Inspection Guidelines for Bridge Post-Tensioning and Stay Cable Systems Using NDE Methods (2017)

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27 Condition Assessment of Post-Tensioning and Stay Cable Systems Introduction This chapter presents information critical for the condition assessment of post-tensioning and stay cable systems. This chap- ter, along with the various supporting appendices presented, could be used for the condition assessment post-tensioning and stay cable systems. The results and discussions about the various NDE methods that are considered in this chapter are based on the evaluation of the full-scale PT girder specimen and the large-scale stay cable specimens. The NDE techniques were used for identifying both strand and grout defects which included corrosion, section loss, breakage, compromised grout, voids, and water infiltration. This chapter reviews the three types of inspection, includ- ing Tier 1, 2, and 3 inspections, followed by the qualifications, responsibilities, and training requirements of the inspectors for the evaluation of post-tensioning and stay cable systems. Planning, scheduling, and the inspection equipment are dis- cussed next. This is followed by the development of the eval- uation metrics for the various NDE methods. The weighted categories considered in this metrics are defined and dis- cussed. The weight factors for two scenarios that were used in this investigation are also discussed. The flowcharts that are developed for the evaluation of a particular defect condi- tion, the ranking, and the decision-making process are briefly discussed. Finally the testing procedures for the various NDE methods are discussed. Types of Inspection Bridge inspections may be broadly classified as Tier 1, 2, or 3 inspections, based on their scope and level of detail. The types of inspections are briefly discussed below. Tier 1 Bridge Inspections Routine maintenance inspection. This level of inspection is typically a routine visual inspection and is performed on the system/network level. Tier 1 inspection typically provides some indication of the existence of damage. Tier 2 Bridge Inspections Detailed component condition inspection. This level of inspection is historically nonroutine and is performed on the project/element level following a recommendation from a Tier 1 inspection. Tier 2 inspections (which can be both destruc- tive and nondestructive) typically provide some indication of damage existence, localization, and/or severity. Tier 3 Bridge Inspections Material testing inspection. This level of inspection is project/ element level and typically follows a Tier 2 inspection where destructive or nondestructive methods suspect deterioration conditions to be present. Tier 3 inspections typically provide some indication of remaining service life and may include mate- rial tests such as tensile tests, chloride concentration, gamma ray spectroscopy, positive material identification, lift-off test, etc. Qualifications, Responsibilities, and Training Requirements of Inspectors The qualifications, responsibilities, and training require- ments of the inspectors for the condition assessment of post- tensioning and stay cable systems are briefly discussed here. Qualifications of Inspectors The inspections for the condition assessment of post- tensioning and stay cable systems should be performed by well qualified inspectors. The lead inspector should meet the quali- fications for a Team Leader specified in the National Bridge Inspection Standards. The inspector should be fully aware of the operational principles of the NDE technology and make C h a p t e r 5

28 necessary adjustments to the inspection technique, if the situa- tion warrants. Apart from being qualified to operate the equip- ment for inspection, the inspector should also be well equipped with using the required data analysis software and techniques for the proper interpretation of data. Responsibilities of Inspectors The inspector is primarily responsible for the overall inspec- tion and the quality of the inspection. It is required that the inspector is fully qualified to handle and operate all the equip- ment required for the performance of the NDE technique. The inspector has to follow the testing procedures, and make note of all relevant parameters. The inspector should also keep note of the measuring fields, and any anomalies that are observed during the testing. The inspector is also responsible for the proper post-processing (if required) of the testing data, and presenting the results and findings from the inspection in a format that is easily understood by the end user. Training Requirements of Inspectors In addition to the qualifications of the inspector, additional training and certifications may be required for the inspector to use and operate certain kinds of NDE equipment for the inspection of post-tensioning and stay cable systems. Train- ing and certification may also be required to use the tools that are required for post-processing. Planning, Scheduling, and Equipment Inspection planning, scheduling, and the required equip- ment are discussed briefly in what follows. Inspection Planning It is essential that all steps towards the inspection of post- tensioning and stay cable systems be adequately planned to avoid unexpected delays and avoid other external factors that may compromise the integrity or accuracy of the NDE. These external factors may change depending on the NDE technique. Various factors and necessary precautions for each NDE method are listed in Appendix C (Testing Procedures). For example, in the case of UST testing the signal to noise ratio may be low due to external noise from other construc- tion activities such as hammer sounding, impact drilling, etc. Proper planning of the inspection is essential, since certain NDE methods require additional resources that may be hard to find. Proper planning also lets for the proper scheduling of the inspection, as in most cases some pre-inspection prepara- tions are required. Inspection Scheduling Under normal circumstances, it may be sufficient to con- duct NDE inspection as part of the routine bi-annual bridge inspection. However, in circumstances where a bridge may require immediate attention, it is best not to delay the