Search Results for bridge support columns

Composites, particularly fiber-reinforced polymer materials, are increasingly being adopted or considered as alternatives to conventional materials for civil infrastructure applications, such as bridges, buildings, waterfront structures, waste treatment facilities, and facilities for transmission and transport of utilities. This article provides information on seismic retrofit applications and discusses the repair and strengthening of components, such as beams, slabs, large-diameter pipes, and bridge decks.

This article discusses the generic situation of steel reacting with the environments found in structures. Two environments are specifically discussed: atmospheric and cementitious. The article describes the utility of different corrosion protection methods for atmospheric corrosion and cementitious systems. It presents examples of problems that have arisen in the corrosion performance of steel.

This article describes the paint systems generally used to protect steel structures, steel sheet, and bridges from corrosion, and how they deter corrosion. It provides a discussion on the basic design criteria of steel structures for corrosion protection. The article also explains the differences between prepaint and postpaint, and the steps involved in prepaint processing of steel. It presents the selection guideline for paint system evaluation. The advantages of corrosion protection are also discussed.

This article illustrates the use of the American Petroleum Institute (API) 579-1/ASME FFS-1 fitness-for-service (FFS) code (2020) to assess the serviceability and remaining life of a corroded flare knockout drum from an oil refinery, two fractionator columns affected by corrosion under insulation in an organic sulfur environment, and an equalization tank with localized corrosion in the shell courses in a chemicals facility. In the first two cases, remaining life is assessed by determining the minimum thickness required to operate the corroded equipment. The first is based on a Level 2 FFS assessment, while the second involves a Level 3 assessment. The last case involves several FFS assessments to evaluate localized corrosion in which remaining life was assessed by determining the minimum required thickness using the concept of remaining strength factor for groove-like damage and evaluating crack-like flaws using the failure assessment diagram. Need for caution in predicting remaining life due to corrosion is also covered.

This article commences with a schematic illustration of a wide range of cutter configurations available for use in milling operations. It describes the various types of milling machines classified based on the type of construction, such as knee-and-column type, bed-type, planer-type, and special type. The article discusses mechanical-electric, mechanical-hydraulic, mechanical-electric-hydraulic, and numerical control of milling machines. It describes various types of milling cutters, such as peripheral mills, face mills, end mills, and special mills. Milling cutters, such as solid milling cutters, inserted-blade cutters, and indexable-insert cutters, are also discussed. The article explains the capabilities and limitations of peripheral milling, face milling, and end milling methods. It concludes with a comparison of milling with broaching, planing or shaping, and grinding.

This article provides a basic overview of bridge corrosion, where it occurs on steel and concrete bridge structures, and how to prevent corrosion by using coatings. It describes types of bridge designs, with illustrations, and presents information on how corrosion occurs in different bridge zones and areas, with illustrations. The article concludes with a discussion on the common methods of coating systems applications on bridge structures and key elements in coating condition assessment.

Rehabilitation is the process of repairing or modifying reinforced concrete structures to a desired useful condition. This article describes the operational steps for the structural assessment of reinforced concrete structures. It discusses the classification of composite materials reinforcing systems for strengthening reinforced concrete structures, such as shop-manufactured and field-manufactured structures. The article reviews the materials property requirements for designing reinforcing systems to strengthen the reinforced concrete structures. It discusses the fiber-reinforced polymer (FRP)-reinforced concrete behavior that depends on flexural, shear, or axial failures. Surface preparation procedures for rehabilitation techniques of reinforced concrete structures using bonded FRP materials are also discussed. The article provides information on the applications of rehabilitation of concrete structures. It explains data recording and acceptance criteria for rehabilitation of concrete structures with composite materials.

This article illustrates the defects, which result because of poor-quality welds in the bridge components. The cracks resulting from the use of low fatigue strength details are also discussed. The article describes the effect of out-of-plane distortion in floor-beam-girder connection plates, multiple-girder diaphragm connection plate, and tied-arch floor beams.

Arc welding is one of several fusion processes for joining metals. This article introduces the fundamentals of arc welding and provides a summary of its history and early discoveries.

Bridges and highways are core components of transportation system and range from pavements with earth, gravel, or stone covered by a thin bituminous surface course to a continually reinforced Portland cement concrete (PCC) roadway with or without a bituminous wear course. This article provides information on bridges and dowels and the reinforcement used in PCC roadways that suffer from corrosion. An overview is provided on the rise in awareness of the corrosion issues affecting bridges and highways. The chemistry and structure of concrete and its role as an electrolyte in promoting corrosion are also discussed. The article addresses reinforcement, including conventional, prestressed, cable stays, and corrosion-resistant reinforcement. It deals with the electrochemical methods for the inspection and corrosion control of embedded reinforcement. The article also reviews the corrosion of metal bridges and corrosion control, including the use of weathering steels and coating systems.

Weathering steels contain deliberate additions of alloying elements intended to increase the atmospheric corrosion resistance of steel. This article provides an overview of atmospheric corrosion testing. It describes the estimation of the atmospheric corrosion behavior of weathering steels by two methods such as short-term exposure tests and calculation of a corrosion index based on the steel composition. The article highlights some generalities about corrosion mechanisms. Based on the mechanism of atmospheric corrosion resistance of weathering steel, working rules for creating the protective oxide film have evolved. The article also provides case histories that illustrate both the violations of these rules and suggestions on how to avoid certain maintenance problems that may be encountered with weathering steels.

This article describes the criteria for selecting a corrosion-monitoring method used in industrial plants. It provides a detailed discussion on the design, advantages, and disadvantages of plant corrosion-testing program. The basic types of racks used to support and insulate the coupons are also discussed. The analysis of electrical-resistance probes, sentry holes, side-stream loop, electrochemical noise, hydrogen-probe, and process streams are used to monitor and estimate corrosion rates. The corrosion rates can also be estimated by ultrasonic thickness measurements, polarization-resistance measurements, corrosion potential measurements, and alternating current impedance measurements. Corrosion monitoring strategies, such as locations, data analysis, redundancy, and other issues, are discussed. The article concludes with information on the interpretation and reporting of corrosion testing.

Additive manufacturing (AM) offers expansive design freedoms for realizing parts that are more complex and customized than their conventionally fabricated counterparts, but all AM technologies impose restrictions on buildable geometries and features. Design rules capture those restrictions in the form of best practices to successfully design for AM. This article discusses how design rules can potentially support and accelerate the process of developing part geometry for AM. The discussion provides examples of design rules that are independent of any specific AM process and then discusses design rules specific to particular AM processes.

Boring is a machining process in which internal diameters are generated in true relation to the centerline of the spindle by means of single-point cutting tools. This article provides a discussion on boring machines and boring tools and presents a comprehensive discussion on the various elements of boring. The elements are composition and hardness of workpiece metal, cutting fluid, speeds and feeds, and methods for piloting and supporting tools in boring applications. The article explains the role of workpiece size in selecting the equipment and processing procedure and the use of techniques to overcome difficulties presented by workpiece configuration. It describes the factors related to accuracy of boring and factors affecting them. The article also presents a discussion on close-tolerance boring and methods of controlling vibration and chatter. It concludes with a section presenting information on the use of boring equipment for machining operations other than boring.

Eddy-current inspection is based on the principles of electromagnetic induction and is used to identify or differentiate among a wide variety of physical, structural, and metallurgical conditions in electrically conductive ferromagnetic and nonferromagnetic metals and metal parts. This article discusses the advantages and limitations of eddy-current inspection, as well as the development of the eddy-current inspection process. It reviews the principal operating variables encountered in eddy-current inspection: coil impedance, electrical conductivity, magnetic permeability, lift-off and fill factors, edge effect, and skin effect. The article illustrates some of the principal impedance concepts that are fundamental to understanding of and effective application of eddy-current inspection. It discusses various types of eddy-current instruments, such as the resistor and single-coil system, bridge unbalance system, induction bridge system, and through transmission system. The article concludes with a discussion on the inspection of aircraft structural and engine components.

Planing is a machining process for removing metal from surfaces in horizontal, vertical, or angular planes. This article discusses the process capabilities of planing and the operations of double-housing and open-side planers. It reviews workpiece setup procedures, including platelike workpieces, irregularly shaped workpieces, and workpieces used for tandem planning. The article provides information on the applications of high-speed steels and carbides in planer tools. It analyzes the tools available in a variety of configurations suited to the undercutting, slotting, and straight planing of either horizontal or vertical surfaces. These include carbide roughing, finishing, gooseneck-holder finishing, and double-cutting tools. The article lists recommended speeds and feeds for planing with high-speed steel or carbide tools. It concludes with a comparison of planing with sawing and milling.

Microjoining with high energy density beams is a new subject in the sense that the progress of miniaturization in industry has made the desire to make microjoints rapidly and reliably a current and exciting topic. This article summarizes the current state of microjoining with both electron and laser beams. It considers the elementary physical processes such as heat and fluid flow to introduce the reader to the phenomena that affect melting, coalescence, and solidification needed for a successful microweld. The various forces driving (and resisting) fluid flow are analyzed. The article discusses the equipment suitable for microjoining and the metallurgical consequences and postweld metrology of the process. It also provides examples of developmental welds employing laser and electron beam microwelding techniques.

Braided structures are unique in their high level of conformability, torsional stability, and damage resistance. This article describes the classifications of braiding such as two-dimensional braiding and three-dimensional braiding. It presents the governing equations for computer-controlled braiding in a table. The article lists the applications of braided fabrics and composites. It discusses the formation, structure, and properties of two-dimensional braid composites and three-dimensional braid composites: the damage tolerance and the impact damage limitation.

The chemical composition of Kevlar aramid fiber is poly para-phenyleneterephthalamide. Para-aramid fibers belong to a class of materials known as liquid crystalline polymers. This article discusses the manufacture of aramid fibers and the major fiber forms, such as continuous filament yarns, rovings, woven fabrics, discontinuous staple and spun yarns, fabrics, and pulp. Key representative properties of para-aramid fibers are listed in a table. The article reviews the properties of aramid fibers, including tensile modulus, tensile strength, creep and fatigue, compressive properties, toughness, thermal properties, as well as electrical and optical properties. It concludes with a discussion on the environmental behavior of para-aramid fibers.

This article is a pictorial guide to forms of corrosion that draws attention to common pitfalls or situations that have caused premature corrosion, sometimes with expensive consequences. The examples used are not exhaustive; they highlight the necessity to fully examine materials, conditions, and specific circumstances that together can reduce the anticipated service life of a component or plant. The color images in this article are categorized according to the type of corrosion following the general order that is adopted in Volume 13A of ASM Handbook. The first table of the article provides a categorization of the forms of corrosion. It also provides a reference to articles or sections of articles in Volume 13A that detail the particular corrosion form or mechanism. The second table is a guide listing the figures in this article by material and by the corrosion form or mechanism illustrated.