Powder coatings are used in free-flowing powder form; they differ from water/solvent-borne coatings in that they do not need a liquid suspension base.

关键词：西欧；粉末涂料；液体悬浮液；高效能；环保

查看摘要 索取原文[85页]

The French five-point bending (5PB) test provides a laboratory-scale test that allows studying the fatigue resistance of surfacing systems on orthotropic steel deck (OSD) bridges. The surfacing structure for OSD bridges in the Netherlands is mostly a multilayer system: top porous asphalt (PA) layer, guss asphalt (GA) layer, steel deck, and two membrane layers. In this paper, an analytical solution for the 5PB test setup is presented first. To understand better the influence of geometrical, mechanical, and structural parameters on the performance of the typical multilayer surfacing system of OSD bridges in the Netherlands, the 5PB test specimens with five structural layers have been investigated. The parametric study was performed at the numerical platform CAPA-3D, which was developed at the Section of Structural Mechanics of the Delft University of Technology. The thicknesses of the top PA layer, middle GA layer, and the steel plate were varied. The influences of the mechanical properties of both top and bottom membrane layers were studied. The sensitivities of those influence factors were evaluated by examination of the maximum tensile stress at the top surface of the PA layers and the strain distributions through the entire thickness of the specimen at two cross sections.

关键词：五点弯曲；钢铁；抗疲劳性

查看摘要 索取原文[8页]

Chloride ion ingress is an important parameter that helps estimate the durability and service life of reinforced concrete (RC) and prestress concrete (PC) structures, especially in those structures exposed to marine environments and salts applied during the winter season for traffic safety. Current techniques used to detect chloride content and monitor the level of corrosion in RC and PC structures, such as acoustic emission (AE), fiber optics, and electrochemical measurements, are time consuming, and invasive. In addition, they require external power sources, complex test setups, are expensive to implement, and often, it is difficult to interpret the data recorded in the field. In an effort to overcome these restrictions, an inexpensive, wireless corrosion detector sensor based on commercial radio frequency identification (RFID) technology that does not need to be powered by a local source of energy, has been developed by an Oklahoma State Universitys research team. The purpose of the first phase of this project was to implement this innovative RFID corrosion sensor into a new bridge construction to collect data during monitoring to study both the reliability and field performance of the sensor in-situ and under laboratory conditions. The laboratory work attempted to correlate the sensors sensitivity to the level of corrosion in the structure. Phase II of this work will be focused on the long-term monitoring of the sensors installed in the field for a period of approximately 10 years.

关键词：外加剂；氯化物；混凝土路面；钢铁

查看摘要 索取原文[31页]

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

查看摘要 索取原文[11页]

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

查看摘要 索取原文[20页]

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

查看摘要 索取原文[9页]

A data base of 84 pile load tests was developed for steel pipe piles, driven in clay (small amounts of sand near the surface for a few tests), where there was sufficient data to estimate effective overburden pressures with reasonable accuracy, where soil strengths were well defined, and where a load-settlement curve was available for the load test. Measured pile capacities were compared with values predicted using five methods that have been, are being, or potentially may be used in engineering practice. The two lambda methods had the least scatter but tended to overpredict capacities by about 20%. The current API method had slightly more scatter but overpredicted capacities by only about 13% on the average. The two alpha methods had the largest scatter and the greatest differences between measured and predicted capacities.

关键词：荷载试验；钢铁；负载沉降曲线

查看摘要 索取原文[19页]

To develop an effective software for finite element (FE) model updating of bridges, the interface technology between VC++ and MATLAB was investigated firstly, and then a software for updating FE model of bridges, named 'Doctor for Bridges' (version 1.0) was developed. Finally, a model ofconcrete-filled steel tube arch bridge was applied to verify the performance and effectiveness of the proposed software.

关键词：桥梁；有限元模型修正；接口技术

查看摘要 索取原文[10页]

The flutter stability of the steel truss suspension bridge is hard to reach the requirement of the wind resisting stability when lacks the torsional stiffness.This paper discusses the influence of aerodynamic measure combination,such as central stabilizer,air director enclosed anti-collision bar and so on,towards the flutter stability of steel truss through the wind tunnel experiment of the bridge of Liu Jia gorge.The result shows:the effect of using both the upper and lower stabilized plate is better than separated used it.when sectionalized dispose upper stabilized plate,the flutter critical wind speed of attack angle will decrease rapidly.Outlaying the horizontal guide plate is better than internally installed; The flutter stability of different attack angle tend to be balanced by widening the horizontal guide plate.The anti-collision bar can be functionalized as the central stabilizer by heightening and enclosing,and effectively increase the critical wind speed of different attack angles of the high truss suspension bridge.

关键词：悬索桥；风洞试验；抗风措施；钢铁

查看摘要 索取原文[4页]

The objective of this research is to evaluate the feasibility to employ quantitative acoustic emission (AE) techniques for monitoring of fatigue crack initiation and propagation in steel bridge members. Three A36 compact tension steel specimens were tested in the laboratory according the ASTM E647. AE sensor networks were deployed and recorded AE during the fatigue-type loading. Noise from the load application points represented a significant challenge. However, a number of events could be located and for a selected few a moment tensor inversion (MTI) was performed. Despite the challenges, the methodology has been completely established and evaluated, and can be used in future testing.

关键词：声探测;桥梁（结构）；裂纹扩展；裂纹（断裂）

查看摘要 索取原文[47页]