01 April 2001
and record conditions encountered using standard engineering practice. All rules
governing workplace safety should apply.
SECTION 4 BACKGROUND
General. An understanding of the following information regarding the
testing of mooring hardware is essential. Each test will consider the following:
Orientation: The position (x, y, z coordinates) of the hardware
should be based on the coordinate system established during the
mooring hardware inspection. Direction of forces applied should be
established and recorded utilizing the same coordinate system.
Magnitude: The load applied to the hardware should be 110% of its
rated load capacity. The rated load capacity of the hardware can
be gathered from existing data.
Duration: The duration that test loads are applied should be
dependent upon the level of the test, and the discretion of the
supervising engineer (P.E.).
Load Path. The load path followed by the mooring line load through the
fitting into the supporting concrete slab is essentially the same for all the mooring
The mooring line load is applied under the horn or lip at the mooring post. The upward
vertical load component from the mooring line causes a vertical shear at the base of the
horn or lip for loads with nonzero vertical load components. The horizontal load
component at the load point induces shear stresses in the cross section of the mooring
post. The upward tensile force causes tensile stress in the cross section of the mooring
post as well as a constant bending moment along the mooring post axis about a
horizontal axis normal to the load. The horizontal load component induces a bending
moment that increases with distance from the load point toward the base of the mooring
post. This bending moment is a maximum at the base of the mooring post.
The axial and shear forces and bending moments at the base of the mooring post are
resisted by the base plate through flexure and shear action. At the bottom of the base
plate, the resulting forces and moments are resisted by the tensile and shear stresses in
the anchor bolts. However, a small portion of these forces and moments is resisted by
friction between the toe of the base plate and the concrete and by bearing of the vertical
sides of the base plate against the adjacent concrete. The shear and tensile forces in
the anchor bolts are resisted by the concrete base through bearing, shear and tensile
stresses in the slab. The concrete slab transfers these loads from the anchor bolts to
the pile cap through shear and tensile stresses and then to the support piles. In turn,
the piles transfer the forces to the supporting soil.
Load Failure. The failure of any component along the load path described
above from the load point to the ground disrupts the flow of forces unless there are
sufficiently strong adjacent parallel load paths to take up the load carried by the failed
component. A disruption of the load path can lead to the failure of the load resisting
system as a whole."