The axial force in the horizontal pipe bracing is scaled up by 10.76 to 10.76(32.3) = 344 k (1530 KN).
The bracing enhanced performance objectives will be checked as if the bracing were a concentrically
Collectors / Chords along grid lines B & H
These beams act as collectors and chords for the low sloped roof areas in addition to supporting the
concrete walls. Scale up forces by 10.96
Chord force = 32.3 kips (10.96) = 354 k (1575 KN) Collector force = 4.46 k (10.96) = 48.7 k (217 KN)
wu = 1.2D + 0.2D = 1.4D = 1.4(1325 plf) = 1855 plf (27.1 KN/m)
Mu = wuL2/8 = (1855)(18' 2/8 = 75 kft (102 KNm)
D-5 Identify force-controlled and deformation controlled structural components.
The concrete shear walls have very low axial load demands. Footnote 1 of Table 7-3 requires that the
axial load be less than 0.15 Agf' to be governed by shear. The maximum shear stress in all of the wall is
less than 6 f c' and therefore, the walls are checked as deformation controlled structural components.
The steel moment frames are checked as deformation controlled components.
The horizontal bracing is checked as a deformation controlled component.
The connection of the horizontal bracing to the shear walls along lines 2 & 7 and the collectors along lines
B & H are checked as force controlled actions.
D-6 Determine QUD and QCE for deformation controlled components
Shear Wall Segments
The highest demand / capacity ratio to any wall pier element from step B.11 is 16.2k / 109k = 0.15 (for the
lower portions of wall line 7). Only this element is checked;
QUD = (10.76)(16.2 k) = 174.3 kips (775 KN)
QCE = 109 kips (485 KN) (determined previously)
The expected strength of the steel members is based on Fye = RyFy = 1.5(36) = 54 ksi ( 372 N/mm2) and Z
for the section.
Moment Strength = ZFye = 101(54) = 455 kft (617 KNm)
Shear Strength = 0.6Fye(d x tw) = 0.6(54)(17.99" x 0.355") = 207 k (921 KN)
Axial Strength = 340 kips (this is for 36 ksi; scale up by 54/36 to obtain FYE strength)
Axial Strength = (340 k)(54/36) = 510 k (2268 KN)
Moment Demand = 180 kft (244 KNm)
Shear Demand = 11.8 k (52.5 KN)
(Elastic analysis not shown)
Axial Demand = 41 k (182 KN)