inspec- tion of the bridge components. The type of NDE techniques used for inspection also greatly influences the scheduling of inspection. For example, when using infrared thermography for inspection, it is very important that the inspection be sched- uled for early morning or late evening hours when the atmo- spheric temperature gradients are high for the identification of defect conditions. Proper scheduling is also necessary to let the general public know about any lane or road closures that may cause delays and inconveniences. Inspection Equipment The NDE equipment, and all facilities to operate the equip- ment such as proper power source, should be made available at the test site for proper inspection. Other tools that aid in the testing, such as a proper testing grid, cleaning surfaces, etc., should also be taken care of, for the proper inspection of the post-tensioning and stay cable systems. Evaluation Metrics for Post-Tensioning and Stay Cable Systems The development of a set of metrics to evaluate any general NDE technology for specific defect conditions is discussed here. The purpose of the metrics is to provide end users with a systematic approach for choosing the optimal NDE tech- nology starting with a known condition. In order to rank the methods, a weighted sum model (WSM) is used to provide a final score for each method, given its individual scores in chosen weighted categories. The first subsection presents the rationale for the WSM approach, specifically describing the advantages of this approach compared to other decision analysis methods. The next sub- section presents the chosen weighted categories, including a detailed explanation of the various sub-categories. The rank- ing of the NDE technologies, the development of flowcharts for assessing the different defect conditions, and the decision- making process are discussed next in this subsection. Weighted Sum Model The WSM has been used in decision analysis for decades and is a popular multi-criteria decision-making tool. Triantaphyllou and Mann (1989) compared the WSM to other methods, namely the weighted product model, analytic

29 hierarchy process, revised analytic hierarchy process, ELECTRE (Elimination and Choice for Reality, translated from French) method, and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods. They found that, while there is no perfectly effective tool, the WSM is most widely used for normalized multi-dimensional prob- lems. While other models may incorporate more parameters for effective decision-making, the additional information required for these more complex decision analysis tools makes their use undesirable. The WSM works by providing an overall score for each one of M alternatives by summing their individual scores under N criteria multiplied by the weight of the associated crite- rion. Mathematically, the score for Alternative 1 (SA1) can be expressed as A1 i i i 1 N S a w∑= = where ai is the individual score for Criterion i and wi is the weight of Criterion i. Each score must be normalized so as not to mix units and lose meaning; therefore, the scores are chosen within a consistent range. For this research, the range of scores are from zero to 10, with zero representing the low- est score possible (least desirable), and 10 representing the highest score possible (most desirable). Furthermore, each of the criteria must be weighted to emphasize their desired influence among the various criteria, and all of the individual weights must sum to unity. Weighted Categories The criteria consist of five categories considered to be most important in the ranking of NDE technology. Each category defines a specific relationship between the usefulness of the NDE method and a potential need in the structural engi- neering condition assessment process. The five categories are listed in the following paragraphs. Precision Precision is considered as the repeatability, where repeat- ability is how closely the same NDE method reports the same measurement under repeated testing using similar testing procedures. Precision is a very important category for NDE technology manufacturers and may or may not be necessary from a structural engineering perspective, depending on application and scope of inspection. Although this is a valuable criterion, a low weight is recom- mended for this criterion unless otherwise needed for a spe- cific investigation. The reason is the often misperception of a highly ranked method in terms of precision. Many methods are highly repeatable with poor accuracy. This is the case with GPR used to detect defects within metal ducts. The metal duct reflections will dominate the radargrams, making internal investigation impossible. However, a user will almost always measure the same response for an internal condition (i.e., high precision). High precision is, however, a very valuable criterion when investigating the ability of a technique to be used by dif- ferent personnel or with different manufacturer’s NDE tool. To avoid this misinterpretation, a weight of only 5% was assigned for the scoring of the precision criteria. Accuracy This category is based on correlation and is a measure of how closely the measured data from the technique compares to the ground truth. Accuracy is differentiated between the accuracy of damage localization and evaluating damage severity. Accu- racy is rated based on the ability of the NDE method to both detect the location and quantitatively evaluate the severity of detrimental condition in comparison to the true condition. Accuracy is an extremely important category for both NDE technology manufacturers and structural engineering needs, but the required level of accuracy may vary depending on appli- cation. Table 5-1 lists the ranking values for different accuracy levels for damage localization and for evaluating severity of damage compared to ground truth. Ranking Accuracy for damage localization Accuracy for damage severity (Worst) 0 Not Applicable or 0% Not Applicable or > 100 % 1 1 – 10 % 91 – 100 % 2 11 – 20 % 81 – 90 % 3 21 – 30 % 71 – 80 % 4 31 – 40 % 61 – 70 % 5 41 – 50 % 51 – 60 % 6 51 – 60 % 41 – 50 % 7 61 – 70 % 31 – 40 % 8 71 – 80 % 21 – 30 % 9 81 – 90 % 11 – 20 % (Best) 10 91 – 100 % 0 – 10 % Table 5-1. Definition of ranking for accuracy.

