SEISMIC DESIGN
December 4, 2024 11:18 AM
SEISMIC DESIGN FOR BUILDING AND STRUCTURES
1. SEISMIC LOAD COMBINATION
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MOST OF OUR PROJECTS HAVE A SDS =< 0.125, THUS THE VERTICAL SEISMIC LOAD EFFECR IS PERMITTED TO BE ZERO
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(IBC 2018)
GENERALLY, THE LIVE LOAD ON OPERATING PLATFORM IS 3KPA LESS THAN 4.79KPA, THUS, THE LOAD FACTOR ON L IN
COMBINATION 5 IS PERMITTED TO BE 0.5
THE CONCRETE DECK IN MILLING AREA HAS A LIVE LOAD EQUAL TO 10KPA, THIS IS DUE TO RELINER MACHINE AND
LINERS. USE A LOAD FACTOR AS 1 IN THIS CASE.
IT IS A BIT CONSERVATIVE BECAUSE 10KPA LOAD SHOULD ONLY BE APPLIED AT AN AREA OF 3mX10m - THE RELINER
MACHINE IS 3m WIDTH BY 10m LONG, INSTEAD OF APPLYING THE WHOLE AREA.
TO BE MORE ACCURATE, ONLY APPLY THE 10 KPA AT THE AREA WHERE THE RELINER MACHINE CAN DRIVE THROUGH.
APPLY 15KPA ONLY AT THE AREA WHERE THE LINER IS GOING TO BE RESTORED. APPLY 3KPA FOR THE REMAINING
AREAS.
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AREAS.
ALINE WITH LYCO LOAD COMBINATION 501 TO 508, 511 TO 518, 521 TO 528
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MOST OF OUR PROJECTS HAVE A SEISMIC SITE CLASS OF C. THE OCCUPANCY CATEGORY IS II. THUS, THE IMPORTANCE
FACTOR IS 1.0. MOST OF CASES, THE S1<0.04, SS<0.15.
THE BUILDING/STRUCTURE BELONGS TO SEISMIC DESIGN CATEGORY A.
FOR CATEGORY A, Each structure shall be analyzed for the effects of static lateral forces applied independently in each
of two orthogonal directions. In each direction, the static lateral forces at all levels shall be applied simultaneously.
TO BE CONSERVATIVE, CONSIDER THE EFFECT OF THE COMBINATION OF 100% OF FORCE FOR ONE DIRECTION AND 30%
OF FORCE FOR THE PERPENDICULAR DIRECTION.
THIS ALIGNS WITH LYCO LOAD COMBINATION LC181 TO LC188 AND LC189 TO LC196
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2. SEISMIC CALCULATION FOR BUILDING AND STRUCTURES IN STAADPRO
STAADPRO IS USING THE EQUIVALENT LATERAL FORCE ANALYSIS
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RZ=RX =3
TO CALCULATE Cs, AND V
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For braced structure, the story drift is relative small, so the stability coefficient is likely to less than 0.1. therefore the
push over study is not applied.
In case of irregular structure or moment frame structure, check the push over analysis
SEISMIC DESIGN REQUIREDMENT FOR NONSTRUCTURAL COMPONENTS
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Ip =1.0 FOR MOST EQUIOMENT
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TANK AND RING BEAM SEISMIC DESIGN (API650)
For combining horizontal and vertical seismic forces, API 650 combines 100% of the seismic load from horizontal
acceleration with 40% of the seismic load from vertical acceleration.
wt (1+0.4Av) IS THE BEARING FORCE GENERATED BY THE TOTAL COMPRESSION FORCE APPLIED ON THE RING BEAM
(THE WEIGHT OF TANK, TOT PLATFORM, AND THE WEIGHT OF SLURRY (ON THE RING BEAM) PLUS THE OPERATION
LOAD) AND 40% OF THE VERTICAL SEISMIC LOAD (wt x Av). THIS IS AN UNIFORM PRESSURE
1.273Mrw/D^2 IS THE MAXIMUM COMPRESSION FORCE GENERATED DUE TO THE SEISMIC OVERTURNING MOMENT
INDUCED BY HORIZONTAL SEISMIC FORCE
Mrw IS OBTAINED FROM MECHANICAL CALS. Mrw INCLUDES THE OVERTURNING MOMENT DUE TO WEIGHT
OF TOT PLATFORM AND EQUIPMENT WEIGHT (LC5+LC6+LC7) AND THE TOTAL OPERATING LOAD OF
PERMANENT EQUIPMENT (LC41)
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