<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3ARbmdxsqy" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>Assessment of Provisions for Load Rating Gusset Plates in Steel Truss Bridges</title><link>http://pubsindex.trb.org/view/1872060</link><description><![CDATA[Many states have load rated their truss bridge gusset plates following the guidelines published in 2009 by the Federal Highway Administration in response to the catastrophic failure of the I-35W Bridge. As the Manual of Bridge Evaluation released new load rating provisions after 2014, the urgency in adopting and applying these mandated provisions became a pending burden for state agencies requiring extensive work to update the ratings of gusset plates. Moreover, this paper argues that the current states’ load rating practices do not involve the rating for the welded gusset plate owing to the lack of established provisions. In addition, the gusset plate with no plans also poses particular challenges for the state agencies. To provide state agencies with better insights on the load rating approach of gusset plates, this paper presents a study that carefully reviewed the states’ current practices and load rating provisions. The results of the study indicate the necessity of adopting the new provisions, as the former load rating methodology exhibited inaccurate results in some cases. Additionally, this paper reviews extensive work done for welded connections and proposes a load rating guidance for welded gusset plates. To deliver better interpretations, a case study is provided for the welded gusset plates. This paper also reviews the evaluation method for deteriorations and staggered bolt patterns with relevant case studies. Lastly, the paper provides guidance on estimating the unknown bolt strength as well as weld metal strength for the gusset plate.]]></description><pubDate>Sun, 15 Aug 2021 18:07:22 GMT</pubDate><guid>http://pubsindex.trb.org/view/1872060</guid></item><item><title>Fatigue Resistance of Minnesota's Traffic Signal Structures</title><link>http://pubsindex.trb.org/view/776444</link><description><![CDATA[In recent years, there has been increasing numbers of research projects to determine the fatigue resistance of welded details used in traffic signal poles and mast arms. The impetus being the publishing of the revised American Association of State and Highway Transportation Officials (AASHTO) design standards in 2001. Many of the details in the design standard are thought to have been assigned unnecessarily conservative fatigue categorizations, which was based on little or no full-scale testing. This paper will present results from fatigue resistance testing of two common details used in the State of Minnesota's traffic signal structural designs. These being the fatigue resistance of multi-sided tube-to-plate connections, as well as the built-up box connections for bolting a mast arm to a pole.]]></description><pubDate>Thu, 08 Jun 2006 11:26:05 GMT</pubDate><guid>http://pubsindex.trb.org/view/776444</guid></item><item><title>FATIGUE ASSESSMENT OF CABLE SYSTEMS OF LONG-SPAN CABLE-STAYED BRIDGES</title><link>http://pubsindex.trb.org/view/450978</link><description><![CDATA[Cable systems of a cable-stayed bridge consist of cable and cable anchorage.  Cable tension caused by prestress, dead load, and live load acts directly on the cable anchorage.  In addition to direct tension, bending deformation caused by live load, temperature changes, and wind load act on the anchored stay cables.  Furthermore, wind-induced oscillations may be considered.  Because the cable tension and bending deformation occur repeatedly, it is necessary to verify fatigue behavior. The structural details of cable anchorages are complex, making it difficult to evaluate their fatigue resistance.  Therefore, fatigue tests were conducted on full-scale specimens that include proposed anchorages and cables to examine their performance.  The obtained results show that fatigue cracks initiated at the welded toe of the bearing plate to anchor web plates were caused by plate bending; therefore, some refinements of structural details are necessary.  The bending fatigue strength of semi-parallel wire cables socketed by two types of anchorage were both proved to be sufficient for use as stay cables for an 870-m span cable-stayed bridge.]]></description><pubDate>Wed, 06 Sep 1995 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/450978</guid></item><item><title>DESTRUCTIVE TESTING OF TWO 80-YEAR-OLD TRUSS BRIDGES</title><link>http://pubsindex.trb.org/view/425263</link><description><![CDATA[Two decommissioned 80-year-old steel truss bridges were subjected to a series of nondestructive and destructive tests. The trusses had built-up members that were rigidly connected by rivets at the gusset plates.  The floor system, many truss members, and the connections exhibited considerable deterioration.  The bridges were retrofitted at critical connections by welding A36 plates on the pre-A7 steel.  Both bridges exhibited acceptable performance during the tests at all the limit states.  One bridge yielded initially at 371 tons and failed at 415 tons.  The other bridge yielded initially at 458 tons, and failure could not be induced under as much as 622 tons because of displacement limits in the loading equipment.  