location of the centroids of the various portions of the

(3) Offset beams model. The elements for this

slab will need to be placed at the same elevation,

model are all placed at the centroid of the thin section

when in fact they are at different elevations.

of the base slab. At the location where the slab is

thicker, a grid of beams is added. The locations of

the elements and beams are shown in Figure A-12.

The elevation of these beams should be located at the

output supplied by finite element programs is often in

centroid of the additional thickness being modeled,

the form of stresses and displacements, steps must be

and the section properties should also be computed

taken to convert the resulting stresses into moments,

based on the tributary area of the additional thickness.

axial thrusts, and shears which can used for design.

In order to use this model, the finite code being used

To assist in obtaining the necessary shears, moments,

must be capable of offsetting the location of the

and thrusts needed from a finite element analysis, the

beams through a member eccentricity command since

program CSMT was developed. The program is

the beams are located at the same nodes as the plates.

documented in Huff et al. (1988). The user inputs

stresses along a given line from the finite element

(4) Single centroid model. The base slab may

analysis into the CSMT program, and the program

be modeled using shell elements and assigning the

computes the thrust and moment from the axial stress

elements within the model with different thicknesses.

block as well as the resulting shear on the section

This will require some approximation since the

from the shear stress block. If the designer chooses,

A-27

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