what i see is logic is....
1)for analysis you can model the frame or whatever it is by computer and you can define the column section as tapered..
2)for buckling calculations use the properties of an intermediate section between the min and the max sections
3)for design and checking stresses...
in that particular case
the shear flow = Q.S/2I.b
Q=max shear on that beam
S=first moment of area of the flange plate about the beam's horizontal axis
I=moment of inertia of the C.S
b=web plate's thickness
2 is for two longitudinal welds on sides od web plate
in that particular case
the shear flow = Q.S/2I.b
Q=max shear on that beam
S=first moment of area of the flange plate about the beam's horizontal axis
I=moment of inertia of the C.S
b=web plate's thickness
it's not necessary that the weld suffers bending in this case..just like the RFT bars in an RC beam..
the beam bends but the RFT bars suffers a tension force only and not bending..
the flange plate bends while attached to the web plate so they bend together...what prevent slippage between them...
zaes73
the equations that the ACI uses for deriving the extra moment generated from buckling are the P-Delta equations..if you use P-delta option in any analysis program you don't calculate the extra added buckling moments coz they're already taken into account in ETABS analysis
i forgot to answer the first question..
when to take the effect of dynamic load...
when you have an acting significant dynamic load like earthquake or vibrating machines...sometimes you're gonna multiply the static loads by a dynamic amplification factor to count for the dynamic effect like in...
for columns it's not an option to use the P-delta effect if you're using american codes coz it's a necissity..if you didn't use p-delta analysis in the ETABS you'r gonna use it when designing columns and getting their buckling lenghths to get additional moments due to buckling
thanx for the replies , and thanx for the chopra's text recommendation it's been a useful text to get the missing things..
now that i got that the response spectrum is a plot of the maximum response of STRUCTURES with different natural periods.
in design of structures...how to prevent...
ok, i got the answer
the values of moments and axial forces displayed on members are absolute values of what's the maximum value of (moment,shear) will occure here regardless sign of them..the designer should account for the both signs..and make combinations once with -ve values and another...
UCFSE thanx for the reply
i meant are the periods of the mode shapes are the natural periods or they are just periods that these modes will occur?
2-the response spectrum curve that's provided by the different loading codes is for the ground or for the structures?
hello fellow engineers
i've been reading in the building dynamics field and i think i'm missing something
1-i understand the physical definition of the natural frequency but (is it the reciprocal of the periods at which the different mode shapes take place)?
2-due to seismic action does the...
hello
do you trust the moment values resulting from sap , Etabs...etc analysis?? even if it differs from values resulting from manual load distribution and solving beams?
another thing for flat slabs
how do you handle the huge values of shells -ve momnets at column joints? and what are the...
all the modifier factors in sap & Etabs for steel members are 1
when you design RC you design sections as cracked section according to ultimate limit state design so moment of inertias of all the RC members are lesser in the reality than that in the computer model which gives lower values of...
thanx for replies ,
ash060 ,about the connectivity to the slab with the shear wall..that's why we make body constraints between the joints acting on the actual shear wall with the storey joints of the frame element so those joints will have the same deformations
hello...
1 : when modelling cores and or shear walls , their are 2 methods to use..structurally who is more accurate?
a-modelling them as frame element acting in the centroid of the actual core , shear wall and making body constraints between the joints on the same shear wall or core of the...
does the ACI318 or/and the BS8110 allow for using stirrups for shear resistance in shallow foundation isolated or combined footing in case it needs?
or just when the footing cross section is out of shear capacity increase dimensions?
as a structural system this's a stable system if
1-the movement is allowed in one girder support only and not the other one too
2-concrete columns are assumed to be fixed to their foundation and not hingly supported coz their's no framing action between the girder and the columns so any...
