices of the T-15 Technical Committee on Substructures and Walls of the American Association of State Highway and Transportation Officials (AASHTO) Bridge Subcommittee, was formed to reevaluate the design specifications for mechanically stabilized earth (MSE) walls contained in the AASHTO Standard Specifications for Highway Bridges (1996). One of the areas of focus was the internal stability design of MSE walls. Several methods for calculating the backfill reinforcement loads were available at that time in the AASHTO Standard Specifications, and the intent was to unify the design methods to simplify and clarify the specifications. To accomplish this, full-scale MSE wall case history data were gathered and analyzed so that the unified method developed could be calibrated to the empirical data, since all of the methods available were empirical in nature. The effect of simplifications in the method, such as how vertical soil stresses are calculated and how reinforcement stiffness is considered in the design, could also be evaluated with these full-scale wall data to ensure that the unified method developed was adequately accurate. From this effort, the AASHTO Simplified Method was developed.This report summarizes the development of the Simplified Method. It uses a number of full-scale MSE wall case histories to compare the prediction accuracy of the Simplified Method to that of the other methods currently available and focuses primarily on steel reinforced MSE walls. The theoretical assumptions used by the Simplified Method, as well as the other methods, are also evaluated and compared in light of the empirical evidence. This evaluation showed that the prediction accuracy of the Simplified Method is at least as good as that of the other methods, while the Simplified Method still simplifies calculations. This evaluation also showed, however, that all of the methods have limitations that must be considered.
Authors:
Allen,T. M., Christopher,B., Elias,V., DeMaggio,J.
Keywords:
soil reinforcement, mechanically stabilized earth walls, MSE walls, earth pressure, stability, sands, loads
In 1994, a technical working group under the auspices of the T-15 Technical Committee on Substructures and Walls of the American Association of State Highway and Transportation Officials (AASHTO) Bridge Subcommittee, was formed to reevaluate the design specifications for mechanically stabilized earth (MSE) walls contained in the AASHTO Standard Specifications for Highway Bridges (1996). One of the areas of focus was the internal stability design of MSE walls. Several methods for calculating the backfill reinforcement loads were available at that time in the AASHTO Standard Specifications, and the intent was to unify the design methods to simplify and clarify the specifications. To accomplish this, full-scale MSE wall case history data were gathered and analyzed so that the unified method developed could be calibrated to the empirical data, since all of the methods available were empirical in nature. The effect of simplifications in the method, such as how vertical soil stresses are calculated and how reinforcement stiffness is considered in the design, could also be evaluated with these full-scale wall data to ensure that the unified method developed was adequately accurate. From this effort, the AASHTO Simplified Method was developed.This report summarizes the development of the Simplified Method. It uses a number of full-scale MSE wall case histories to compare the prediction accuracy of the Simplified Method to that of the other methods currently available and focuses primarily on steel reinforced MSE walls. The theoretical assumptions used by the Simplified Method, as well as the other methods, are also evaluated and compared in light of the empirical evidence. This evaluation showed that the prediction accuracy of the Simplified Method is at least as good as that of the other methods, while the Simplified Method still simplifies calculations. This evaluation also showed, however, that all of the methods have limitations that must be considered.
Authors:
Allen,T. M., Christopher,B., Elias,V., DeMaggio,J.
Keywords:
soil reinforcement, mechanically stabilized earth walls, MSE walls, earth pressure, stability, sands, loads
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http://www.wsdot.wa.gov/research/reports/fullreports/513.1.pdf http://wsdot.wa.gov/Research/Reports/500/513.1.htm |
| Allen,T. M. | WA-RD 522.1 | Prediction of Soil Reinforcement Loads in Mechanically Stabilized Earth Walls | 2001 |
Abstract:
Proper estimation of soil reinforcement loads and strains is key to accurate design of the internal stability of geosynthetic and steel reinforced soil structures. Current design methodologies use limit equilibrium concepts to estimate reinforcement loads for internal stability design, with empirical modifications to match the prediction to observed reinforcement loads at working stresses. This approach has worked reasonably well for steel reinforced walls but appears to seriously overestimate loads for geosynthetic walls. A large database of full-scale geosynthetic walls (16 fully instrumented, full-scale geosynthetic walls and 14 walls with limited measurements) and 20 fully instrumented, full-scale steel reinforced MSE wall sections was utilized to develop a new design methodology based on working stress principles, termed the K0-Stiffness Method. This new methodology considers the stiffness of the various wall components and their influence on reinforcement loads. Results of simple statistical analyses to evaluate the ratio of predicted to measured peak reinforcement loads in geosynthetic walls were telling: the AASHTO Simplified Method results in an average ratio of predicted to measured loads of 2.9 with a coefficient of variation (COV) of 86%, whereas the proposed method results in an average of 1.12 and a COV of 41%. The proposed method remains accurate up until the point at which the soil begins to fail (approximately 3 to 5% strain). For steel reinforced MSE walls the improvement was more modest: AASHTO's Simplified Method results in an average ratio of predicted to measured loads of 1.04 with a (COV) of 51%, whereas the new K0-Stiffness Method results in an average of 1.12 and a COV of 35%. The objective of the method is to design the wall reinforcement so that the soil within the wall backfill will not reach a state of failure consistent with the notion of working stress conditions. This soil failure limit state is not considered in the design methods currently available, yet, given the research results presented herein, is likely to be a controlling limit state for geosynthetic structures.The fruit of this research is a more accurate method for estimating reinforcement loads, thereby reducing reinforcement needs and improving the economy of MSE walls. The scope of this research was limited to MSE walls that utilize granular (non-cohesive, relatively low silt content) backfill.
Authors:
Allen,T. M., Bathurst,R. J.
