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How do you calculate development length of reinforced cement concrete section?
Wiki User
∙ 13y ago
apply Ld/db = 3/40 (rad f'c/fy) * (Alpha*beta*gamma*lamda) / ([C + Ktr]/db)
Check ACI 318-08 Eq 12-1. It was developed by some smart south African dude.
Enjoy.
Ld={(3*fy*Ѱt*Ѱe*Ѱs)/(40*λ*(f'c)^.5*[(cb+Ktr)/db)])}*db
Ktr = (40*Atr)/sn read ACI -Ψ reinforcement factors related to coatings, size & position
however an easy check for cases where f'c = 4000 ; Gr 60 steel
Lb = 47db
(these are cases with min cover, min clear spacing, min clear cover, min ties & stirrups)
if less coverage and closer spacing
Lb = 71db
caveat - Structural engineers are paid to perform this design.....use 'em
Wiki User
∙ 13y ago
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What is the difference Between under reinforced section and over reinforced section?
When the maximum stresses in steel and concrete simultaniously reaches allowable value the section is called balanced section when the %of steel in a section is less than that required for a balanced section it is under reinforced section when the %of steel in a section is more than that required for a balanced section it is over reinforced sectionover reinforcement is as per section design I.e Ast1+Ast2>Ast Ast1+Ast2
Why it is undesirable to design over reinforced sections?
There are two basic reasons 1. In over reinforced section failure happens due to concrete which is sudden without any type of warning like bending or deflection.... 2. Steel is one of the most costly material used in construction work so from the economical view it is also undesirable to provide over reinforced section...
What is the purpose of strength reduction factors and why they are smaller for columns than beams?
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What are advantages of pre stressed concrete sleeper?
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How is Reinforced concrete made?
Reinforced concrete is made by placing steel bars in the tension zone of the beam x-section.
What is the difference Between under reinforced section and over reinforced section?
When the maximum stresses in steel and concrete simultaniously reaches allowable value the section is called balanced section when the %of steel in a section is less than that required for a balanced section it is under reinforced section when the %of steel in a section is more than that required for a balanced section it is over reinforced sectionover reinforcement is as per section design I.e Ast1+Ast2>Ast Ast1+Ast2
If the neutral axis of a reinforced section is above the critical section what is the section called?
Under Reinforced Section
Why it is undesirable to design over reinforced sections?
There are two basic reasons 1. In over reinforced section failure happens due to concrete which is sudden without any type of warning like bending or deflection.... 2. Steel is one of the most costly material used in construction work so from the economical view it is also undesirable to provide over reinforced section...
Why we use double reinforced section?
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What has the author V K Yudin written?
V. K. Yudin has written: 'Behavior of reinforced concrete beams with rectangular cross-section subjected to combined torsion and flexure'
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A section which has twice as much as the usual amount of reinforcement.
What is the difference of singly reinforced beam from doubly reinforced beam?
Singly reinforced beams have reinforcing only on the tension face. Doubly reinforced beams have reinforcing on the tension and compression face. Doubly reinforced beams can increase section capacity, but are primarily used to increase the ductility of the concrete beam. In certain codes, if the concrete section is controlled by the concrete failing in compression before the tension steel rebar yields (called a compression-controlled or brittle section), the calculated section capacity must be reduced to account for the brittle and sudden/unpredictable nature of a compression controlled (also called a brittle) failure. In order to make the section controlled by the yielding of the tension reinforcement (called a tension-controlled or ductile section), the ductility must be increased. This can be accomplished by adding steel in the compression zone, which gives strength to the compression area, thereby delaying the failure of the concrete. Enough compression steel can cause the section to switch from a brittle mode-of-failure to a ductile mode-of-failure, thereby permitting the designer to not decrease the section capacity from its calculated value. When identifying a doubly- reinforced beam, be sure that the steel in the compression area is meant to be for strength. Oftentimes, all faces of a beam will have some reinforcing for temperature/shrinkage protection and to tie the stirrups to. Steel that is only there for temp/shrinkage or to facilitate tying the rebar will usually be small and not much of it. In buildings, they will be often #3 bars @ 12" centers. In bridges, they may be #4 bars. These small bars should not be counted as compression-zone reinforcing. Look for bars in the compression zone that are of similar size to the main tension reinforcing.
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