Author: Cenek, P D Opus International Consultants Sutherland, A J Opus International Consultants McIver, I R GREENBeing Consulting Engineers | Size: 3.15 MB | Format:PDF | Quality:Original preprint | Publisher: New Zealand Transport Agency | Year: 2012 | pages: 79 | ISBN: 978-0-478-39444-3
There is an increasing requirement to control and manage ground vibrations generated by road construction and maintenance activities through project specific construction management plans. The objective is to minimise any potential adverse effects. The ability to reliably estimate vibration levels of specific construction activities at the project planning stage and to assess their likely effect on structures and their occupants is therefore required. Typical vibration characteristics for various activities, including site preparation, dynamic compaction and piling were measured for representative equipment and soil types to obtain baseline values for use in preconstruction assessments and to enable validation of available prediction methods. A review of international standards was also undertaken leading to two proposed criteria against which predicted vibrations can be assessed for damage and human perception. The possible application of data acquired from commonly used geotechnical methods, notably scala penetrometer for estimating soil attenuation and falling weight deflectometer to generate site-specific predictor curves for impact-related construction activity, was additionally investigated. This led to the recommendation of three methods, which make use of readily available data, for estimating vibration levels from construction activity at any specified distance from the vibration source.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Developing a Mixture Design Specification for Flexible Base Construction
Author: Epps, Jon Sebesta, Stephen Sahin, Hakan Button, Joe Luo, Rong Lytton, Robert | Size: 2.18 MB | Format:PDF | Quality:Original preprint | Publisher: Texas Transportation Institute | Year: 2012 | pages: 172
In the Texas Department of Transportation (TxDOT), flexible base producers typically generate large stockpiles of material exclusively for TxDOT projects. This large “state-only” inventory often maintained by producers, along with time requirements for testing and reduced manpower within TxDOT offices, resulted in this project’s investigation into a mixture-design specification for flexible base. The goals of this project are to develop a flexible base specification that reduces TxDOT’s burden for sampling and testing, reduces time and space burdens on producers for maintaining TxDOT-only stockpiles, and maintains or improves the quality of the base. To facilitate accomplishing these goals, this project developed a draft quality control/quality assurance (QC/QA) specification for flexible base. Based on a thorough review of background information, sampling and testing placeholders for placement and production aggregate and mixture tests were selected and incorporated into a classical QC/QA format draft specification. While the current draft specification largely uses existing TxDOT test procedures, improvements may be realized by considering the Grace methylene blue method and the use of index tests as surrogates for modulus and permanent deformation properties. The methylene blue method may be able to better control the quantity and amount of fines, while linking index tests to mechanistic properties could enable acceptance testing better linked to design assumptions. The second year of this project will sample and test flexible base quarries around the state to determine material variability that is attainable in the real world without compromising the design strength.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Posted by: mahyarov - 11-10-2012, 08:07 AM - Forum: Concrete
- No Replies
Performance of Lap Splices in Large-Scale Column Specimens Affected by ASR and/or DEF
Author: Bracci, Joseph M Gardoni, Paolo Eck, M Kathleen Trejo, David | Size: 26.59 MB | Format:PDF | Quality:Original preprint | Publisher: Texas Transportation Institute | Year: 2012 | pages: 380
This research program conducted a large experimental program, which consisted of the design, construction, curing, deterioration, and structural load testing of 16 large-scale column specimens with a critical lap splice region, and then compared and calibrated models developed in the analytical program with the experimental behavior. Specimens were carefully instrumented both internally and externally to monitor the strain behavior of the concrete and reinforcing steel from specimen construction, curing, deterioration, and final structural load testing.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Posted by: mahyarov - 11-10-2012, 08:05 AM - Forum: Concrete
- No Replies
Preparation and Testing of Drilled Shafts with Self-Consolidating Concrete
Author: Ozyildirim, H Celik Sharp, Stephen R | Size: 1.20 MB | Format:PDF | Quality:Original preprint | Publisher: Virginia Center for Transportation Innovation and Research | Year: 2012 | pages: 36
In this study, self-consolidating concrete (SCC) was evaluated in drilled shafts and the integrity of drilled shafts was determined using cross-hole sonic logging (CSL), a low-strain nondestructive integrity testing technique. SCC has very high flowability. It was placed in the drilled shafts of the bridge on Route 28 over Broad Run in Bristow in Prince William County, Virginia. There were two bridges at the site; the one carrying the northbound traffic had drilled shafts using conventional concrete with high consistency (i.e., flowability). Half of the shafts of the bridge carrying the southbound traffic were cast with SCC. During placement, properties of the fresh concrete were tested and specimens were prepared to determine the hardened properties. The integrity of the shafts within the reinforcing cage was determined using CSL, with sonic echo/impulse response also used to evaluate several test shafts. The use of acousto-ultrasonic (AU) measurements to determine the cover depth outside the reinforcing cage was also evaluated during laboratory testing. In addition to the Route 28 shafts, three test shafts with conventional and SCC concretes were cast in an area headquarters. These shafts had intentional voids created through the use of sand bags and Styrofoam to investigate further the ability of the nondestructive test equipment. The results indicated that SCC is highly desirable for drilled shafts; it flows easily, filling the hole, and the removal of the temporary casing is facilitated by this highly workable material. CSL is a satisfactory nondestructive method to determine the integrity of shafts. Sonic echo/impulse response also showed promise as a method that complements CSL for determining the integrity of a shaft.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Posted by: mahyarov - 11-10-2012, 08:02 AM - Forum: Concrete
- No Replies
Durability Assessment of Recycled Concrete Aggregates for use in New Concrete
Author: Ideker, Jason H Adams, Matthew P Tanner, Jennifer | Size: 1.99 MB | Format:PDF | Quality:Original preprint | Publisher: Oregon State University, Corvallis | Year: 2012 | pages: 72
The primary goal of this research project was to investigate the long-term durability of concrete incorporating recycled concrete aggregate (RCA) through accelerated laboratory testing. Overall it was found that modifications to standard aggregate testing and characterization standards were necessary for testing RCA. This included modifications to standard tests including ASTM C 128, C 305 and C 1260. It was found that the potential for alkali silica reactivity did exist for new concrete containing RCA. The characteristics of the RCA also had a profound effect on alkali silica reaction (ASR) related expansion. RCA with a higher content of reactive coarse or fine aggregate (compared to paste fraction) exhibited greater reaction and would therefore require higher levels of mitigation. Based on testing in this research project precision and bias statements in ASTM C 1260 (for virgin aggregate) do not apply to RCA. Recommendations for future work are also included in this report.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Posted by: mahyarov - 11-10-2012, 07:58 AM - Forum: Concrete
- No Replies
Materials Selection for Concrete Overlays
Author: Kim, Dong H Fowler, David W Ferron, Raissa P Trevino, Manuel M Whitney, David P | Size: 14.46 MB | Format:PDF | Quality:Original preprint | Publisher: University of Texas, Austin | Year: 2012 | pages: 210
Concrete overlays have been a rehabilitation method for many years. It has been extensively utilized and studied in other states, but Texas is still at an initial stage of fully implementing the method. The large volume of concrete highways in Texas makes bonded concrete overlays, unbonded concrete overlays, and whitetoppings very viable options. However, there is a lack of educational guidelines for pavement engineers for concrete overlay construction. This research presents the information gathered from literature review, condition survey, and evaluation of existing concrete overlays in Texas. Also, a laboratory research was performed for recommendations for materials selection and construction for concrete overlays. From these, guidelines for materials selection and construction method developed that will assist in future concrete overlays in Texas are presented.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
The Federal Highway Administration's (FHWA) "Every Day Counts" initiative aims to shorten the overall project delivery time, enhance safety, and protect the environment both on and around construction projects. Using innovative planning, design, and construction methods, Accelerated Bridge Construction (ABC) techniques reduce on-site construction time for new or replacement bridges. One aspect of ABC is Prefabricated Bridge Elements and Systems (PBES), where bridge components are fabricated off site to reduce on-site construction activities. Many state departments of transportation (DOTs) are currently making efforts to implement PBES for construction of their off-system bridges. The purpose of this research project was to investigate other states' standards and to evaluate them for possible implementation in Florida. An exhaustive search was made, and new literature was reviewed, to learn about current DOT standards and practices. The search revealed that the states with the most prefabricated bridge standards or activities are as follows: Utah, Alabama, Texas, Minnesota, and a collaboration of Northeastern states. These standards were reviewed for details such as the presence of post-tensioning, joint types, design load, and inspectability. The two standard bridge types that show the most promise for adoption by Florida Department of Transportation (FDOT) are Minnesota's Inverted-tee Beam, and PCI's "Northeastern Extreme Tee" (NEXT) Beam. A summary of the findings, including advantages and disadvantages of the bridge systems, is included in this report. Also included is a comprehensive list of Web links to standard drawings from all state DOTs, as well as more information on ABC and PBES, which could also be helpful to expedite other research that involves standards and bridge construction/design practices.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Measurement of Temperature and Soil Properties for Finite Element Model Verification