Keywords:
reinforcement, walls, loads, strains, creep, design
Proper estimation of soil reinforcement loads and strains is key to accurate design of the internal stability of geosynthetic and steel reinforced soil structures. Current design methodologies use limit equilibrium concepts to estimate reinforcement loads for internal stability design, with empirical modifications to match the prediction to observed reinforcement loads at working stresses. This approach has worked reasonably well for steel reinforced walls but appears to seriously overestimate loads for geosynthetic walls. A large database of full-scale geosynthetic walls (16 fully instrumented, full-scale geosynthetic walls and 14 walls with limited measurements) and 20 fully instrumented, full-scale steel reinforced MSE wall sections was utilized to develop a new design methodology based on working stress principles, termed the K0-Stiffness Method. This new methodology considers the stiffness of the various wall components and their influence on reinforcement loads. Results of simple statistical analyses to evaluate the ratio of predicted to measured peak reinforcement loads in geosynthetic walls were telling: the AASHTO Simplified Method results in an average ratio of predicted to measured loads of 2.9 with a coefficient of variation (COV) of 86%, whereas the proposed method results in an average of 1.12 and a COV of 41%. The proposed method remains accurate up until the point at which the soil begins to fail (approximately 3 to 5% strain). For steel reinforced MSE walls the improvement was more modest: AASHTO's Simplified Method results in an average ratio of predicted to measured loads of 1.04 with a (COV) of 51%, whereas the new K0-Stiffness Method results in an average of 1.12 and a COV of 35%. The objective of the method is to design the wall reinforcement so that the soil within the wall backfill will not reach a state of failure consistent with the notion of working stress conditions. This soil failure limit state is not considered in the design methods currently available, yet, given the research results presented herein, is likely to be a controlling limit state for geosynthetic structures.The fruit of this research is a more accurate method for estimating reinforcement loads, thereby reducing reinforcement needs and improving the economy of MSE walls. The scope of this research was limited to MSE walls that utilize granular (non-cohesive, relatively low silt content) backfill.
Authors:
Allen,T. M., Bathurst,R. J.
Keywords:
reinforcement, walls, loads, strains, creep, design
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http://www.wsdot.wa.gov/research/reports/fullreports/522.1.pdf http://wsdot.wa.gov/Research/Reports/500/522.1.htm |
| Allen,T. M. | WA-RD 528.1 | Application of the K 0-Stiffness Method to Reinforced Soil Wall Limit States Design | 2001 | Washington State Dept. of Transportation |
Abstract:
A new design methodology for estimating reinforcement loads in reinforced soil walls, termed the K 0-Stiffness Method, has been developed. This new method has been demonstrated to more accurately estimate reinfocement loads and strains in reinforced soil walls than do current design methodologies. Step-by-step procedures are provided to lead the designer through the reinforced soil wall internal stability design process using this new methodology. These step-by-step design procedures have been developed with a limit states design approach consistent with current design codes (in North America this is termed Load and Resistance Factor Design, or LRFD). Specifically, consideration has been given to strength and serviceability limit states. Load and resistance factors, based on statistical data where feasible, have been developed for use with this method. The results of examples from actual wall case histories were summarized and analyzed to assess how well the new methodology performs relative to current design practice. From this analysis of the design examples, the following was observed: For geosynthetic walls, the K 0-Stiffness Method has the potential to reduce required backfill reinforcement capacity relative to current design methodology by a factor of 1.2 to 3. For steel reinforced soil walls, the reduction in the reinforcement capacity relative to what is required by current design methodology is more modest, on the order of 1.0 to 2.1. Given these findings, use of the K 0-Stiffness Method can result in substantial cost savings, especially for geosynthetic walls, because of reduced reinforcement needs.
Authors:
Allen,T. M., Bathurst,R. J.
Keywords:
reinforcement, walls, loads, strains, creep, design, research, methodology, soil, developed, stability, design process, codes, North, resistance, strength, data, analysis, geosynthetic, steel, cost
A new design methodology for estimating reinforcement loads in reinforced soil walls, termed the K 0-Stiffness Method, has been developed. This new method has been demonstrated to more accurately estimate reinfocement loads and strains in reinforced soil walls than do current design methodologies. Step-by-step procedures are provided to lead the designer through the reinforced soil wall internal stability design process using this new methodology. These step-by-step design procedures have been developed with a limit states design approach consistent with current design codes (in North America this is termed Load and Resistance Factor Design, or LRFD). Specifically, consideration has been given to strength and serviceability limit states. Load and resistance factors, based on statistical data where feasible, have been developed for use with this method. The results of examples from actual wall case histories were summarized and analyzed to assess how well the new methodology performs relative to current design practice. From this analysis of the design examples, the following was observed: For geosynthetic walls, the K 0-Stiffness Method has the potential to reduce required backfill reinforcement capacity relative to current design methodology by a factor of 1.2 to 3. For steel reinforced soil walls, the reduction in the reinforcement capacity relative to what is required by current design methodology is more modest, on the order of 1.0 to 2.1. Given these findings, use of the K 0-Stiffness Method can result in substantial cost savings, especially for geosynthetic walls, because of reduced reinforcement needs.
Authors:
Allen,T. M., Bathurst,R. J.
Keywords:
reinforcement, walls, loads, strains, creep, design, research, methodology, soil, developed, stability, design process, codes, North, resistance, strength, data, analysis, geosynthetic, steel, cost
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http://www.wsdot.wa.gov/research/reports/fullreports/528.1.pdf http://wsdot.wa.gov/Research/Reports/500/528.1.htm |
| De Bolt,P. G. | WA-RD 341.1 | Heavy Vehicles vs. Urban Pavements | 1993 |
Abstract:
An analysis was conducted of the impact that overweight vehicles have and will have on the life of the pavements in the Seattle metropolitan area. The study focuses on major Metro bus routes with both rigid and flexible pavements.Recommendations arc made to mitigate the impact of the higher loads from the bus fleet. These recommendations include route modifications to avoid streets with thinner, under designed pavements, increasing pavement thickness for rebuild or overlaid streets, and the purchase of vehicles, which meet legal axle loads.
Authors:
De Bolt,P. G., Chinn,E.
Keywords:
analysis, axle, bus, buses, heavy vehicles, impact, loads, overweight, pavement, pavement design, pavement service life, pavements, seattle, urban
An analysis was conducted of the impact that overweight vehicles have and will have on the life of the pavements in the Seattle metropolitan area. The study focuses on major Metro bus routes with both rigid and flexible pavements.Recommendations arc made to mitigate the impact of the higher loads from the bus fleet. These recommendations include route modifications to avoid streets with thinner, under designed pavements, increasing pavement thickness for rebuild or overlaid streets, and the purchase of vehicles, which meet legal axle loads.
Authors:
De Bolt,P. G., Chinn,E.
