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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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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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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This paper presented the results of testing reinforced concrete beams strengthening with the BFRP sheets. Five specimens were cast and tested. All specimens were 2600 mm total span with a cross section of 150mm width and 250mm depth. Out of the specimens, two specimens were designed as reference specimens. The rest specimens were repaired with the BFRP sheets. The variables examine in the experiment were the longitudinal tensile reinforcement ratio, the different layers of the BFRP sheets and the anchoring measures of BFRP sheets. All specimens were tested under simply supported condition. 3D nonlinear finite element (FE) numerical models by ANSYS10.0 software were conducted to accurately predict the ultimate bearing capacity and response of reinforced concrete specimens strengthening with BFRP sheets subjected to four-point bending loading. The nonlinear constitutive material properties of concrete and steel reinforcement were considered in the finite element model. The results of the FEM simulation were compared with that of the experimental specimens. The results showed that it was significantly effective for the flexural capacity of the BFRP sheet-bonded reinforcement in tensile zone for reinforced concrete beams. Moreover, it implied excellent results on the stiffness of the reinforced concrete beams. The flexural strength enhancement of the reinforced concrete beams strengthening with the BFRP sheets varied between 19% ~ 44% over the control beam. This study further identified that the BFRP sheet technique significantly enhanced the stiffness and flexural capacity of reinforced concrete beams.

关键词：增强复合材料（BFRP）；钢筋混凝土梁（RC）；承载力

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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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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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Accurate estimates of bearing stiffnesses are often necessary for bridge design and construction calculations. In the case of steel-reinforced elastomeric bearing pads, the compression stiffness or roll stiffness is sometimes difficult to estimate because of complex deformations of the elastomer. A method of numerical analysis for estimating the axial and roll stiffnesses of bearing pads is presented. To validate the axial calculation method, experimental compression tests were performed on pad specimens constructed in accordance with Florida design standards. A method for calculating roll stiffness is also presented in which the pad is modeled as a grillage of compression-only axial springs. The grillage method was partially derived from roll stiffness data measured in a separate experimental study. The grillage method was demonstrated to accurately capture both the nonlinear moment-rotation behavior caused by liftoff of the girder from the pad and the observed sensitivity of roll stiffness to initial compressive loading caused by self-weight of the girder. Reductions in roll stiffness that are caused by girder slope relative to the pad were also examined.

关键词：轴承刚度；精确估计；钢铁

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The influence of yttrium on the corrosion resistance of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of fuel oil containing 10 wt. % of biocomponents has been studied at 1173K under thermal shock conditions. These experiments have been carried out by rapid heating of the studied materials up to 1173K and after two hours cooling down to room temperature. These thermal shocks have been repeated hundreds of times, determining after every shock the mass changes of the corroded samples. It has been found that small amount of yttrium deposited on the steel surface using electrochemical treatment considerably improves the scale adherence and consequently corrosion resistance in the case of X33CrNiMn23-8 steel, containing the highest chromium concentration.

关键词：阀门钢；腐蚀；燃烧气体；;热冲击；钇效果

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The spatial structure of sintered metal powders is described by many qualitative and quantitative micro-geometrical properties. The statistical approach based on univariate and multivariate distributions is very useful for consistent and objective description of such structures. It provides information appropriate for a whole population of sinters, not only particular specimen. Empirical distributions of quantitative properties obtained from the image analysis are very irregular and for this reason inconvenient for further numerical simulations. The smoothing of these distributions is required for data conditioning and preprocessing however, the use of simple regression techniques is limited due to the strict lower and upper bound of cumulative distribution function. Authors propose to use a multilayer perceptron as a non-parametric regression model because of its the well-known smoothing properties. The technical application of such model requires additionally providing of the confidence band or any equivalent measure of uncertainty. The highly non-linear structure of the neural network model makes not possible to use typical linear techniques to estimate variance. Additionally, the simple confidence band estimation leads to non-physical values of the cumulative distribution function: lower than 0 or greater than 1. Authors propose to avoid such difficulties by two methods. Firstly, the lower and upper bound limitation are satisfied by the logit transformation which projects the range into unlimited real range. Secondly, the variance of the neural network model is estimated by jackknife estimator. The article presents such approach with preliminary attempt to an automated data processing by ADCIS Aphelion image analysis software and STATSOFT Statistica data analysis software. The almost full automation of the process is required by materials science engineers due to the lack of the sufficient data processing knowledge and skills. Both software systems provide suitable embedded programming environments: C# for Aphelion and Visual Basic for Statistica. The proposed approach has been tested on the example of pore size distribution in sintered stainless steel AISI 434L.

关键词：神经网络逼近；准确估计；重叠

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The Auger export pipelines are connected to the TLP by steel catenary risers (SCRs). This is believed to be the first time steel pipe has been used for catenary risers. SCRs offer advantages over tensioned risers, since SCRs need no heave compensation and no subsea connections, and over risers made of "flexible pipe", since SCRs are much less expensive. However, significant design effort was required to prove that the SCRs could safely withstand environmental loads and the effects of TLP motions. The design effort consisted of extensive dynamic analyses as well as full scale fatigue testing of both the riser joint welds and the flexible joint that connects the riser to the TLP pontoon. Devices which suppress vortex induced vibrations were also tested. SCR installation is accomplished by lowering the riser on the abandonment and recovery cable from the J-Lay installation vessel and transferring the riser on a chain that is run through a chain jack hung from the TLP upper deck structure. A special Installation and Maintenance System was built for this purpose.

关键词：出口管道；立管接头焊缝；钢铁

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