30 Ease of Use Ease of use is measured by power demand (direct power, battery-powered, etc.) and personnel required (large crew, two to three personnel, automated testing, manual testing, etc.). Ease of use is a category that may more heavily influence the structural engineer, as more complicated systems tend to be more expensive to inspect. The importance of this category may vary depending on application and scope of inspection. • Power demand: Power demand is ranked based on the power requirements of the equipment, as equipment can require anywhere from long-life battery power to high voltage direct power. • Number of personnel: This category determines what the personnel requirement is for optimal testing and directly affects the labor cost. Whether the NDE method is auto- mated, requires one inspector, a large inspection crew, or anywhere in between is addressed in this category. Table 5-2 lists the ranking values for the power demand and number of personnel required for inspection. Inspection Requirements The inspection requirements differentiate between operator qualifications (level of experience and/or training necessary for operation), operator training (in U.S. dollars per person), and complexity of data interpretation [extensive, moderate, or minimal prior knowledge, experience, or required certifica- tions of operator(s)]. Complex or potentially hazardous NDE methods typically require extensive inspection requirements which can increase the cost of implementation. The impor- tance of this category may vary depending on application and scope of inspection. • Operator qualifications: Qualifications of the operator are ranked based on required educational background for proper inspection. • Operator training: Required trainings of the operator are ranked in this category based on the cost of training. • Labor cost per hour: This category estimates the relative cost of inspection, based on the average cost of the chief operator and all assistants. • Complexity of data interpretation: Different methods can require high, moderate, or low data analysis in order to obtain useful data after testing. Required data analysis expe- rience and certifications are ranked for the operator. Table 5-3 lists the ranking values for the above sub-categories under inspection requirements. Cost This is a measure of the cost of the technique, and differ- entiates between the cost of equipment and labor costs for Ranking Power demand No. of personnel 0 Requires 480 V - 1 >10 2 Requires 220/240 V – 3 Phase 9 3 8 4 Requires 220/240 V 7 5 6 6 Requires 110/120 V 5 7 4 8 Battery operated 3 9 2 10 No power required 1 Table 5-2. Definition of ranking for ease of use. Ranking Operator qualification Operator training Labor cost per hour Complexity of data interpretation 0 Post-doctoral > $ 9000 > $ 300 High complexity 1 $ 8001 – 9000 2 Doctoral degree $ 7001 – 8000 $ 251 – 300 3 $ 6001 – 7000 4 Masters degree $ 5001 – 6000 $ 201 – 250 5 $ 4001 – 5000 Moderate complexity 6 Bachelors degree $ 3001 – 4000 $ 151 – 200 7 $ 2001 – 3000 8 High school diploma $ 1001 – 2000 $ 101 – 150 9 $ 0 – 1000 10 Layman No Training $ 50 – 100 Low complexity Table 5-3. Definition of ranking for inspection requirements.