Keywords:
analysis, axle, bus, buses, heavy vehicles, impact, loads, overweight, pavement, pavement design, pavement service life, pavements, seattle, urban
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| Dames & Moore- Inca Engineering | WA-RD 324.1 | Foundation-Soil Interaction Analysis of Bridges - Volumes I and II 478 | 1993 |
Abstract:
Dames & Moore And their subcontractor, Inco Engineers, have prepared this Manual of Practice for conducting bridge foundation-soil interaction analyses. The manual is intended to assist engineers in the Bridge Design office at the Washington State Department of Transportation (WSDOT) who perform dynamic analysis of bridge-foundation systems. The primary purpose of the manual is to present practical and accurate methods of estimating the foundation stiffness matrices for abutment or pier foundations supported on footings or piles. These matrices are needed for soil-structure interaction analysis to more accurately determine the seismic loads acting on the bridge superstructure and on the abutment and pier foundations.This Manual of Practice consists of two volumes. Volume I presents five bridge example problems:1. Coldwater Creek2. Deadwater Slough3. Ebey Slough4. Northup Way5. FHWAThe first four examples are actual WSDOT bridges and the fifth example is a fictitious bridge that appeared in a 1991 FHWA course notebook on seismic design of highway bridges.Volume II presents the input and output files of the SEISAB computer program for the dynamic soil-structure interaction analysis of bridges. The SEISAB computer program is currently used by WSDOT in the seismic design of Washington state bridges.Dames & Moore recommends the FHWA and Novak methods to estimate bridge foundation stiffness matrices. These methodologies are presented in detail in the Coldwater Creek example problem in Volume I. In this example, the basic theory and relevant equations or inputs for implementing these methodologies are provided first and are immediately followed by their application to the Coldwater Creek bridge. The appropriate equations or inputs from the FHWA and Novak methodologies presented not the Coldwater Creek example problem are identified and applied in the other four bridge example problems. Volume I also contains three appendices. The basis for the recommendation of the FHWA and Novak methods is provided in Appendix A, which is a reproduction of the 1992 Dames & Moore report to WSDOT on the evaluation of methods to estimate foundation stiffnesses. Appendix B consists of selected pages from the BMCOL 76 computer program user guide; this computer program, which computes the load-deflection and moment-rotation curves for single piles, is part of the FHWA methodology. Appendix C presents the method for transforming the foundation stiffness matrices from one coordinate system to another. This transformation process is important because the coordinate systems assumed in the FHWA and Novak methods are generally different and therefore are not necessarily the same as the SEISAB coordinate system. Coordinate transformations are also discussed in the ColdWater Creek example problem.
Authors:
Dames & Moore- Inca Engineering
Keywords:
analysis, bridge, bridge design, bridge foundation, bridges, computer, computer program, design, equations, evaluation, Foudation-Soil, foundation, foundation stiffness, highway, interaction, loads, manual, methodology, methods, piles, program, seismic, seismic design, soil-structure interaction, superstructure, System, systems, transportation, volume, Volumes I & II, Washington, Washington state, WSDOT
Dames & Moore And their subcontractor, Inco Engineers, have prepared this Manual of Practice for conducting bridge foundation-soil interaction analyses. The manual is intended to assist engineers in the Bridge Design office at the Washington State Department of Transportation (WSDOT) who perform dynamic analysis of bridge-foundation systems. The primary purpose of the manual is to present practical and accurate methods of estimating the foundation stiffness matrices for abutment or pier foundations supported on footings or piles. These matrices are needed for soil-structure interaction analysis to more accurately determine the seismic loads acting on the bridge superstructure and on the abutment and pier foundations.This Manual of Practice consists of two volumes. Volume I presents five bridge example problems:1. Coldwater Creek2. Deadwater Slough3. Ebey Slough4. Northup Way5. FHWAThe first four examples are actual WSDOT bridges and the fifth example is a fictitious bridge that appeared in a 1991 FHWA course notebook on seismic design of highway bridges.Volume II presents the input and output files of the SEISAB computer program for the dynamic soil-structure interaction analysis of bridges. The SEISAB computer program is currently used by WSDOT in the seismic design of Washington state bridges.Dames & Moore recommends the FHWA and Novak methods to estimate bridge foundation stiffness matrices. These methodologies are presented in detail in the Coldwater Creek example problem in Volume I. In this example, the basic theory and relevant equations or inputs for implementing these methodologies are provided first and are immediately followed by their application to the Coldwater Creek bridge. The appropriate equations or inputs from the FHWA and Novak methodologies presented not the Coldwater Creek example problem are identified and applied in the other four bridge example problems. Volume I also contains three appendices. The basis for the recommendation of the FHWA and Novak methods is provided in Appendix A, which is a reproduction of the 1992 Dames & Moore report to WSDOT on the evaluation of methods to estimate foundation stiffnesses. Appendix B consists of selected pages from the BMCOL 76 computer program user guide; this computer program, which computes the load-deflection and moment-rotation curves for single piles, is part of the FHWA methodology. Appendix C presents the method for transforming the foundation stiffness matrices from one coordinate system to another. This transformation process is important because the coordinate systems assumed in the FHWA and Novak methods are generally different and therefore are not necessarily the same as the SEISAB coordinate system. Coordinate transformations are also discussed in the ColdWater Creek example problem.
Authors:
Dames & Moore- Inca Engineering
Keywords:
analysis, bridge, bridge design, bridge foundation, bridges, computer, computer program, design, equations, evaluation, Foudation-Soil, foundation, foundation stiffness, highway, interaction, loads, manual, methodology, methods, piles, program, seismic, seismic design, soil-structure interaction, superstructure, System, systems, transportation, volume, Volumes I & II, Washington, Washington state, WSDOT
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| Itani,R. | WA-RD 155.1 | Design of Continuous Bridges Using Precast, Prestressed Concrete Girders without Endblocks | 1987 |
Abstract:
This study investigated the feasibility of eliminating endblocks from pretensioned continuos bridge girders. The removal of endblocks is estimated to reduce girder costs by 5 to 10 percent. The girders studied were the Washington State Department of Transportation\'s \"Series 14\". These girders are characterized by 5 inch thick webs and are prestressed with both harped and straight 1/2 inch diameter grade 270 stands. Previous research had recommended the elimination of endblocks for simple span bridges. This study dealt with continuous bridges.The research consisted test and a destructive laboratory test. The field test was used identify bases for the destructive testing. \"Series14 \" girder with endblocks and \"Series 60\" girders without endblocks were instrumented with strain gages and monitored from the time they manufactured to the time thel oads were tested on the bridge. The laboratory test was performed with a balanced cantilever arrangement using two \"14\" girders without without endblocks. The joint at the support was made continuous by providing deck reinforcement in a manner similar to reinforcing details used by WSDOT. Concentrated incrementally applied at a distance of 13 ft.10 inches from the continuous support. The modified girders performed effectively under applied loads. Therefore, endblocks may be removedfrom continuous Series \"14\" girders with normal diaphragms. The study recommends that one \"Series 14\" continuous girder without endblocks be designed and monitored through the various stages ofconstruction and service in another bridge.
