The discovery in the 1980's of local brittle zones (LBZ's) in and near the heat-affected zone (HAZ) of the fabrication welds in certain offshore platform steels caused great concern among the engineers and welding specialists of the period and led directly to the preparation and adoption of API RP2Z in May 1987 of Recommended Practice for Preproduction Qualification for Steel Plates for Offshore Structures. This recommended practice describes a procedure by which steel producers could prequalify their product in advance of purchase and delivery and thereby reduce the risk of steel plate being delivered to the jobsite which would exhibit weldability problems from the standpoint of low HAZ toughness or HAZ cracking problems when using typical and conventional welding procedures, i.e., the need for extensive fracture toughness testing by the fabricator on each weld procedure was eliminated in favor of a more sophisticated one-time test program in the laboratory of the producer. This recommended practice covers two areas: (1) testing weld HAZ for toughness using CTOD tests and (2) delayed cracking tests using the controlled thermal severity test (CTS) and Y-groove test. This RP was developed for use with API steel specifications 2H, 2Y, and 2W. Most of the effort has been toward the quantification of API 2Y and 2W steels in thicker sections s4" (100 mm). This program has been scientifically successful albeit with a significant penalty of time and cost to the steel producer. There has been sufficient standardization that various purchasers have and will accept the same qualification performed previously for another job. This, of course, is exactly what API standards are intended to accomplish. API RP2Z was revised in 1992 and is currently being reviewed for a second revision intended to reduce some of the conservatism built into the original document by our lack of full understanding of the embrittling mechanisms in the HAZ of welded structural steels but now strongly supported by a substantial data base of good material. The paper discusses some of the proposed changes and contains data on the currently achievable fracture toughness levels.

关键词：海洋平台；钢铁；断裂韧性

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The transformation of the solidification microstructure in AISI M2 grade high-speed steel inoculated with powder addition of WC have been studied focusing on the effect of austenitisation. In order to investigate the kinetics of both the microstructure and phase transformations in eutectic carbides, primarily M_2C carbide decomposition, upon heat treatments with respect to diffusion processes, electron scanning microscopy, XRD analysis and EDS have been used.

关键词：高速钢；热处理；结构体；碳化物

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In recent decades, orthotropic steel decks (OSDs) have been routinely incorporated into long-span bridges. The most widely used method to reduce stress concentration, improve fatigue performance, and control crack propagation is to cut out the diaphragms (or subfloor beams) into which the OSDs frame. However, the capital cost of cutout fabrication in the United States is high and may not be economically feasible. Study is required of cost-effective modified design details without cutouts as well as comparisons with their corresponding flexural and fatigue performance against current design details that use cutouts. Alternative design details (e.g., deck ribs welded directly to the transverse diaphragms using full-penetration welds) with thicker deck plates, but without cutouts, were investigated for potential improvements in fatigue resistance and capital cost. A parametric study was conducted with calibrated finite element models of a portion of the Bronx-Whitestone Bridge in New York City to study the effects of cutouts, deck plate thickness, and other important parameters on fatigue performance. Various traffic load combinations and truck types were considered with the use of an elaborate weigh-in-motion database. Results detail the equivalent stress ranges at critical locations in the OSDs that were calculated to quantitatively estimate fatigue lives for two OSD models: one with cutouts and one without. On the basis of these comparisons, recommendations related to overall structural performance were made to ensure a safe and rational design for various OSD options in long-span bridges.

关键词：正交异性钢桥；钢铁；桥面

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This paper presents a field investigation of pullout resistance of steel anchors in rock. The field testing involves pullout tests of six steel anchors installed in biotite gneiss rock by gravity grouting and pressure grouting methods. The field pullout tests suggest a progressive failure mechanism, which was manifested through the progressive elongation of the bond zone. The pressure-grouted anchors yielded higher pullout resistance than did the gravity-grouted anchors. The increase in rock-grout bond strength from pressure grouting is likely due to a combination of several factors including the resultant higher grout strength, higher rock-grout contact stresses, and grout injected under pressure into the fractures/fissures that existed in the bedrock.

关键词：岩石钢锚；钢铁；抗拔力

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Two kinds of welding methods,including SMAW and GTAW,were employed to connect 16MnR steel and 2205 steel.OM and TEM was used to observe the microstructure.EDX line scan was used to analyze elements in special areas of the joint.The results show that the degree of carbon migration in the side of 16MnRofthe seam welded by GTAW is larger than that by SMAW.Particle and chain-island are two maiin form of Fe3C in micro-area of carbon migration.The grain size of seam material in GTAW section is larger than that of SMAW and the content of austenitic of seam material in GTAW section is more than that of SMAW.The tongues in the side of 16MnR appear in both two seams welded by SMAW and GTAW and they are parts from base metal.

