IS 456 2000 PT SL Example 001
User Manual: IS 456-2000 PT-SL Example 001
Open the PDF directly: View PDF 
.
Page Count: 6
| Download | |
| Open PDF In Browser | View PDF |
Software Verification PROGRAM NAME: REVISION NO.: ETABS 0 IS 456-2000 PT-SL EXAMPLE 001 Post-Tensioned Slab Design PROBLEM DESCRIPTION The purpose of this example is to verify the slab stresses and the required area of mild steel strength reinforcing for a post-tensioned slab. A one-way simply supported slab is modeled in ETABS. The modeled slab is 254 mm thick by 914 mm wide and spans 9754 mm, as shown in shown in Figure 1. Prestressing tendon, Ap Mild Steel, As 229 mm 254 mm 25 mm Length, L = 9754 mm 914 mm Section Elevation Figure 1 One-Way Slab IS 456-2000 PT-SL EXAMPLE 001 - 1 Software Verification PROGRAM NAME: REVISION NO.: ETABS 0 A 254-mm-wide design strip is centered along the length of the slab and has been defined as an A-Strip. B-strips have been placed at each end of the span, perpendicular to Strip-A (the B-Strips are necessary to define the tendon profile). A tendon with two strands, each having an area of 99 mm2, has been added to the A-Strip. The self weight and live loads have been added to the slab. The loads and post-tensioning forces are as follows: Loads: Dead = self weight, Live = 4.788 kN/m2 The total factored strip moments, required area of mild steel reinforcement, and slab stresses are reported at the mid-span of the slab. Independent hand calculations were compared with the ETABS results and summarized for verification and validation of the ETABS results. GEOMETRY, PROPERTIES AND LOADING Thickness Effective depth Clear span T, h = d = L = 254 mm 229 mm 9754 mm Concrete strength Yield strength of steel Prestressing, ultimate Prestressing, effective Area of Prestress (single strand) Concrete unit weight Modulus of elasticity Modulus of elasticity Poisson’s ratio f 'c fy fpu fe Ap wc Ec Es = 30 = 400 = 1862 = 1210 = 198 = 23.56 = 25000 = 200,000 = 0 Dead load Live load wd wl = = MPa MPa MPa MPa mm2 kN/m3 N/mm3 N/mm3 self kN/m2 4.788 kN/m2 TECHNICAL FEATURES OF ETABS TESTED Calculation of the required flexural reinforcement Check of slab stresses due to the application of dead, live, and post-tensioning loads RESULTS COMPARISON Table 1 shows the comparison of the ETABS total factored moments, required mild steel reinforcing, and slab stresses with the independent hand calculations. IS 456-2000 PT-SL EXAMPLE 001 - 2 Software Verification PROGRAM NAME: REVISION NO.: ETABS 0 Table 1 Comparison of Results FEATURE TESTED Factored moment, Mu (Ultimate) (kN-m) Area of Mild Steel req’d, As (sq-cm) Transfer Conc. Stress, top (D+PTI), MPa Transfer Conc. Stress, bot (D+PTI), MPa Normal Conc. Stress, top (D+L+PTF), MPa Normal Conc. Stress, bot (D+L+PTF), MPa INDEPENDENT RESULTS ETABS RESULTS DIFFERENCE 175.60 175.69 0.05% 19.53 19.775 1.25% 5.058 5.057 -0.02% 2.839 2.839 0.00% 10.460 10.467 0.07% 8.402 8.409 0.08% COMPUTER FILE: IS 456-2000 PT-SL EX001.EDB CONCLUSION The ETABS results show an acceptable comparison with the independent results. IS 456-2000 PT-SL EXAMPLE 001 - 3 Software Verification