30 Sep 04
empirical correlation also compare well with a derivation of the mechanical model for the impact of a
rigid barge train on a rigid wall.
c. However, based on field observations and limitations of the field data, the values from the empiri-
cal correlation are limited to an Fm of less than 3.56 MN (800 kips). The designer should consult with
CECW-CE if the value of the maximum impact force exceeds 3.56 MN (800 kips). This limitation is
imposed because the equation does not account for the effects of lashing failures or deck buckling of the
corner plates under higher impact loads. The empirical correlation is defined as:
Fm = 0.435⋅ m⋅ (V0x ⋅ sin θ +V0y ⋅ cosθ)
Fm ≤ 800 kips
V0 x = initial longitudinal velocity of barge in x-direction, ft/sec
V0 y = initial transverse velocity of barge in y-direction, ft/sec
m = mass, kip-sec2 /ft, calculated as
W = weight of barge train in short tons, including towboat (but excluding hydrodynamic added mass)
2 = conversion factor from short tons to kips
g = 32.2 ft/sec2
B-3. Return Periods for Barge Impact Analysis
a. Background. The ability to define the loads to which a structure will be subjected during its
service life is critical in the design of navigation structures. A method of defining load conditions due to
barge impacts needs to be defined on a basis equivalent with other loading conditions such as pool levels
or seismic events. To accomplish this, the use of the return period or an annual probability has been
adopted to design the structure to maintain a certain level of structural performance.
b. Definition of design events for barge impact.
(1) The return periods for barge impact can be defined using the following three load condition
Usual These loads can be expected to occur frequently during the service life of a structure, and
no damage will occur to either the barge or wall. This typically corresponds to a 50 percent
chance of being exceeded in any given year.
Unusual These loads can be expected to occur infrequently during the service life of a structure,
and minor damage can occur to either the barge or wall. This damage is easily repairable without
loss of function for the structure or disruption of service to navigation traffic. This typically
corresponds to a 50 percent chance of being exceeded within a 100-year service life.