Authors:
Itani,R., Hiremath,G. S., Vasisth,U.
Keywords:
base, bridge, bridges, concrete, construction, cost, costs, Deck, design, diaphragms, endblocks, field test, girders, loads, prestressed, prestressed concrete, Prestressing, pretensioned, reinforcement, research, span, transportation, Washington, Washington state, WSDOT
This study investigated the feasibility of eliminating endblocks from pretensioned continuos bridge girders. The removal of endblocks is estimated to reduce girder costs by 5 to 10 percent. The girders studied were the Washington State Department of Transportation\'s \"Series 14\". These girders are characterized by 5 inch thick webs and are prestressed with both harped and straight 1/2 inch diameter grade 270 stands. Previous research had recommended the elimination of endblocks for simple span bridges. This study dealt with continuous bridges.The research consisted test and a destructive laboratory test. The field test was used identify bases for the destructive testing. \"Series14 \" girder with endblocks and \"Series 60\" girders without endblocks were instrumented with strain gages and monitored from the time they manufactured to the time thel oads were tested on the bridge. The laboratory test was performed with a balanced cantilever arrangement using two \"14\" girders without without endblocks. The joint at the support was made continuous by providing deck reinforcement in a manner similar to reinforcing details used by WSDOT. Concentrated incrementally applied at a distance of 13 ft.10 inches from the continuous support. The modified girders performed effectively under applied loads. Therefore, endblocks may be removedfrom continuous Series \"14\" girders with normal diaphragms. The study recommends that one \"Series 14\" continuous girder without endblocks be designed and monitored through the various stages ofconstruction and service in another bridge.
Authors:
Itani,R., Hiremath,G. S., Vasisth,U.
Keywords:
base, bridge, bridges, concrete, construction, cost, costs, Deck, design, diaphragms, endblocks, field test, girders, loads, prestressed, prestressed concrete, Prestressing, pretensioned, reinforcement, research, span, transportation, Washington, Washington state, WSDOT
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| Fragaszy,R. J. | WA-RD 138.1 | Seismic Response of Tieback Retaining Walls, Phase I | 1987 |
Abstract:
The current design practice used by WSDOT for the design of permanent tieback walls is to assume that the static design of a tieback wall retaining clayey soils provides an adequate reserve of strength to prevent failure during seismic loading. This design procedure is based largely on the assumption that the soil and the wall move together ground shaking and that significant loads are not produced. For tieback walls retaining sandy soils, it is assumed that dynamic loads are produced. Mononobe-Okabe dynamic soil pressures are added to the design pressure to account for the dynamic load. The validity of these assumptions and the resultant design practices is evaluated in this study. A pilot numerical study was conducted on a forty foot high wall with three levels of tiebacks using the program FLUSH. It was found that the wall and the soil tend to move in-phase and only negligible dynamic tie forces are generated. However, the soil above and below the excavation level tends to move out-of-phase, leading to significant dynamic pressures and bending moments in the wall and near the excavation level. It appears that in least some cases, tieback walls with an adequate static safety factor may suffer significant damage or fail during seismic loading and that the use of Mononobe-Okabe dynamic pressures may be conservative.
Authors:
Fragaszy,R. J., Denby,G., Higgins,J. D., Ali,Nmjad
Keywords:
account, bending, damage, design, earthquake, forces, loads, pressure, program, retaining wall, retaining walls, safety, Sandy soils, seismic, seismic loading, seismic response, soil, soil pressure, strength, Tieback Walls, tiebacks, walls, WSDOT
The current design practice used by WSDOT for the design of permanent tieback walls is to assume that the static design of a tieback wall retaining clayey soils provides an adequate reserve of strength to prevent failure during seismic loading. This design procedure is based largely on the assumption that the soil and the wall move together ground shaking and that significant loads are not produced. For tieback walls retaining sandy soils, it is assumed that dynamic loads are produced. Mononobe-Okabe dynamic soil pressures are added to the design pressure to account for the dynamic load. The validity of these assumptions and the resultant design practices is evaluated in this study. A pilot numerical study was conducted on a forty foot high wall with three levels of tiebacks using the program FLUSH. It was found that the wall and the soil tend to move in-phase and only negligible dynamic tie forces are generated. However, the soil above and below the excavation level tends to move out-of-phase, leading to significant dynamic pressures and bending moments in the wall and near the excavation level. It appears that in least some cases, tieback walls with an adequate static safety factor may suffer significant damage or fail during seismic loading and that the use of Mononobe-Okabe dynamic pressures may be conservative.
Authors:
Fragaszy,R. J., Denby,G., Higgins,J. D., Ali,Nmjad
Keywords:
account, bending, damage, design, earthquake, forces, loads, pressure, program, retaining wall, retaining walls, safety, Sandy soils, seismic, seismic loading, seismic response, soil, soil pressure, strength, Tieback Walls, tiebacks, walls, WSDOT
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| Sorensen,H. | WA-RD 084.1 | Determination of the Capability of a Side Bearing Block Foundation as a Fixed Support to Resist Overturning | 1986 |
Abstract:
A side bearing block foundation is used to resist overturning moments and lateral forces. Theoretical and experimental investigations were made to determine the ultimate moment capacity of a reinforced concrete footing subjected to vertical and horizontal loads and an overturning moment. The theoretical ultimate moment capacity was assumed to occur when the ultimate soil resistance was reached along the side bearing walls. It was found the resultant friction force at the base of the foundation greatly influenced the foundation to resist an overturning moment. The experimental ultimate moment capacity was determined from a deflection curve obtained from field data. A theoretical ultimate moment capacity was determined with the use of a finite el computer The results each of the three determinations were in acceptable agreement. Recommendations for further are made.
Authors:
Sorensen,H., Toreh,R.
Keywords:
base, computer, concrete, data, experimental, finite element, footing, forces, foundation, foundations, friction, loads, overturning, piles, reinforced concrete, resistance, soil, soil mechanics, soil pressure, stability, walls
A side bearing block foundation is used to resist overturning moments and lateral forces. Theoretical and experimental investigations were made to determine the ultimate moment capacity of a reinforced concrete footing subjected to vertical and horizontal loads and an overturning moment. The theoretical ultimate moment capacity was assumed to occur when the ultimate soil resistance was reached along the side bearing walls. It was found the resultant friction force at the base of the foundation greatly influenced the foundation to resist an overturning moment. The experimental ultimate moment capacity was determined from a deflection curve obtained from field data. A theoretical ultimate moment capacity was determined with the use of a finite el computer The results each of the three determinations were in acceptable agreement. Recommendations for further are made.
Authors:
Sorensen,H., Toreh,R.
Keywords:
base, computer, concrete, data, experimental, finite element, footing, forces, foundation, foundations, friction, loads, overturning, piles, reinforced concrete, resistance, soil, soil mechanics, soil pressure, stability, walls
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| Tai Wik,David Chui | WA-RD 039.12 | Highway Runoff In Washington State: Model Validation And Statistical Analysis 898 | 1982 |
Abstract:
Statewide sampling of highway runoff continued through 1980-81, and the resulting data has been aggregated with that from previous years to further investigate pollutant loadings. Results have validated the solids loading model previously proposed by Asplund (1980) for Western Washington Highways and tentatively extended the model to Eastern Washington. Loading of there pollutants can be predicted from total suspended solids loading using ratios derived from the data. These ratios may be taken as constants at any Washington State location for some pollutants or as linear functions of traffic or other contaminants. Comparison of runoff from a sulfur-extended asphalt pavement with runoff elsewhere indicates higher sulfate loads in the former case. A limited sampling program along an uncurbed highway section observed higher pollutant concentrations from these sections to curbed areas. Sampling of solids adhering to the undercarriage of automobiles produced widely varying results but suggested that vehicles traveling on rural or unpaved roads accumulate significant amounts of solids that can be released on highways. The final year of field sampling will concentrate on improving the loading models, especially for Eastern Washington application, and continuing the sulfur extended asphalt study with a functional control site experiencing the same conditions.
Authors:
Tai Wik,David Chui, Mar,B. W., Horner,R. R.
Keywords:
analysis, asphalt, asphalt pavement, Concentrations, condition, control, data, extended asphalt, highway, highway runoff, Highways, loads, model, models, pavement, pollutant loading, Pollutants, program, runoff, rural, sampling, statistical analysis, sulfur, suspended solids, traffic, Washington, Washington state
Statewide sampling of highway runoff continued through 1980-81, and the resulting data has been aggregated with that from previous years to further investigate pollutant loadings. Results have validated the solids loading model previously proposed by Asplund (1980) for Western Washington Highways and tentatively extended the model to Eastern Washington. Loading of there pollutants can be predicted from total suspended solids loading using ratios derived from the data. These ratios may be taken as constants at any Washington State location for some pollutants or as linear functions of traffic or other contaminants. Comparison of runoff from a sulfur-extended asphalt pavement with runoff elsewhere indicates higher sulfate loads in the former case. A limited sampling program along an uncurbed highway section observed higher pollutant concentrations from these sections to curbed areas. Sampling of solids adhering to the undercarriage of automobiles produced widely varying results but suggested that vehicles traveling on rural or unpaved roads accumulate significant amounts of solids that can be released on highways. The final year of field sampling will concentrate on improving the loading models, especially for Eastern Washington application, and continuing the sulfur extended asphalt study with a functional control site experiencing the same conditions.
Authors:
Tai Wik,David Chui, Mar,B. W., Horner,R. R.
Keywords:
analysis, asphalt, asphalt pavement, Concentrations, condition, control, data, extended asphalt, highway, highway runoff, Highways, loads, model, models, pavement, pollutant loading, Pollutants, program, runoff, rural, sampling, statistical analysis, sulfur, suspended solids, traffic, Washington, Washington state
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| Mahoney,J. P. | WA-RD 036.1 | Pavement Testing and Analysis Of Heavy Hauls For SR-12 /Problem Area Highway On SR-12 940 | 1979 |
Abstract:
The pavement structure of SR 12 between Montesano and Elma, Washington was evaluated for the proposed heavy loads associated with construction of the Satsop power plant. Information used in evaluating SR-12 resulted from two sources which included field studies conducted by the Washington State Department of Transportation and development of various material strength parameters by the University of Washington. These data were used to model the pavement structure as a layered elastic system. By use of this analysis procedure, the stresses, strains, and deflections were estimated for the expected range of loading conditions. The results indicate that the most probable amount of damage (fatigue and rutting) expected for the non-cement treated base structural sections is less that one to two percent of available pavement life for the "expected" loading condition. An increase in either or both the trailer wheel load and pavement temperature will act to produce greater losses in pavement life. It is estimated that the tensile stresses in the cement treated base may exceed the tensile strength of this material.
Authors:
Mahoney,J. P., Tsunetta,Jerrold Y., Terrel,Ronald L.
Keywords:
analysis, base, condition, construction, damage, data, development, fatigue, highway, loads, materials, model, pavement, Pavement Evaluation, Materials Characterization, Layered Elastic System, Failure Criteria, Heavy Loads, pavement life, pavement temperature, strains, strength, stresses, System, temperature, transportation, Washington, Washington state, wheel load
The pavement structure of SR 12 between Montesano and Elma, Washington was evaluated for the proposed heavy loads associated with construction of the Satsop power plant. Information used in evaluating SR-12 resulted from two sources which included field studies conducted by the Washington State Department of Transportation and development of various material strength parameters by the University of Washington. These data were used to model the pavement structure as a layered elastic system. By use of this analysis procedure, the stresses, strains, and deflections were estimated for the expected range of loading conditions. The results indicate that the most probable amount of damage (fatigue and rutting) expected for the non-cement treated base structural sections is less that one to two percent of available pavement life for the "expected" loading condition. An increase in either or both the trailer wheel load and pavement temperature will act to produce greater losses in pavement life. It is estimated that the tensile stresses in the cement treated base may exceed the tensile strength of this material.
Authors:
Mahoney,J. P., Tsunetta,Jerrold Y., Terrel,Ronald L.
Keywords:
analysis, base, condition, construction, damage, data, development, fatigue, highway, loads, materials, model, pavement, Pavement Evaluation, Materials Characterization, Layered Elastic System, Failure Criteria, Heavy Loads, pavement life, pavement temperature, strains, strength, stresses, System, temperature, transportation, Washington, Washington state, wheel load
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| Terrel,R. | WA-RD 017.1 | Pavement Response And Equivalencies For Various Truck Axle Tire Configurations 984 | 1974 |
Abstract:
There are indications that many trucks now have front axle loads approaching the maximum allowable for single axles which increases the potential for pavement damage. This report is intended to be a State-Of-The-Art approach to answer several pertinent questions from a theoretical study based on hypothetical pavements and loads, but based on reasonable material characteristics and pavement behavior from previous research. The results are a series of relationships based on pavement life which can be used to determine any number of "equivalencies." These equivalencies can be used to compare the destructive effects of various sizes of single and dual tires, axle loads , pavement thicknesses , speed and temperatures. The general nature of this report provides a wide range of conditions for comparison.on a relative basis.
