TY - GEN A1 - Niederleithinger, Ernst A1 - Niederleithinger, Ernst A1 - Katzenbach, R. A1 - Hillmann, S. A1 - Schallert, M. A1 - Unseld, H. A1 - Willmes, M. ED - Bullock, P. ED - Verbeek, G. ED - Paikowsky, S. ED - Tara, D. T1 - A Framework for Nondestructive Testing Used in Foundation Reuse Projects T2 - Stress Wave Theory and Testing Methods for Deep Foundations, 10th International Conferenece N2 - The reuse of existing foundations is considered in various construction Projects to save time and costs while avoiding unnecessary interference with other underground objects. Because the design and as-built drawings might not be complete and questions may arise regarding the condition of the foundations, a detailed investigation is a prerequisite for the planning process in most cases. Nondestructive testing (NDT) techniques are a core part of this endeavor. The processes and procedure for foundation reuse planning are not yet standardized, and the possibilities and limitations of NDT methods are not known to many planners and stakeholders. The German research Project REFUND (2014–2016) has developed charts for the planning and Investigation process that consider available standards and the current state of the art in NDT. These charts are separately available for single and strip, slab, and pile foundations. Available NDT methods have been compiled and evaluated for specific tasks at these foundation types, including their respective limitations. The procedures have been successfully tested in two real-world projects. The results from these projects enable planners to improve the reliability of the process while potentially saving significant resources. This paper discusses the procedures for pile foundations and demonstrates the use of various NDT methods in a project on the reuse of electrical tower foundations. KW - Foundation reuse KW - Pile integrity testing KW - Parallel seismic PY - 2019 SN - 978-0-8031-7667-6 DO - https://doi.org/10.1520/STP161120170159 VL - 1611 SP - 238 EP - 253 PB - ASTM International CY - West Conshohoken, PA, USA AN - OPUS4-48795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Ertel, Jens-Peter A1 - Niederleithinger, Ernst ED - Bullock, P. ED - Verbeek, G. ED - Paikowsky, S. ED - Tara, D. T1 - Impulse Response Measurement for Pile Integrity Testing Using a Shaker as Excitation Source and Regularized Deconvolution T2 - Stress Wave Theory and Testing Methods for Deep Foundations, 10th International Conferenece N2 - Concrete piles are used as a foundation when the load capacity of the soil is insufficient or when the sustainable soil is found at a higher depth. Among other impact factors, the load capacity depends on the pile’s integrity and length. Therefore, verifying these parameters using adequate methods is recommended. The most common procedure is the low-strain integrity test using the hammer impact method. Developed and established in the 1970s, this method uses stress waves induced by a hammer impact at the pile head and its reflections at impedance changes (length, defects, geometry changes) to estimate the length and defect locations. Although this method is widely used due to its low cost and fast conduction in situ, one disadvantage is its inability to classify the exact type of defect, i.e., crack, change in diameter, or concrete quality. Furthermore, very long and slender piles are difficult to test and small defects cannot be detected. In addition, it is necessary for the test engineer to hold a high level of experience and expertise in this field. The European Union–funded PileInspect project (2013–2016) aimed to compensate for these disadvantages by using a low-cost shaker as the excitation source and sophisticated artificial intelligence algorithms for damage detection (higher-order spectra method). Because this technology lacks the capacity to localize damages and verify the pile length, an additional impulse response (IR) measurement technique was developed using vibrational excitation and regularized deconvolution to extract the depth information from the data in a similar manner as the hammer method. Simulations and subsequent experiments conducted at a test facility on 90-cm-diameter bored piles 11 m in length and containing cracks at approximately 4 m below the pile head confirmed the capacity to determine the pile length. Damage diagnosis and localization, however, are more difficult than for the hammer method. Although the damaged piles could be distinguished from the intact piles, in a blind test, this method might lead to misinterpretations caused by perturbations arising from the deconvolution process. The results also indicated that the low-cost shaker used for these measurements might be inappropriate for the transferal of sufficient energy. Although the IR method cannot compensate for the disadvantages of the hammer method by itself, it may enable the possibility of using long and fully controllable and repeatable signals (chirp, synthetic impacts, even noise, etc.) for pile integrity testing in the future. KW - Pile integrity testing KW - L-curve KW - Tikhonov regularization KW - NDT PY - 2019 SN - 978-0-8031-7667-6 DO - https://doi.org/10.1520/STP161120170162 VL - 1611 SP - 184 EP - 204 PB - ASTM International CY - West Conshohoken, PA, USA AN - OPUS4-48794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -