Kattendijk Lock – Wooden vs steel mitre gates
SBE’s lock specialists have for over 30 years been involved in the design and construction of lock gates. This blog discusses the challenges resulting from the transition from wooden to steel mitre gates.
Mitre gates are the most common lock gate type used in small to medium navigation locks. The first advantage compared to single leaf gates is the mean in which forces are transferred to the civil works. A considerable amount of the hydrostatic load is transferred by means of normal forces instead of bending, resulting in a more efficient material use. Additionally lower hydrodynamic forces are introduced when opening and closing the gate.
Historically mitre gates where fabricated in wood. By the middle of the last century, engineers started to replace the wooden gates with steel equivalents. This transition allowed the construction of more sustainable and wider lock gates.
This transition, however, also introduced some new challenges originating from the greater axial stiffness of steel compared to wood. This greater, in and out of plane, stiffness of the steel mitre gates results in a higher sensitivity to misalignment and tolerances. Therefore, contractors need to install the gates with exceptional precision to avoid sudden failure of the pintle, top hinge and quoin blocks. In the recent past, this sensitivity to misalignment has caused some severe damage to lock gates resulting in substantial economic losses.
It is therefore crucial that the engineer is aware of these unusual difficulties and can design steel mitre gates which are less dependent of tolerances. This way, unforeseen costs during the execution due to exceptional tolerance requirements can be avoided and the risk of damage to the gate can be significantly reduced. It is not enough to simply replace a wooden mitre gate with a steel replica without reconsidering the full concept of the gate.
SBE’s lock specialists have for over 30 years been involved in the design and construction of new and existing locks in Belgium and the Netherlands, the cradle of hydraulic engineering. Our expertise in this field has also been recognised internationally, as proven by recent project completed in India, Iran, Spain, Panama and Italy.