关键词：异种钢；焊接方法；热输入；微观结构

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The 2007 edition of AASHTO LRFD Bridge Design Specifications contains prescriptive requirements for the quantity and placement of confinement reinforcement located in the bottom bulb of pretensioned concrete Ⅰ-girders. The proposed model can be used to design confinement reinforcement as an alternative to AASHTO's prescriptive requirements. The model considers a range of Ⅰ-girder conditions and variations, yet is intended to be practical enough for use by bridge design engineers. Variables in the design model include flange and bearing geometry, strand size and placement, effective prestress force, concrete and steel material properties, and the effects of steel bearing plates. The model is based on strut-and-tie and shear-friction concepts and considers the lateral-splitting failure mode. Derivation of the model is presented, and the model is compared with experimental results from the published literature.

关键词：桥梁设计；钢铁；混凝土

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The State Loop 481 steel truss bridge over the Llano River in Junction, Texas, is classified as a historic structure. The bridge is approximately 1,423 ft long and has a railing that attaches directly to the steel truss members and does not meet the current AASHTO Test Level 2 (TL-2) strength requirements. Many supporting truss members were not adequate to resist TL-2 crash force. The purpose of this research was to design a crashworthy retrofit bridge rail that met the current AASHTO TL-2 strength requirements without overstressing the supporting truss members. The new design maintains the historic appearance of the structure. This paper presents details of the new bridge rail design and an analytical procedure for determining the magnitude of force transmitted to the supporting truss members. Crushable-pipe blockouts located between the new retrofit rail design and the truss members were developed as part of this research and were used to minimize the crash force transmitted to the steel truss members. The new bridge rail design was successfully crash tested in accordance with the TL-2 requirements of NCHRP Report 350. A bridge rail expansion splice was developed for the new bridge rail design and was successfully crash tested in accordance with the Test Level 3 requirements of NCHRP Report 350. This paper presents the results of this research, details of the expansion splice, the new bridge rail design, the design procedure, and the results of the crash testing.

关键词：铁路桥梁；钢铁；钢桁梁桥

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A new chloroacetic-acid modified imidazoline (CAMI) was synthesized via the quaternization of imidazoline intermediate,obtained from the amidation and cyclization reactions of benzoic acid and diethylene triamine,with chloroacetic-acid.The performance of the synthesized compound CAMI as corrosion inhibitor for Q235 carbon steel in 5％ sulfuric acid solution was investigated by weight loss measurement and potentiodynamic polarization technique.The results show that CAMI possesses strong inhibitive effect on the corrosion of Q235 carbon steel in acid medium and restrains the corrosion without changing the cathodic and anodic corrosion mechanism as a mixed-type inhibitor.

关键词：季铵化咪唑啉；缓蚀剂；失重法；极化曲线

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Structural Health Monitoring has great potential to provide valuable information about the actual structural condition and can help optimize the management activities. However, few effective and robust monitoring methods exist which hinders a nationwide use of SHM in structural condition evaluations. The objective of this project was to research and develop methods for structural identification and damage detection based on strain monitoring using long-gauge fiber-optic sensors. In particular two universal parameters of beam-like structures were studied in detail: the neutral axis and deformed shape. Data from two structures were used for validation purposes: from on-site monitoring of the US202/NJ23 overpass and from lab testing of a scale-model of a similar structure. The conclusions are that while the neutral axis varies during dynamic events, it changes the location due to damage, and it can be located accurately using a probabilistic approach. Thus, it can be used as a damage sensitive feature. At least two sensors per cross-section are necessary for an accurate evaluation of the location of the neutral axis. The vertical displacement of beams can be calculated by double integration of the curvature. However, the double integration method affects the accuracy of the evaluation, and to achieve the most accurate result a linear combination of integration methods is recommended. At least three locations along each girder should be instrumented with two parallel sensors for accurate evaluation of the vertical displacement. The methodologies researched in this project are presented in this report and recommendations for the use of the methods provided.

关键词：复合材料；纤维光学；钢筋混凝土；钢铁

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A new project to analyse neutrino features is under development within the frame of the High Intensity Neutrino Oscillation EURONu project [1]. The final shape of the magnetic horns supporting system is proposed. This system is designed for four horns joined in one assembly. For the support structure a search for the optimal parameters is made with respect to the static loads. After that dynamic analysis is performed, this is used, if necessary, for the final tuning of the designing parameters. The above approach is investigated for two different materials used for the support system.

关键词：磁喇叭；中微子振荡颗粒；支持系统

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