Concrete Design Ali N. Attiyah, Ph.D.
Fourth Year 2015-2016
1
Lecture three
Direct Design Method
To analyze building structural systems, there are different methods and Ch. 6 in ACI stated
the provisions required for analysis. ACI 6.2.4 stated that Direct Design Method DDM
could be used to analyze two-way slab systems applied to gravity loads (dead plus love
loads).
The DDM can be summarized in the following steps:
The slab is divided into two types of strips: column strips and middle strips as stated in
ACI 8.4.1.5 and ACI 8.4.1.6, respectively.
Concrete Design Ali N. Attiyah, Ph.D.
Fourth Year 2015-2016
2
Concrete Design Ali N. Attiyah, Ph.D.
Fourth Year 2015-2016
3
Hence, each frame will composed of column strip and part of middle strip.
DDM is not general method and apply only for slabs satisfying the limitations of ACI
8.10.2:
Concrete Design Ali N. Attiyah, Ph.D.
Fourth Year 2015-2016
4
Example: