Live Load Distribution Factors for Prestressed Concrete I-beam Bridges PDF Download
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Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 103
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Book Description
Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 103
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Book Description
Author: Jason Langdon Millam
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages :
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Book Description
"The Alaska Department of Transportation (AKDOT) uses the decked precast, prestressed concrete bulb-tee girder for most of its bridge construction. The live load distribution factor (DF) equations provided by the American Association of State Highway and Transportation Officials (AASHTO) for the decked bulb-tee girder system do not differentiate between a single or multilane loaded condition. This practice results in a single lane load rating penalty for decked bulb-tee girder bridges. The research objective of this thesis is to determine DF simplified equations that accurately predict the distribution factor of the decked bulb-tee girder system when it is only subjected to single lane loading. Eight decked bulb-tee bridges were instrumented. Each bridge was loaded with a single load vehicle to simulate the single lane loaded condition. The experimental data were used to calibrate grillage models of the decked bulb-tee girder system. The calibrated grillage models were used to conduct a parametric study of the bulb-tee girder system subjected to single lane loaded condition. Eight new simplified equations that describe the single lane loaded distribution factor for both shear and moment forces of these bridges are developed in this thesis"--Leaf iii.
Author: Stephen J. Druschel
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 91
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Book Description
Lower than desirable shear ratings at the ends of prestressed concrete beams have been the topic of ongoing research between MnDOT and the University of Minnesota. A recent study by the University of Minnesota entitled Investigation of Shear Distribution Factors in Prestressed Concrete Girder Bridges (French et al., 2016) sought to increase the shear rating of a prestressed concrete beam via a refined live load distribution factor, considering the location-based load distribution of each axle along the span. The study also presented a screening tool to determine the likelihood that the refined methodology would improve the shear rating of a given prestressed concrete beam bridge. The research presented within this report implemented the refined shear rating methodology presented by French et al. (2016). MnDOT selected 522 bridges from its inventory noted as having shear rating deficiencies for potential re-evaluation as part of this research. After employing the screening tool, the initial selection was reduced to 127 applicable bridges, of which 50 were selected for re-evaluation. For the 50 bridges evaluated, the refined rating methodology was found to improve the shear ratings by an average of 16 percent. The screening tool also proved to be an effective means of determining the candidacy of a given bridge for re-evaluation.
Author: Jai B. Kim
Publisher: CRC Press
ISBN: 1466566884
Category : Technology & Engineering
Languages : en
Pages : 349
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Book Description
Helping readers prepare for the civil and structural PE exam, this book presents numerous design examples that serve as a comprehensive, step-by-step guide to basic bridge design using the AASHTO LRFD Bridge Design Specifications, Fifth Edition. It offers a simplified explanation of load resistance factor design (LRFD) method-based bridge design principles and lists the AASHTO reference section numbers alongside formulas and where topics are introduced, to refer the reader to the primary source material. This is a valuable reference for civil engineering students as well as for practicing engineers.
Author: Ernesto S. DeCastro
Publisher:
ISBN:
Category :
Languages : en
Pages : 62
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Book Description
Author: Daryl Eugene Young
Publisher:
ISBN:
Category : Box beams
Languages : en
Pages : 160
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Book Description
Author: Mark Mlynarski
Publisher: Transportation Research Board
ISBN: 0309213444
Category : Technology & Engineering
Languages : en
Pages : 104
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Book Description
TRB’s National Cooperative Highway Research Program (NCHRP) Report 700: A Comparison of AASHTO Bridge Load Rating Methods documents an analysis of 1,500 bridges that represent various material types and configurations using AASHTOWareTM Virtis® to compare the load factor rating to load and resistance factor rating for both moment and shear induced by design vehicles, American Association of State Highway and Transportation Officials (AASHTO) legal loads, and eight additional permit/legal vehicles.
