This project addressed the goal of National Strategy for Surface Transportation Research to improve highway structures by enhanced materials, in particular by design and implementation of new, drastically improved steels with respect to strength, low-temperature fracture toughness, weldability, and weatherability. The goal of the project was to develop, standardize and commercialize a family of low-cost, high-performance steels for infrastructure applications. As a result we developed steels with yield strength of 50 to 80 ksi, with Charpy absorbed fracture energy significantly exceeding requirements of bridge construction codes at temperatures down to -100DGF, steels that are easy to weld without pre-heat or post-heat, steels that exhibit best weathering performance among other commercially available steels. In addition these steels are easy to produce; production does not involve any heat treatment or thermo-mechanically controlled processing which is available only to several US Steel companies. The steels developed in this project were commercially produced in the form of plate and wide-flange I-beams. The steels were used for seismic retrofitting of one bridge (in 2000) and for construction of two new bridges (in 2006 and 2010).

关键词：钢材；成本；营销；桥梁；建筑

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The thermal performance Rov of Flat-Plate Closed-Loop Pulsating Heat Pipe(FCLPHP) are effected by several elements such as the heat load Q, the tilt angle θ and the filling ratio F, they are interacted each other.In order to predict the effect of Q and θ on the thermal performance at locations Q and θ other than the experimental data conditions, and to study the relationship among the Rov, Q and θ in the range of the experimental data, we need a fitted regression model to estimate the function relationship that describes the data.The postulated depends on the range of the regression variables encountered in the data.In this paper, a simple model was developed.Since the coefficients in the model have been estimated from the experimental data, studies were carried out on an experimental set-up.FC72 was employed as working fluid.Method of least squares was used for building the model.By using the model, effects of the beat load and the tilt angle on the thermal performance of FCLPHP were discussed.It was found that the tilt angle had minimum value in a certain heat load in the experimental range (θ=30°-70°), and it increases with the increase of heat load.A sensitivity analysis was done with the model.

关键词：钢铁；脉动热管；热性能；整体热阻

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Multi-layered plates consisting of DH-36 steel coated by a thick layer of polyurea, for increased blast and impact protection, are of increasing importance to the Department of Defense. A hybrid approach of experiments and simulation was performed to characterize fracture and plasticity of DH-36 Navy steel, which is the first step in creating an accurate model of the composite material. The performance limit to this material during an impact is ductile fracture. The prediction follows that the onset of fracture occurs when a certain critical value of plastic strain is reached. This value is highly dependent on the state of stress. Seven different types of tests were performed, including tensile tests on dog-bone and notched specimens and punch indentation tests on circular blanks. Also, tensile and shear tests were performed on butterfly specimens using the dual actuator loading frame. Fracture surface strains were measured using digital image correlation. Local fracture strains were obtained by using an inverse engineering method of matching measured displacement to fracture with computer simulations. The results are used to calibrate the Modified Mohr Coulomb fracture model which is expressed by the stress state invariants of Lode angle and triaxiality.

关键词：钢铁;断裂（力学）;钢;海军;塑料涂料

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This article presents a new type of stress assessment method for double-layered pressure vessel. Due to its robust strength, a steel-concrete composite pipe is generally installed in poor burial conditions. However, it is difficult to directly define the stress state on pipe sections. For the convenient stress estimation of pipes encased in non-circular concrete, this article suggests a Stress Index (SI), a function of the interface pressure and changed diameter, based on the interface pressure. The ovalization characteristics of plain pipes and of pipes encased by circular and rectangular concrete are examined. The resultant stresses are replaced by the non-dimensional ratio of diameter change; thus, the stress index has the advantage of application for stress assessment irrespective of pipe characteristics.

关键词：钢铁；压力管道；压力指数；压力评估；界面压力

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The construction industry has historically made use of four materials: stone, timber, concrete, and steel. In recent years, civil engineers have been seeking alternative materials to steel and concrete that may be less vulnerable to environmental damage. Rising public concern about traffic delays experienced during construction have increasingly influenced civil engineers to seek materials and methods that allow more rapid construction. At the same time, costs must be competitive with traditional materials because of reduced public sector resources to maintain transportation infrastructure. Fiber-reinforced polymer (FRP) composites have emerged as an attractive potential alternative. Inspections of sign structures by the Florida Department of Transportation (FDOT) have revealed the occurrence of premature corrosion of galvanized steel structural members. As a result, FDOT engineers are also seeking alternative materials that may be employed in these structures.

