Evaluation of Post-Tension Strengthened Steel Girder Bridge Using FRP Bars, 2003

Many state, county, and local agencies are faced with deteriorating bridge infrastructure composed of a large percentage of relatively short to medium span bridges. In many cases, these older structures are rolled or welded longitudinal steel stringers acting compositely with a reinforced concrete deck. Most of these bridges, although still in service, need some level of strengthening due to increases in legal live loads or loss of capacity due to deterioration. Although these bridges are overstressed in most instances, they do not warrant replacement; thus, structurally efficient but cost-effective means of strengthening needs to be employed. In the past, the use of bolted steel cover plates or angles was a common retrofit option for strengthening such bridges. However, the time and labor involved to attach such a strengthening system can sometimes be prohibitive. This project was funded through the Federal Highway Administration’s Innovative Bridge Research and Construction program. The goal is to retrofit an existing structurally deficient, three-span continuous steel stringer bridge using an innovative technique that involves the application of post-tensioning forces; the post-tensioning forces were applied using fiber reinforced polymer post-tensioning bars. When compared to other strengthening methods, the use of carbon fiber reinforced polymer composite materials is very appealing in that they are highly resistant to corrosion, have a low weight, and have a high tensile strength. Before the post-tensioning system was installed, a diagnostic load test was conducted on the subject bridge to establish a baseline behavior of the unstrengthened bridge. During the process of installing the post-tensioning hardware and stressing the system, both the bridge and the post-tensioning system were monitored. The installation of the hardware was followed by a follow-up diagnostic load test to assess the effectiveness of the post-tensioning strengthening system. Additional load tests were performed over a period of two years to identify any changes in the strengthening system with time. Laboratory testing of several typical carbon fiber reinforced polymer bar specimens was also conducted to more thoroughly understand their behavior. This report documents the design, installation, and field testing of the strengthening system and bridge.

Letter health consultation : Manganese emissions from Amsted Rail Company, Inc. (Griffin Wheel Facility) Keokuk, Iowa (2010)

This letter has been prepared as a consultation to evaluate human health impacts from manganese emissions from the Amsted Rail Company, Inc. (Griffin Wheel) facility located in Keokuk, Iowa. We understand your concern and the concern of the Keokuk community, and want you to know that the Iowa Department of Public Health’s priority is to ensure that you have the best information possible to safeguard the health of the citizens of Keokuk. That information is included in the following discussion.

Health consultation : Chicago Milwaukee and St. Paul rail yard targeted brownields assessment, Spring Valley Township, Perry, Dallas County, Iowa (2007)

The Iowa Department of Natural Resources (IDNR) has requested the Iowa Department of Public Health (IDPH) Hazardous Waste Site Health Assessment Program evaluate future health impacts of exposures at the formerly utilized Chicago Milwaukee St. Paul Rail Yard located on the west side of Perry, Iowa. This site has undergone a Targeted Brownfields Assessment conducted by the Contaminated Sites Section of the IDNR. This health consultation assesses potential health risks to people from future exposure to soil and surface water within the property boundary, and any health impacts resulting from contaminated groundwater beneath the site property from an evaluation of the data collected during the Targeted Brownfields Assessment. The information in this health consultation was current at the time of writing. Data that emerges later could alter this document’s conclusions and recommendations.

Remote Continuous Evaluation of a Bridge Constructed Using High-Performance Steel, 2006

Of the approximately 25,000 bridges in Iowa, 28% are classified as structurally deficient, functionally obsolete, or both. The state of Iowa thus follows the national trend of an aging infrastructure in dire need of repair or replacement with a relatively limited funding base. Therefore, there is a need to develop new materials with properties that may lead to longer life spans and reduced life-cycle costs. In addition, new methods for determining the condition of structures are needed to monitor the structures effectively and identify when the useful life of the structure has expired or other maintenance is needed. High-performance steel (HPS) has emerged as a material with enhanced weldability, weathering capabilities, and fracture toughness compared to conventional structural steels. In 2004, the Iowa Department of Transportation opened Iowa's first HPS girder bridge, the East 12th Street Bridge over I-235 in Des Moines, Iowa. The objective of this project was to evaluate HPS as a viable option for use in Iowa bridges with a continuous structural health monitoring (SHM) system. The scope of the project included documenting the construction of the East 12th Street Bridge and concurrently developing a remote, continuous SHM system using fiber-optic sensing technology to evaluate the structural performance of the bridge. The SHM system included bridge evaluation parameters, similar to design parameters used by bridge engineers, for evaluating the structure. Through the successful completion of this project, a baseline of bridge performance was established that can be used for continued long-term monitoring of the structure. In general, the structural performance of the HPS bridge exceeded the design parameters and is performing well. Although some problems were encountered with the SHM system, the system functions well and recommendations for improving the system have been made.