31 inspection (in USD per linear ft of stay cable or external PT, and per ft2 of concrete surface for internal PT and anchorage regions). Cost is an extremely important category for both NDE technology manufacturers and structural engineering needs, but the cost limit may vary depending on application. • Cost of equipment: This category ranks each NDE method based on the cost of both the testing equipment and neces- sary data analysis tools. • Labor costs for inspection: Labor costs are estimated based on testing personnel requirements, operator costs, and if applicable, data analysis personnel costs. Table 5-4 lists the ranking values for the cost of the equip- ment and the labor cost per unit length or area. Weight Factors This section describes in detail how to use the developed metrics, and in particular, how to modify the decision matrix. As future users may not be inclined to make many changes, but rather use the recommendations from this investigation, two scenarios believed to be most common in bridge inspec- tions are: Scenario 1: Cost-Driven Approach and Scenario 2: Accuracy-Driven Approach. The first expectedly emphasizes (by weight) the category Cost, and the second emphasizes (by weight) the category Accuracy. The rationale behind these two scenarios is that end users will likely be choosing meth- ods for either a large-scale bridge inspection program (where cost of the NDE technique is a primary deciding factor), or a single bridge inspection in which possible areas of deteriora- tion are known or expected to exist (where accuracy of the NDE technique is a primary deciding factor). The associated weight factors for these scenarios are given in Table 5-5. This metric system is proposed as it is relatively straightfor- ward for the end user to modify the decision matrix. Details about customizing the decision matrix are in Appendix D. Ranking Based on the WSM, the various NDE techniques are ranked depending on their overall score for the cost-driven and accuracy-driven approaches. Each NDE technique is ranked based on the five weighted categories and their respec- tive weight factors. Each method is evaluated for internal metal and nonmetal ducts, external metal and nonmetal ducts, and the anchorage regions. Based on this ranked list of NDE methods, flowcharts are created to help choose the most appro- priate NDE method for investigating a particular defect condi- tion, or a combination of defect conditions. Methods that are not applicable for detecting a particular defect condition are not listed in the flowcharts, even though they have a high overall score. Flowcharts The flowcharts for choosing the most appropriate NDE technology for the inspection of a particular type of strand or grout defect in post-tensioning and stay cable systems are discussed herein. The flowchart is presented in a way that is easy for the decision-makers in choosing the most appropri- ate NDE methods applicable in evaluating a particular defect condition in post-tensioning and stay cable systems. The flowchart differentiates if the region of interest is an internal Ranking Cost of equipment Labor cost per unit length/area 0 > $ 100,000 > $ 10 1 $ 90,001 – 100,000 $ 9 – 10 2 $ 80,001 – 90,000 $ 8 – 9 3 $ 70,001 – 80,000 $ 7 – 8 4 $ 60,001 – 70,000 $ 6 – 7 5 $ 50,001 – 60,000 $ 5 – 6 6 $ 40,001 – 50,000 $ 4 – 5 7 $ 30,001 – 40,000 $ 3 – 4 8 $ 20,001 – 30,000 $ 2 – 3 9 $ 10,001 – 20,000 $ 1 – 2 10 $ 0– 10,000 $ 0 – 1 Table 5-4. Definition of ranking for cost. Weighted Category Scenario 1 Weight Factors (Cost-Driven Approach) Scenario 2 Weight Factors (Accuracy-Driven Approach) C1 Precision W1 5% W1 5% C2 Accuracy W2 10% W2 60% C3 Ease of use W3 15% W3 15% C4 Inspection requirements W4 10% W4 10% C5 Cost W5 60% W5 10% Table 5-5. Categories and weight factors for Scenario 1 and Scenario 2.

32 duct, an external duct, or an anchorage region. Based on the choice made between internal and external ducts, different ranked NDE methods are presented for metal and nonmetal ducts. The flowchart for a particular condition assessment directs the user to a list of recommended NDE methods ranked according to the evaluation metrics. Flowcharts are presented for the two scenarios considered in this investigation. Scenario 1 is a cost-driven approach, whereas Scenario 2 is an accuracy-driven approach. If the user decides to assign different weights to the various assess- ment parameters, the flowcharts may be modified accord- ingly. Only methods applicable for detecting a given defect condition are listed in the flowchart. Flowcharts for the dif- ferent defect conditions, based on the two scenarios, are pre- sented in Appendix A. As an example, the flowcharts for detecting compromised grout using Scenario 1 (Figure 5-1) and Scenario 2 (Figure 5-2) weights are discussed in the following sections. Note that the test- No Yes Start compromised grout condition assessment for Scenario 1 Location of interest: internal duct? Collect bridge structure files Yes Is duct metal? Location of interest: external duct / stay cable? For compromised grout in internal metal ducts: 1. USE (TP09), (low) For compromised grout in anchorage system: No applicable NDE method was identified based on this study. For compromised grout in end cap of anchorage region: 1. Sounding (TP12), (high) 2. IRT (TP02), (low) For compromised grout in internal nonmetal ducts: 1. IE (TP07), (low) 2. USE (TP09), (low) No For compromised grout in external metal ducts: 1. Sounding (TP12), (moderate) For compromised grout in external nonmetal ducts: 1. Sounding (TP12), (low) 2. IRT (TP02), (low) 3. GPR (TP01), (low) 4. LFUT (TP11), (low) 5. IE (TP07), (moderate) 6. ECT (TP03), (low) No Yes Yes Is duct metal? No Figure 5-1. Flowchart for detecting compromised grout with Scenario 1 weights.

33 ing procedure and the overall accuracy of each of the methods that can detect compromised grout are included in parentheses. As a first step in using the flowchart, it is important that the inspector collects bridge structure files in order to deter- mine certain important parameters such as the location of the ducts (internal/external) and the material of the ducts (metal/ nonmetal) that needs to be investigated. If it is established that the internal ducts need to be inspected for compromised grout, then it has to be determined if the internal ducts are metal or nonmetal. If the internal duct is made of metal, then the flowchart shows USE to be the appropriate NDE technique. However, if the internal duct is nonmetallic then the flowchart suggests two methods, namely, IE and USE. The two methods are listed from the most preferred NDE method to the least preferred NDE method that may be used for detecting com- promised grout in internal nonmetal ducts. Incidentally, in this case the ranking of the two NDE methods are the same irrespective of the scenario being considered. No Yes Start compromised grout condition assessment for Scenario 2 Location of interest: internal duct? Collect bridge structure files Yes Is duct metal? Location of interest: external duct / stay cable? For compromised grout in internal metal ducts: 1. USE (TP09), (low) For compromised grout in anchorage system: No applicable NDE method was identified based on this study. For compromised grout in end cap of anchorage region: 1. Sounding (TP12), (high) 2. IRT (TP02), (low) For compromised grout in internal nonmetal ducts: 1. IE (TP07), (low) 2. USE (TP09), (low) No For compromised grout in external metal ducts: 1. Sounding (TP12), (moderate) For compromised grout in external nonmetal ducts: 1. IE (TP07), (moderate) 2. Sounding (TP12), (low) 3. IRT (TP02), (low) 4. LFUT (TP11), (low) 5. ECT (TP03), (low) 6. GPR (TP01), (low) No Yes Yes Is duct metal? No Figure 5-2. Flowchart for detecting compromised grout with Scenario 2 weights.

34 However, if it is established that the external tendons are to be inspected for compromised grout, based on the duct material another set of NDE methods are suggested. If the external duct is metallic, then sounding is the only NDE method available for detecting compromised grout. However, if the external duct is nonmetallic then six methods are listed in a ranked order from one to six. In the case of cost-driven Scenario 1 weights, the list of ranked NDE methods, from most to least preferred include sounding, IRT, GPR, LFUT, IE, and ECT. However, if the accuracy-based Scenario 2 weights are being considered, then the ranked list of NDE methods, from most to least preferred include IE, sounding, IRT, LFUT, ECT, and GPR. Finally, if the region of interest is the anchorage region, then a different list of methods may be used. Based on the current investigation of NDE technologies, there are no NDE methods that can be used to detect compromised grout in the anchor- age region. However, sounding and IRT may be used for the inspection of the end caps in the anchorage zones. Flowcharts for assessment of combined condition of corrosion/section loss/breakage and compromised grout/ voids/water infiltration also are in Appendix A. The flowcharts present a combination of NDE methods that may be used to detect both strand and grout defects. Based on the flowcharts (irrespective of the scenario in this particular case), there are no NDE methods that are available to detect both strand and grout defects in the internal ducts, be it metallic or nonmetallic ducts. However, in the case of external metal ducts, a combination of