I see, I evaluate, I write...

Wednesday, June 27, 2007

mari belajar concrete..

I have been struggling to understand this but its actually easy!!

shear strength is the most important thing in concrete however it is so complicated.this is what i have just found out after hours of understanding the notes

Shear strength in reinforced concrete can be distinguished between the one with shear reinforcement and the one without it. As for reinforced concrete (RC) without shear reinforcement, the shear is totally resisted by concrete aggregates. For a short, when the beam is sheared due to loads, the beam will develop sumthing that we call ARCH ACTION where compression struts and tensile ties are developed locally to resist shear. The shear strenth for this kind of of beam is given by V = reduction factor*Vc*b*d..i m not going into details.

As for long beam without shear reinforcement, the shear is totally resisted by 3 mechanisms namesly, the compression region, particles interlock and the dowel action. Particles interlocks account for 70% of the shear strength. Vn = Vc*b*d..where Vc = (0.07 + 10p )(fc')^(1/2). Vc cannot exceed 0.2(fc')^0.5 and cannot be less than 0.08(fc')^0.5...p on the other hands is the reinforcement ratio...it is also worth noting that for a column dat is having axial compression,the shear strength increases slightly. However if it is having tensile action, the shear strength reduces. I reckon it is because when the column is compressed the particles will be locked well hence increase the strength.

So finished with beam without shear reinforcement..how bout the one with it?..hehe..its easy!! This beam will definitely stronger in shear because not only the concrete aggregates will take the shear, the transverse reinforcement also does work together...and the strength is given by V = Vc + Vs = vc*b*d + AsFy(D/S) where d is the lenght of the section crossed by shear crack and s is the spacing of the stirrups (shear reinforcement)...it is assumed that the crack will cross at 45 degree and crossing a few stirrups..

So what kind of failure can we expect from shear effect?.....to list a few; stirrups yield, loss of stirrups anchorage, crushing of the web,and many more..

In most international codes though.50% of the design shear demand must be carried by the stirrups regardless of how much the concrete can take.

Basically thats wat ive learnt just now.i was trying to type it out with minimum reference so dat i understand and remember those key things..hehe...till then.

ps: tak sabar nak main masa bersatu lepas tgk gambar kontijen2 lain..gagaga

2 Comments:

Blogger rational thinker said...

that's pretty cool dude. :)

2:32 AM

 
Anonymous Nerina said...

People should read this.

3:51 AM

 

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