Download or read book Investigation of the Performance of a Skewed Steel Bridge with and Without Cross frames written by Asmaa Taha Ibrahim Abo Alouk and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In addition to this test, another test was previously conducted for the same bridge with the presence of the intermediate cross-frame, which gave an opportunity to compare the bridge's performance with and without cross-frames. The difference in the distribution factor between the bridge with the cross-frame and the bridge without them was less than or equal to 5%, according to the results of the comparison. Field data shows that the bridge with the cross-frames is subjected to higher lateral and warping stresses than the bridge without them. In addition to the field tests, a finite element analysis (FEA) was conducted, and compared to the field data. The FEA predictions closely match the field data. In addition, The FEA showed that at the inelastic load level, the cross-frames did not contribute to redistributing the load, as these cross-frames yielded much earlier than the heavily loaded girder. Finally, a unique finding in this study was that cross-frames induce concentrated major-axis bending moments that change the bridge's expected behavior.

Download or read book Skewed Steel Bridges Part II written by James Zhou and published by . This book was released on 2017 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Skewed bridges in Kansas are often designed such that the cross-frames are carried parallel to the skew angle up to 40°, while many other states place cross-frames perpendicular to the girder for skew angles greater than 20°. Skewed-parallel cross-frames are longer and may require different connections than cross-frames oriented perpendicular to the girder. Therefore, it is important to determine whether the cross-frames and their corresponding connecting elements placed in a parallel-to-skew configuration are sufficiently designed to resist lateral torsional buckling demands using current KDOT practices. The authors have performed a study to investigate the effect of cross-frame orientation, skew angle, and cross-frame connection upon bridge system behavior and cross-frame stresses. In a suite of detailed 3D, solid finite element analyses models of skewed bridge systems, cross-frame layout, connection thickness and type, and skew angle were varied. Skewed bridge systems with cross-frames placed parallel to the skew angle as well as systems with cross-frames arranged in a staggered configuration were considered. Varying bent plate connection thicknesses and a half-pipe connection were also analyzed. Cross-frame spacing of 4.6 m [15 ft] and 9.14 m [30 ft] were examined; severe cross-frame spacing of 13.7 m [45 ft] was also considered to examine behavior at very long unbraced lengths. The findings of this study showed that skew angle, skew configuration, and connection type all influenced the strength and stiffness of system. The data showed that cross-frame placed parallel to skew up to an angle of 40° performed similar or better than cross-frames oriented perpendicular to skew for every given skew angle and connection type.

Download or read book Skewed Steel Bridges written by James Zhou and published by . This book was released on 2016 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lateral flange bending stresses can arise from a number of sources, such as wind loading or eccentric concrete placement, but of particular interest are lateral flange bending stresses, fl, that occur due to skew. Lateral flange bending stresses that occur in skewed bridge systems tend to develop due to lateral forces transferred through cross frames which may connect adjacent girders at different span points. In lieu of a refined analysis, the AASHTO (2010) LRFD Bridge Design Specifications currently permit engineers examining bridges skewed more than 20° to use a minimum value of fl = 10 ksi for an interior girder and fl = 7.5 ksi for an exterior girder. The estimates for fl provided within the AASHTO LRFD Bridge Design Specifications are based on a limited data set for skewed bridges. Additionally, since the AASHTO LRFD Bridge Design Specifications state that cross frames or diaphragms should be placed in a staggered configuration when a bridge is skewed more than 20°, the approximate values provided for fl should not be expected to be indicative of the lateral flange bending stresses experienced when cross frames are instead carried parallel to the skew in bridges skewed beyond 20°. The authors have performed a study to investigate the effects of cross frame orientation and skew angle upon lateral flange bending stresses, by examining lateral flange bending stresses in a suite of detailed 3D solid finite element analyses of skewed bridge systems, in which cross frame layout, spacing, and skew angle were varied. The findings of this study showed that cross frames placed parallel to the angle of skew produced significantly lower values for fl than cases in which cross frames were placed perpendicular to the girder line and staggered. Both reducing the skew angle and decreasing cross frame spacing were found to reduce lateral flange bending stresses. The values of lateral flange bending stress for all configurations were greater than the bounds of the approximate values suggested by AASHTO.