MFL and sounding can be used to detect both the strand defects and the grout defects. In the case of external nonmetal duct, a combination of two methods may be used for the inspection. The preferred method based on the ranking would be a combi- nation of MFL and sounding, while a second combination of MFL and IE may also be used. Incidentally, the combination of methods and their ranking are unaltered by the scenario weights being considered in this case. A different set of flowcharts are presented in Appendix B, wherein the different defect conditions that can be identified by a particular NDE technique are presented. As in the con- dition assessment flowcharts presented in Appendix A, the location and the material of the ducts are considered in these flowcharts as well. These flowcharts are self-explanatory and are not further discussed here. Decision-Making The developed flowcharts guide users in choosing a pre- ferred NDE technique, or a combination of techniques for a particular defect, or a combination of defects. If multiple methods are available for inspecting a particular defect, then they are listed according to their overall rank, from most pre- ferred to least preferred. These flowcharts will assist end users in choosing the appro- priate NDE technique from a ranked list of methods, for the assessment of a particular condition in post-tensioning and stay cable systems. The flowchart will walk the user through in choosing the appropriate NDE technique based on the location of interest, such as internal duct, external duct, or an anchorage region, and the type of duct, such as metal or non- metal ducts. The flowcharts were developed based on the two different scenarios: the cost-driven approach and the accuracy- driven approach. Testing Procedures Testing procedures (see Appendix C) were developed for each of the NDE technologies that were used in the condi- tion assessment of the post-tensioning and stay cable systems. A generic template for the NDE testing procedure that may be adapted to perform, analyze, document, and evaluate any NDE technique that may be used for the condition assessment of bridge post-tensioning and stay cable systems is presented in this section. The testing procedures include two sub-sections, namely, introduction and procedures. These sections are dis- cussed in more detail in the following paragraphs. Introduction The introduction component of the testing procedures briefly describes the NDE technology, all appropriate infor- mation concerning technical applicability issues, and rel- evant terminology. This section also contains a detailed list of capabilities and limitations describing the technique’s per- formance under different physical parameters. It is essential that this section be used in conjunction with ranked methods as it allows the user to fully understand parameters affecting performance. • Scope: The scope briefly introduces the method and describes the physical measurements used, and any fur- ther information that differentiates categories of method application. As an example, the UST testing procedure may describe the different ultrasonic techniques commonly used, such as pitch-catch, through-transmission, or indirect- transmission methods. • Terminology: This section describes typical language used for the method, including terminology for the physics behind the method and language specific to the device, test- ing techniques, and data interpretation. • Significance and use: This section briefly introduces the most common use of the method with regard to bridge inspec- tions. It is not meant to limit application of the method, but provides an understanding of typical usage.

35 • Capabilities and limitations: Perhaps one of the most impor- tant components of the testing procedures, this section allows the end user to determine whether or not the most optimal method chosen by the ranked methods is actually suitable for the specific inspection application. As the rankings were scored using defined typical conditions, the following cat- egories are discussed to explain the technology’s capabilities and limitations in light of different physical parameters that may exist. In rare instances, the user will have to determine through these limitations if any of the ranked methods are actually suitable for a particular inspection. Also note that depending on the weights of the categories, one significant low rating for a category can make some methods (in par- ticular radiography) score well below other methods that are not as suitable for a given application. The following physical parameters are discussed for each NDE technology. – Duct location: This describes the ability for inspection of internal, external, and/or anchorage systems. – Duct type: This describes the applicability for metal and/ or nonmetal duct inspection. – Effect of concrete cover: This describes the effect of varying concrete cover for the technology. – Effect of layered ducts: This describes the performance of the technology when attempting to inspect ducts behind other ducts (i.e., ducts laying side by side wherein inspec- tion of the farthest duct requires penetration through a nearer duct or group of ducts). – Effect of reinforcement congestion: This describes the effect of reinforcement congestion on technology perfor- mance. Closer spacing of reinforcement will negatively affect certain methods. – Accessibility requirements: This describes the required accessibility of the method for external, internal, and/ or anchorage regions. Some methods require very lit- tle accessibility, while others require a great deal of free