From Table 7-1 of the manual:
R = 5.5, ς = 2.5, Cd = 5.0
Transverse direction:
Special reinforced concrete shear walls
o
R = 8, ς = 3.0, Cd = 5.5
Longitudinal direction: Special reinforced concrete moment frames
o
A-10 Determine preliminary member sizes for gravity load effects.
(1) Roof and Floor framing
Roof and floor framing to consist of hollow core concrete slabs. Slabs span in the longitudinal direction
between bearing walls.
Roof:
Determine Loading:
wL = 20 psf (0.96KN/m2)
Live load;
(per ANSI/ASCE 7-95 Table 4-1)
Dead load;
wD;
Roofing;
5 psf
Insulation;
3 psf
Suspended ceiling;
1 psf
Mechanical & Electrical; 3 psf
Total = wD =
12 psf (0.57KN/m2)
Therefore, the total superimposed service load = wD + wL = 12 psf + 20 psf = 32 psf (1.53KN/m2). Per the
hollow-core concrete slab manufacturers catalog, using a span of 23' 6" (7.17m) and the superimposed
-
service load of 32 psf, choose a 6" (152.4mm) thick x 4' 0" (1.22m) wide hollow-core slab of normal
-
weight concrete (wt. of slab with a 2-1/2" (63.5mm) topping = 80.3 psf or 3.84KN/m2).
Floor:
Determine design loads:
wL = 40 psf (1.92KN/m2)
Live load;
(per ANSI/ASCE 7-95
Table 4-1)
Dead load;
wD;
Floor finish;
1 psf
Partitions;
10 psf
Suspended ceiling;
1 psf
Mechanical & Electrical; 3 psf
15 psf (0.72KN/m2)
Total = wD =
Therefore, the total superimposed service load = wD + wL = 15 psf + 40 psf = 55 psf (2.63KN/m2). Per the
hollow-core concrete slab manufacturers catalog using a span of 23' 6", and the superimposed service load
-
of 55 psf, choose a 6" thick x 4' 0" wide hollow-core slab of normal weight concrete (wt. of slab with a 2-
-
1/2" topping = 80.3 psf or 3.84KN/m2).
(2) Transverse bearing wall design
The transverse bearing walls run almost continuously through the building being interrupted only by the 6-
ft. wide interior corridor. The thickness of the walls is determined based on their dual function as both
shear and bearing walls; the building is located in a high seismic zone and two curtains of reinforcement
are anticipated. Therefore, a wall thickness of 9-in (228.6mm). is chosen in order to accommodate the
placement of two curtains of reinforcement. For gravity loads, the empirical design method of ACI 318-95
Section 14.5 will be used to check this 9-in. thickness for bearing. The empirical design method is
determined to be applicable because the resultant of all factored loads is located within the middle third of
the wall. Additionally, it is anticipated that reinforcement requirements will be governed by seismic
considerations, and therefore, the design of the wall reinforcement will be addressed during the lateral load
design.
Determine design loads;
Note: Loading will be determined per unit of wall length using a tributary width per floor or roof of 23' 6"
-
(7.17m).
Live load;
H2-9
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