Authors:
Terrel,R., Rimsritong,S.
Keywords:
asphalt pavement, axle, behavior, condition, damage, dual tires, equivalencies, loads, pavement, pavement damage, pavement life, pavements, research, single axle, speed, speed and temperature, state-of-the-art, temperature, tire, tire contact pressure, tires, truck, trucks, wheel load
There are indications that many trucks now have front axle loads approaching the maximum allowable for single axles which increases the potential for pavement damage. This report is intended to be a State-Of-The-Art approach to answer several pertinent questions from a theoretical study based on hypothetical pavements and loads, but based on reasonable material characteristics and pavement behavior from previous research. The results are a series of relationships based on pavement life which can be used to determine any number of "equivalencies." These equivalencies can be used to compare the destructive effects of various sizes of single and dual tires, axle loads , pavement thicknesses , speed and temperatures. The general nature of this report provides a wide range of conditions for comparison.on a relative basis.
Authors:
Terrel,R., Rimsritong,S.
Keywords:
asphalt pavement, axle, behavior, condition, damage, dual tires, equivalencies, loads, pavement, pavement damage, pavement life, pavements, research, single axle, speed, speed and temperature, state-of-the-art, temperature, tire, tire contact pressure, tires, truck, trucks, wheel load
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| Terrel,Ronald L. | WA-RD 006.1 | Resilient Behavior Of Asphalt Treated Base Course Materials 1003 | 1972 |
Abstract:
In many parts of the world, the design of flexible pavement is still based on empirical methods which have developed from engineering experience. These empirical methods cannot be extrapolated beyond their limits without full scale trials to prove their applicability. In recent years, however, the increase of traffic, both in volume and axle loads, has led to the failure of many roads previously considered well designed. For this reason, therefore, researchers realized that a closer look at the pavement materials was desirable in order to develop a rational design procedure. Due to the complexity of characterizing pavement materials, and the limitations of instrumentation, much of the reported work offered little help in changing design practice. This is, perhaps, due to many simplifying assumptions which had to be introduced in the experimental procedure as well as the interpretation of the test results. Recently, however, there has been a sharp advancement in test instrumentation and an outstanding progress in processing the experimental results. This has been reflected through many fine investigations and has increased the demand for more improvements. An asphalt pavement is a complex structure whose function is to provide a suitable surface for a highway, an airport, or other off-highway facility. The load of a vehicle or an aircraft is transmitted through the multilayered system of processed materials which have different mechanical properties. The stress distribution within this system is highly complex and to a large extent is dependent on the relative stiffnesses of the individual layers.
Authors:
Terrel,Ronald L., Awad,S.
Keywords:
asphalt, asphalt pavement, axle, base, behavior, demand, design, developed, experimental, facilities, fine, highway, improvement, loads, materials, methods, pavement, stiffness, stresses, System, traffic, volume
In many parts of the world, the design of flexible pavement is still based on empirical methods which have developed from engineering experience. These empirical methods cannot be extrapolated beyond their limits without full scale trials to prove their applicability. In recent years, however, the increase of traffic, both in volume and axle loads, has led to the failure of many roads previously considered well designed. For this reason, therefore, researchers realized that a closer look at the pavement materials was desirable in order to develop a rational design procedure. Due to the complexity of characterizing pavement materials, and the limitations of instrumentation, much of the reported work offered little help in changing design practice. This is, perhaps, due to many simplifying assumptions which had to be introduced in the experimental procedure as well as the interpretation of the test results. Recently, however, there has been a sharp advancement in test instrumentation and an outstanding progress in processing the experimental results. This has been reflected through many fine investigations and has increased the demand for more improvements. An asphalt pavement is a complex structure whose function is to provide a suitable surface for a highway, an airport, or other off-highway facility. The load of a vehicle or an aircraft is transmitted through the multilayered system of processed materials which have different mechanical properties. The stress distribution within this system is highly complex and to a large extent is dependent on the relative stiffnesses of the individual layers.
Authors:
Terrel,Ronald L., Awad,S.
Keywords:
asphalt, asphalt pavement, axle, base, behavior, demand, design, developed, experimental, facilities, fine, highway, improvement, loads, materials, methods, pavement, stiffness, stresses, System, traffic, volume
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| Krukar,M. | WA-RD 015.5 | Pavement Research At WSU Volume No. 5 - Evaluation and Analysis of Results From Experimental Rings No. 1-4 1020 | 1971 |
Abstract:
The purpose of this study was threefold: (1) Develop empirical equivalencies from all four rings, (2) develop a design method for overlays based on field deflections; and (3) evaluate the validity of data obtained from instrumentations in terms of n-layer elastic theory and then develop theoretical equivalencies.This was done. Field equivalencies were developed and they indicated that superiority of the treated base materials over the untreated. A design method was developed which could be used for predicting when an overlay was needed and what thickness was needed to withstand certain equivalent wheel loads and deflections.Using computer programs for n-layer elastic theory developed by Chevron Research Company, deflection stresses and strains were computed and compared with field data. Assumptions about the material behavior and condition were made based on laboratory data obtained from The Asphalt Institute and field knowledge, and were used to help predict the behavior of pavements. The results were encouraging and indicate that field measurements generally were comparable with elastic layer theory predictions. This will help to develop and modify existing design limits for stresses, strains and deflection for future work.Equivalencies based on theoretical deflections, stresses and strains indicate the difficulty of assigning precise values. These values also indicate the superiority of treated materials over the untreated materials.
Authors:
Krukar,M., Cook,J. C.
Keywords:
analysis, asphalt, base, base materials, behavior, computer, computer program, condition, data, design, equivalencies, evaluation, experimental, loads, materials, overlay, overlays, pavement, pavements, prediction, program, research, strains, stresses, volume, wheel load
The purpose of this study was threefold: (1) Develop empirical equivalencies from all four rings, (2) develop a design method for overlays based on field deflections; and (3) evaluate the validity of data obtained from instrumentations in terms of n-layer elastic theory and then develop theoretical equivalencies.This was done. Field equivalencies were developed and they indicated that superiority of the treated base materials over the untreated. A design method was developed which could be used for predicting when an overlay was needed and what thickness was needed to withstand certain equivalent wheel loads and deflections.Using computer programs for n-layer elastic theory developed by Chevron Research Company, deflection stresses and strains were computed and compared with field data. Assumptions about the material behavior and condition were made based on laboratory data obtained from The Asphalt Institute and field knowledge, and were used to help predict the behavior of pavements. The results were encouraging and indicate that field measurements generally were comparable with elastic layer theory predictions. This will help to develop and modify existing design limits for stresses, strains and deflection for future work.Equivalencies based on theoretical deflections, stresses and strains indicate the difficulty of assigning precise values. These values also indicate the superiority of treated materials over the untreated materials.
