Assessing the Role of Quoin Gaps on Miter Gates Damage States Through Optimization

Abstract

Miter gates are cyclically loaded structures present along waterways that allow for ships and cargo to traverse significant changes in elevation. The miter gate leaves are mounted on either end of a lock chamber from a gudgeon anchorage system, typically in pairs, and function by being swung into place about a pintle assembly by mechanical operating machinery. Along either side of a miter gate leaf run the quoin and miter contact blocks. When gates are placed into service or undergo maintenance, engineers use procedures to set tolerance gaps between the quoin contact blocks and the lock wall. If the gaps are set too tight, then when the gates are brought to miter, premature contact can cause prying action between the gudgeon and wall. This causes significant increases in stress in the gudgeon anchorage, a failure critical member (FCM), and has been observed during several structural health monitoring (SHM) initiatives on in-service infrastructure. Alternatively, if the gap tolerance is not set tight enough, when hydrostatic load is applied to horizontally framed miter gates, the transfer of load causes the gate to thrust towards the wall until the quoin contact blocks bear against the lock wall. When contact is delayed or does not occur, the load is transferred to the pintle and gudgeon, which resist this thrusting, rather than the lock wall. This significantly raises the stresses in these regions and leads to damage. SHM techniques have been previously developed to detect the presence of quoin gaps using both contact sensors and visionbased methods in an effort to inform maintenance decisions. The specifics of gap sizes and locations can be confirmed under gravity load using instruments known as feeler gages. There is currently no standardized procedure for setting these quoin gaps; therefore, there is a need for a rigorous analysis to standardize gap lengths that assesses tolerance gap sizes and their consequences. In this study, a suite of experiments is run using finite element analysis (FEA) on a series of numerical models. Focus is placed on horizontally framed miter gates around the typical size of 60 ft tall. Within the numerical experiments, optimization techniques are employed to find the optimal quoin gaps sizes that results in the minimization of stresses in the gudgeon and pintle. Validation of this optimization will occur though the physical testing of a miter gate fully instrumented with an SHM system. The experimental test set up that is currently under development will also be discussed.