Midwest Regional Rail Passenger Initiative and Passenger Rail Service in Iowa status report

This report provides the status of the Passenger Rail Service Revolving Fund and the development and operation of the Midwest regional rail system and the state’s passenger rail service.

Laboratory Investigation of Bridge Strip Seal Joint Termination Details, SPR RB08-014, 2016

Bridge expansion joints, if not properly designed, constructed, and maintained, often lead to the deterioration of critical substructure elements. Strip seal expansion joints consisting of a steel extrusion and neoprene gland are one type of expansion joint and are commonly used by the Iowa Department of Transportation (DOT). Strip seal expansion joints are susceptible to tears and pull outs that allow water, chlorides, and debris to infiltrate the joint, and subsequently the bearings below. One area of the strip seal that is particularly problematic is where it terminates at the interface between the deck and the barrier rail. The Iowa DOT has noted that the initial construction quality of the current strip seal termination detail is not satisfactory, nor ideal, and a need exists for re-evaluation and possibly re-design of this detail. Desirable qualities of a strip seal termination detail provide a seal that is simple and fast to construct, facilitate quick gland removal and installation, and provide a reliable, durable barrier to prevent chloride-contaminated water from reaching the substructure. To meet the objectives of this research project, several strip seal termination details were evaluated in the laboratory. Alternate termination details may not only function better than the current Iowa DOT standard, but are also less complicated to construct, facilitating better quality control. However, uncertainties still exist regarding the long-term effects of using straight-through details, with or without the dogleg, that could not be answered in the laboratory in the short time frame of the research project.

Constant and variable amplitude fatigue strength of high strength steel welds treated with ultrasonic impact treatment

Hitsattujen rakenteiden väsymiskestävyyttä pystytään parantamaan jälkikäsittelymenetelmillä, joistayksi, ultraäänikäsittely muokkaa hitsin geometriaa ja aiheuttaa puristusjäännösjännitystilan. Tässä tutkimuksessa verrataan kokeellisesti kuormaa kantamattoman hitsatun ja ui -käsitellyn rivan väsymislujuutta toisiinsa. Tutkimusohjelmaan kuuluu kahta teräslajia ja sekä vakio - että vaihtuva - amplitudista kuormitusta. Ultraäänikäsittelyllä saavutetaan väsymiskestoiän parantuminen vakio - ja vaihtuva - amplitudisella kuormituksella. Perusaineen lujuudella ei ole merkittää vaikutusta väsymislujuuteen kun liitos on hitsatussa tilassa. Tällöin väsymiskestävyyden määrää hitsin rajaviivan jännityskeskittymä. Ultraäänikäsitellyn hitsatunliitoksen väsymiskestävyys on suurempi korkeamman lujuuden omaavilla teräksillä. Tästä syystä korkealujuuksisten terästen käyttö ultraäänikäsiteltynä väsyttävästi kuormitetuissa kevytrakenteissa on perusteltua.

Laser Cutting of Austenitic Stainless Steel with a High Quality Laser Beam

The thin disk and fiber lasers are new solid-state laser technologies that offer a combinationof high beam quality and a wavelength that is easily absorbed by metal surfacesand are expected to challenge the CO2 and Nd:YAG lasers in cutting of metals ofthick sections (thickness greater than 2mm). This thesis studied the potential of the disk and fiber lasers for cutting applications and the benefits of their better beam quality. The literature review covered the principles of the disk laser, high power fiber laser, CO2 laser and Nd:YAG laser as well as the principle of laser cutting. The cutting experiments were made with thedisk, fiber and CO2 lasers using nitrogen as an assist gas. The test material was austenitic stainless steel of sheet thickness 1.3mm, 2.3mm, 4.3mm and 6.2mm for the disk and fiber laser cutting experiments and sheet thickness of 1.3mm, 1.85mm, 4.4mm and 6.4mm for the CO2 laser cutting experiments. The experiments focused on the maximum cutting speeds with appropriate cut quality. Kerf width, cutedge perpendicularity and surface roughness were the cut characteristics used to analyze the cut quality. Attempts were made to draw conclusions on the influence of high beam quality on the cutting speed and cut quality. The cutting speeds were enormous for the disk and fiber laser cutting experiments with the 1.3mm and 2.3mm sheet thickness and the cut quality was good. The disk and fiber laser cutting speeds were lower at 4.3mm and 6.2mm sheet thickness but there was still a considerable percentage increase in cutting speeds compared to the CO2 laser cutting speeds at similar sheet thickness. However, the cut quality for 6.2mm thickness was not very good for the disk and fiber laser cutting experiments but could probably be improved by proper selection of cutting parameters.

Fiber Laser Cutting of Mild Steel

Fiber laser for materials processing have undergone a rapid development in the pastseveral years. As fiber laser provides a combination of high beam quality and awavelength that is easily absorbed by metal surfaces, the named future laser isexpected to challenge the CO2 and Nd:YAG lasers in the area of metal cutting. This thesis studied the performance of fiber laser cutting mild steel. In the literature review part, it introduced the laser cutting principle and the principle of fiber laser including the newest development of fiber laser cuttingtechnology. Because the fiber laser cutting mild steel is a very young technology, a preliminary test was made in order to investigate effect of the cutting parameters on cut quality. Then the formal fiber laser cutting experiment was madeby using 3 mm thickness S355 steel with oxygen as assistant gas. The experimentwas focused on the cut quality with maximum cutting speed and minimum oxygen gas pressure. And the cut quality is mainly decided by the kerf width, perpendicularity tolerance, surface roughness and striation patterns. After analysis the cutting result, several conclusions were made. Although the best result got in the experiment is not perfect as predicted, the whole result of the test can be accepted. Compared with CO2 laser, a higher cutting speed was achieved by fiber laser with very low oxygen gas pressure. A further improvement about the cutting quality might be possible by proper selection of process parameters. And in order to investigate the cutting performance more clearly, a future study about cutting different thickness mild steel and different shape was recommended.

A novel procedure for establishing clinching parameters for high strength steel sheet

The building industry has a particular interest in using clinching as a joining method for frame constructions of light-frame housing. Normally many clinch joints are required in joining of frames.In order to maximise the strength of the complete assembly, each clinch joint must be as sound as possible. Experimental testing is the main means of optimising a particular clinch joint. This includes shear strength testing and visual observation of joint cross-sections. The manufacturers of clinching equipment normally perform such experimental trials. Finite element analysis can also be used to optimise the tool geometry and the process parameter, X, which represents the thickness of the base of the joint. However, such procedures require dedicated software, a skilled operator, and test specimens in order to verify the finite element model. In addition, when using current technology several hours' computing time may be necessary. The objective of the study was to develop a simple calculation procedure for rapidly establishing an optimum value for the parameter X for a given tool combination. It should be possible to use the procedure on a daily basis, without stringent demands on the skill of the operator or the equipment. It is also desirable that the procedure would significantly decrease thenumber of shear strength tests required for verification. The experimental workinvolved tests in order to obtain an understanding of the behaviour of the sheets during clinching. The most notable observation concerned the stage of the process in which the upper sheet was initially bent, after which the deformation mechanism changed to shearing and elongation. The amount of deformation was measured relative to the original location of the upper sheet, and characterised as the C-measure. By understanding in detail the behaviour of the upper sheet, it waspossible to estimate a bending line function for the surface of the upper sheet. A procedure was developed, which makes it possible to estimate the process parameter X for each tool combination with a fixed die. The procedure is based on equating the volume of material on the punch side with the volume of the die. Detailed information concerning the behaviour of material on the punch side is required, assuming that the volume of die does not change during the process. The procedure was applied to shear strength testing of a sample material. The sample material was continuously hot-dip zinc-coated high-strength constructional steel,with a nominal thickness of 1.0 mm. The minimum Rp0.2 proof stress was 637 N/mm2. Such material has not yet been used extensively in light-frame housing, and little has been published on clinching of the material. The performance of the material is therefore of particular interest. Companies that use clinching on a daily basis stand to gain the greatest benefit from the procedure. By understanding the behaviour of sheets in different cases, it is possible to use data at an early stage for adjusting and optimising the process. In particular, the functionality of common tools can be increased since it is possible to characterise the complete range of existing tools. The study increases and broadens the amount ofbasic information concerning the clinching process. New approaches and points of view are presented and used for generating new knowledge.

