Browsing by Subject "Nondestructive tests"
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Item Detecting Foundation Pile Length of High-Mast Light Towers(Minnesota Department of Transportation, 2022-08) Kennedy, Daniel; Guzina, Bojan; Labuz, JosephThe goal of the project is to establish a non-destructive field testing technique, including a data analysis algorithm, for determining in-place pile lengths by way of seismic waves. The length of each pile supporting a high-mast light tower (HMLT) will be identified through a systematic sensing approach that includes (i) collection and classification of the pertinent foundation designs and soil conditions; (ii) use of ground vibration waveforms captured by a seismic cone penetrometer; (iii) three-dimensional visco-elastodynamic finite element analysis (FEA) used as a tool to relate the sensory data to in situ pile length; (iv) use of machine learning (ML) algorithms, trained with the outputs of FEA simulations, to solve the germane inverse problem; (v) HMLT field testing; and (vi) analysis-driven data interpretation. Several hundred HMLTs throughout Minnesota have foundation systems, typically concrete-filled steel pipe piles or steel H-piles, with no construction documentation (e.g., pile lengths). Reviews of designs within current standards suggest that some of these foundations may have insufficient uplift capacity in the event of peak wind loads. Without knowledge of the in situ pile length, an expensive retrofit or replacement program would need to be conducted. Thus, developing a screening tool to determine in situ pile length - as compared to a bulk retrofit of all towers with unknown foundations - would provide significant cost savings.Item Development and Integration of Advanced Timber Bridge Inspection Techniques for NBIS(Center for Transportation Studies, University of Minnesota, 2015-01) Brashaw, Brian; Dahlberg, Justin; Hosteng, Travis; Wacker, JamesMinnesota has over 2,000 bridges that contain structural timber in the superstructure or the substructure. Historically, inspections for timber bridges have been mostly limited to visual inspection, hammer sounding and probing. These techniques have proven appropriate for advanced decay detection, but are inadequate for early stage or internal deterioration. During this project, new advanced inspection techniques and equipment were identified that were capable of improving the quality of timber bridge inspection. This equipment and technologies were introduced into routine bridge inspections through the development of standard inspection protocols, integration of the results into bridge data management software, development of a customized inspection manual, outreach training for MnDOT districts and state counties, recommendation of equipment purchases, and completion of an economic assessment on the use of advanced inspection techniques. Implementation of these inspection techniques will support the long-term service life of Minnesota’s timber bridges and will improve the safety and reliability of Minnesota’s bridges.Item Development of Flexural Vibration Inspection Techniques to Rapidly Assess the Structural Health of Rural Bridge Systems: Phase II(Minnesota Department of Transportation, 2009-12) Brashaw, Brian K.; Vatalaro, Robert J.; Wang, Xiping; Verreaux, Matthew; Sarvela, KevinCurrent timber bridge inspection procedures used in Minnesota and across the United States are mostly limited to visual inspection of the wood components. Use of advanced techniques like stress wave timing, moisture meters, resistance drills will significantly improve the reliability of the inspections but these inspection techniques are time consuming. The objective of this project was to conduct vibration testing of dowel laminated timber bridge systems to better understand the potential for using vibration testing to assess the structural health and condition of bridges in Minnesota. A second key objective was to improve and automate the vibration testing system that is currently being used. This research showed that the forced vibration system developed is an effective tool for conducting forced vibration tests of timber bridges and that there is a noted increase in frequency during each successive stage of construction. A reliable means for assessing the peak frequencies and an identification of the mode still needs to be developed for this system to use the vibration response to predict the EI product for use in load ratings. Each bridge has a unique set of vibration characteristics that were identified using the automated system. These characteristics showed peaks in amplitude as the frequency of the vibration was increased from 0 - 35 Hz during testing. It is believed that monitoring of the characteristic vibration response for each bridge would be a means of identifying changes in structural health over time due to wood decay, accidents, vandalism, or lack of maintenance.Item Evaluation, Development, and Implementation of 3D GPR for Assessment of Minnesota Infrastructure(Center for Transportation Studies, University of Minnesota, 2016-12) Hoegh, Kyle; Thompkins, Derek; Khazanovich, LevThis research project evaluated the 3D Radar ground penetrating radar (3D GPR) equipment to determine applications and develop software for immediate use. A major focus was the use of 3D GPR to determine asphalt compaction uniformity. Other pavement assessment applications were explored. The research resulted in the development of new software that provides on-site mapping shortly after the last roller pass is completed on new construction. This provides the potential to select validation locations and give feedback to the contractor detailing the as-constructed performance during the paving process. The outputs of the software were also designed to allow for comparison with other technology and as-constructed information. (A user’s guide for the software is included in the project final report.) Overall, the use of 3D GPR with the developed software, combined with as-constructed data such as Intelligent Compaction pass counts, vibration amplitude, and other measures, can lead to better asphalt compaction and longer lasting roads.Item Portland Cement Concrete Pavement Thickness Variation Versus Observed Pavement Distress(Minnesota Department of Transportation, 2016-09) Khazanovich, Lev; Hoegh, Kyle; Barnes, Randal; Conway, Ryan; Salles, LucioBenefits from a potential significant correlation between distresses and slab thickness can be broadly applied in all stages of highway development from design and construction to maintenance decisions. In order to comprehensive explore this possibility, thickness data and existing distresses were related for three highway projects in Minnesota. Thickness was obtained through non-destructive ultrasonic testing, while distresses were recorded for the same location with a distress image software. Significant thickness variation was observed in both longitudinal and transverse directions. The combined results of thickness, shear wave velocity and distresses analysis revealed that an increase in shear wave velocity was coincident with a less damaged pavement area within a section. An in-depth statistical analysis confirmed this observation showing that shear surface velocity variation was better correlated with overall pavement performance than thickness variation. Differences in cracking behavior within a section were traced back to changes in construction and design practices, showing the potential of using shear velocity analysis for pavement maintenance. A survey and analysis procedure for shear wave velocity testing of concrete pavements is proposed.