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Author : Todd Aaron Helwig
Publisher :
ISBN 13 :
Total Pages : 256 pages
Book Rating : 4.3/5 (555 download)
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:
Author : Liqun Wang
Publisher :
ISBN 13 :
Total Pages : 590 pages
Book Rating : 4.:/5 (531 download)
Download or read book Cross-frame and Diaphragm Behavior for Steel Bridges with Skewed Supports written by Liqun Wang and published by . This book was released on 2002 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Todd Helwig
Publisher :
ISBN 13 :
Total Pages : 4 pages
Book Rating : 4.:/5 (617 download)
Download or read book Cross-frame and Diaphragm Behavior for Steel Bridges with Skewed Supports written by Todd Helwig and published by . This book was released on 2005 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : W. M. Kim Roddis
Publisher :
ISBN 13 :
Total Pages : 70 pages
Book Rating : 4.3/5 (555 download)
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.
Author : Matthew Eric Moore
Publisher :
ISBN 13 :
Total Pages : 422 pages
Book Rating : 4.:/5 (123 download)
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
Author : James Zhou
Publisher :
ISBN 13 :
Total Pages : 170 pages
Book Rating : 4.:/5 (1 download)
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.
Author : Sreekalyan Bobba Bobba
Publisher :
ISBN 13 :
Total Pages : 396 pages
Book Rating : 4.:/5 (556 download)
Download or read book Field Measurements of Diaphragm and Cross-frame Stresses in Steel Box Girder Bridge with Skewed Support written by Sreekalyan Bobba Bobba and published by . This book was released on 2003 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : James Zhou
Publisher :
ISBN 13 :
Total Pages : 20 pages
Book Rating : 4.:/5 (939 download)
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.
Author : Craig Quadrato
Publisher :
ISBN 13 :
Total Pages : 393 pages
Book Rating : 4.:/5 (739 download)
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:
Author : Anthony David Battistini
Publisher :
ISBN 13 :
Total Pages : 302 pages
Book Rating : 4.:/5 (664 download)
Download or read book Skewed Cross Frame Connection Stiffness written by Anthony David Battistini and published by . This book was released on 2009 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cross frames and diaphragms are essential to the stability of straight steel girder bridge systems as they help to resist lateral torsional buckling during construction and horizontal loading conditions. In skewed bridge systems, cross frames are often oriented parallel to the supports and hence, at an angle to the girder. To facilitate construction fit-up, plates, bent to match the skew angle, form the cross frame to stiffener connection. While the bent plate connection is a simple solution, it could introduce undesirable flexibility into the system, potentially compromising the effective brace stiffness. A proposed detail utilizing half pipe stiffeners may provide enhanced structural performance, while possibly reducing overall fabrication costs. Field and laboratory tests to determine the stiffness of both connection types are presented in the thesis.
Author : Cagri Ozgur
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (794 download)
Download or read book Influence of Cross-frame Detailing on Curved and Skewed Steel I-girder Bridges written by Cagri Ozgur and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Curved and skewed I-girder bridges exhibit torsional displacements of the individual girders and of the overall bridge cross-section under dead loads. As a result, the girder webs can be plumb in only one configuration. If the structure is built such that the webs are plumb in the ideal no-load position, they generally cannot be plumb under the action of the structure's steel or total dead load; hence, twisting of the girders is unavoidable under dead loads. The deflected geometry resulting from these torsional displacements can impact the fit-up of the members, the erection requirements (crane positions and capacities, the number of temporary supports, tie down requirements, etc.), the bearing cost and type, and the overall strength of the structure. Furthermore, significant layover may be visually objectionable, particularly at piers and abutments. : If the torsional deflections are large enough, then the cross-frames are typically detailed to compensate for them, either partially or fully. As specified in Article C6.7.2 of the AASHTO LRFD Specifications, different types of cross-frame detailing methods are used to achieve theoretically plumb webs under the no-load, steel dead load, or total dead load conditions. Each of the cross-frame detailing methods has ramifications on the behavior and constructability of a bridge. Currently, there is much confusion and divergence of opinion in the bridge industry regarding the stage at which steel I girder webs should be ideally plumb and the consequences of out-of-plumbness at other stages. Furthermore, concerns are often raised about potential fit-up problems during steel erection as well as the control of the final deck geometry (e.g., cross-slopes and joint alignment). These influences and ramifications of cross-frame detailing need to be investigated and explained so that resulting field problems leading to needless construction delays and legal claims can be avoided.
Author : Matthew Craig Reichenbach
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (134 download)
Download or read book Experimental and Analytical Evaluation of Cross-frame Fatigue Behavior in Steel I-girder Bridges written by Matthew Craig Reichenbach and published by . This book was released on 2020 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 bridge systems. They primarily act as stability braces to enhance the lateral-torsional buckling resistance of the girders during erection and deck construction, but also distribute live loads in the final composite condition. Under repetitive load cycles caused by heavy truck passages, cross-frames and their connections are susceptible to load-induced fatigue cracking if not properly designed. Cross-frames have historically been detailed and fabricated based on general rules-of-thumb and experience. In recent years, however, developments in bridge design specifications have necessitated the modernization of cross-frame design and analysis practices. Cross-frames are now designed and detailed based on rational analysis for all stages of construction and service life, which has further emphasized the importance of accurate and reliable analysis techniques and design criteria. Although considerable research over the past several decades has improved cross-frame design and analysis, the design industry has generally lacked quantitively based guidance on load-induced behavior of cross-frames in composite, in-service bridges. As such, this dissertation explores two major concepts: (i) the influence of skewed and curved superstructure geometry on the fatigue response of cross-frames and (ii) the limitations of simplified analysis techniques commonly utilized in commercial software programs with respect to estimating cross-frame force effects. Field experiments were performed on three steel I-girder bridges in the greater Houston area, and the stress ranges induced in key cross-frame members from truck traffic were monitored for one month each. Upon validating a finite-element approach with the measured data, an extensive analytical parametric study was conducted to expand the breadth and depth of knowledge gained from the limited field studies. In general, the load-induced fatigue behavior of conventional X- and K-type cross-frames were examined for a variety of bridge geometries commonly found in the United States. These analyses were performed with different levels of computational refinement, ranging from sophisticated three-dimensional approaches to simplified two-dimensional approaches. Based on the data collected and processed from the experimental and analytical studies, recommendations are proposed to improve the design and analysis of cross-frames in composite bridge structures. Because cross-frames represent a costly component of fabrication and erection, these recommendations ultimately lead to improved efficiency and economy of new steel bridge construction
Author : Asmaa Taha Ibrahim Abo Alouk
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.3/5 (797 download)
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.
Author :
Publisher :
ISBN 13 :
Total Pages : 279 pages
Book Rating : 4.:/5 (54 download)
Download or read book Cross Frame Diaphragm Fatigue and Load Distribution Behavior in Steel Highway Bridges written by and published by . This book was released on 1997 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Shane David Murphy
Publisher :
ISBN 13 :
Total Pages : 241 pages
Book Rating : 4.:/5 (823 download)
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:
Author : Weihua Wang
Publisher :
ISBN 13 :
Total Pages : 462 pages
Book Rating : 4.:/5 (858 download)
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.
Author : Wassef E. Elmir
Publisher :
ISBN 13 :
Total Pages : 502 pages
Book Rating : 4.:/5 (193 download)
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:
