01 April 2001
must be able to determine the differences between the various types of cracks, their
causes and the structural implications of those cracks. Cracks of a concerning nature
include: shear cracks near the edge of the pier deck (running at 45 degrees through the
corner); diagonal cracking on the deck surface running at 45 degrees from the hardware
to the edge; and radial cracking around fasteners indicating cone failure. Gaps at the
hardware base or crushing of bedding grout indicate movement or overloading and
should be noted. General deterioration of the concrete should be observed and noted.
The mooring hardware should be founded on a solid concrete matrix and/or bedded in
grout to provide full contact on the bottom and sides. The concrete should be solid and
Timber. Timber structures should be inspected for structural failures such
as: crushing of the timber under the hardware or the fastener bearing plates, cracking or
forms such as: dry rot, marine borers, termites or other insects. These conditions should
be noted and assessed based on their impact to the structure and mooring hardware.
Steel. Steel supporting structures exhibit conditions such as corrosion,
buckling, and cracking. Steel members are generally fastened with either bolts or welds.
Bolts should be inspected for tightness, loss of cross sectional area due to corrosion,
and bearing. Welds should be inspected visually for cracking.
Fender System. Visual observation of the fender system should be made
in sufficient detail to establish the typical cross-section and to detail the energy
absorbing characteristics of the system. Where timber fender systems are employed the
general condition of the timber components should be noted in terms of berthing
capability. Where other types of fender systems are in place, the over all capacity of the
system should be documented. Locations where damage has occurred should be
noted. Missing fender units should be noted and identified.
Global Conditions. Global conditions refer to the condition of the
supporting pier, wharf or dolphin structure. The inspection of these structures is closely
related to the condition of the mooring hardware with respect to the capacity of the
mooring system. For example, the sum of the capacities of the mooring hardware may
exceed the total capacity of the structure to resist these loads. In this case the mooring
hardware cannot be fully developed. Berthing plans are required to factor these
limitations into the allowable berthing capacity for the facility. Inspection of pier facilities
is addressed in UFC 4-150-07, Maintenance of Waterfront Facilities.
Pier Structure. The significant loading imposed on the pier structure by
mooring hardware is in the lateral direction (horizontal "x" direction), which in most
cases is resisted by batter piles or passive earth pressure. Piers vary in their
construction and the methods employed to transmit these loads to the soil. Open pier
structures generally have battered piles (piles at an angle) along with plumb piles
(vertical piles,) as well as significant dead loads to resist the lateral and resulting uplift
loads. Solid pier structures rely on their massive dead load for stability, as in cellular
structures or in the resistance of deadman in the case of tied back sheet pile bulkheads.
Structural Analysis. The inspecting engineer should collect all available
data to ascertain the capacity of the pier structure to resist lateral loads. Available
information may include: