A közlekedésépítési szakterület mérnöki és tudományos folyóirata. ISSN: 2064-0919
15. szám
9. évfolyam
2021 július
15
Bejegyzés

Nemzetközi szemle: Március

Szál adalékok aszfalt keverékekben
Fiber Additives in Asphalt Mixtures
Szerző(k):
Rebecca S. McDaniel, Purdue University, USA

Terjedelem: 67 oldal

The report documents the current state of the practice regarding the use of fiber additives in asphalt mixtures. It outlines the many types of fibers that have been used, their properties and how they are tested, mix design tests for fiber mixes, the types of applications in which fibers have been used, and lab and performance of fiber mixes. This synthesis can aid state asphalt engineers and researchers on the use of fibers. A literature review and detailed survey responses from 48 of 50 state agencies, yielding a response rate of 96%, are provided. Also, six case examples offer more detailed information on the use of fibers.

 

 

Felületi bevonatok viselkedése helyi és minimálisan feldolgozott adalékanyagokkal kis forgalmú utak állagmegóvásához
Performance of chip seals using local and minimally processed aggregates for preservation of low traffic volume roadways

Szerző(k):
Scott Shuler,
International Journal of Civil Engineering and Construction Science 2014; 1(1): 9-17

Terjedelem: 9 oldal

Many roadways in the world are in locations without high quality aggregates. Therefore, high quality aggregates must be transported to these locations when pavement construction or preservation activities are needed. This transportation increases the cost of pavement construction and preservation in these areas of the state. Increased costs often mean that timely pavement preservation activities are postponed. This postponement leads to deterioration of the infrastructure and, ultimately, increased costs. In addition, many of the pavements requiring preservation are low volume facilities. These low volume roads may not require the very high quality aggregates necessary on higher traffic volume facilities. Therefore, if more economical local aggregates could be demonstrated to perform acceptably, pavement preservation could be accomplished within budget at appropriate intervals. This would save costs in both the short and the long terms. Chip seals are used extensively by many road authorities for extending pavement life. Chip seals utilizing locally available and minimally processed aggregates should be a more economical pavement preservation treatment than chip seals constructed with higher quality, more expensive aggregates. Although chip seals constructed on high traffic roadways require high quality, crushed and approximately single-sized aggregates, low traffic roadways may not demand such materials to perform acceptably. Therefore, an experiment was designed to demonstrate the performance of chip seals constructed using two different aggregates on two low volume state highways. The control aggregate was the material routinely used for chip seal construction and the second aggregate was a material that did not meet specifications for gradation or fracture. Construction of the test sections was conducted by agency maintenance forces in 2009. Condition surveys were performed to determine pre-chip seal condition and then periodically for the next three years to track performance. Two five hundred foot long evaluation sections were located within each test pavement for each aggregate resulting in two thousand lane-feet of test area for each roadway. Results of the experiment after three years of service indicate no significant difference in performance between the aggregates. Distress in both pavements is limited to a return of transverse and longitudinal cracks, but with low percentages of chip loss. Some limited areas of the pavements also contain longitudinal flushing streaks where distributor nozzles may not have been adjusted correctly and higher quantities of asphalt were applied. Based on the results of this research it appears that locally available, minimally processed aggregates can be successfully applied as chip seal aggregate on low volume roadways. The report includes a recommended chip seal design procedure, aggregate and construction specification for low traffic volume roadways.

 

 

Az aszfalt pályaszerkezetek előnyei
Eurobitume, EAPA

Terjedelem: 37 oldal
Az aszfalt pályaszerkezetek előnyeit átfogóan bemutató anyag tartalma: Teljes élettartam alatti költségek, Pályaszerkezet-tervezés, Aszfaltkeverékek közutak fenntartásához, Aszfaltanyagok speciális alkalmazásai, Pályaszerkezeti anyagok újrafelhasználása európai távlatban, Kényelem és biztonság, Környezet.

 

 

Projekt menedzsment stratégiák komplex projektekhez

Project Management Strategies for Complex Projects

Szerző(k):
Jennifer S., Shane, Douglas D.,
Gransberg Iowa State University, USA
Kelly C. Strong Colorado State University, USA

Terjedelem: 105 oldal

Infrastructure needs within the United States have changed from building new facilities to replacing, expanding, or renewing existing facilities. The project management issues involved with infrastructure renewal are different from the issues for new construction. Correspondingly, new project management approaches must be integrated into mainstream practice for all sizes and types of projects to accelerate project delivery, reduce project costs, and minimize project disputes. The difficulties of renewal project complexity have been exacerbated by years of underfunded maintenance and replacement programs. As a result many renewal projects have become even more challenging because of the need to avert major traffic disruptions and in some cases infrastructure failures. Project complexity is introduced by many factors: project types, engineering complexity, size, modality, jurisdictional control, financing approach, contract type, and delivery method. Each project calls for a distinct project management style and approach. The five-dimensional approach for project management of complex projects is not a new subject. However, it is extensively developed, outlined, and clearly mapped for acceptance and integration within the R10 project. The five dimensions are cost, schedule, technical, context, and finance. Successful use of the approach involves five methods which are unique
for each project: Define project success factors by each dimension, as required; Assemble project team; Select project arrangements; Prepare early cost model and finance plan; and Develop project action plans. Although a number of additional research ideas have been identified during the project, the most pressing next steps are the implementation of the material on actual complex projects and the integration of the philosophy and tools within agency existing program and project management policies and procedures through demonstration projects, training, and change-management assistance.

