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Title:Full-scale Laboratory Testing of Embedded Miter Gate Anchorages to Inform Fatigue Life Estimates
Author(s):Eick, Brian A.; Levine, Nathaniel M.; Smith, Matthew D.; Spencer, Billie F., Jr.
Subject(s):anchorages
load test
hydraulic structures
structural behavior
fatigue
strength
miter gate
lock and dam
testing of materials
USACE
Abstract:On the inland navigation system, miter gates are common structures that are supported by steel frames known as anchorages embedded in the concrete lock chamber wall. These anchorages primarily resist the overturning moment caused by the self-weight of the gate as it swings open and closed. Typically, miter gates will swing open and closed many times per day such that the loading experienced by the miter gate anchorages is cyclic in nature, and so, fatigue life of anchorages must be considered. A significant concern regarding miter gate anchorages is that many of the anchorages have been in service since the construction of the lock, oftentimes more than eighty years ago. The typical analysis approach to miter gate anchorages is to ignore the embedding concrete and treat the anchorage as a freestanding truss. This approach to analysis leads to unreasonably high estimation of stresses in the anchorage components, further exacerbating fatigue concerns. To aid in understanding the stress distribution of embedded anchorage components, the researchers of this study perform a full-scale test of a miter gate anchorage. The test is performed in three phases. In phase one, the anchorage is supported in a manner to represent the assumptions of the traditional analysis of anchorages, where the embedding concrete is ignored. In phase two and three, the anchorage is embedded in concrete. In phase two, the extent of the embedding concrete is intended to represent the configuration typical to so-called miter or primary anchorages. In phase three, a portion of the embedding block is cut away to simulate the reduced concrete coverage typical of the so-called recess or secondary anchorages. In all phases, the anchorage is pulled to simulate the reaction of the hanging miter gate that the in-service anchorage would support and the strain response throughout the anchorage is recorded with strain gages. In this initial study, the results are used to inform the code-based fatigue analysis typically performed by design engineers. A metric is defined, termed the strain-modulus, that is used to estimate the magnitude of axial stress in anchorage components given an applied load. It is seen that in all but one case, the strain modulus decreases in the anchorage when embedded in concrete in phase 2 and 3 as opposed to the unembedded anchorage in phase 1. The strain modulus is then leveraged to update the code-based fatigue analysis and it is shown that, for most of the unembedded portions of the anchorage, the stress in well below the endurance limit of steel such that fatigue limit states likely need not be considered. As such, design engineers may wish to reevaluate plans to excavate and replace these anchorages in kind. Ultimately, this testing is intended to develop a representative dataset that can be used to quantify the interaction between steel and concrete in miter gate anchorages. The dataset will be used to calibrate modeling procedures, inform future design, as well as adjust existing lifecycle estimates.
Issue Date:2021-10-19
Publisher:Newmark Structural Engineering Laboratory. University of Illinois at Urbana-Champaign.
Series/Report:Newmark Structural Engineering Laboratory Report Series {add number}
NSEL-052
Genre:Technical Report
Type:Text
URI:http://hdl.handle.net/2142/111718
ISSN:1940-9826
Sponsor:US Army Corps of Engineers through a subaward from the University of California, San Diego
Rights Information:Copyright held by the authors. All rights reserved.
Date Available in IDEALS:2021-10-19


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