Page 320 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch07.qxd 9/29/05 5:16 PM Page 7.4

FLOOR AND ROOF SYSTEMS

7.4 CHAPTER SEVEN

FIGURE 7.4 Cellular steel deck with trench header placed within the concrete slab to feed wiring to cells.

Another consideration is that use of shoring can sometimes affect the construction schedule, since the
shoring is usually kept in place until the concrete fill has reached at least 75% of its specified 28-day
compressive strength. In addition, when shoring is used, the concrete must resist the stresses resulting
from the total dead load combined with all superimposed loadings.
When concrete is cast on unshored metal deck, the weight of the concrete causes the deck to deflect
1
3
between supports. This deflection is usually limited to the lesser of / 180 the deck span or / 4 in. If the

FIGURE 7.5 Floor layout for cellular deck with cells in different directions. Length of trench header serving them is less for (a) cells in
the longitudinal direction than for (b) cells in the transverse direction.

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.