Download or read book Monitoring Dead Load and Construction Stresses of a Heavily Skewed HPS Bridge written by Jason Winterling and published by ProQuest. This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, bridge engineers have begun to take advantage of the increased yield strengths and weldability provided by High Performance Steel. This type of steel, including HPS Grade 70W which is covered in this study, allows for lighter structural dead loads of bridges and increased span lengths without growth in cross-section depth of the main load supporting members. In turn, this reduction in girder depth results in a reduced moment of inertia and an increased flexibility of the members. Dead load deflections of the girders, resulting from the reduced moment of inertia, can be challenging to model and design for in a highly skewed structure such as the Churchman's Road Bridge, the 772'-3" four span continuous bridge in Christiana, Delaware instrumented for this study. The sizeable deflections require large precut cambers of the plate girders and, additionally, increased flexibility about the x-axis can increase the probability of girder torsion during the construction of a highly skewed bridge. The objective of this project was to develop and apply an instrumentation plan for the girders and the cross-frames of Churchman's Road Bridge prior to its erection and monitor the stresses developed in the members throughout construction and the load testing. The placement of these gauges prior to erection allows for more accurate analysis of the dead load stresses in the steel and allows for the comparison of expected values determined through finite element modeling to measured stresses. An evaluation of the bridge and the High Performance Steel as a useful bridge material was then made. Through the successful completion of this project, a complete dead load and construction stress timeline has been captured and analyzed. The original structure, designed with cross-frames that were parallel to the skew, was found to be torsionally flexible and was deemed to be insufficiently braced by the design engineers to support a deck pour. After adding additional cross-frames perpendicular to the girders, the hybrid HPS girder system performed well throughout the remainder of construction and during a diagnostic load test. Recommendations for future instrumentation plans of this type have been provided that allow for more effective structural analysis. Additionally, through the retrofit and redesign of the lateral load resisting system occurring during the course of this project, conclusions on skewed bridge construction and design have been developed.

Download or read book Cross frame Diaphragm Bracing of Steel Bridge Girders written by W. M. Kim Roddis and published by . This book was released on 2008 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steel plate girder bridges make use of traditional cross-frame diaphragms to stabilize the compression flange of girders. These braces are required during construction, especially during deck placement, to prevent lateral torsional buckling of bridge girders. Girder buckling capacity is a function of cross-frame diaphragm spacing as well as strength and stiffness. Recent developments in bridge design may cause the governing girder limit state to shift from one of strength to one of stability. These developments include the elimination of in-plan bracing, composite girders, High Performance Steels, and phased deck replacements. In addition, the American Association of State Highway and Transportation Officials (AASHTO) has changed its code requirement for cross-frame diaphragm spacing in the 1998 AASHTO LRFD Bridge Design Specifications. The requirement for 25-foot maximum brace spacing has been removed. The current requirement is for a "rational analysis" to determine cross-frame diaphragm spacing. Explanations of the problems these changes cause in design are discussed. A case study is presented of a bridge that suffered construction difficulties during deck placement. This investigation found that the cross-frame diaphragms were not stiff enough to brace the plate girders during the deck placement. Suggestions are given as to an efficient, economical design and spacing for cross-frame diaphragms on plate girder bridges.

Download or read book Cross frame Forces in a Straight Bridge with Normal Supports written by Matthew Eric Moore and published by . This book was released on 2018 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cross-frame and diaphragm systems are important structural elements in steel I-girder bridges. These members enhance the lateral-torsional buckling resistance in straight girder systems by reducing the unbraced length. The critical stage for the braces from a stability perspective often occurs during construction of the concrete bridge deck when the non-composite steel girders must resist the entire construction load. The braces not only enhance the lateral-torsional buckling resistance of the girders, but are also necessary to resist the torsion applied to the girders due to the deck overhang construction, and distribute lateral loads across the structure from sources such as wind. In horizontally curved bridges, the braces are primary structural elements in the superstructure and engage the girders across the width of the bridge to behave as a structural system to resist the torsion that develops as a result of the curved geometry. For straight girder systems, the specifications of the American Association of State Highway and Transportation Officials (AASHTO) have generally provided little guidance in the sizing of the braces other than recommended connection plate (web stiffener) details or slenderness limits. While there have been many advances in recent years towards improving the understanding of the behavior of cross-frame systems, there has not been sufficient research carried out on the proper loading conditions for assessing the fatigue performance of cross-frames. The work outlined in this thesis is part of a larger study on the behavior of cross-frames in steel bridge system. The study is funded by the National Cooperative Highway Research Program (NCHRP 12-113). The fundamental goals of the research investigation are to produce methodologies and design guidelines for the following: evaluation of fatigue design stresses in cross-frames in straight and horizontally curved steel I-girder bridges; calculation of minimum cross-frame strength and stiffness requirements for stability bracing of I-girders during construction and in-service; development of improved methods to account for the influence of end connection details on cross-frame stiffness that extend beyond and improve upon the suggested guidance currently provided in Article C4.6.3.3.4 of the AASHTO LRFD Bridge Design Specifications. This work includes field monitoring and parametric FEA studies. The field studies are focused on three bridges: 1) a straight bridge with normal supports, 2) a straight bridge with skewed supports, and 3) a horizontally curved bridge. The field studies include rainflow monitoring of fatigue induced stresses in select cross-frames and the girders for a period of approximately 1 month as well as live load tests using trucks of known weights. This thesis focuses on some of the background studies, a survey of bridge owners around the United States, as well as the instrumentation and live load tests on the straight bridge with normal supports

