July 2006
H-18-8
3.3 Special Provisions for structures assigned to Seismic Design Categories D,
E, or F.
The provisions of this section shall apply to all new Critical and Essential Facilities.
a. Bay spacing essentially shall be equal and uniform throughout.
b. Transfer beams or trusses supporting upper level columns shall not be used
unless permitted on a case by case basis by VA.
c. Seismic joints shall be avoided, in so far as possible. When required, they shall
be specifically identified in the schematic design phase of the project and
approved by VA, subject to the following provisions:
1. Seismic joints shall be properly detailed on the working drawings;
2. Seismic joints shall be sized based on the maximum expected
displacements, considering the effects of story drift, diaphragm
displacements and rotations, and a realistic approximation of element
section properties. For materials designed considering the ultimate limit
state, such as concrete, the stiffness representative of this state shall be
used. Seismic separations shall be 125% of the separation required by
ASCE 7; and
3. Adjacent structures that are not integral with an existing structure shall be
separated by not less than 2 inches per story.
3.4 Limitations on Reinforced Concrete Structures
Structures assigned to Seismic Design Categories D, E, or F, the provisions of this
section shall apply to all new Critical and Essential Facilities.
a. Prestressed concrete structural members, including pretensioned and post-
tensioned members, and precast elements such as tilt-up wall panels, and
precast beam and column elements shall not be used to resist seismic forces.
b. Lightweight concrete shall not be used in structural members resisting
earthquake forces, except in concrete floors and roof slabs used as diaphragm
elements to distribute earthquake forces to vertical lateral-load resisting
elements.
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