Electromagnetic Design of a Solid Steel Rotor Motor for Demanding Operation Environments

The solid-rotor induction motor provides a mechanically and thermally reliable solution for demanding environments where other rotor solutions are prohibited or questionable. Solid rotors, which are manufactured of single pieces of ferromagnetic material, are commonly used in motors in which the rotationspeeds exceed substantially the conventional speeds of laminated rotors with squirrel-cage. During the operation of a solid-rotor electrical machine, the rotor core forms a conductor for both the magnetic flux and the electrical current. This causes an increase in the rotor resistance and rotor leakage inductance, which essentially decreases the power factor and the efficiency of the machine. The electromagnetic problems related to the solid-rotor induction motor are mostly associated with the low performance of the rotor. Therefore, the main emphasis in this thesis is put on the solid steel rotor designs. The rotor designs studied in thisthesis are based on the fact that the rotor construction should be extremely robust and reliable to withstand the high mechanical stresses caused by the rotational velocity of the rotor. In addition, the demanding operation environment sets requirements for the applied materials because of the high temperatures and oxidizing acids, which may be present in the cooling fluid. Therefore, the solid rotors analyzed in this thesis are made of a single piece of ferromagnetic material without any additional parts, such as copper end-rings or a squirrel-cage. A pure solid rotor construction is rigid and able to keep its balance over a large speed range. It also may tolerate other environmental stresses such as corroding substances or abrasive particles. In this thesis, the main target is to improve the performance of an induction motor equipped with a solid steel rotor by traditional methods: by axial slitting of the rotor, by selecting a proper rotor core material and by coating the rotor with a high-resistive stainless ferromagnetic material. In the solid steel rotor calculation, the rotor end-effects have a significant effect on the rotor characteristics. Thus, the emphasis is also put on the comparison of different rotor endfactors. In addition, a corrective slip-dependent end-factor is proposed. The rotor designs covered in this thesis are the smooth solid rotor, the axially slitted solid rotor and the slitted rotor having a uniform ferromagnetic coating cylinder. The thesis aims at design rules for multi-megawatt machines. Typically, mega-watt-size solidrotor machines find their applications mainly in the field of electric-motor-gas-compression systems, in steam-turbine applications, and in various types of largepower pump applications, where high operational speeds are required. In this thesis, a 120 kW, 10 000 rpm solid-rotor induction motor is usedas a small-scale model for such megawatt-range solid-rotor machines. The performance of the 120 kW solid-rotor induction motors is determined by experimental measurements and finite element calculations.

Automated formulation of optimisation models for steel beam structures

Over 70% of the total costs of an end product are consequences of decisions that are made during the design process. A search for optimal cross-sections will often have only a marginal effect on the amount of material used if the geometry of a structure is fixed and if the cross-sectional characteristics of its elements are property designed by conventional methods. In recent years, optimalgeometry has become a central area of research in the automated design of structures. It is generally accepted that no single optimisation algorithm is suitable for all engineering design problems. An appropriate algorithm, therefore, mustbe selected individually for each optimisation situation. Modelling is the mosttime consuming phase in the optimisation of steel and metal structures. In thisresearch, the goal was to develop a method and computer program, which reduces the modelling and optimisation time for structural design. The program needed anoptimisation algorithm that is suitable for various engineering design problems. Because Finite Element modelling is commonly used in the design of steel and metal structures, the interaction between a finite element tool and optimisation tool needed a practical solution. The developed method and computer programs were tested with standard optimisation tests and practical design optimisation cases. Three generations of computer programs are developed. The programs combine anoptimisation problem modelling tool and FE-modelling program using three alternate methdos. The modelling and optimisation was demonstrated in the design of a new boom construction and steel structures of flat and ridge roofs. This thesis demonstrates that the most time consuming modelling time is significantly reduced. Modelling errors are reduced and the results are more reliable. A new selection rule for the evolution algorithm, which eliminates the need for constraint weight factors is tested with optimisation cases of the steel structures that include hundreds of constraints. It is seen that the tested algorithm can be used nearly as a black box without parameter settings and penalty factors of the constraints.