Projekt menedzsment stratégiák útmutatója komplex projektekhez
Guide to Project Management Strategies for Complex Projects

Szerző(k):
Jennifer Shane, Kelly Strong, Douglas Gransberg, and David Jeong
Iowa State University USA

Terjedelem: 187 oldal

The research scope of SHRP 2 Renewal Project R10, Project Management Strategies for Complex Projects, involved the development of this guide, as well as a companion report, surveys, case studies, training, and technical tools, to address the challenges of managing modern infrastructure projects that are considerably more complex than traditional projects. These products facilitate the use of effective strategies in managing complex projects of any size and type. Acceptance and use of this guidance should improve the state of the practice by focusing on practical tools and techniques that are designed to be immediately beneficial to transportation professionals.

Projekt menedzsment stratégiák komplex projektekhez esettanulmányok
Project Management Strategies for Complex Projects Case Study Report

Szerző(k):
Jennifer Shane, Kelly Strong, Douglas Gransberg, Junyong Ahn, John Owens
Iowa State University, USA
Debra Brisk, Kimley-Horn and Associates, St. Paul, Minnesota, USA
James Hunt, PBS&J Corporation, Norman Oklahoma, USA
Dr. Carla Lopez del Puerto, Colorado State University, USA
Sidney Scott III, PE, Trauner Consulting Services, Inc., Philadelphia, Pennsylvania, USA
Dr. Ali Touran, PE, Northeastern University, Boston, Massachusetts, USA
Dr. Susan Tighe, PEng, University of Waterloo, Ontario, Canada
Dr. Neil Allan, University of Bath, United Kingdom
Eric Scheepbouwer, University of Canterbury, New Zealand

Terjedelem: 333 oldal

Successful management of complex transportation projects requires a fundamental change in how projects are planned, developed, designed, procured, and constructed. The Strategic Highway Research Program 2 (SHRP 2) Renewal Research Project R10, Project Management Strategies for Complex Projects, is investigating strategies, tools, techniques, and methods that can be effectively used for complex-project management. The following report for Project R10 describes the results of Task 4 (Develop Case Studies) and a portion of Task 5 (Analyze Case Studies). Fifteen projects in the United States and three international projects were investigated through in-depth case studies to identify tools that aid project managers of complex projects to successfully deliver projects. These 18 projects represent a number of different project types, locations, project sizes, and phases of project development. The tools identified from these projects fall into two areas: project development and project execution.

Hidak 100 év feletti élettartammal: innovatív rendszerek, alrendszerek és összetevők
Bridges for Service Life Beyond 100 Years: Innovative Systems, Subsystems, and Components

Szerző(k):
Atorod Azizinamini, Florida International University, USA
Edward H. Power, HDR Engineering, Inc. , USA
Glenn F. Myers, Atkins North America Inc. , USA
H. Celik Ozyildirim, Virginia Center for Transportation Innovation and Research, USA

Terjedelem: 259 oldal

The design of bridges for service life is gaining importance. This report, Bridges for Service
Life Beyond 100 Years: Innovative Systems, Subsystems, and Components, discusses the main product of SHRP 2 Project R19A within the Renewal area: the Design Guide for Bridges for Service Life (the Guide). Both are available at the Transportation Research Board website. The main objective of the Guide is to provide information and guidance and to define procedures to systematically approach service life and durability for both new and existing bridges. The Guide equips users with knowledge to develop specific solutions for a bridge under consideration in a systematic manner by using a standard framework with specifics being different. In some respects, the R19A Guide may be considered a foundational reference that will be built on, expanded, modified, and progressively embraced differently at project and program levels by the bridge and structures community. The future path of development and mainstream acceptance and implementation may be similar to that of load resistance factor design (LRFD) specifications. Results from the knowledge gained through the project are communicated throughout the report in ways that bridge professionals can implement in practice. Providing safety for the public by having adequate strength is the cornerstone of the framework used by engineers for bridge design. This approach has not been restricted to bridges; for example, it has also been the framework used in various building codes. Significant changes to our contemporary bridge design practice have also been mainly related to strength issues. The transition to LRFD is a well-known recent example. A review of bridges that have lasted more than 100 years provides valuable lessons related to achieving long service lives. The R19A Report details the steps undertaken in the development of the Guide. The report also provides results from extensive individual research efforts that have led to new concepts that can mitigate factors historically limiting the service life of bridges. The report highlights the research approach, topics, and challenges in developing the Guide, as well as the literature searches that were conducted and identifies Phase 1 and Phase 2 tasks within the project. The report also provides information on a related project, R19B. Practical approaches to using the Guide, along with future development of the Guide, are also presented in the report.

