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of the lock foundation should be carefully assessed
quantities calculated for the DM; detail all secondary
during this phase since the depth can have a signifi-
reinforcement; prepare and check contract drawings;
cant impact on construction cost.
develop and edit specifications; and calculate quanti-
ties for use in developing the government cost
b. Feasibility report (FR).
2-3. Types of monoliths.
(1) Lock design during the feasibility phase (FP)
must be sufficient to fully define the project scope
and to develop an adequate baseline cost estimate
with reasonable contingencies. The design will be
(1) As a result of the functional requirement for
presented in the engineering appendix to the FR.
a lock to contain large tows, the chamber length
Also during the FP, the structural engineer must
parallel to flow can become very long. On a major
determine schedule and cost requirements for the
waterway the chamber length can be up to 1,200 ft
remaining phases of the design. This information
long. Consequently, it becomes necessary to incorpo-
must be included in the Project Management Plan.
rate monolith joints along the chamber length. The
locations of these joints are used to define monoliths
(2) Structural content in the engineering appendix
which have unique requirements towards the operabil-
will include a full definition of functional and tech-
ity of the overall lock. Additional guidance with
nical design criteria, and initial analyses used to
respect to locations, requirements, and lengths needed
establish the basic geometry for the project. The
for the various types of monoliths is available in
suitability of a U-frame configuration must be firmly
established during the FP. Decisions should be made
on foundation type (soil or piles), chamber size, wall
(2) Monoliths that compose a lock can be cate-
height and thickness, sill height, slab thickness, and
gorized into five general groups. These five groups
foundation depth. The design team should also select
types and sizes of guidewalls, filling and emptying
systems, and closure systems for maintenance and
(a) Intake/discharge monoliths.
emergencies. The structural engineer must be directly
involved in this process, and sufficient analysis
(b) Gate monoliths.
should be performed to verify these decisions.
(c) Culvert valve monoliths.
c. Design memorandum (DM). Detailed design
and analysis of the lock structure are documented in a
(d) Chamber monoliths.
DM. The DM is prepared either during PED or EDC
phases. While design details may remain incomplete,
(e) Other monoliths (e.g., guardwall monolith,
the DM should contain an essentially complete design
of the U-frame lock. During this design effort the
structural engineer should accomplish the following:
(3) The complexity of design of these monoliths
verify all design criteria; define all loads and load
varies and the degree of complexity should be consid-
cases; select controlling load cases; develop a final
ered when assigning the design tasks for these various
pile layout if required; verify all member geometries;
monoliths. Gate monoliths are the most difficult to
determine required concrete reinforcing steel; and
design primarily due to the three-dimensional loading
calculate quantities for use in developing the cost
which is applied to these monoliths. Design of a gate
estimate. This work should be thoroughly docu-
monolith should be performed by a senior engineer.
mented in the text and plates of the DM.
Intake/discharge monoliths and culvert valve mono-
liths can be difficult to design due to the fact that the
d. Plans and specifications (PS). Contract
geometries of these monoliths are difficult to evaluate
requirements are defined by the PS. The PS for the
in two dimensions. The chamber monolith is the
lock are usually prepared during the EDC phase since
simplest of the monoliths listed to design since it can
the PED phase ends with the initial construction
usually be designed in two dimensions without con-
contract for any other project feature. Structural
cern about the out of plane direction. Design of a
engineering work for preparing the PS includes the
chamber monolith can be performed by a junior
following: lay out main reinforcement using