Authors:
Krukar,M., Cook,J. C.
Keywords:
analysis, asphalt, base, base materials, behavior, computer, computer program, condition, data, design, equivalencies, evaluation, experimental, loads, materials, overlay, overlays, pavement, pavements, prediction, program, research, strains, stresses, volume, wheel load
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| Krukar,M. | WA-RD 015.4 | Pavement Research at the WSU Test Track - Volume No. 4 Experimental Ring No 4 A Study of Untreated, Sand Asphalt, and As... | 1970 |
Abstract:
Three different kinds of base material of varying base thicknesses were tested at the Washington State University Test Track on Ring #3 during the fall of 1967 and the spring of 1968. Twelve 18-foot test sections consisting of 4.5, 7.0, 9.5 and 12 inches of untreated crushed rock surfacing top course base; 3.0, 5.0, and 7.0 and 9.0 inches of emulsion treated crushed surfacing top course base; and 0.0, 2.0, 3.5 and 5.0 inches of special non-fractured screened aggregate asphalt treated base, covered by a uniform 3.0-inch thick Class "B" asphalt concrete wearing course were tested during this period. This pavement structure was built on a clay-silt subgrade soil.Instrumentation consisted of moisture tensiometers, strain gages, pressure cells, LVDT gages and thermocouples for measuring moisture, strain, stress, dynamic deflections and temperatures. Benkleman beam readings were taken.The testing period revealed that the fall failure modes were different from the spring failures. The fall failure patter started from transverse cracks in the thin sections which developed into alligator cracking patterns. These cracks appeared after a period of cold weather and heavy rains followed by a warming period. It seems that thermal and mechanical loads were responsible for the fall failures on the thin sections. The spring failures were very rapid and sudden and were due to environmental factors which led to saturated subgrade, thus resulting in poor bearing capacity. Punching shear was the failure mode. The thickest sections survived without cracks but developed severe rutting. Examination revealed that these ruts extended into the subgrade and that fatigue cracking was developing on the bottom of the bases.Comparison of the results with those obtained from Ring# 2, which was similar in base materials and thickness, show that they were similar in many respects. This indicates that the test track is capable of replicating results and is a reliable research instrument.Equivalencies were developed for the different materials. On this basis the special aggregate asphalt treated base was superior to the emulsion treated and untreated crushed rock bases in that order. These results were comparable to those obtained from test Ring #2.Maximum values for static and dynamic deflections, strains and stresses for different times and temperatures were developed. The lateral position of the dual tires with respect to the gage severely affected the strain, stresses and deflection values. Temperature also caused variations in the measurements. Spring instrument readings for static and dynamic deflections, strain and stress show increased values by as much as 2 to 4 times of those obtained in the fall. Spring subgrade conditions probably are responsible for these differences.Ring #3 series operational time was twice that of Ring #2 and sustained four times the wheel load applications. Construction and testing environmental conditions were superior to those for Ring #2 and hence contributed to the longer test period. This points out that environmental factors are very important in pavement life.
Authors:
Krukar,M.
Keywords:
aggregate, Alligator Cracking, applications, asphalt, asphalt concrete, base, base materials, bearing capacity, Benkleman beam, concrete, condition, construction, cracking, dual tires, environmental, experimental, fatigue, fatigue cracking, loads, materials, pavement, pavement life, pressure, pressure cell, rain, research, research at the WSU, strains, stresses, subgrade, temperature, test track, tire, tires, volume, Volume No.4, Washington, Washington state, wheel load
Three different kinds of base material of varying base thicknesses were tested at the Washington State University Test Track on Ring #3 during the fall of 1967 and the spring of 1968. Twelve 18-foot test sections consisting of 4.5, 7.0, 9.5 and 12 inches of untreated crushed rock surfacing top course base; 3.0, 5.0, and 7.0 and 9.0 inches of emulsion treated crushed surfacing top course base; and 0.0, 2.0, 3.5 and 5.0 inches of special non-fractured screened aggregate asphalt treated base, covered by a uniform 3.0-inch thick Class "B" asphalt concrete wearing course were tested during this period. This pavement structure was built on a clay-silt subgrade soil.Instrumentation consisted of moisture tensiometers, strain gages, pressure cells, LVDT gages and thermocouples for measuring moisture, strain, stress, dynamic deflections and temperatures. Benkleman beam readings were taken.The testing period revealed that the fall failure modes were different from the spring failures. The fall failure patter started from transverse cracks in the thin sections which developed into alligator cracking patterns. These cracks appeared after a period of cold weather and heavy rains followed by a warming period. It seems that thermal and mechanical loads were responsible for the fall failures on the thin sections. The spring failures were very rapid and sudden and were due to environmental factors which led to saturated subgrade, thus resulting in poor bearing capacity. Punching shear was the failure mode. The thickest sections survived without cracks but developed severe rutting. Examination revealed that these ruts extended into the subgrade and that fatigue cracking was developing on the bottom of the bases.Comparison of the results with those obtained from Ring# 2, which was similar in base materials and thickness, show that they were similar in many respects. This indicates that the test track is capable of replicating results and is a reliable research instrument.Equivalencies were developed for the different materials. On this basis the special aggregate asphalt treated base was superior to the emulsion treated and untreated crushed rock bases in that order. These results were comparable to those obtained from test Ring #2.Maximum values for static and dynamic deflections, strains and stresses for different times and temperatures were developed. The lateral position of the dual tires with respect to the gage severely affected the strain, stresses and deflection values. Temperature also caused variations in the measurements. Spring instrument readings for static and dynamic deflections, strain and stress show increased values by as much as 2 to 4 times of those obtained in the fall. Spring subgrade conditions probably are responsible for these differences.Ring #3 series operational time was twice that of Ring #2 and sustained four times the wheel load applications. Construction and testing environmental conditions were superior to those for Ring #2 and hence contributed to the longer test period. This points out that environmental factors are very important in pavement life.
Authors:
Krukar,M.
