Using Pseudostrain Damage Theory to Characterize Reinforcing Benefits of Geosynthetic Materials in Asphalt Concrete Overlays

2003 ◽  
Vol 1849 (1) ◽  
pp. 202-211 ◽  
Author(s):  
Gregory S. Cleveland ◽  
Robert L. Lytton ◽  
Joe W. Button
Keyword(s):  
Relative Effectiveness ◽  
Relaxation Modulus ◽  
Reflective Cracking ◽  
Concrete Overlays ◽  
Complex Interactions ◽  
Local Experience ◽  
Damage Process ◽  
Maintenance Techniques ◽  
Loading And Unloading ◽  
Better Than

Reflective cracking is one of the more serious distresses associated with existing hot-mix asphalt (HMA) or portland concrete cement pavements overlaid with a thin bituminous layer. Preventive maintenance techniques have included incorporating geosynthetic materials (defined here as grids, fabrics, or composites) into the pavement structure. These materials have exhibited varying degrees of success, and their use within a particular agency has been based primarily on local experience or a willingness to try a product that appears to have merit. A methodology is described that was used to compare the relative effectiveness of six commercially available geosynthetic materials in reducing the severity or delaying the appearance of reflective cracking in HMA overlay. Each geosynthetic material was incorporated into compacted HMA specimens and tested to failure. Engineering fracture mechanics and pseudostrain energy concepts based on the elastic-viscoelastic correspondence principle were used and demonstrated to be appropriate and efficient in characterizing the fatigue damage process. By considering the effects of the geosynthetic products on the loading and unloading paths of the HMA specimens, a new concept was developed and termed the reinforcing factor, R. The use of this value allows the industry to characterize the relative reinforcing benefits of geosynthetic materials in reducing reflective cracking in HMA overlays. A crack speed index was then derived to summarize the complex interactions of the material properties. In general, grids and composites performed better than fabrics, which in turn performed better than a thin tacked surface as compared with unreinforced specimens. Design equations were developed between the fracture properties of the geosyntheticmixture system and the relaxation modulus properties of the HMA, which can be used in forward-calculating design methods to predict the rate of crack growth and support the design of an HMA overlay to resist reflective cracking. To calibrate the design equations, comparative field test pavements were constructed in three regions of Texas (Amarillo, Waco, and McAllen) using each geosynthetic material. These pavements will be monitored over the next 4 years.

scholarly journals Study on Relaxation Damage Properties of High Viscosity Asphalt Sand under Uniaxial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yazhen Sun ◽  
Zhangyi Gu ◽  
Jinchang Wang ◽  
Chenze Fang ◽  
Xuezhong Yuan
Keyword(s):  
Uniaxial Compression ◽  
Viscoelastic Model ◽  
Relaxation Modulus ◽  
Maxwell Model ◽  
High Viscosity ◽  
Secondary Development ◽  
Compression Tests ◽  
Crack Control ◽  
Different Temperatures ◽  
Damage Process

Laboratory investigations of relaxation damage properties of high viscosity asphalt sand (HVAS) by uniaxial compression tests and modified generalized Maxwell model (GMM) to simulate viscoelastic characteristics coupling damage were carried out. A series of uniaxial compression relaxation tests were performed on HVAS specimens at different temperatures, loading rates, and constant levels of input strain. The results of the tests show that the peak point of relaxation modulus is highly influenced by the loading rate in the first half of an L-shaped curve, while the relaxation modulus is almost constant in the second half of the curve. It is suggested that for the HVAS relaxation tests, the temperature should be no less than −15°C. The GMM is used to determine the viscoelastic responses, the Weibull distribution function is used to characterize the damage of the HVAS and its evolution, and the modified GMM is a coupling of the two models. In this paper, the modified GMM is implemented through a secondary development with the USDFLD subroutine to analyze the relaxation damage process and improve the linear viscoelastic model in ABAQUS. Results show that the numerical method of coupling damage provides a better approximation of the test curve over almost the whole range. The results also show that the USDFLD subroutine can effectively predict the relaxation damage process of HVAS and can provide a theoretical support for crack control of asphalt pavements.