Author: Baidar Bakht
Publisher: McGraw-Hill Companies
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 312
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Book Description
Author: Abhijeet Kumar Singh
Publisher:
ISBN:
Category : Continuous bridges
Languages : en
Pages : 186
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Book Description
A new precast-prestressed cross section was recently developed by a consortium of engineers from the six New England states, New York and members of the northeast region of PCI. The northeast extreme Tee (NEXT) beam is efficient for medium Bridge spans (50 to 80 ft long). Field formwork savings are introduced by having a flange cast integrally during fabrication of the beams at the precasting plant. Job safety is increased because a working platform is created. The flange width of the NEXT Beams can be adjusted during fabrication to accommodate roadways of different widths and skew angles. Because the section is new with complexity in its shape, the present design guidance cannot be used to evaluate LLDFs for NEXT beams within the context of the AASHTO LRFD. In particular, the use of live-load distribution factors (LLDFs) equations in LRFD for NEXT beams is not straightforward. The distance between the beam webs is variable depending on whether it is measured within a beam module or between adjacent modules. In absence of detailed information a PCI technical committee evaluated LLDFs (through AASHTO 2010 Bridge specification) for the NEXT beams used in the Brimfield Bridge by two different approaches and found one of them conservative. The conservative approach was single stem which uses the average spacing (between webs ([S1+S3]/2)) for use in the LLDF equations. The committee expressed concerns about whether trends of LLDFs would be similar for other parametric sets, and would like to standardize the methodology for the Bridge projects in Massachusetts with NEXT beam as the girder. To verify the conservativeness of single stem methodology (for the evaluation of LLDFs) for other parameters this research project was initiated. LLDFs are evaluated based on the two approaches and compared with the LLDFs obtained through finite element modeling. The results of 40-3D finite element models have been used to compare the LLDFs obtained from AASHTO 2010 Bridge design specification. The results were also used to compare different parameters that affect LLDFs of NEXT beams including span, skew angle, and beam end fixity. The finite element models were created using a Bridge prototype that is being instrumented for future field verification of the analyses. The models were created using frame elements for the beams and shell elements for the cast in place deck. The integral abutment and foundation of the Bridges was included in the models in which piles are created using frame elements and abutments are created using shell elements. The results indicate that the approach taken for the design of NEXT beams is in general conservative for interior girders of the Bridge. On the contrary such the adopted approach was not yielding the higher value of LLDFs. The variation in strains due to losses are compared by two methods (strains variation obtained from field data and strain variation obtained based on AASHTO equation of losses) to verify the AASHTO equation of losses.
Author: Carlos Victor Aguilar
Publisher:
ISBN:
Category : Prestressed concrete bridges
Languages : en
Pages : 318
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Book Description
Bridges without design plans are an existing problem as conventional load rating techniques cannot be utilized when there is no design documentation available to indicate the amount and location of reinforcement. A project was conducted for the New Mexico Department of Transportation to evaluate bridges without plans with various superstructures (T-beam, I-girder, and box girder) using advanced structural analysis and non-destructive experimental methods, with the goal of developing specific load rating procedures. This study presents two of the bridges that were evaluated. Bridge 7701 is a prestressed concrete double T-beam bridge located in Doña Ana County, NM. Upon inspection, it was discovered that many of the shear keys connecting the bridge beams were damaged or missing. Prestressing strand estimates were made based on Magnel diagrams and verified with a Hilti Ferroscan system. Diagnostic load testing was performed to determine the impact of the damaged shear keys on the live load distribution of the bridge. The results were then used to plan and conduct a proof test. Final legal load rating factors were subsequently determined from the proof test, and compared with the results from an AASHTOWare BrR load rating analysis. The final load rating factors show that Bridge 7701 needs to be load posted. Bridge 8588 is a prestressed concrete I-girder bridge located in Eddy County, NM. Similar to Bridge 7701, Magnel diagrams were used to develop prestressing strand estimates (based on composite and non-composite behavior) and attempts were made to verify layouts using a Hilti Ferroscan system. Since no significant girder damage was found during the inspection, no diagnostic load test was performed. Only a proof test was conducted and the results were used to compute load rating factors. The factors from the proof test were subsequently checked with the AASHTOWare BrR results, and final legal load rating factors were determined showing that Bridge 8588 does not need to be load posted. Using the evaluation procedures developed for Bridges 7701 and 8588, as well as three other bridges that were separately evaluated in this project, a final implementation plan for load rating prestressed concrete bridges without plans is presented.
