ETL 1110-2-355
31 Dec 93
4-9. Seismic loads. There are two types of seis-
bulkhead crane pedestal, support columns for control
houses, tainter valve trunnion anchorages, miter gate
mic analyses, psuedostatic and dynamic. The psuedo-
gudgeon pin anchorages, miter gate pintle bases,
static analysis is used in low seismic zones and with
miter gate latches, emergency bulkheads and mainte-
low peak ground accelerations (PGA). The dynamic
nance bulkheads, emergency bulkheads lowering
analysis is used in higher seismic zones and with
carriage machinery, jacking forces on gatebay mono-
higher PGA's. The extent of seismic analysis
liths due to gate diagonals tensioning operations, area
required depends upon the results of the seismological
lighting towers, etc. In the case of jacking forces on
site investigation. Detailed requirements on the seis-
gatebays due to gate diagonals tensioning operations,
mic design of U-frame locks are covered in other
anchors and/or jacking points should be provided for
guidance.
in the design of the gatebays to ensure that sufficient
means are available to tension miter gate diagonals.
4-10. Gate reactions. Any force resulting from
the dead weight of lock gates or culvert valves and
4-15. Other loads. Wind loads are relatively
forces transferred from the gates due to hydrostatic
small and should be neglected. Ice loads on lock
pressure acting on the gates should be considered in
walls are not ordinarily included in the structural
the design of the gatebay or valve monoliths.
design. However, approach walls and mooring facili-
EM 1110-2-2703 describes how these forces should
ties, particularly those items in the upper approach,
be determined and applied to the monolith.
are sometimes subjected to moving ice and the effects
should be accounted for. For isolated installations
4-11. Thermal. Thermal loads are caused by volu-
where ice conditions are severe, and the ice sheet is
metric changes caused by changes in temperature,
short and can be restrained or wedged between struc-
temperature gradients through sections of the concrete
tures, its magnitude should be estimated, with consid-
structure, geometric discontinuities in the structure
eration given to availability of records of ice condi-
(e.g. culverts), and external restraints (e.g. piles).
tions. It is recommended that an impact pressure of
Thermal loads must be evaluated in a U-frame lock
not more than 5,000 lb/sq ft be applied to the contact
structure because large member thicknesses prevent
surface of the structure, based on the expected ice
the heat generated from hydration from being dissi-
thickness. In the United States the ice thickness
pated as quickly as it is generated and therefore the
assumed for design normally will not exceed 2 ft.
temperatures within the structure rise. Effects of
Ice pressure should be applied at the upper pool
thermal loads can be evaluated through a nonlinear,
elevation. For further information, see EM 1110-2-
incremental structural analysis as described in
1612, ETL 1110-2-295, and ETL 1110-2-320. Super-
paragraph 7-5.
structure loads include the reactions to control houses
and access bridge spans. Miscellaneous loads include
4-12. Cofferdam tie-in. The forces exerted on the
large temporary surcharge loads and mobile equip-
structure by cofferdams should be incorporated into
ment loads. Typical items may include cranes for
the appropriate monoliths. The forces in sheetpile
maintenance and placement of stoplogs, construction
interlocks as well as any horizontal loads and drag
equipment used for concrete placement, etc.
loads from the fill within the sheetpile cells should be
added to the appropriate monolith.
5. Load Cases
4-13. Sheetpile cutoff reaction. The sheetpile
cutoff reactions on U-frame monoliths are generally
small and neglected. For further information, see
various loads described in paragraph 4. The forces in
other guidance.
the load cases are factored or unfactored depending
upon the analysis being performed. The load factors
4-14. Localized loads. Loads from equipment
used depend upon the type of load, certainty of mag-
and appurtenant items are discussed in other gui-
nitude of load, and frequency of load being applied.
dance. These loads must be carried by the lock
monolith. Localized loads normally do not control
5-2. Categories of load cases. The structure
the structure design or overall stability, but may con-
during its life will be subjected to many differing
trol the design in localized areas. Examples of this
loads. The severity of these loads and the frequency
type of load include the horizontal thrust from the
of their occurrence along with the consequences of
miter gate bull gear support frame, the emergency
A-8
Previous Page