Tandem-GMA Welding of Low Alloy Structural Steel

The Tandem-GMAW method is the latest development as the consequences of improvements in the welding methods. The twin-wire and then the Tandem-method with the separate power sources has got a remarkable place in the welding of many types of materials with different joint types. The biggest advantage of Tandem welding method is the flexibility of choosing both the electrodes of different types from each other according to the type of the parent material. This is possible because of the feasibility of setting the separate welding parameters for both the wires. In this thesis work the effect of the variation in three parameters on the weld bead in Tandem-GMA welding method is studied. Theses three parameters are the wire feed rate in the slave wire, the wire feed rate in the master wire and the voltage difference in both the wires. The results are then compared to study the behaviour of the weld bead with the change in these parameters.

Assessing intellectual capital in a research institute environment in steel industry

Diplomityön tavoitteena oli tutkia aineettoman pääoman hallintaa terästeollisuuden tutkimuslaitosympäristössä, sekä luoda mittaristo kuvaamaan sen tilaa ja kehitystä. Työn rajausten mukaan aineeton pääoma jaettiin Annie Brookingin jaottelun mukaan, ja tarkasteluun valittiin teollisoikeudet sekä henkilöstövoimavarat. Empiirinen osa työstä perustui pääasiassa haastatteluihin sekä Case –yrityksen sisäisiin julkaisuihin. Näitä pyrittiin tulkitsemaan kvalitatiivisten tutkimusmenetelmien oppien mukaan. Tutkimustulosten perusteella voidaan todeta teollisoikeuksien hyödyntämisen olevan suhteellisen vähäistä terästeollisuuden parissa. Syitä tähän on työssä käsitelty melko laajasti. Henkilöstön kehittäminen pitkällä tähtäimellä sekä tiedonkulun tehostaminen henkilöstön keskuudessa ovat puolestaan asioita, joihin kiinnitetään kyseisellä teollisuudenalalla kiitettävässä määrin huomiota. Työn loppupuolella esitelty aineettoman pääoman mittaristo tarjoaa yritykselle työkalun, jonka avulla voidaan monipuolisesti arvioida tätä yrityksille nykyisin elintärkeää asiaa. Lopullista ratkaisumallia se ei aineettoman pääoman mittaamiseen tarjoa, mutta luo kuitenkin tärkeän ensiaskeleen kohti tulevaisuuden yhä kehittyneempiä mittausmenetelmiä.

Roolit, vuorovaikutus ja päätöksenteko johtoryhmätyöskentelyssä, case Imatra Steel Imatran terästehdas

Tutkimus on luonteeltaan laadullinen ja sen tavoitteena on tarkastella johtoryhmätyöskentelyä ja päätöksentekoa roolien ja vuorovaikutuksen kautta. Roolit perustuvat havainnointitutkimukselle Imatra Steelin Imatran terästehtaan johtoryhmässä. Tutkimuksessa on lisäksi hyödynnetty teemahaastatteluja ja yrityksen dokumentteja, ja näin ollen aineistotriangulaatiota. Tutkimuksen painotus on empiirisellä osalla. Tutkimuksen avulla todetaan, että johtoryhmätyöskentely kohdeyrityksessä on perinteitä noudattelevaa ja keskittynyt informaation jakamiseen sekä toiminnan koordinointiin. Strateginen päätöksenteko ja dynaaminen johtoryhmätyöskentely ovat vähemmän painottuneita. Päätökset johtoryhmän kokouksissa syntyvät keskustelujen tuloksena puheenjohtajan tehdessä lopullisen ratkaisun.