Effectiveness of Various Omission Training Procedures as a Function of Reinforcement History

1982 ◽  
Vol 50 (3) ◽  
pp. 927-941 ◽  
Author(s):  
M. Patricia Brockman ◽  
J. Michael Leibowitz
Keyword(s):  
Lever Press ◽  
Response Rate ◽  
Relative Effectiveness ◽  
Time Dependent ◽  
Omission Training ◽  
Treatment Combination ◽  
Schedule Of Reinforcement ◽  
Reinforcement History ◽  
Rate Of Response ◽  
Better Than

This experiment analyzed the relative effectiveness of three different omission-training conditions (OT 5 sec., OT 20 sec., and gradual OT with a time-dependent criterion) in reducing a lever-press response following three different histories of reinforcement. 36 children between the ages of 4½ and 11 yr. were initially trained to press a lever according to a VR 35 schedule of reinforcement for 10 min. (Period I). Following acquisition, subjects were exposed to one of three conditions: DRL 10 sec. followed by OT, maintenance of VR followed by OT, or OT alone (Periods II and III). Over-all results indicated a significant reduction in response rate with the introduction or continuation of the various OT schedules. The DRL-OT treatment combination was significantly more effective in reducing response rate than the introduction of the same OT schedules following the lengthened VR history, but the use of the DRL-OT treatment combination was not significantly better than the OT condition of the same duration. OT was equally effective following both short (10 min.) and long (25 min.) VR histories. No significant differences were found in the relative effectiveness of the three types of OT schedules. These findings, however, may be related to the use of a time-dependent gradual OT schedule, as opposed to one in which the temporal values are increased as a function of the subjects' rate of response.

scholarly journals New Sources of Temperature-Sensitive Resistance to Wheat streak mosaic virus in Wheat

Plant Disease ◽  
2013 ◽  
Vol 97 (8) ◽  
pp. 1051-1056 ◽  
Author(s):  
Dallas L. Seifers ◽  
Steve Haber ◽  
T. J. Martin ◽  
Guorong Zhang
Keyword(s):  
Mosaic Virus ◽  
Relative Effectiveness ◽  
Wheat Streak Mosaic Virus ◽  
Temperature Sensitive ◽  
Yield Losses ◽  
Sources Of Resistance ◽  
Small Grains ◽  
Virus Isolates ◽  
Better Than

Expressing temperature-sensitive resistance (TSR) protects wheat against yield losses from infection with Wheat streak mosaic virus (WSMV). In examining how 2,429 wheat accessions from the National Small Grains Collection responded to inoculation with the Sid81 isolate of WSMV, 20 candidate TSR sources were discovered. To differentiate their relative effectiveness, accession responses over 21 days to inoculation with GH95, Sid81, and PV57 virus isolates in regimes of 18 and 20°C were observed. At 18°C, all 20 candidate TSR sources were uniformly or nearly uniformly asymptomatic 21 days after inoculation with the PV57 isolate, resistance indistinguishable from resistant checks KS96HW10-3 and RonL. By contrast, the Sid81 isolate induced symptoms in low but significant proportions of plants of two candidates, and the GH95 isolate in high proportions for four candidates and low but significant proportions for two others. In the more stringent 20°C regime, the uniform or near-uniform induction of symptoms in response to inoculation with GH95 failed to differentiate among the 20 candidate TSR sources and two resistant checks, while PV57 and Sid81 identified several candidates that performed similarly to KS96HW10-3 and significantly better than RonL. By identifying new sources of resistance, this study contributes to the control of WSMV.

Research on Flexural Behavior of Coarse Recycled Aggregate-Filled Plain Concrete Beam

2011 ◽  
Vol 250-253 ◽  
pp. 379-382
Author(s):  
Jing Li ◽  
Lin Fu Wang ◽  
Juan Li ◽  
Xian Feng Qu ◽  
Lin Jang
Keyword(s):  
Concrete Beam ◽  
Concrete Beams ◽  
Plain Concrete ◽  
Recycled Aggregate ◽  
Flexural Behavior ◽  
Recycled Aggregates ◽  
Ordinary Concrete ◽  
Finite Element Software ◽  
Damage Process ◽  
Better Than

In order to study the flexural behavior of coarse recycled aggregate-filled plain concrete beams, two beams were made. The experiment of simply supported beam under concentrated loads is performed, which makes us get the ultimate flexural capacity, midspan deflection and the development of cracks of each beam, and the numerical simulation of the damage process of beams is also carried out using finite element software. The results indicated that the tension property of coarse recycled aggregate-filled plain concrete beam is better than ordinary concrete beam, and some failure forms of bending is similar; the strength of recycled aggregates greatly influences flexural behavior of coarse recycled aggregate-filled plain concrete beam.