PROGRAM NAME: REVISION NO.: ETABS 0 HAND CALCULATIONS: Design Parameters: Mild Steel Reinforcing fck = 30MPa fy = 400MPa s = 1.15 Post-Tensioning fpu = 1862 MPa fpy = 1675 MPa Stressing Loss = 186 MPa Long-Term Loss = 94 MPa fi = 1490 MPa fe =1210 MPa c = 1.50 = 0.36 = 0.42 f 250 xmax 0.53 0.05 y d 165 250 f y 415 MPa if xu ,max 0.484 d Prestressing tendon, Ap Mild Steel, As 229 mm 254 mm 25 mm Length, L = 9754 mm Elevation 914 mm Section Loads: Dead, self-wt = 0.254 m 23.56 kN/m3 = 5.984 kN/m2 (D) 1.50 = 8.976 kN/m2 (Du) Live, = 4.788 kN/m2 (L) 1.50 = 7.182 kN/m2 (Lu) Total = 10.772 kN/m2 (D+L) = 16.158 kN/m2 (D+L)ult =10.772 kN/m2 0.914 m = 9.846 kN/m, u = 16.158 kN/m2 0.914 m = 14.768 kN/m Ultimate Moment, M U IS 456-2000 PT-SL EXAMPLE 001 - 4 wl12 2 = 14.768 9.754 8 = 175.6 kN-m 8 Software Verification PROGRAM NAME: REVISION NO.: ETABS 0 Ultimate Stress in strand, f PS from Table 11: fp = 1435 MPa Ultimate force in PT, Fult , PT AP ( f PS ) 197.4 1435 1000 283.3 kN Compression block depth ratio: m M bd f ck 2 175.6 0.3392 0.914 0.229 2 0.36 30000 Required area of mild steel reinforcing, x xu 1 1 4 m 1 1 4 0.42 0.3392 0.4094 > u ,max 0.484 d d 2 2 0.42 The area of tensile steel reinforcement is then given by: x z d 1 u 229 1 0.42 0.4094 189.6 mm d ANET Mu 175.6 1e6 2663 mm 2 f y / s z 400 1.15189.6 f 1435 2 As = ANET AP P 2663 198 1953 mm fy 400 Check of Concrete Stresses at Midspan: Initial Condition (Transfer), load combination (D+PTi) = 1.0D+0.0L+1.0PTI Tendon stress at transfer = jacking stress stressing losses =1490 186 = 1304 MPa The force in the tendon at transfer, = 1304 197.4 1000 257.4 kN Moment due to dead load, M D 5.984 0.914 9.754 8 65.04 kN-m 2 Moment due to PT, Stress in concrete, M PT FPTI (sag) 257.4 102 mm 1000 26.25 kN-m F M M PT 257.4 65.04 26.23 f PTI D A S 0.254 0.914 0.00983 where S=0.00983m3 f 1.109 3.948 MPa f 5.058(Comp) max, 2.839(Tension) max IS 456-2000 PT-SL EXAMPLE 001 - 5 Software Verification PROGRAM NAME: REVISION NO.: ETABS 0 Normal Condition, load combinations: (D+L+PTF) = 1.0D+1.0L+1.0PTF Tendon stress at normal = jacking stressing long-term=1490 186 94 = 1210 MPa The force in tendon at normal, = 1210 197.4 1000 238.9 kN Moment due to dead load, M D 5.984 0.914 9.754 8 65.04 kN-m 2 Moment due to live load, M L 4.788 0.914 9.754 8 52.04 kN-m 2 Moment due to PT, M PT FPTI (sag) 238.9 102 mm 1000 24.37 kN-m Stress in concrete for (D+L+PTF), F M M PT 238.8 117.08 24.37 f PTI D L A S 0.254 0.914 0.00983 f 1.029 9.431 f 10.460(Comp) max, 8.402(Tension) max IS 456-2000 PT-SL EXAMPLE 001 - 6
Source Exif Data:
File Type : PDF File Type Extension : pdf MIME Type : application/pdf PDF Version : 1.5 Linearized : Yes Author : Create Date : 2016:08:04 16:11:21-07:00 Modify Date : 2016:08:04 16:11:21-07:00 XMP Toolkit : Adobe XMP Core 4.2.1-c043 52.372728, 2009/01/18-15:08:04 Producer : Acrobat Distiller 9.5.5 (Windows) Creator Tool : PScript5.dll Version 5.2.2 Format : application/pdf Creator : Title : Document ID : uuid:da3c276a-074e-4c2c-ae13-4f10d09f2d96 Instance ID : uuid:e3ef23f0-9eb0-4956-9f3b-f5b84f0a8bfe Page Count : 6EXIF Metadata provided by EXIF.tools