Download or read book A Study of Stiffness of Steel Bridge Cross Frames written by Weihua Wang and published by . This book was released on 2013 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cross frames are critical components in steel bridge systems. Cross frames brace girders against lateral torsional buckling and assist in distributing live loads to girders during the service life of the bridge. In curved bridges, cross frames also serve as primary structural members in resisting torsion generated by the traffic loads. The conventional cross frames are often constructed in X- or K- type shapes with steel angle sections. However, the actual stiffness of these cross frames are not well understood or quantified, leading to potentially inaccurate prediction of bridge behavior and safety during construction and in service. Previous studies have shown the possibility of employing new sections, such as tubular members and double angles, in cross frame designs. In addition, a type-Z cross frame, or single diagonal cross frame was also found to be a potential use to simplify the design. However, the effectiveness of these innovative cross frame types has not been completely examined. And these new cross frames have yet compared with the conventional ones in terms of their stiffness and strength capacity. This dissertation documents the results of a study on the stiffness of various types of cross frame systems. Full size cross frames were tested to establish actual stiffness of the cross frames specimens. The tests results revealed a significant discrepancy between the actual measured stiffness and the stiffness calculated using methods commonly employed by bridge designers. The research showed that the major source of this discrepancy was eccentricity in the connection. The stiffness reduction was quantified by employing analytical derivation and finite element modeling. As a result, methods were developed to account for the stiffness reduction.

Download or read book Skewed Steel Bridge Cross frame Response to Truck Loading written by Shane David Murphy and published by . This book was released on 2012 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cross frame Connection Details for Skewed Steel Bridges written by Craig Quadrato and published by . This book was released on 2010 with total page 393 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Guidelines for Analysis Methods and Construction Engineering of Curved and Skewed Steel Girder Bridges written by and published by Transportation Research Board. This book was released on 2012 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: "TRB's National Cooperative Highway Research Program (NCHRP) Report 725: Guidelines for Analysis Methods and Construction Engineering of Curved and Skewed Steel Girder Bridges offers guidance on the appropriate level of analysis needed to determine the constructability and constructed geometry of curved and skewed steel girder bridges. When appropriate in lieu of a 3D analysis, the guidelines also introduce improvements to 1D and 2D analyses that require little additional computational costs."--Publication information.

Download or read book Proposed Modification to AASHTO Cross frame Analysis and Design written by Matthew Craig Reichenbach and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cross-frames are important structural components that serve many functions throughout the service life of steel I-girder bridges. Under repetitive load cycles caused by heavy truck passages, cross-frames and their connections can be susceptible to load-induced fatigue cracking if not properly designed. The TRB National Cooperative Highway Research Program's NCHRP Research Report 962: Proposed Modification to AASHTO Cross-Frame Analysis and Design addresses knowledge gaps in an attempt to improve the reliability and economy of cross-frames in steel I-girder bridges and produces quantitatively based methodologies and design guidelines. Appendices B through F provide examples of cross-frame design for a straight bridge and a curved bridge as well as a comprehensive overview of the work completed in Phases I, II, and III of the project. Appendix A, Proposed Modifications to AASHTO LRFD, will be published by AASHTO.

Download or read book Maintenance Safety Risk Management and Life Cycle Performance of Bridges written by Nigel Powers and published by CRC Press. This book was released on 2018-07-04 with total page 5447 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges contains lectures and papers presented at the Ninth International Conference on Bridge Maintenance, Safety and Management (IABMAS 2018), held in Melbourne, Australia, 9-13 July 2018. This volume consists of a book of extended abstracts and a USB card containing the full papers of 393 contributions presented at IABMAS 2018, including the T.Y. Lin Lecture, 10 Keynote Lectures, and 382 technical papers from 40 countries. The contributions presented at IABMAS 2018 deal with the state of the art as well as emerging concepts and innovative applications related to the main aspects of bridge maintenance, safety, risk, management and life-cycle performance. Major topics include: new design methods, bridge codes, heavy vehicle and load models, bridge management systems, prediction of future traffic models, service life prediction, residual service life, sustainability and life-cycle assessments, maintenance strategies, bridge diagnostics, health monitoring, non-destructive testing, field testing, safety and serviceability, assessment and evaluation, damage identification, deterioration modelling, repair and retrofitting strategies, bridge reliability, fatigue and corrosion, extreme loads, advanced experimental simulations, and advanced computer simulations, among others. This volume provides both an up-to-date overview of the field of bridge engineering and significant contributions to the process of more rational decision-making on bridge maintenance, safety, risk, management and life-cycle performance of bridges for the purpose of enhancing the welfare of society. The Editors hope that these Proceedings will serve as a valuable reference to all concerned with bridge structure and infrastructure systems, including students, researchers and engineers from all areas of bridge engineering.

