In contrast to composite long rods, composite post insulators are subjected mainly to loads which act perpendicular to the longitudinal axis of the insulator and thus produce bending stresses over the cross-section of the insulator. These bending stresses reach their maximum value at the point at which the FRP rod is fixed in the metal fitting (circled in red in Fig. 3.1), the latter being located where the insulator is attached to the support structure, whether this be the cross-arm of a steel lattice tower for an overhead transmission line, the coupling plate of a tubular steel or concrete pole, or the platform in a pole-mounted substation. Calculation of these bending stresses is discussed in detail in Sect. 3.9.

关键词：复合长棒；绝缘体；钢铁

查看摘要 索取原文[43页]

Illinois, like many other large states, has several microclimates where temperature and rainfall can vary. These variations can affect the corrosion rates of sign and signal structures, light poles, and other highway structures. Each atmospheric zone, whether they are rural, semirural, suburban, industrial, or marine areas, may be subjected to salt fall or salt spray, which can affect metals or coatings after prolonged exposure. These highway structures are typically fabricated from weathering steel, galvanized steel, painted steel, or aluminum. Each of these metals and their coatings bear a fabrication cost and have distinct ranges of durability in different atmospheres. Rural and semi-rural atmospheres cause the least corrosion damage to metal and coated surfaces. Suburban environments generally have moderate effects, compared to industrial and saline areas, which have the most corrosive atmospheres. Weathering steels have greater durability in moderate and many industrial atmospheres compared to carbon steels, such as ASTM A36 or SAE 1020. The cost differences between ASTM A36 and ASTM A588 vs. the ASTM A710 Grade 50 steel described in this report are small. Based on data obtained from WorldSteelPrices.com, as of July 2013, the price of ASTM A36 was about $0.295 per lb compared to $0.340 per lb for ASTM A588. Because A710 has slightly higher nickel and copper contents than A588, its cost is estimated to be about $0.36 per lb, based on a metric tonne.

关键词：涂料；耐腐蚀；损害；钢铁

查看摘要 索取原文[54页]

The structural reliability analysis is the widely accepted method for bridge safety assessment. Identification the subset of significant failure modes is the most important part of system reliability estimation. In this paper, a stage critical strength branch and bound algorithm is proposed for the failure mode identification of bridge systems. The innovative method is implemented in the combination with the finite element package ANSYS and the MATLAB procedure. The suggest method is applied to a concrete filled steel tubular (CFST) arch bridges. The results reveal various combinations of the failure modes in significantly reduced time and efforts in comparison to the previous permutation method. Additionally, the suggested method can be used for the verification of the system reliability with more specific predictions of the failure mode.

关键词：拱桥；故障模式；识别策略；交通负荷

查看摘要 索取原文[9页]

Bridge foundations contribute significantly to the serviceability and efficiency of in-service transportation networks. Foundation failure may lead to catastrophic failure of the entire structure, which in turn results in system failure, loss of life, and detours. When the soil within ground surface layers fails to satisfy the bearing capacity requirements, deep foundations such as tubular-steel concrete-filled piles are commonly used in practice. A challenge that often exists with these systems is the uncertainty surrounding in-service capacity as well as condition, which is difficult to determine from the surface. As a consequence, transportation agencies such as the Wisconsin Department of Transportation use conservative approaches, such as neglecting the tubular-steel contribution or bounding the compressive strength of the core concrete, to design these systems. This approach, while effective for safety, can yield overly conservative and costly designs. The main purpose of this investigation was to evaluate the behavior of tubular-steel, concrete-filled, cast-in-place pilings, with a concentration on the compressive strength and composite behavior between concrete core and steel shell. In this regard, a series of experimental studies, including composite and noncomposite compression loading, core samples, push-through, and flexural testing together with a compatible finite element analysis, were conducted on a series of field-cast piles with different geometrical properties. The results indicated that the steel shell made a significant contribution to the axial loading capacity of the cast-in-place piles. Moreover, no evidence of bond loss was observed during the corresponding experimental studies.

关键词：管状钢铸；钢铁；打桩

查看摘要 索取原文[11页]

In recent decades, bridge fires have become a major concern in the U.S. Fire hazard in bridges can result in significant economic and public losses. New construction of bridges often use Weathering Steel (also known as Corten Steel), which has a corrosion-retarding effect since the steel forms a protective rust layer on its surface under the influence of the weather. To date, no information exists on the high temperature mechanical properties of weathering steel. The objective of this work is to develop a database of mechanical properties of A588 weathering steel that has been exposed to high temperatures. These properties include the residual (after heating and cooling) stress-strain, fracture toughness, and surface hardness. The parameters that are investigated include temperature (800 degrees F, 1000 degrees F, 1200 degrees F, and 1500 degrees F), cooling methods (in air (CIA), and in water (CIW), representing fire-fighting effects), and material. Experiments are also done in a steady-state elevated temperature condition. A comparison is made between A588 weathering steel, used widely for bridges, and another material whose chemical composition and mechanical properties allows it to be classified by ASTM as both an older weathering steel (A242), a steel commonly used in building construction (A992), and also a non-weathering steel used for bridges (A709 Grade 50).