Framework for Selecting Effective Preventive Maintenance Treatments for Flexible Pavements

1997 ◽  
Vol 1597 (1) ◽  
pp. 1-10 ◽  
Author(s):  
R. Gary Hicks ◽  
Kimberly Dunn ◽  
James S. Moulthrop
Keyword(s):  
Cost Effectiveness ◽  
Preventive Maintenance ◽  
Fatigue Cracking ◽  
Asphalt Pavements ◽  
Maintenance Strategies ◽  
Concrete Overlays ◽  
Traffic Level ◽  
Maintenance Techniques ◽  
The Right ◽  
The Cost

Preventive maintenance techniques are considered useful in extending the life of a pavement if applied at the right time. Discussed here is a framework for a process that can be used to select the proper maintenance strategies for different distress types in asphalt pavements, depending on traffic level and environment. Maintenance treatments addressed include only crack seals, fog seals, slurry seals, microsurfacings, chip seals, thin asphalt concrete overlays, and other thin surface treatments. Types of distress considered include roughness, rutting, fatigue cracking, longitudinal cracking, raveling, weathering, and bleeding. Decision trees, based on the authors' experiences, are presented to illustrate the process in selecting appropriate maintenance treatments. A framework for evaluating the cost-effectiveness of the various maintenance treatments is presented. Existing methods for evaluating cost-effectiveness of maintenance are discussed together with their strengths and weaknesses. An example of cost-effectiveness for different maintenance treatments is also briefly presented.

Birth Order and Relative Effectiveness of Social and Nonsocial Reinforcers

1973 ◽  
Vol 36 (1) ◽  
pp. 35-38 ◽  
Author(s):  
George H. Hines
Keyword(s):  
Birth Order ◽  
Probability Learning ◽  
Relative Effectiveness ◽  
Learning Task ◽  
Social Reinforcement ◽  
Probability Learning Task ◽  
Social Reinforcers ◽  
Social Dependence ◽  
The Relationship ◽  
Better Than

Undergraduates were administered a probability learning task to determine the relationship between birth order and the relative effectiveness of social and nonsocial reinforcers. Firstborn individuals performed better than later-born Ss under social reinforcement conditions. Over-all, social reinforcers enhanced performance more than nonsocial reinforcers. Findings were interpreted as supporting greater social dependence of firstborns.

STUDY OF BLAST DNA MATCHING TOOLKITS

2004 ◽  
Vol 04 (03) ◽  
pp. 341-359
Author(s):  
E. Y.-K. NG ◽  
L. L. TAY
Keyword(s):  
Nucleic Acid ◽  
Search Strategy ◽  
Relative Effectiveness ◽  
Protein Sequences ◽  
Computation Time ◽  
Word Size ◽  
Sequence Search ◽  
Exchange Information ◽  
The Web ◽  
Better Than

The beginning of bioinformatics saw the development of algorithms that enabled the storage of nucleic acid and protein sequences in the form of annotated databases in a manner that would allow researchers to exchange information about gene and protein sequences easily and quickly. Databases are growing extremely fast, hence it is essential to use the current databases, which are easily available on the Web. This tutorial deals with the concept of DNA matching by using BLAST programs such as BLASTN and MEGABLAST to perform similarity sequence search and to evaluate their relative effectiveness. Interpretation of the BLAST results is done. Comparisons between the two algorithms are included based on varying parameters such as word sizes, query sequences length and gap X drop-off values, etc. It is found that as the word size increases, the computation time for both BLASTN and MEGABLAST algorithms decreases. BLASTN is more sensitive than MEGABLAST since it uses a shorter default word size of 11 as compared to MEGABLAST, which uses a default word size of 28. The search strategy offers a tradeoff between speed and sensitivity. As for BLAST 2 Sequences, MEGABLAST could perform better than BLASTN only for large word sizes greater than or equal to 16 and for longer sequences.

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