UFC 3-260-03
15 Apr 01
d. Load Repetitions.
(1) Repetitions of load or aircraft passes is an aspect of structural capacity. A pavement cap-
able of sustaining a certain aircraft loading on a regular repeating basis for some design life of the facility
(commonly 10 years for Navy and Marine Corps Airfields) can sustain repeated application of a larger
loading, but for a reduced pavement life (less number of passes).
(2) It follows that an evaluation of the structural capacity of a pavement may determine not only
a maximum allowable number of repetitions for a specific loading, but also a maximum allowable loading
for a given number of repetitions of traffic.
(3) This pattern of load and repetitions implies that a single application of a given load can be
considered to represent a number of applications of a load of a lower magnitude. The number of appli-
cations can therefore be taken as the equivalent applications of one load to another. These equivalent
applications or equivalencies will normally be uneven or fractional numbers. For example, one application
of a load which is 20 percent heavier than another, when applied to a pavement, may be considered
equivalent to 6.5 applications of the smaller load, or one application of the lighter load may be considered
equivalent to 0.15 applications of the larger load.
(4) Extension of this concept permits the reduction of an array of loadings and the repetitions of
each to an equivalent number of repetitions of a single selected load. By stating each loading in the array
as equivalent applications of a selected basic load, multiplying each by its actual number of repetitions,
and accumulating the total, then the total applied traffic can be stated as equivalent repetitions (or
applications) of the selected basic loading. This methodology is an important adjunct to evaluation, since
it permits comparisons of cumulative past traffic, design traffic, traffic associated with load evaluation, and
increments of pavement life associated with overloading.
3.
EVALUATION PROCEDURE.
a. Steps in the Procedure. Evaluation is the assessment of pavement strength and condition and
the computation of the load-carrying capacity. The following steps are generally used in pavement
evaluations:
(1) Thorough study of all existing information regarding design, construction, maintenance,
traffic history of the pavements, results of physical-property tests of the pavements, and weather records
for the vicinity.
(2) Determination of pavement condition by formal Pavement Condition Index (PCI) method as
delineated in American Society for Testing and Materials (ASTM) D 5340 wherever possible, but as a
minimum by direct visual inspection.
(3) Designating pavement facilities and subdividing into pavement features where a facility is a
part of an airfield or heliport used by aircraft such as a runway, taxiway, apron, etc., and where features
are segments of a pavement with consistent structural thickness and materials were constructed at the
same time, subject to approximately the same traffic, and have a uniform condition.
(4)
Determination of the scope, validity of available data, and need for additional information or
tests.
(5) Determination of pavement element characteristics and/or pavement response to loading
for input to the evaluation method using one or a combination of the following procedures:
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