TANKS WITH SUPPORTED BOTTOMS

LATERAL FORCE ON NON BUILDING STRUCTURENSCP 208.9OBJECTIVESTO WHERE WOOD DIAPHRAGMS ARE USED TO LATERALLY SUPPORT CONCRETE OR MASONRY WALLS, THE ANCHORAGE SHALL CONFORM TO SECTION 208.8.2.7. IN SEISMIC ZONE 2 AND 4, ANCHORAGE SHALL NOT BE ACCOMPLISHED BY USE OF TOENAILS OR NAILS SUBJECT TO WITHDRAWAL, WOOD LEDGES OR FRAMING SHALL NOT BE USED IN CROSSGRAIN BENDING OR CROSS-GRAIN TENSION , AND THE CONTINUOUS TIES REQUIRED BY ITEM 4 SHALL BE IN ADDITION TO THE DIAPHRAGM SHEATHING.

CONNECTION OF DIAPHRAGMS TO THE VERTICAL ELEMENTS IN STRUCTURES IN SEISMIC ZONE 4, HAVING A PLAN IRREGULARITY OF TYPE 1, 2, 3 OR 4, IN TABLE 208-10, SHALL BE DESIGNE WITHOUT CONSIDERING EITHER THE ONE THIRD INCREASE OR THE DURATION OF LOAD INCREASE CONSIDERED IN ALLOWABLE STRESSES FOR ELEMENTS RESISTING EARTHQUAKE FORCE.

IN STRUCTURES IN SEISMIC ZONE 4 HAVING A PLAN IRREGULARITY OF TYPE 2 IN TABLE 208-10, DIAPHRAGM CHORDS AND DRAG MEMBERS SHALL BE DESIGNED CONSIDERING INDEPENDENT MOVEMENT OF THE PROJECTING WINGS OF THE STRUCTURE. EACH OF THESE DIAPHRAGM ELEMENTS SHALL BE DESIGNED FOR THE MORE SEVERE OF THE FOLLOWING TWO ASSUMPTION;MOTION OF THE PROJECTING WINGS IN THE SAME DIRECTION.MOTION OF THE PROJECTING WINGS IN OPPOSING DIRECTION.

EXCEPTION:

THIS REQUIREMENT MAY BE DEEMED SATISFIED IF THE PROCEDURES OF SECTION 208.6 IN CONJUNCTION WITH THREE-DIMENTIONAL MODEL HAVE BEEN USED TO DETERMINE THE LATERAL SEISMIC FORCES FOR DESIGN.

208.8.2.9 FRAMING BELOW THE BASE. THE STRENGHT AND STIFFNESS OF THE FRAMING BETWEEN THE BASE AND THE FOUNDATION SHALL NOT BE LESS THAN THAT OF THE SUPERSTRUCTURE. SPECIAL DETAILING REQUIREMENTS OF CHAPTERS 4, 5 AND 7, AS APPROPRIATE, SHALL APPLY TO COLUMNS SUPPORTING

NSCP 208.9.4TANKS WITH SUPPORTED BOTTOMSNSCP 208.9.4FLAT BOTTOM TANKS OR OTHER TANKS WITH SUPPORTED BOTTOMS, FOUNDED AT OR BELOW GRADE, SHALL BE DESIGNED TO RESIST THE SEISMIC FORCES CALCULATED USING THE PROCEDURES IN SECTION 208.7 FOR RIGID STRUCTURES CONSIDERING THE ENTIRE WEIGHT OF THE TANK AND ITS CONTENTS. ALTERNATIVELY, SUCH TANKS MAY BE DESIGNED USING ONE OF THE TWO PROCEDURES:NSCP 208.9.4A RESPONSE SPECTRUM ANALYSIS THAT INCLUDES CONSIDERATION OF THE ACTUAL GROUND MOTION ANTICIPATED AT THE SITE AND THE INERTIAL EFFECTS OF THE CONTAINED FLUID.A DESIGN BASIS PRESCRIBED FOR THE PARTICULAR TYPE OF TANK BY AN APPROVED NATIONAL STANDARD, PROVIDED THAT THE SEISMIC ZONES AND OCCUPANCY CATEGORIES SHALL BE IN ACCORDANCE WITH THE PROVISIONS OF SECTIONS 208.4.4 AND 208.4.2, RESPECTIVELY.NSCP 208.9.5OTHER NONBUILDING STRUCTURESNSCP 208.9.5

NONBUILDING STRUCTURES THAT ARE NOT COVERED BY SECTIONS 208.9.3 AND 208.9.4 SHALL BE DESIGNED TO RESIST DESIGN SEISMIC FORCES NOT LESS THAN THOSE DETERMINED IN THE ACCORDANCE WITH THE PROVISIONS IN SECTION 208.5 WITH THE FOLLOWING ADDITIONS AND EXCEPTIONS:

NSCP 208.9.5NSCP 208.9.5THE VERTICAL DISTRIBUTIONOF THE DESIGN SEISMIC FORCES IN STRUCTURES COVERED BY TIS SECTION MAY BE DETERMINED BY USING THE PROVISIONS OF SECTION 208.5.5 OR BY USING THE PROCEDURES OF SECTION 208.6.

EXCEPTION:FOR IRREGULAR STRUCTURES ASSIGNED TO OCCUPANCY CATEGORIES I AND II THAT CANNOT BE MODELED AS A SINGLE MASS, THE PROCEDURES OF SECTION 208.6 SHALL BE USED.NSCP 208.9.5WHERE AN APPROVED NATIONAL STANDARD PROVIDES A BASIS FOR THE EARTHQUAKE-RESITANT DESIGN OF A PARTICULAR TYPE OF NONBUILDING STRUCTURE COVERED BY THIS SECTION, SUCH A STANDARD MAY BE USED, SUBJECT TO THE LIMITATONS OF THIS SECTION:

THE SEISMIC ZONE AND OCCUPANCY CATEGORIES SHALL BE IN CONFORMANCE WITH THE PROVISIONS OF SECTIONS 208.4.4 AND 208.4.2, RESPECTIVELY.

THE VALUES FOR TOTAL LATERAL FORCE AND TOTAL BASE OVERTURNING MOMENT USED IN DESIGN SHALL NOT BE LESS THAN 80% OF THE VALUES THAT WOULD BE OBTAINED USING THESE PROVISIONS.NSCP 208.9.5NSCP 208.9.5NSCP 208.9.5