I need this information for a project I have on NDT applications on bridges. I couldn't find any actual cases to show the significance of these tests.
129732
Well, NDT won't prevent problems on bridges. It only identifies potential problems once the work has been constructed. If you are referring to NDT on materials prior to the release of construction documents / design, you need to go either to state agencies, or to the engineering firms that design them.\n\nTry getting a hold of the Big Dig construction managers for the city / state. I hear that they are doing extensive NDT to try to detect materials problems. You may also want to try the new Potomic Crossing Authority (or something close to that) in DC regarding their new bridge, and CalTrans for their bay bridge in SF.\n\nNDT information is usually only available to the engineers, you can try an FOIA request to see if they will let the information out.
149300
I honestly don't know. I always wanted to find out though. Is there a valid test available that doesn't charge for the results? It would be an interesting thing to see.
380890
An OTDR works by firing light down a fibre optic cable and then measuring the levels of reflected light and knowing the time it takes for the reflected light to be sensed it can tell how far the point of reflection is. They operate in a very similar fashion to radar and are designed to pick up faults in fibre optic cables, be they joints/splices, pressure faults, or clean breaks as these will all reflect light back down the fibre. The principles are also the same for radar in that the shorter the pulse the better the discrimination and the more accurate the outcome. In some case in fibre fault finding the operators of the OTDR will introduce faults on the fibre by submersing it in liquid nitrogen and then using it as a reference point to find the true fault. Having worked in fields where its not easy to find a fault with excavating kilometres of earth the nitrogen method is a god send if somewhat damaging to the cable.
423731
When sound (or other waveform of similar shape, like an AC signal) travels through a medium, its intensity diminishes with distance. In idealized materials, signal amplitude is only reduced by the spreading of the wave. Natural materials, however, all produce an effect which further weakens the sound. This further weakening results from scattering and absorption. Scattering is the reflection of the sound in directions other than its original direction of propagation.  Absorption is the conversion of the sound energy to other forms of energy.  The combined effect of scattering and absorption is called attenuation.  Ultrasonic attenuation is the decay rate of the wave as it propagates through material.\n\nAttenuation of sound within a material itself is often not of intrinsic interest. However, natural properties and loading conditions can be related to attenuation. Attenuation often serves as a measurement tool that leads to the formation of theories to explain physical or chemical phenomenon that decreases the ultrasonic intensity. \n\nThe amplitude change of a decaying plane wave can be expressed as:\n\n A = A0*e^(-kz)\n\nIn this expression "A0" is the amplitude of the propagating wave at some location. The amplitude "A" is the reduced amplitude after the wave has traveled a distance "z" from that initial location. The quantity "k" is the attenuation coefficient of the wave traveling in the z-direction. The dimensions of are nepers/length, where a neper is a dimensionless quantity. The term "e" is Napier's constant which is equal to approximately 2.71828. \n\nAttenuation is generally proportional to the square of frequency. Quoted values of attenuation are often given for a single frequency, or an attenuation value averaged over many frequencies may be given. Also, the actual value of the attenuation coefficient for a given material is highly dependent on the way in which the material was manufactured. Thus, quoted values of attenuation only give a rough indication of the attenuation and should not be automatically trusted. Generally, a reliable value of attenuation can only be obtained by determining the attenuation experimentally for the particular material being used.\n\nThis is why higher-frequency signals tend to produce what is called "skin effect" ... basically, the energy isn't there for the wave to penetrate to any significant depth.
655099
http://www.allaboutcircuits.com/vol_6/chpt_7/5.html\nhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/nandlatch.html
1522
it has to do with estimating the steel weight (of a pipe)
176653
Not sure this helps....there are other pages at this Portland Cement Assn site.  Browse around this site.\n\nhttp://www.cement.org/countonconcrete/Wall%20Systems%20Backgrounder.pdf
597119
1 ksi = 1000 psi\n\nWhat do your points represent and how did you get that answer?\n\nLater...\nE= stress * length/deflection, or force*length/(deflection*area)\nIf the tester was zeroed, your result is non-linear - .004 deflection for the first 150# and .006 for the next 150#. Could indicate yielding - or slipping. If you're sure of your work, check the data and the setup.
60844
As far as the issue is concerned that it broke because they wanted it to break, in structural engg such testing doesnt suggest that something is weak and should not make press headlines in that case.\n\nBut if this news is out there, it means that there are some structural issues with the wing or its joints or something like that. And discussion on these can be done based on exact technical data which will be with Airbus Engineers.\n\nIt would be too vague to comment whether or not there will be requirement for major modifications. I think it answers your questions
384510
This link for a PDF File in Rapid Share website, it a book called "Bridges Design Manaual"\n\nI hope it will help you.\n\nhttp://rapidshare.de/files/37074217/bridgedesignmanual.rar
651143
You could get a civil or mechanical engineering Forensics book (see below).\n\nMath is commonly used in traffic accident reconstruction.  Examples:\nMomentum and collisions\ndistance, speed, and time\nwork and energy\nmaximum braking distance\nCenters of Mass\nCoefficient of Friction\nCollision dynamics\nImpact analysis\nTrajectory\nAnanlysis of Variance\nSequence of events\n\nI'd say the most interesting of these is the braking distance thing.\nIt is common that accident reconstructionists will calculate braking distance and compare their results to the length of the skid marks left by a car that was stopping fast.  In this way they can determine if the vehicle was speeding or not.
