Design Considerations for Economical Formwork - Simplified Design of Reinforced Concrete Buildings - page 262

• Spandrel beams are more cost intensive than interior beams due to their location at the edge of a floor
slab or at a slab opening. Fig. 9-5 lists some of the various aspects to consider when designing these members.

Overhangs difficult
and costly

Upturned spandrel
may be more
economical

Narrow deep beam can cause
difficulty in placing concrete and/or
rebars; widen to minimize
problems

Spandrel projection
beyond face of column
difficult and costly

Figure 9-5 Spandrel Beams

• Beams should be as wide as, or wider than, the columns into which they frame (see Fig. 9-6). In addition
for formwork economy, this also alleviates some of the reinforcement congestion at the intersection.

Greatest formwork economy
achieved when beam is the same
width as the column

Figure 9-6 Beam-Column Intersections

• For heavy loading or long spans, a beam deeper than the joists may be required. In these situations, allow
for minimum tee and lugs at sides of beams as shown in Fig. 9-7. Try to keep difference in elevation
between bottom of beam and bottom of floor system in modular lumber dimensions.