7/25/2019 Reinforcement Concrete Ductile Frame

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Stifness:

1. i serviceability criteria are to be satised with a reasonable degree o

condence the extent and inuence o cracking in member and the

contribution o concrete or masonry in tension must be considered in

conjunction with the traditionally considered asect o section and element

geometry and material roerties.!. "n early task within the design rocess will be the checking o tyical

interstory deection #drit$% using realistic stifness values to satisy local

re&uirements or serviceability. #'aulay '(11$). *n routine design% the contribution o nonstructural comonents to both

stifness and strength is ignored #rovided that nonstructural comonents are

deliberately and roerly searated rom the structural$+. *t must be recongnised that inll anels% either artial or ull height within

structural rames cannot be considered nonstructural% even whent the inll is

o light weight low(strength masonary,. -he in(lane stifness o the oor system is considered to be innitely large.

. /or regular multistory rame may be subdivided into a series o vertical two(dimensional rame% which are analy0ed searately but or irregular rame )

comuter analyses should be emloyed.2. -he efects on the behavior o rames o axial deormation in columns and

beams can usually be neglected3. 4odes where column and beam meets are always considered as rigid joint5. *n case o only the gravity load analysis% the crack in member will be

comaritivley minor at service load condition and relative rather than the

absolute values o stifness are all that re&uired to obtain accurate member

orces.6owever% under seismic action% because o moment reversal% each end may

get exural cracking and erhas the central region may be un(cracked.

-hereore% or roer distribution o moments realistic stifness o memberwill be mandatory. 6owever% it is imractical to evaluate roerties at several

cross(section so7 reasonable average values should be assumed. see age(

1) o 'auly 'ris"8*41!)