ETL 1110-2-355
31 Dec 93
4-1. Dead loads. Dead loads consist of concrete
d. Foundation material. This information is
generally determined by the geotechnical discipline
and structural steel items such as miter gates, tainter
and furnished to the structural engineer. Bearing
valves, and emergency closure and maintenance bulk-
strength for soils and methods for determining bear-
heads. The weight of the concrete structure is com-
ing strength based on field and laboratory data are
monly the predominate force in the design of a
described in EM 1110-1-1905.
U-frame lock. This load must be appropriately dis-
tributed so that its centroid coincides with the geo-
3-4. Seismic design criteria. Seismic design
metric centroid of the concrete item being analyzed.
Effects of buoyancy on the concrete are accounted for
criteria are defined in other guidance. Seismic load
separately as uplift forces described below.
cases are generally considered unusual or extreme
conditions and have reduced factors of safety associ-
4-2. Water. Water is either free standing or con-
ated with the criteria. The design that results from
static analysis for usual and unusual conditions can be
fined. Free-standing water refers to water above the
adequate for seismic response integrity. This is due
soil, which is unaffected by either seepage or head
to the use of damping effects, more sophisticated
loss. For example, water contained within the lock
analyses, and different load factors in seismic analysis
chamber, lock culverts, or outside the lock walls
and design of reinforced concrete monoliths.
above any backfill, silt, ground surface, or concrete
surface is free-standing water. This water produces
3-5. Serviceability. Serviceability requirements
pressures normal to any surface or plane which it
contacts. For convenience, water pressures are con-
are unique among projects, and the designers are
sidered such that the forces are either horizontal
responsible for establishing these requirements. To
pressures or vertical weights. Confined water is that
establish serviceability requirements the design team
water which exists below the saturation line in any
should consider a number of aspects in the lock struc-
backfill and foundation material. This water produces
ture. Considerations should include minimization of
pressure normal to any surface just as free-standing
concrete cracking, seepage and leaking, and reinforce-
water except that the effect of seepage and head loss
ment corrosion. Global deflections, settlement, and
may need to be considered in determining the value
relative deflections are other primary concerns, espec-
of the pressure at any point. Water forces on mono-
ially those that affect mechanical interaction with the
lith expansion or contraction joints resulting from
structure such as near the miter gate sill or valve
broken waterstops must also be considered in analysis
locations. Additionally, maintenance, personnel
and design. The value of the horizontal pressure
access, and safety are important considerations for
must equal the value of the vertical uplift pressure at
serviceability.
any given point.
4-3. Uplift. The pressure of water creates forces
4. Loads
acting upward on the bottom of the U-frame lock
The most common loads on a U-frame lock are those
base. These uplift pressures are determined by multi-
due to the dead weight of the concrete structure, and
plying the head of water above the bottom of the base
those loads imposed from the soil and water which
by the density of water. The value of head used must
surround the structure. Additional loads from service
include the effects of seepage from the upper pool to
gates, valves, bulkheads, emergency closure equip-
the lower pool. The rate of head loss must be deter-
ment, and operating machinery are also present. The
mined for each project depending upon the permeabil-
stresses imposed by temporary loads must also be
ity of the foundation, total head for the project, and
considered. Such loads are barge impact, ice, earth-
presence of pressure relief systems (foundation
quake, wind, etc. Other loads such as surcharge and
drains). See Sherman (1968 and 1972) for additional
debris and ice loads may exist, depending upon the
details.
site-specific conditions. The following paragraphs
provide a brief discussion on each of the commonly
4-4. Soil pressures.
encountered loads and also provide guidance on how
these loads are determined. Further information on
a. Vertical. The vertical weight of any soil
these loads is contained in other guidance.
acting on the structure is determined by multiplying
A-6
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