Download or read book Live Load Distribution Factors in Two girder Bridge Systems Using Precast Trapezoidal U girders written by Salahudin Mensah and published by . This book was released on 2010 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Single Lane Live Load Distribution Factor for Decked Precast prestressed Concrete Girder Bridges written by John Zhongguo and published by . This book was released on 2005 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The live load distribution factor (DF) equations provided by AASHTO-LRFD for the decked precast/prestressed concrete (DPPC) girder bridge system do not differentiate between a single or multilane loaded condition. This practice results in a single lane load rating penalty for DPPC girder bridges. The objective of this project is to determine DF equations which accurately predict the distribution factor of the DPPC girder bridge system when it is only subjected to single lane loading. Eight DPPC girder bridges were instrumented. Each bridge was loaded with a single load vehicle to simulate the single lane loaded condition. The experimental data was used to calibrate 3D FE models and 2D grillage models of the DPPC girder bridge system. The calibrated models were used to conduct a parametric study of the DPPC girder bridge system subjected to a single lane loaded condition. Two sets of new equations that describe the single lane loaded distribution factor for both shear and moment forces of these bridges are proposed and compared with AASHTOLRFD DF equations.
Download or read book Simplified Live Load Distribution Factor Equations written by BridgeTech, Inc and published by Transportation Research Board. This book was released on 2007 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report contains the findings of research performed to develop recommended Load and Resistance Factor Design (LRFD) live load distribution factor design equations for shear and moment. The report details the development of equations that are simpler to apply and have a wider range of applicability than current methods. The appendices are not published in this report, but are available online at http://www.trb.org/news/blurb_detail.asp?id=7938.
Download or read book Live Load Distribution in One and Two cell Box girder Bridges written by Paul Chung and published by . This book was released on 2008 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the focus is to investigate the load distribution factors (LDF) for moment and shear of cast-in-place one and two-cell box girders for bridges with typical dimensions. The computed LDFs will be compared with those computed from AASHTO. It will be demonstrated that the current AASHTO LDFs are not adequate for the design of CIP one- and two-cell box girders. A modified ste of equations is proposed and further verified through parametric studies carried out for two-and three-span bridges.
Download or read book Live Load Distribution Factors for Exterior Girders in Steel I girder Bridges written by Gregory K. Michaelson and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Live Load Distribution in Multi cell Box Girder Bridges and Its Comparison with the AASHTO LRFD Bridge Design Specifications written by Shin-Tai Song and published by . This book was released on 2001 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bulb T Girder Bridge Barrier Effect on Live Load Distribution written by Tal Stricker and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Bulb-T girder bridges are composed of precast, prestressed concrete beams with a reinforced concrete slab. Typically, the slab extends transversely beyond the exterior beam, and there is a traffic barrier on the edge. The bridges are designed for dead and live loads and prestressing effects. For the live loads, the transverse distribution of moment and shear load effects to interior and exterior girders is determined by using equations in the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications. These equations give the designer a factor, which is then multiplied by the moment or shear load effect determined by a line analysis. The equations assume that barriers are not present. The Florida Department of Transportation (FDOT) Structures Research Lab has made field measurements on a Bulb-T bridge, both before and after the barriers were placed, due to a truck loaded with blocks. For this project, this data was analyzed to determine the barrier's effect on the live load distribution. The results of this project may be used to determine if load ratings can be improved by consideration of the barrier effect, which can be done as a Posting Avoidance (Exception) technique.
Download or read book Live load Distribution on Glued laminated Timber Girder Bridges written by and published by . This book was released on 2011 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increased use of timber bridges in the U.S. transportation system has required additional research to improve the current design methodology of these bridges. For this reason, the U.S. Forest Service, Forest Products Laboratory (FPL), and the Federal Highway Administration have supported several research programs to attain the objective listed above. This report is a result of a study sponsored by the FPL, with the objective of determining how highway truckloads are distributed to girders of a glued-laminated timber bridge. The American Association of State Highway and Transportation Official (AASHTO) load and resistance factor design (LRFD) Bridge Design Specification provides live-load distribution provisions for glued-laminated girder timber bridges that were used in previous AASHTO Specifications. The AASHTO live-load distribution provisions were reviewed in this report. Field-test results were used to review the current AASHTO LRFD glued-laminated timber girder bridge-design specifications and to validate analytical results obtained by finite-element analyses. With the validated analytical models, parametric studies were performed to determine the worst-case live-load distribution factors that can be used to calculate the design moment and shear for glued-laminated timber girders. Simplified live-load distribution equations that can be used to determine these distribution factors were developed and are provided in this report. These equations take into account how load is distributed to the bridge girders, considering the effects of span length, girder spacing, and clear width of the bridge.
