Finite Element Methods for Structures with Large Stochastic Variations

If the beam is clamped at x = 0 and free at x = L and is subjected to a load q( x), then the governing equations for the bending moment are given by eqns (4.2) and (4.6). The boundary conditions are
For an arbitrary bending moment m( y), we obtain:
Similarly,
The boundary conditions (E2) and (E3) in explicit form become, after substituting into eqn (4.8):
We first determine f 2( x) from the fourth equation; the third equation then yields f 1( x), after substituting f 2( x) into it; the second equation yields g 2( y), whereas the first equation yields g 1( y).
The solution of covariance function becomes:
where
To obtain the boundary conditions for the covariance function we first note that the boundary conditions for displacement for the beam are:
For an arbitrary displacement w( y), we have:
Similarly,
In explicit form, the boundary conditions (E9) and (E10) are:
By solving for F 1( x), F 2( x), G 1(