Continuous Reinforced Concrete Structures - Design of Reinforced Concrete - page 461

Figure 14.32
The shear in column CD is 2.5 k; in GH it is 5.0 k; and so on. Similarly, the mem-
ber shears were determined for the columns on the first and second levels, where
the total shears are 75 k and 45 k, respectively.
2. Column moments. The columns are assumed to have points of inflection at their
middepths; therefore, their moments, top and bottom, equal the column shears
times half the column heights.
3. Girder moments and shears. At any joint in the frame, the sum of the moments
in the girders equals the sum of the moments in the columns. The column mo-
ments have been previously determined. By beginning at the upper left-hand
corner of the frame and working across from left to right, adding or subtracting
the moments as the case may be, the girder moments were found in this order:
DH , HL , LP , CG , GK , and so on. It follows that with points of inflection at
girder centerlines, the girder shears equal the girder moments divided by half-
girder lengths.
4. Column axial forces. The axial forces in the columns may be directly obtained
from the girder shears. Starting at the upper left-hand corner, the column axial
force in CD is equal to the shear in girder DH . The axial force in column GH is
equal to the difference between the two girder shears DH and HL , which equals
zero in this case. (If the width of each of the portals is the same, the shears in the