The formula here for the stiffness ratio Φ assumes that
the external load enters the joint between the washers and
flange. The use of a multiplicative factor to characterize
the prying effect has been common for many years; one example
is in Reference [16]. More sophisticated approaches
to prying exist17 but are not assessed here. Some hand calculation
methods18, 19 also include a “loading plane factor,”
which is meant to characterize the distribution of external
load through the thickness of the flange; that factor is simply
another multiplier on the external load and need not
be broken out separately when a prying factor is used.
susceptible