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A different effective length for frames

Effective length can be found easily on isolated columns by using Table C-C2 in the Commentary of the SpecificationSection of the Manual . However, this table will not work very well with rigid frames. Columns ina frame are not independent, they are continuous. The buckling of one member will affect all the members aroundit. Therefore, the end conditions necessary for using Table C-C2 are not sufficient. It is important to account for thedegree of restraint by connecting members of a column in a frame.

A frame can be unbraced or braced, where unbraced means horizontal displacement in possible. A frame can also havesidesway.

"The rotational restraint provided by beams, or girders, at the end of a column is a function of rotational stiffnessesof the members intersecting at the joint." LRFD Steel Design Second Edition -- William T. Segui, 1999. The restraint is proportional to E I L .

G E c I c L c E g I g L g I c L c I g L g

K , then depends on the ratio of column stiffness to the girder stiffness at each end.

G and k relationships

K is relatively small when a slender column is connected to a girder of large crosssection. This is because the girder effectively prevents rotation and acts as a fixed end. The G value for this case is rather small too. K (or G ) is relatively large when the ends of very stiff columns are connected to ratherflexible beams. This is because the ends of the column can more freely rotate and approach the pinned condition.

"The relationship between G and K has been quantified in the Jackson-Mooreland Alignment Charts (Johnston, 1796),which are reproduced in Figure C-C2.2 in the Commentary. To obtain a value of K from one of the nomograms, first calculate the value of G at each end of the column, letting one value be G A and the other be G B . Connect G A and G B with a straight line, and read the value of K on the middle scale. The effective length factor obtained in this manner is withrespect to the axis of bending, which is the axis perpendicular to the plane of the frame. A separateanalysis must be made for buckling about the other axis. Normally the beam-to-column connections in this directionwill not transmit moment, sidesway is prevented by bracing, and K can be taken as 1.0.

Value of g for pinned support

G can be taken as 10 at a pinned support because at a pin connection, the situation isjust like a very stiff column attached to infinitely flexible girders. This means the girders have zerostiffness. Then, the ratio of column stiffness to girder stiffness would be infinite for a perfectly frictionlesshinge. This end condition can only be approximated in practice, so the discussion accompanying the alignment chartrecommends that G be taken as 10.

Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
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Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Steel design (civi 306). OpenStax CNX. Jan 22, 2004 Download for free at http://cnx.org/content/col10153/1.3
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