space in order to operate. • Safety requirements: This section describes any special safety requirements for the particular NDE method. All safety requirements from the manufacturer’s manuals and proce- dures should be strictly adhered. • Referenced documents: This section provides any sources used in the testing procedures, as well as any resource that should be consulted or that can provide additional insight for the testing. This may include typical user manuals, ASTM standards, relevant specifications, reports in which the technology was used for similar testing, etc. Procedure The procedure component of the testing procedures out- lines general testing parameters, data collection practices, a list of all typical apparatuses, a step-by-step description of data collection, any photos helpful for testing, and information regarding validation of testing data and data interpretation. This is not meant to replace the user manual for the technol- ogy, but provide additional insight and testing instructions for the use of the method and to obtain repeatable and mean- ingful results. • Data collected. This section provides a list of the actual data collected for the technology. As an example, some methods use time-of-flight measurements, some use intensity varia- tion within a testing frame, etc. • Apparatus. This section describes all necessary equipment needed for testing. Some of this list may vary with manu- facturer, but is typical for methods used by the research team. • Process description/data collection principle. This section describes the principles and processes behind the technol- ogy use, explaining in further detail the items within the “Data Collected” section. • Photos. This section provides helpful photos of device operation and/or typical results. • Data collection procedure. This step-by-step procedure fol- lows the generic flowchart shown in Figure 5-3 for each method. This procedure should be followed in addition to the user manual for the method. • Criteria for data validation. This section describes the typical criteria used for data validation and includes any necessary procedures for obtaining such validation. • Data analysis procedures. This section describes the typi- cal process of interpreting or calculating the results of the method. This section also describes the level of training typically required for data interpretation. The testing procedures for the various NDE methods used for the evaluation of post-tensioning and stay cable systems are presented in Table 5-6. Data Processing Data processing and interpretation of data from the tests is an important step, as any misinterpretation could lead to incor- rect conclusion about the condition of the post-tensioning and stay cable systems. The data processing for interpreting the data from the scans has to be performed by well qualified and trained individuals, and the final outcomes from the scans pre- sented in a manner that can be easily understood by the final user. The information pertaining to data processing for the various NDE methods may be found in the data analysis and evaluation of results subsection in the references provided in Table 5-6.

36 Start testing procedure Enter span and ensure marking system exists relative to station marking Perform preliminary walk-through inspection, noting damage indicators Power on necessary tools/equipment and calibrate per manufacturer’s recommendation Submit completed inspection form to inspection program manager Inspection complete for all selected span/sections? Go to next span Yes No No Yes Has ambient temperature or humidity varied since last test? Collect bridge structure files Gather all tools, equipment, and inspection report forms Record ambient temperature, humidity, and time of inspection Collect data along marking system Store and/or backup data Figure 5-3. General flowchart for testing procedure for NDE techniques.

37 NDE method Reference GPR Appendix C – TP01 IRT Appendix C – TP02 ECT Appendix C – TP03 MFL Appendix C – TP04 MMFM-Permanent Magnet Appendix C – TP05 MMFM-Solenoid Appendix C – TP06 IE Appendix C – TP07 UST Appendix C – TP08 USE Appendix C – TP09 S/UPV Appendix C – TP10 LFUT Appendix C – TP11 Sounding Appendix C – TP12 EIS Appendix C – TP13 GPR/USE Appendix C – TP14 GPR/IE Appendix C – TP15 MFL/Sounding Appendix C – TP16 MFL/IE Appendix C – TP17 IRT/USE Appendix C – TP18 VT Appendix C – TP19 Table 5-6. References to testing procedures for the various NDE methods. Preparing the Report This component of the testing procedures describes expected formats for reporting the testing results, including recording testing areas (subdivisions) and any additional next steps for a full and accurate report. • Subdivision of the structure for inspection and recordkeep- ing: Specifically, this section instructs the user to record the appropriate subdivisions of testing the specific bridge component. As an example, this may be segments within segmental bridge construction with appropriately marked starting and ending spans and identified cardinal directions for scanning. • Next process: This section describes any other next steps or processes for data recording, such as delivering the report to the file manager, identifying all anomalies requested by the investigation, clearly marking, presenting, and labeling the findings with respect to a defined start and end location detailed in the section, Subdivision of the Structure for Inspection and Recordkeeping. Closing Remarks The various aspects necessary for the condition assessment of post-tensioning and stay cable systems were discussed in detail in this chapter.