322545
Working Stress Method\n• Material is assumed to behave elastically.\n• The allowable stresses are obtained by dividing the limiting stresses of material by factor of safety.\n• Ignores uncertainties in different types of load.\n• Does not use the full range of strains in the material.\n• Therefore, disregards the nonlinear part of the material\ncurve.\n• Considers failure as a function of stress while it is a\nfunction of strain.\n• Stress as a measure of safety does not give true margin of\nsafety against failure. A stress factor of safety 3 for\nconcrete does not mean that the member will fail at a load\nthree times the working load.\n• The structure must carry loads safely. It is logical to use\nthe method based on load causing failure.\n• The additional load carrying capacity of the structure due\nto redistribution of moment can not be accounted for.\n• Produces conservative designs.\n\n\n\nUltimate Load Method\n• The loads are enhanced by load factor-\n• Design load = LF * service load\n• The method uses total stress-strain curves of the\nmaterial.\n• Strain based failure.\n• LF=3 means the structure has 3 times more\ncapacity\n• Since the method considers the plastic region of\nthe stress-strain curve also, it utilizes the reserve\ncapacity of the member.\n• Uncertainty in load only is considered. Uncertainty\nin material is ignored.
483797
Emplacement Gantry ITS Standards Identification Study Rev 00A, ICN 00\n\n800-3OR-HEOO-00200-000-OOA\n\n \nApril 2005 \n\n\n\n1. PURPOSE AND SCOPE \nTo date, the project has established ITS performance requirements for SSCs based on identification and \ncategorization of event sequences that may result in a radiological release. These performance \nrequirements are defined within the NSDB. Further, SSCs credited with performing safe functions are \nclassified as ITS. In turn, perform confirmation for these SSCs is sought through the use of consensus \ncode and standards. \nThe purpose of this study is to identify applicable codes and standards for the WP Emplacement Gantry \nITS SSCs. Further, this study will form the basis for selection and the extent of applicability of each code \nand standard. \nThis study is based on the design development completed for LA only. Accordingly, identification of ITS \nSSCs beyond those defined within the NSDB are based on designs that may be subject to further \ndevelopment during detail design. Furthermore, several design alternatives may still be under \nconsideration to satisfy certain safety functions, and that final selection will not be determined until \nfurther design development has occurred. Therefore, for completeness, throughout this study alternative \ndesigns currently under considered will be discussed. Further, the results of this study will be subject to \nevaluation as part of a follow-on GAP analysis study. \nBased on the results of this study the GAP analysis will evaluate each code and standard to ensure each \nITS performance requirement is fully satisfied. When a performance requirement is not fully satisfied a \n“gap” is highlighted. Thereafter, the study will identify supplemental requirements to augment the code or \nstandard to meet performance requirements. Further, the GAP analysis will identify non-standard areas of \nthe design that will be subject to a Development Plan. Non-standard components and non-standard \ndesign configurations are defined as areas of the design that do not follow standard industry practices or \ncodes and standards. Whereby, performance confirmation cannot be readily sought though use of \nconsensus standards. \nThe ITS codes and standards identified in this document were developed by the Yucca Mountain Project \npersonnel from the Emplacement & Retrieval Project and are intended solely for the use of the Design \nand Engineering group in its work regarding the Emplacement and Retrieval system, specifically \nidentification of Emplacement and Retrieval equipment codes and standards. \n2. QUALITY ASSURANCE \nThis document was prepared in accordance with LP-ENG-014-BSC, Engineering Studies. The results or \nthis document are only to be used as the basis for selection of applicable codes and standards and are not \nto be used directly to generate quality products. Therefore, this engineering study is not subject to \nrequirements of the Quality Assurance Requirements and Description document (DOE 2004). \n3. USE OF COMPUTER SOFTWARE \nComputer software used, Microsoft Word 2000, in this study is classified as exempt from procedure \nLP-SI.11Q-BSC, Software Management. All software used to prepare this analysis is listed under Section \n2.1 Software Not Subject To This Procedure, of LP-SI.11Q-BSC, Software Management. \n4. EMPLACEMENT GANTRY FUNCTIONAL DESCRIPTION \nThe function of the waste package emplacement gantry, is to maneuver a waste package and its associated \nemplacement pallet, from the bedplate of the waste package transporter positioned at the emplacement \ndrift dock, to the final emplacement position of the waste package within the emplacement drift. The \n\nsame waste package emplacement gantry can be used for waste package and pallet retrieval, where the \nprocess, is a reversal of the emplacement procedure. \nThe gantry design is that the waste package emplacement gantry will be an electrically powered, self-\npropelle
410215
in no way whatsoever ( it is not accurate enough for court ) sorry for the pause - at work\n\neven if we ever get a test that is 100% accurate the effect will be minimal \n\nwe would not use it in crime solving ( self incrimination ) nor in business ( right to privacy )
175932
You may be talkig about a square, sine, and sawtooth (triangle) waveforms. They look like their names imply on an oscilloscope. They have no special significance other than they are descriptive of the type of AC wave they describe. It is like asking what are the different colors and what are their significance?
171146
Try this website; it has several links:\nhttp://www.answers.com/main/ntquery?s=Methods+of+soil+testing&gwp=11&ver=1.0.2.84&method=2
199508
The ultimate strength of a beam is found by US = max load/CSA.  There's not a lot of math to it, but you do need to measure pretty carefully.\n\nThere comes a problem, however, where some materials "stretch" before actually failing, thus making the measurement of the max load difficult.  As an example, if you've ever pulled plastic wrap apart, it gets easier at a point right before it breaks into two.  The point where after you pull on it and it gets easier is called the yield strength.  After you pass the yield strength, you don't need as much force to cause failure in the material.\n\nNow in steel, the yield and ultimate strengths are pretty close to each other that the above discussion really doesn't affect it if you are trying to break a beam on your own.  But the ultimate strength of steel is probably something you can look up in a table somewhere.  Then you can use the above formula to see how much your beam can take based on the US and the cross sectional area.