Hidak 100 év feletti élettartammal: működési határállapot tervezés
Bridges for Service Life Beyond 100 Years: Service Limit State Design

Szerző(k):
Modjeski and Masters, Inc., University of Nebraska, University of Delaware, NCS Consultants, LLC, USA

Terjedelem: 521 oldal

The topic of limit state design, also known as load resistance factor design (LRFD), within the
United States has been under development and implementation for more than 25 years. The benefits of this design platform are now well understood by the bridge and structures community as well as by transportation decision makers. Generally, it has been assumed that maintenance activities will be sufficient to prevent significant loss of the strength and stiffness that would result in unsatisfactory service level performance. It has been recognized that advancements and further maturity of the LRFD platform need to focus on quantification and calibrations of the SLSs. Although previous work has been published in this area, the R19B study serves as a foundational reference to partially fill knowledge gaps and, perhaps more importantly, for direct application and reference for future study in this emerging technical area of design. This report, Bridges for Service Life Beyond 100 Years: Service Limit State Design, describes research, outcomes, and products on the basis of the R19B project objectives. The objectives were to develop design and detailing guidance and calibrated service limit states (SLSs) to provide 100-year bridge life and to develop a framework for further development of calibrated SLSs. The products of this study are expected to be directly usable by the American
Association of State Highway and Transportation Officials (AASHTO) and departments of transportation (DOTs) and include: Provisions needed to implement SLSs and the associated load and resistance factors necessary to produce calibrated bridge components and systems expected to have a predictable service life; Detailed design and detailing provisions required to design and construct the calibrated component or system; Databases used in the calibration, as well as instructions for a calibration spreadsheet, for use by DOTs to track and adjust service-based reliability with time. Consideration of SLSs requires different input data from the previously calibrated Strength Limit State I (also known as “ultimate or strength limit states,” or ULSs). In ULSs, the limit state function is defined by resistance, which is considered constant in time, and loads. For SLSs, a different approach is needed because: Exceeding a service limit state does not lead to a clear, immediate loss of functionality; Acceptable performance can be subjective (full life-cycle analysis is required); Resistance and load effects can be and often are correlated; Load must be considered to be a function of time, described by magnitude and frequency of occurrence; Resistance may be strongly affected by quality of workmanship, operation procedures, and maintenance; Resistance is subject to changes in time, mostly but not only by deterioration; Resistance can depend on geographical location (e.g., climate, exposure to industrial pollution, or deicing agents).

Tervezési útmutató hidak élettartam tervezéséhez
Design Guide for Bridges for Service Life

Szerző(k):
Atorod Azizinamini, Florida International University, USA
Edward H. Power, HDR Engineering, Inc. , USA
Glenn F. Myers, Atkins North America Inc. , USA
H. Celik Ozyildirim, Virginia Center for Transportation Innovation and Research, USA
Eric Kline, KTA-Tator, Inc. , USA
David W. Whitmore, Vector Corrosion Technologies Ltd. , USA
Dennis R. Mertz, University of Delaware, USA

Terjedelem: 628 oldal

Compared with traditional approaches, which are based solely on strength considerations, this guide advances an emerging approach to bridge design, rehabilitation, and preservation that is based on service life considerations. The main objective of the Guide is to provide information and guidance and to define procedures to systematically approach service life and durability for both new and existing bridges. The Guide equips users with knowledge to develop specific solutions for a bridge under consideration in a systematic manner by using a standard framework. In some respects, the R19A Guide may be considered a foundational reference that will be built on, expanded, modified, and progressively embraced at different project and program levels by the bridge and structures community. The future path of development and mainstream acceptance and implementation may be similar to that of load resistance factor design (LRFD) specifications. Providing safety for the public by having adequate strength is the cornerstone of the framework used by engineers for bridge design. This approach has not been restricted to bridges; for example, it has also been the framework used in various building codes. Significant changes to our contemporary bridge design practice have also been mainly related to strength issues. The transition to LRFD is a well-known recent example. A review of bridges that have lasted more than 100 years provides valuable lessons related to achieving long service lives. These bridges – which have proved to be maintainable and well maintained over their lives and adaptable to functional changes – were all originally overdesigned. As limited resources demand enhancing the service life of existing and new bridges, the design for service life is gaining more importance. The cost of addressing service life issues at the design stage is significantly lower than taking maintenance and preservation actions while the bridge is in service. In general, design for service life is approached by using individual strategies, each capable of enhancing the service life of a particular bridge element that historically has experienced unsatisfactory performance. The R19A Guide addresses service life in a systematic manner by using a framework that is general and applicable for all bridges, while having specifics that differ from one bridge to another. These differences reflect that design for service life is a context-sensitive problem-solving method that necessarily considers local experiences, practice, and owner preferences. The Guide includes both well-proven and new concepts and approaches capable of enhancing the service life of bridges. The Guide’s objective is achieved through 11 chapters, each devoted to certain parts of a bridge or aspects of the service life design process.


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