Criteria for Post Tensioned Design Followed by PTSI
     (Ref.: ACI 318-2008, IS 1343 : 1980 and IS 456 : 2000)

PT-beam and one-way PT-slab

• Live Load (LL): Loading as recommended by structural consultant in kN/m2
• Floor Finish (FF): Loading as recommended by structural consultant in kN/m2
• Wall Load (SDL): Loading as recommended by structural consultant in kN/m2
• Self Weight (SW): as per the section size (considering prestressed concrete weight 23.5kN/m3 as per IS 875 part 1 : 1987)
• Grade of Concrete (Fck): M35 cube strength
• Live Load skipping (pattern effect) is recommended in case of continuous member.
• Tensile Stress Limit of concrete section for “Sustained Load Combination” (i.e. 1*SW+1*FF+1*SDL+0.3*LL+1*PT) as well as for “Total Service Load Combination” (i.e. 1*SW+1*FF+1*SDL+1*LL+1*PT): Type 2 design: Tensile stresses within 3N/mm2. This can be extended to 4.5N/mm2, provided, the member should be in compression in absence of Temporary Design Loads as per IS 1343 : 1980
• Moments considered in design are reduced moments at the face of column (as per the provision of moment reduction at the face of support)
• Additional reinforcement provided as per the criteria of ACI 318-2008
• Ductile detailing criteria provided in IS 13920 and minimum reinforcement criteria provided in IS 456 shall be considered additionally as per its applicability considering HYSD 415 grade (or 500 grade if recommended by the structural consultant) steel.
• Effective flange width is considered as per ACI 318
• For Beam shear: Stirrup design as per IS 456 and IS 13920
• Deflection values (Long Term with creep effect) as per IS 1343 for “Total Service Load Combination” (i.e. 1*SW+1*FF+1*SDL+1*LL+1*PT);
• Downward Deflection due to SW+LL+FF+SDL+PT+Creep (All loads) should not be more than span/250
• Downward Deflection due to SW+FF+SDL+PT+Creep (without LL) should not be more than span/350 or 20mm whichever is lesser shall be considered.
• Total upward deflection should not exceed span/300 unless uniformity of camber between adjacent units can be ensured.

PT Flat slab

• Live Load (LL): Loading as recommended by structural consultant in kN/m2
• Floor Finish (FF): Loading as recommended by structural consultant in kN/m2
• Wall Load (SDL): Loading as recommended by structural consultant in kN/m2
• Self Weight (SW): as per the section size (considering prestressed concrete weight 23.5kN/m3 as per IS 875 part 1 : 1987)
• Grade of Concrete (Fck): M35 (cube strength)
• Live Load skipping (pattern effect) is recommended in case of continuous member.
• Tensile Stress Limit of concrete slab section for “Sustained Load Combination” (i.e. 1*SW+1*FF+1*SDL+0.3*LL+1*PT) as well as for “Total Service Load Combination” (i.e. 1*SW+1*FF+1*SDL+1*LL+1*PT): Type 2 i.e. less than 3N/mm2 as per IS 1343 : 1980 and/or Class U (i.e. Uncracked section) as per ACI-318-2008.
• Criteria for maximum spacing of tendon placement as per ACI 318
• Additional reinforcement provided as per the criteria of ACI 318 as well as IS 456.
• Deflection values (Long Term with creep effect) as per IS 1343 : 1980 for “Total Service Load Combination” (i.e. 1*SW+1*FF+1*SDL+1*LL+1*PT);
• Downward Deflection due to SW+LL+FF+SDL+PT+Creep (All loads) should not be more than span/250
• Downward Deflection due to SW+FF+SDL+PT+Creep (without LL) should not be more than span/350 or 20mm whichever is lesser shall be considered.
• Total upward deflection should not exceed span/300 unless uniformity of camber between adjacent units can be ensured.