Download or read book Spatial Interaction Between Cross Frames and Girders of Multi stringer Skewed Steel Bridges written by Wassef E. Elmir and published by . This book was released on 1988 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance based Seismic Assessment of Skewed Bridges with and Without Considering Soil structure Interaction Effects for Various Site Classes written by Abdoulreza Ghotbi and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This study aims to investigate the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction (SSI) due to near-fault ground motions. Both deterministic (i.e., pushover and nonlinear dynamic analyses) and probabilistic approaches were utilized. A set of response sensitivity analyses was performed considering various skew angles, column elements, and soil properties for bridge considered both as fixed-base and SSI models. It has been observed that as the skew angle increased, the bridge responded more severely to the ground motion. For instance, the deck rotation and shear-keys displacement increased with an increase in the skew angle. A modal pushover analysis was also performed in conjunction with the nonlinear dynamic analysis. It has been found that combining the bridge responses for various modes of vibration resulted in a relatively accurate seismic response compared to the nonlinear dynamic analysis while saving time and analysis cost, to a great extent. A probabilistic analysis was also performed considering record-to-record variability in ground motion, and a set of probabilistic seismic demand and fragility plots was generated. The effects of change in the skew angle and also SSI were studied to see various bridge responses. The damage probability increased especially with respect to deck rotation as the skew angle increased. The SSI had a decreasing effect on the overall response of the bridge with pile foundation.

Download or read book Engineering for Structural Stability in Bridge Construction written by Federal Highway Federal Highway Administration and published by . This book was released on 2020-07-19 with total page 669 pages. Available in PDF, EPUB and Kindle. Book excerpt: This manual is intended to serve as a reference. It will provide technical information which will enable Manual users to perform the following activities:Describe typical erection practices for girder bridge superstructures and recognize critical construction stagesDiscuss typical practices for evaluating structural stability of girder bridge superstructures during early stages of erection and throughout bridge constructionExplain the basic concepts of stability and why it is important in bridge erection* Explain common techniques for performing advanced stability analysis along with their advantages and limitationsDescribe how differing construction sequences effect superstructure stabilityBe able to select appropriate loads, load combinations, and load factors for use in analyzing superstructure components during constructionBe able to analyze bridge members at various stages of erection* Develop erection plans that are safe and economical, and know what information is required and should be a part of those plansDescribe the differences between local, member and global (system) stability

Download or read book Cross frame and Diaphragm Behavior for Steel Bridges with Skewed Supports written by Todd Aaron Helwig and published by . This book was released on 2003 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Verification of Performance and Design Criteria for High Performance Steel Bridges written by and published by . This book was released on 2006 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Performance Steel (HPS) has quickly gained popularity in United States bridge applications due to its high yield strength and better weldability, toughness, ductility, and weathering characteristics. However, a great deal of information is missing from the body of knowledge on HPS performance and design criteria, especially concerning HPS-70W (485W) produced by thermo-mechanical controlled processing (TMCP). This research examines material characteristics and fatigue performance of HPS-70W (485W) TMCP, as well the performance of Ohio's first HPS bridge in service. Data from 96 tensile tests show that yield and ultimate strengths of HPS-70W (485W) TMCP are dependent upon plate thickness and orientation. 75 Charpy V-Notch (CVN) specimens were tested, and all met the ASTM A709 requirement for minimum toughness. Twenty-nine specimens were tested to investigate the fatigue resistance of continuous plates with punched, drilled, and reamed holes. Results from this investigation suggest that current restrictions mandated by some state departments of transportation concerning punching holes are not overly restrictive when HPS-485W (70W) is utilized. Performance of drilled and sub-punched and reamed specimens met or exceeded American Association of State Highway and Transportation Officials (AASHTO) (2004) requirements for Category B details. Performance of Submerged Arc Weld (SAW) and Narrow Gap Improved Electroslag Weld (NGI-ESW) welded butt-splices utilizing HPS-70W (485W) were examined. All specimens performed considerably better than predicted by the AASHTO fatigue life equation.