Author: Darrow, Margaret M | Size: 25.92 MB | Format:PDF | Quality:Original preprint | Publisher: Alaska University Transportation Center | Year: 2012 | pages: 295
In recent years, Alaska Department of Transportation and Public Facilities personnel have used TEMP/W, a commercially available two-dimensional finite element program, to conduct thermal modeling of various embankment configurations in an effort to reduce the thawing of ice-rich permafrost through thermally stable embankment designs. This modeling was done with historic air temperature data and input parameters derived from the literature, since site-specific data is typically not available. The overall goal of this study was to verify the thermal modeling results produced by TEMP/W. Temperatures and soil properties were measured at two different sites underlain by permafrost in Interior and Southcentral Alaska. A sensitivity analysis of certain input parameters was conducted on models of each site. Analysis indicates that the most critical input parameter is air temperature. While historic air temperature data provided an approximation of the regional climate, this data produced model results that were too cold by several degrees. Using air temperatures measured at each site resulted in models that closely matched the measured soil temperatures, and either matched or overestimated active layer depths. Using the overestimated active layer depth for design purposes would result in a more conservative embankment construction, which is a favorable approach if a warming climate is considered.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
This book contains chapters detailing significant advances and applications in fluid dynamics modeling with focus on biomedical, bioengineering, chemical, civil and environmental engineering, aeronautics, astronautics, and automotive. We hope this book can be a useful resource to scientists and engineers who are interested in fundamentals and applications of fluid dynamics.
Contents
Preface
1 Surface Friction and Boundary Layer Thickening in Transitional Flow
2 Bubble Rise Phenomena in Non-Newtonian Crystal Suspensions
3 Physical Modeling of Gas Pollutant Motion in the Atmosphere
4 Numerical Investigation for Steady and Unsteady Cavitating Flows
5 Incorporation of Computational Fluid Dynamics into a Fluid Mechanics Curriculum
6 Numerical Simulation on Mechanical Ventilation- Two Case Studies with Different Operation Modes
7 The New Use of Diffusion Theories for the Design of Heat Setting Process in Fabric Drying
8 Identification from Flight Data of the Aerodynamics of an Experimental Re-Entry Vehicle
9 Computer Modelling of Automobile Fires
10 Blast Wave Simulations with a Runge-Kutta Discontinuous Galerkin Method
11 pMDI Sprays: Theory, Experiment and Numerical Simulation
12 A New Correlation for Prediction of Viscosities of Omani Fahud-Field Crude Oils
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Procurement of Airport Development and Planning Contracts
Author: Alfert Jr, Robert Ryan, Karen M Block, Roy | Size: 453 KB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2012 | pages: 46 | ISBN: 9780309258524
Most airport operators, as public agencies, are subject to some type of procurement law or regulation for carrying out procurements and awarding contracts. Airports procure a variety of contracts for construction services, professional services, and the purchase of equipment. Typically, some form of competitive selection is required. The various competitive procurement requirements exist to promote fair and open competition and to ensure integrity and confidence in the public procurement system. Which procurement requirements apply to any given procurement will depend upon the type of goods and services required and the funding source. This digest provides guidance to airport operators, their counsel, and bidders on how to determine which requirements apply to any given procurement and an overview of the consequences for noncompliance so that airports can better understand the inherent risks associated with each funding source.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
![[Image: info.png]](http://postgen.civilea.com/icon/info.png){kind=icon}
![[Image: download.png]](http://postgen.civilea.com/icon/download.png){kind=icon}
![[Image: 09230454327807012958.png]](https://pic.civilea.com/images/09230454327807012958.png)
![[Image: 59131062107915451222.png]](https://pic.civilea.com/images/59131062107915451222.png)
![[Image: 92317883415897941837.png]](https://pic.civilea.com/images/92317883415897941837.png)
![[Image: 93768543241748714633.png]](https://pic.civilea.com/images/93768543241748714633.png)
![[Image: 00173728644301034111.png]](https://pic.civilea.com/images/00173728644301034111.png)
![[Image: 08005531690392644603.png]](https://pic.civilea.com/images/08005531690392644603.png)
![[Image: 53200841108875651572.jpeg]](https://pic.civilea.com/images/53200841108875651572.jpeg)
![[Image: 64483412152998676713.png]](https://pic.civilea.com/images/64483412152998676713.png)