关键词：桥梁（构）筑物；化学成分；腐蚀；钢铁

查看摘要 索取原文[35页]

The development length of reinforcements embedded into ultra-high performance concrete (UHPC) can be significantly shorter than the lengths normally associated with conventional concrete. Shortening the development length of prestressing strand can allow for a redesign of some structural systems, including spliced girder and continuous-for-live-load bridges. Ultra-high performance concrete (UHPC), when used in field-cast connections between prefabricated bridge elements, can create robust connections which emulate monolithic components. This study investigated the development length of 0.5 and 0.6 inch (12.7 and 15.2 mm) diameter untensioned prestressing strands embedded in steel fiber and PVA fiber reinforced UHPC. The volumetric fiber content was 2 percent. A novel tension test method allowed for replication of the tension-tension stress state that would occur when two strands are lap spliced within a connection between two linear elements. The results suggest that, for the steel fiber reinforced UHPC, the 0.5 inch (12.7 mm) diameter strands can be fully developed within 20 inches (0.51 m) and the 0.6 inch (15.2 mm) diameter strands can be fully developed in approximately 24 inches (0.61 m). The 0.5 inch (12.7 mm) diameter strands can be fully developed in the PVA fiber reinforced UHPC in approximately 36 inches (0.91 m).

关键词：高强度混凝土；钢绞线;桥梁；纤维增强混凝土

查看摘要 索取原文[46页]

Austenitization is a solid-phase transformation process accompanied by nucleation and nucleus growth controlled by long-range carbon diffusion. In our work, a method was developed for constructing spheroidite model structures in such a way that their different parameters (the size of ferrite grains, the average value of carbon concentration, the size of cementite spheroids) could be changed optionally. In addition, a nucleation model of free energy base was created by which the difference between the two different places of nucleation can be distinguished on the basis of their free energy. The effects of structure parameters, interface free energies and temperature on the nucleation rate of austenite were investigated by cellular automaton simulations.

关键词：奥氏体化；成核速率；球状渗碳体；元胞自动机

查看摘要 索取原文[8页]

Based on the shape detecting principle and the digital signal technology,a new shape meter was developed thorough theoretical analysis and industrial adjustment to develop the shape detecting roll,the shape signal processing method,the original signal compensation mechanism and so on.The shape meter has good performance and stability,which can effectively avoid the scratchof steel strip surface,accurately detect real online strip shape and provide accurate online shape datum for shape control system.It was applied in 1250 mm cold rolling mill,the actual industrial tests prove that the shape signal was stable and reliable,met the harsh condition and the online technical requirements,and could improve shape quality significantly.

关键词：板形仪；形状检测；形状控制；冷轧带钢

查看摘要 索取原文[5页]

The world shipbuilding industry since the beginning of the last century with flux cored wire material.Since the flux cored wire material use welding materials has developed into a more efficient submerged arc welding consumables and gas shielded welding welding consumables and can be more easily combined with automated welding and robot welding.So far,flux cored material applications favored.Gas shielded arc welding consumables mainly divided solid wire and flux cored wire,flux cored wire applications has increased year by year because of its practicality and efficiency.Flux cored wire as the main welding consumables trends,especially in the thick carbon steel plate welded favored.In order to understand the nature of the thick-walled components weld cracking and produces original Due on a thick-wailed T-joints butt weld ultrasonic flaw found Two crack metallographic and SEM fracture analysis.

关键词：药芯焊丝材料；气体保护；焊接裂纹

查看摘要 索取原文[5页]

High hard armor steels are used on many tactical vehicles, such as the Stryker and the mine-resistant, ambush-protected vehicle. Although they provide good protection against armor-piercing threats, these steels corrode rapidly without the use of a good corrosion protective coating. Corrosion on military ground vehicles increases the infrared signal from the vehicle that the topcoat camouflage usually inhibits, making the vehicle more vulnerable to detection by the enemy. Stryker vehicles are prohibited from using hex-chrome and are currently coated without any pretreatment or conversion coating. The products demonstrated here will satisfy the hexavalent chrome prohibition while minimizing environmental impact and worker safety. This demonstration plan is designed to generate the data necessary for authorization and implementation decisions by appropriate authorities within the U.S. Department of Defense.

关键词：护甲；腐蚀；六价铬；高硬度装甲腐蚀

查看摘要 索取原文[98页]