Correct Answer - Option 2 : 0.40
Concept:
Effective reinforcement ratio:
As per IS 1343:2012, Annex D, Table 11,
- It is based on effective concrete tension area and given by -
\(\rho _{\rho , ~eff} = \frac{A_{ps}f_{pu}}{bdf_{ck}}\)
Here,
Aps - area of pretensioning tendons in the tension zone
fpu - characteristic tensile strength of tendon
d - effective depth to the centroid of the steel area
b - width of the section
- The maximum and minimum values of effective reinforcement ratio of a bonded prestressed concrete beam with Pre-tensioned Tendons or with Post-tensioned Tendons having Effective Bond at failure is equal to -
\(\rho _{max , ~eff} = 0.40 \)
\(\rho _{min , ~eff} = 0.025\)
- The values of fpb (i.e. tensile stress in tendons at failure) and xu (i.e. neutral axis depth) both depends on effective reinforcement ratio.
As per IS 1343:1980, Anenex B,
- The maximum and minimum values of effective reinforcement ratio of a bonded prestressed concrete beam with Pre-tensioned Tendons or with Post-tensioned Tendons having Effective Bond at failure are equal to -
\(\rho _{max , ~eff} = 0.40 \)
\(\rho _{min , ~eff} = 0.025\)
- The maximum and minimum values of effective reinforcement ratio of a Post-tensioned beam with unbonded tendons are equal to -
\(\rho _{max , ~eff} = 0.20 \)
\(\rho _{min , ~eff} = 0.025 \)