关键词：建筑材料；石材；木材；混凝土；钢材

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The paper presents experimental data generated for calibrating finite element models to predict the performance of reinforced concrete panels with a wide range of construction details under blast loading. The specimens were 1.2 m square panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consisted of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bars; FRC panels without additional reinforcement; FRC panels with steel bars; NWC panels with glass fiber reinforced polymer (GFRP) bars; and NWC panels reinforced with steel bars and external GFRP laminates on both faces. Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. FRC panels with steel bars had the best performance for new construction. NWC panels reinforced with steel bars and external GFRP laminates on both faces had the best performance for strengthening or rehabilitation of existing structures. The performance of NWC panels with GFRP bars was strongly influenced by the bar spacing. The behavior of the panels is classified in terms of damage using immediate occupancy, life safety, and near collapse performance levels. Preliminary dynamic simulations are compared to the experimental results.

关键词：钢铁；混凝土；纤维；玻璃纤维；性能

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The paper presents changes of natural frequencies of industrial steel hall due to simplifications or changes of numerical model.Firstly,the natural frequencies were calculated for basic Variant A of the numerical model of the steel hall which consisted of the main frames,footings,roofpurlins and girts.In this Variant columns were fixed at bases,both purlins and girts were rigidlyconnected to main frames and designed as continuous beams.Then,in Variant B of the model columns were pinned at bases.Next,in Variant C different types of connections (semi-flexible joints)of roof purlins and girts with the main frame were implemented.Finally,in Variant D,soil-structure interaction was taken into consideration.The calculations of the dynamic characteristics of four abovementioned Variants of the numerical model of the hall showed that simplifications or changes of some details of the structure could result in significant errors in values of natural frequencies.

关键词：钢铁;固有频率;柔性接头;土结构相互作用

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Fracture toughness and fatigue properties of pipeline steels play a critical role in developing advanced high-pressure hydrogen infrastructure for alternative fuel pipelines program. The reliability of structure components, particularly resistance to damage and failure in the intended service environment, is highly dependent on the selected materials. An effective surveillance program is also necessary to monitor the material degradation during the course of service. Steels have been proven to be desirable for hydrogen infrastructure. However, hydrogen embrittlement is an important factor that limits steel performance under high-pressure hydrogen conditions. In order to reach the above goal, we have proposed an innovative technology, based on spiral notch torsion test (SNTT) methodology, to effectively investigate the material performance of X52 pipeline steel. The SNTT approach was successfully demonstrated and extended to X52 steels during the performance period. In addition to single notch front geometry, the crack growth behavior of the SNTT process has been effectively established using an integrated experimental, numerical and analytical approach. The results indicate that the proposed protocol not only provides significant advance in understanding the compliance evolution of the SNTT specimen, but also can be readily utilized to assist future development of hydrogen infrastructures. In FY2011, an extensive study was performed to characterize the fracture toughness degradation of AISI 4340 high-strength steel exposed to high-pressure hydrogen using in situ spiral notch torsion tests. This effort included equipment setup and calibration, sample design and fabrication, finite element simulation of the specimen fracture, and fractographic characterization using advanced microscopic techniques. The detailed description of the results is summarized in by Wang (Wang 2011).

关键词：管道；钢；断裂强度；缺口冲击试验

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The Commission instituted these reviews on June 3, 2013 (78 FR 33108,) and determined on September 6, 2013 that it would conduct expedited reviews (78 FR 59371, September 26, 2013).

关键词：钢铁；进口；碳素钢；钢管；焊件

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Severe localized corrosion of a 316 stainless steel autoclave occurred during investigating Type H Portland cement stability in 0.16 M CaCl(sub 2) + 0.02 M MgCl(sub 2) + 0.82 M NaCl brine in contact with supercritical CO(sub 2) containing 4O(sub 2). The system operated at 85 C and pressure of 29 MPa. However, no corrosion was observed in the same type of autoclave being exposed to the same environment, containing Type H Portland cement cylindrical samples, also operating at pressure of 29 MPa but at 50 C. The operation time for the 85 C autoclave was 53 days (1272 hours) while that for the 50 C autoclave was 66 days (1584 hours). Debris were collected from the base of both autoclaves and analyzed by X-ray diffraction (XRD). Corrosion products were only found in the debris from the 85 C autoclave. The cement samples were analyzed before and after the exposure by X-ray florescence (XRF) methods. Optical microscopy was used to estimate an extent of the 316 stainless steel corrosion degradation.

关键词：腐蚀;不锈钢;高压蒸汽灭菌器;盐水

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