16.4 Computer Program for Free Vibration Analysis of Framed Structures
571
Table 16.3 (continued)
estif(9,9)
= 12.0*e*iy/l**3
estif(9,11) = 6.0*e*iy/l**2
estif(10,10) = g*ix/l
estif(11,11) = 4.0*e*iy/l
estif(12,12) = 4.0*e*iz/l
*
Geneartion of lower triangle of the stiffness matrix
do irow=1,12
do icol=1,12
estif(icol,irow)=estif(irow,icol)
enddo
enddo
return
end
*
Subroutine to calculate the transformation matrix of the element
subroutine tran(iel,x1,x2,y1,y2,z1,z2,len,tra)
dimension tra(12,12)
real len
do irow=1,12
do icol=1,12
tra(irow,icol)=0.0
enddo
enddo
cx = (x2-x1)/len
cy = (y2-y1)/len
cz = (z2-z1)/len
cxz = sqrt(cx*cx+cz*cz)
alpha=0.0
pi
=atan(1.)*4.
alpha = alpha*pi/180.0
cosa = cos(alpha)
sina = sin(alpha)
if(x1.eq.x2.and.z1.eq.z2.and.y1.ne.y2) then
tra(1,2) = cy
tra(2,1) =-cy*cosa
tra(2,3) = sina
tra(3,1) = cy*sina
tra(3,3) = cosa
else
tra(1,1) = cx
tra(1,2) = cy
tra(1,3) = cz
tra(2,1) = (-cx*cy*cosa-cz*sina)/cxz
tra(2,2) = cxz*cosa
tra(2,3) = (-cy*cz*cosa+cx*sina)/cxz
(continued)