The test results revealed that serviceability, damageability, and failure behavior of steel truss bridges possessing built-up members rigidly connected by rivets at the gusset plates are not adversely affected by local deterioration.  The built-up members and the connections possessed adequate deformability permitting extensive redistribution.  Connection retrofit by welding plates was feasible and successful.]]></description><pubDate>Mon, 01 May 1995 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/425263</guid></item><item><title>FATIGUE BEHAVIOR OF VARIABLE LOADED BRIDGE DETAILS NEAR THE FATIGUE LIMIT</title><link>http://pubsindex.trb.org/view/282332</link><description><![CDATA[The findings of the current NCHRP Project 12-15(5), "Fatigue Behavior of Variable Loaded Details Near the Fatigue Limit," are highlighted.  The main focus of the research is the examination of welded bridge details in the high-cycle, long-life regime.  Large-scale plate girders with coverplate, web attachment, and web stiffener details are subjected to fatigue loading that simulates actual truck traffic.  A Rayleigh type stress spectrum is used with the inclusion of an occasional overload exceeding the constant-amplitude fatigue limit.  The frequencies of occurrence being considered for the overloads are 0.1, 0.05, and 0.01 percent.  Prior research indicated that fatigue crack propagation occurred even when the effective stress range was below the constant-amplitude fatigue limit and the exceedance rate of the limit was as low as 0.1 percent.  The current test specimens also allow for a detailed study of distortion-induced fatigue cracking at a connection plate web gap detail.  Results indicate that the retrofit method of drilled holes at the crack tip is inadequate at high levels of distortioon.  In addition to the experimental work, a review of fatigue test data generated around the world since the AASHTO fatigue provisions were adopted in 1974 was completed.  This study has allowed for a reassessment of the provisions.  A summary of the proposed revisions to the specifications is given.]]></description><pubDate>Tue, 31 May 1988 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/282332</guid></item><item><title>FATIGUE BEHAVIOR OF FULL-SCALE WELDED BRIDGE ATTACHMENTS</title><link>http://pubsindex.trb.org/view/161041</link><description><![CDATA[This report contains the findings of NCHRP Project 12-15(3). The objective of this study was to examine the fatigue strength of beams with web and flange lateral attachment plates.  In addition to providing a more comprehensive data base for this type of detail, the program was intended to examine the influence of lateral bracing members on the out-of-plane distortion of the lateral plates.  Further work also was undertaken during the experimental studies on the effectiveness of peening and gas tungsten arc remelting the fatigue-damaged connections and on the ability of drilled holes to arrest crack growth.  A total of 18 beams, each with three welded gusset plate details, were tested in fatigue with stress ranges of 6 to 15 ksi. Several other details were welded to the girder web in order to simulate beam flanges framing into a web plate.  The results of these tests were used to assess the adequacy of the applicable provisions of the AASHTO specifications. In addition, the influence of lateral bracing on the fatigue performance of the attachments was evaluated. Recommendations for modifications to current practice are included in the report.]]></description><pubDate>Wed, 15 Apr 1981 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/161041</guid></item><item><title>IMPORTANCE OF REDUNDANCY IN BRIDGE-FRACTURE CONTROL</title><link>http://pubsindex.trb.org/view/146518</link><description><![CDATA[Because of component redundancy, riveted structures have tended to be fail-safe.  It has been far less important to be aware of the limits of fatique and brittle fracture in riveted structures than in welded structures, which are generally not component fail-safe.  In the change from riveted to welded-plate girders, the safety factor protecting against brittle fracture in nonredundant load-path structures has weakened.  The inherent crack stoppers at interfaces between components of riveted structures do not exist in structures that are welded or repaired by welding.  Designers must therefore design fabricators must produce, and inspectors must examine relatively crack-free structures and ensure that they will not develop large cracks during their service lives.  This safe-life approach is an absolute requirement for nonredundant load-path structures.  Several examples of cracked structures that have not collapsed because of redundancy are given, and the effect of welded repairs is dicussed.  The paper illustrates the redundancy of several simple trusses with a discussion of bridge fires.  Strict application of these guidelines will force many designers to change to redundant load-path or component-redundant structures (e.g., bolted) in many instances, particularly in the short-span range, as alternatives to the additional material that may be required to avoid fracture. /Author/]]></description><pubDate>Wed, 30 Jan 1980 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/146518</guid></item></channel></rss>