Keywords:
aggregate, Alligator Cracking, applications, asphalt, asphalt concrete, base, base materials, bearing capacity, Benkleman beam, concrete, condition, construction, cracking, dual tires, environmental, experimental, fatigue, fatigue cracking, loads, materials, pavement, pavement life, pressure, pressure cell, rain, research, research at the WSU, strains, stresses, subgrade, temperature, test track, tire, tires, volume, Volume No.4, Washington, Washington state, wheel load
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| Krukar,M. | WA-RD 015.3 | Pavement Research at the WSU Test Track, Volume No. 3 Experimental Ring No. 3: Study of Untreated Emulsion Treated and A... | 1969 |
Abstract:
Three different kinds of base material of varying base thicknesses were tested at the Washington State University Test Track on Ring #3 during the fall of 1967 and the spring of 1968. Twelve 18-foot test sections consisting of 4.5, 7.0, 9.5 and 12 inches of untreated crushed rock surfacing top course base; 3.0, 5.0, and 7.0 and 9.0 inches of emulsion treated crushed surfacing top course base; and 0.0, 2.0, 3.5 and 5.0 inches of special non-fractured screened aggregate asphalt treated base, covered by a uniform 3.0-inch thick Class "B" asphalt concrete wearing course were tested during this period. This pavement structure was built on a clay-silt subgrade soil.Instrumentation consisted of moisture tensiometers, strain gages, pressure cells, LVDT gages and thermocouples for measuring moisture, strain, stress, dynamic deflections and temperatures. Benkleman beam readings were taken.The testing period revealed that the fall failure modes were different from the spring failures. The fall failure patter started from transverse cracks in the thin sections which developed into alligator cracking patterns. These cracks appeared after a period of cold weather and heavy rains followed by a warming period. It seems that thermal and mechanical loads were responsible for the fall failures on the thin sections. The spring failures were very rapid and sudden and were due to environmental factors which led to saturated subgrade, thus resulting in poor bearing capacity. Punching shear was the failure mode. The thickest sections survived without cracks but developed severe rutting. Examination revealed that these ruts extended into the subgrade and that fatigue cracking was developing on the bottom of the bases.Comparison of the results with those obtained from Ring# 2, which was similar in base materials and thickness, show that they were similar in many respects. This indicates that the test track is capable of replicating results and is a reliable research instrument.Equivalencies were developed for the different materials. On this basis the special aggregate asphalt treated base was superior to the emulsion treated and untreated crushed rock bases in that order. These results were comparable to those obtained from test Ring #2.Maximum values for static and dynamic deflections, strains and stresses for different times and temperatures were developed. The lateral position of the dual tires with respect to the gage severely affected the strain, stresses and deflection values. Temperature also caused variations in the measurements. Spring instrument readings for static and dynamic deflections, strain and stress show increased values by as much as 2 to 4 times of those obtained in the fall. Spring subgrade conditions probably are responsible for these differences.Ring #3 series operational time was twice that of Ring #2 and sustained four times the wheel load applications. Construction and testing environmental conditions were superior to those for Ring #2 and hence contributed to the longer test period. This points out that environmental factors are very important in pavement life.
Authors:
Krukar,M., Cook,J. C.
Keywords:
aggregate, Alligator Cracking, applications, asphalt, asphalt concrete, base, base materials, bearing capacity, Benkleman beam, concrete, condition, construction, cracking, dual tires, environmental, equivalencies, experimental, fatigue, fatigue cracking, loads, materials, pavement, pavement life, pressure, pressure cell, rain, research, research at the WSU, soil, strains, stresses, subgrade, temperature, test track, tire, tires, volume, Washington, Washington state, wheel load
Three different kinds of base material of varying base thicknesses were tested at the Washington State University Test Track on Ring #3 during the fall of 1967 and the spring of 1968. Twelve 18-foot test sections consisting of 4.5, 7.0, 9.5 and 12 inches of untreated crushed rock surfacing top course base; 3.0, 5.0, and 7.0 and 9.0 inches of emulsion treated crushed surfacing top course base; and 0.0, 2.0, 3.5 and 5.0 inches of special non-fractured screened aggregate asphalt treated base, covered by a uniform 3.0-inch thick Class "B" asphalt concrete wearing course were tested during this period. This pavement structure was built on a clay-silt subgrade soil.Instrumentation consisted of moisture tensiometers, strain gages, pressure cells, LVDT gages and thermocouples for measuring moisture, strain, stress, dynamic deflections and temperatures. Benkleman beam readings were taken.The testing period revealed that the fall failure modes were different from the spring failures. The fall failure patter started from transverse cracks in the thin sections which developed into alligator cracking patterns. These cracks appeared after a period of cold weather and heavy rains followed by a warming period. It seems that thermal and mechanical loads were responsible for the fall failures on the thin sections. The spring failures were very rapid and sudden and were due to environmental factors which led to saturated subgrade, thus resulting in poor bearing capacity. Punching shear was the failure mode. The thickest sections survived without cracks but developed severe rutting. Examination revealed that these ruts extended into the subgrade and that fatigue cracking was developing on the bottom of the bases.Comparison of the results with those obtained from Ring# 2, which was similar in base materials and thickness, show that they were similar in many respects. This indicates that the test track is capable of replicating results and is a reliable research instrument.Equivalencies were developed for the different materials. On this basis the special aggregate asphalt treated base was superior to the emulsion treated and untreated crushed rock bases in that order. These results were comparable to those obtained from test Ring #2.Maximum values for static and dynamic deflections, strains and stresses for different times and temperatures were developed. The lateral position of the dual tires with respect to the gage severely affected the strain, stresses and deflection values. Temperature also caused variations in the measurements. Spring instrument readings for static and dynamic deflections, strain and stress show increased values by as much as 2 to 4 times of those obtained in the fall. Spring subgrade conditions probably are responsible for these differences.Ring #3 series operational time was twice that of Ring #2 and sustained four times the wheel load applications. Construction and testing environmental conditions were superior to those for Ring #2 and hence contributed to the longer test period. This points out that environmental factors are very important in pavement life.
Authors:
Krukar,M., Cook,J. C.
Keywords:
aggregate, Alligator Cracking, applications, asphalt, asphalt concrete, base, base materials, bearing capacity, Benkleman beam, concrete, condition, construction, cracking, dual tires, environmental, equivalencies, experimental, fatigue, fatigue cracking, loads, materials, pavement, pavement life, pressure, pressure cell, rain, research, research at the WSU, soil, strains, stresses, subgrade, temperature, test track, tire, tires, volume, Washington, Washington state, wheel load
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