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Actually reinforcement in the concrete structure depends on the type of structure, Design code, Seismic effect and the method of design, it is not always necessary to provide more reinforcement than required. Proper design, proper detailing of reinforcement, joint detailing, providing seismic hook and lapping of reinforcement according to code overall good quality construction can minimize the destructive effect of seismic effect.
Definitely, more reinforcement will generally be needed, mainly stability ties to sustain structural stability.
Design of concrete structures the resistance to seismic depends on the iron Subscribe increase between structural elements and thus The buildings seismic-resistant be more iron-consuming
An excellent question was raised by Young student who is taking degree in civil engineering in UTHM ,Malaysia Why does the accredited standards (BS,Euro-code) limit the percentage of reinforcement in the reinforced concrete ?My reply to him is The main principle is that concrete has strong resistant to compression failure therefore it is strong in compression however it is weak in tension resistance to bending that is why steel compensate this weakness hence it s strong in tension Having more percentage than the specified will cause the concrete to act as steel structure which is basically is not steel aimed structurebesides that the area occupied by more reinforcement will weaken the concrete to act in compression resistance and punching shear and brittle failure may occur especially in the perpendicular structure such as columns at the time of ultimate strength in conclusion ,the standards have undergone plenty of experiences by experts to bring forward simple references for designer I hope you have gained insight hints
Yaser Gamil
There is minimum and maximum ratio from concrete for steel reinforcement depend on column position standard codes.
Design of section according to load combainations even taking into consideration seismic or not
on the other hand due to seismic we can increase Stirrups at joints and location of frame action but also within allowable limit
Also we can increase concrete strength if steel reinforcement need to be more close with maximum limit
Well I'd rather to say not specifically, because as osman guni said " it depends on many factors". You know the truth is that, amount of reinforcement must be restricted to the limit in which a simoltaneous yielding happens between reinforcement and compressive part of concrete section. So, if the amount of steel in a concrete section be more than balance then a brittle failure happens at the time of ultimate strength. Because, the compressive part of concrete which should be in a balance situation with reinforcement will be demolish before the yielding of reinforcement so the excessive volume of steel reinforcement is useless here.
Now, your answer is for seismic zones we have to use specific details in conjunction of beams and columns and also satisfy other clauses of international codes like shear stirrups or ties as well.
No, it should be less reinforcement to have ductile failure - as it will show warning. However, reinforcement detailing should be done accordingly specially for stirrups and ties.
WE HAVE THREE TYPES OF REINFORCEMENT CRTERIA
1 .CRITICAL REINFORCEMNENT
2. OVER REINFORCED
3 UNDER REINFORCED
UNDER REINFORCED STRUCTURES WOULD BE BEST SUITED FOR EARTHQUAKE PRONE AREAS AS THE STEEL SECTION IN CONCRETE WOULD BE FAILING FIRST AND THUS PEOPLE INSIDE THE BUILDING WOULD GET AMBLE TIME TO ESCAPE FROM THE BUILDING BEFORE THE COMPLETE COLLAPSE OF THE BUILDING.
IN OVER REINFORCED SECTIONS STEEL WOULD FAIL FIRST AND THUS THE COLLAPSE WOULD BE SUDDEN THUS IT IS NOT PREFFERED IN EARTH QUAKE PRONE AREAS
cant exactly say..... it should be determined by earth quake resistance analysis......
we must keep the over reinforcement concept in mind... because in case of over reinforcement there will be a risk of concrete failure which may be very much fatal.......
hello ... ushould never add more reinforcement to any concrete member the the max allowed by the code u are using there is always a max area of reinforcement thet can be calculated depending on the capacity of the section because more reinforcement will distabalize the equilibirum state of the section and will lead to an unexpected failure in case of yeild
adding steel reinforcement will enhance the performance of the structure in a seimic zone,because reinforced concrete is a quasi brittle material,advantages are:
1-where steel reinforcement is a ductile material that increase the capacity of the element specifically for lateral loads (Ductility:Is a material property that allow to perform large deformations ,in other meaning more energy dissipation before plastic limit).
2- In modeling and when performing seismic analysis we define a factor "R" called the overstrength or ductility factor used for calculation of BASE SHEAR,and whenever R increases the earthquake force dragged by the structure decreases, so if we are using a lateral resisting system as RC Moment resisting frame the ductility factor is much more greater than that of the shear wall system which will certainly enhance the seismic performance of the structure.
3-noting that the addition of steel reinforcement will enhance the capacity of the elements we should not forgot that the over reinforced section will leads to a brittle failure .