Download or read book Assessment of Live Load Deflections in a Simple Span Composite Brigde with Prestressed Precast Concrete Girders written by Heriberto Charicata Duran and published by . This book was released on 2016 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study is to investigate how accurately the distribution factor method estimates the live load deflections under the principles of the 2012 AASHTO LRFD Bridge Design Specifications (AASHTO LRFD specifications) compared to the results of the NISA finite element analysis software. The simple span bridge model analyzed is developed very similarly to the design example of the PCI Bridge Design Manual. The main difference is a shorter span length and smaller AASHTO-PCI bulb tee sections. Three main finite element models are created to estimate the live load deflections under the recommended live load conditions as per AASHTO LRFD specifications. The first model is simulated with simple support conditions. The purpose of this model is two-fold: compare the deflections to the distribution factor method and to the deflections of the second model that is simulated with elastomeric steel reinforced bearing pads. Thus, the stiffnesses of the elastomeric bearing pads of the second model are varied within the AASHTO LRFD specifications acceptable limits and under low temperature conditions the stiffness is increased accordingly for two cases. The purpose is to investigate if the stiffness have any significant affect on the deflections of the girders. Then a third model is created to investigate if the removal of the intermediate diaphragms have any affect on the deflections. The results of the first and second models, including the models with the allowed varied stiffnesses of the bearing pads, found only the interior girders deflecting up to 4% more and the exterior girders were deflecting up to 5.55% less than the estimates of the distribution factor method. In the case when the diaphragms are removed, the deflections of the inner most interior girders are deflecting up to 10.85% more compared to the same girders of the model which includes the intermediate diaphragms and the bearing pads. In the unique case of the second model where the bearing pads may stiffen significantly under low temperatures, the girders are deflecting up to 23% less than when at room temperature conditions. All these findings and other summarized results are discussed in greater detail in this study.
Download or read book A Comparison of Wheel Load Distribution Factors Used in the Design of Multibeam Non composite Precast Prestressed Concrete Box Girder Bridge Decks written by Daryl Eugene Young and published by . This book was released on 1992 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Volume change Restraining Effects in Continuous Precast prestressed Bridge Girders written by Athul Abraham Alex and published by . This book was released on 2016 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: A variety of design and construction practices are feasible when building precast concrete continuous bridges with long spans. Precast, prestressed concrete continuous bridges have been implemented by countries around the world. Although these bridges have been in service for many years, there has been limited verification of the ability of connection to provide the predicted continuity. Subsequently many states in the United States design the girders as simple spans for both dead and live loads without considering any moments developed by the connection. The effect of thermal expansion and contraction is hardly considered in the analysis, even though it is found to have significant effects on continuity. The objective of this study is to evaluate the current state of the art practices relevant to continuous precast concrete bridges and to recommend the most suitable design methods of analyzing the continuity behavior. This research focuses on providing detailed analysis to evaluate the restraining effects in a continuous bridge system. Detailed analysis was performed using the specifications of the NU-girder system, which has been a widely adopted solution in the State of Nebraska. This research consisted of two phases: Phase 1: Conduct an extensive literature survey to find information regarding existing continuity behavior as investigated by various researchers. Phase 2: Propose the most suitable method for analyzing connection design. Discuss advantages, construction time and cost comparisons of the NU-girder system with other systems adopted in the United States.
Download or read book Behavior of Steel Tub Girders with Modified Cross sectional Geometry written by Yang Wang (Ph. D.) and published by . This book was released on 2019 with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steel trapezoidal box girders, also referred to as steel tub girders, have been an attractive design option for long-span horizontally curved highway bridges. The completed composite bridge system presents an aesthetic appeal profile as well as large torsional stiffness. However, during construction, the open U-shaped steel girder section is relatively flexible in torsion and requires extensive bracing. A recent application on straight bridge system in Waco, Texas showed potential wider utilization of tub girders for span length normally reserved for precast concrete beams. Current design and fabrication practices have several relatively inefficient aspects regarding the section geometry and bracing details. These details include the restrictions on the slope ratio of the webs and the top flange-web attachment. Due to the use of empirical equation for live load distribution factor, the slopes of tub girder webs are restricted to be no greater than 1 Horizontal: 4 Vertical in current AASHTO specification. Significant economy can be achieved by utilizing flatter webs. While keeping the width of bottom flange constant, the use of flatter webs increases the tributary width of individual girder. This leads to potential reduction of the required number of girder lines to support traffic live loads and considerable savings on fabrication time and cost. Additionally, the webs of the tub girder are usually attached at the mid-width of the top flanges. This leaves limited flange width to connect the top lateral braces directly with the flange. Therefore, large gusset plates are frequently used to provide sufficient space for the connection. However, the use of gusset plates leads to poor load transfer and unnecessary fabrication cost. If the top flanges are allowed to offset toward the inside of the box, more flange width would be available for simple bolted bracing connection without using gusset plates. Since these proposed details are not currently permitted by AASHTO Specification, a TxDOT-sponsored research project has been conducted at UT Austin to demonstrate the impact of these improved tub girder details using large-scale experimental study and finite element analyses. This dissertation presents part of the results of this research project to provide better understanding of tub girder behavior as well as design recommendations to improve the efficiency and economy of the steel tub girder system
Download or read book Distribution of Girder Loads in a Composite Highway Bridge written by Clifford Wagner Elling and published by . This book was released on 1985 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Serviceability Criteria in Prestressed Concrete Bridge Girders written by Hassan Hassan El-Hor and published by . This book was released on 1995 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Challenges Opportunities and Solutions in Structural Engineering and Construction written by Nader Ghafoori and published by CRC Press. This book was released on 2009-10-29 with total page 1890 pages. Available in PDF, EPUB and Kindle. Book excerpt: Challenges, Opportunities and Solutions in Structural Engineering and Construction addresses the latest developments in innovative and integrative technologies and solutions in structural engineering and construction, including: Concrete, masonry, steel and composite structures; Dynamic impact and earthquake engineering; Bridges and
Download or read book Development of Live Load Distribution Factor Equations for Girder Bridges written by Nakin Suksawang and published by . This book was released on 2006 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Live Load Distribution Factor Comparison for a Curved Steel Box Girder Bridge written by Cory E. Schultz and published by . This book was released on 2010 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
