Explanation: IS: 1343 code method is used for determining the ultimate flexural strength of rectangular sections and T sections, all the bending stresses and direct force shall remain compressive in any direction, in structures subjected to dynamic loading, under the same circumstances on the other structures a tensile stresses Ft may be allowed which is less than one tenth of maximum permissible compressive stresses.

Explanation: If the neutral axis of the section lies within the flange, then the moment of resistance of the section is given by the equation, Mu = fp ap (0.42Xu), Mu = ultimate moment of resistance, fp= tensile stress developed in tendon at failure, ap = area of prestressing, d= depth, Xu = depth of neutral axis.

Explanation: In pretension & post tensioned members, the value of tensile stress fp and depth of neutral axis xu is obtained based on effective reinforcement ratio (Apf/bdfera) and effective bond (or) un bond between concrete & tendon and these values are given in tables of IS: 1343 code.

Where Apw = area of prestressing steel for web (Ap-Apf), Apf = area of prestressing steel for flange (0.45fck (b-bw) (df/f), f = characteristic tensile strength of the prestressing steel, df = flange thickness, b = width of beam, bw = width of web after considering are the cases in the tendon, the effective prestress fpc should be greater than 0.45f.

Explanation: There are 6 steps involved in designing of a rectangular, prestressed concrete beam 6, moment (M1), section modulus z, width & depth, area amount of steel required As, self weight of beam Wd, Md, position of reinforcement.

Explanation: The required section modulus z from the equation Z= ML/FC fc is the permissible stresses for concrete, but section modulus, Z=bd2/6 where d- depth of beam and the beam should be equal to L/20 or L/25, b-width of the beam, which is given as, b=6z/d2.

Asv/bsv = 0.4/0.8fy.

Explanation: Following are step by step procedure adopted for designing the prestressed beam of I section stress ft, permissible stress of concrete at transferred fr, fc, allowable tensile stress ft, permissible tensile stress in steel, loss of prestress b/w 15 to 20%, moment due to super imposed load ML, total bending Mt over all depth d, final prestressing force f, area required A, thickness of flange & web in b/w 120mm to 150mm, width of the flange bf, area of tendons At, no of cables required after final dimensions check the beam for safety.

The value ranges in between 30-45 adopt average value, this is the seventh step used in designing the I section.

Explanation: The area of tendons `At` is given as At = F/Safe tensile stress in steel by considering this area, provide suitable diameter of wires & determine the required number of wires, find the number of cables required and in each cable provide 8 to 12 wires the spacing for cables should be 120mm, after adopting the final dimensions check the beam for safety.