SBPPrestressed concrete sections

iPhone app

Prestressed concrete
section analysis

Stresses in the uncracked section (elastic analysis) and the cracked section (concrete in tension neglected), crack width, required passive steel and ultimate resistance.

Describe the concrete, tendons and passive steel, then the stressing and loading stages: every stage and every combination can be checked.

Download on the App StoreSee the analyses

French app interface · On-device computation · No account · One-time purchase

Uncracked section stressesVIPP beam
σc bottom −0.40−4.68−9.70
−9.70σc [MPa]−0.40

Supported codes

Eurocode 2BPELSIA 262

Eurocode 2, BPEL 91 and SIA 262: modular ratios, prestress variants and checks for the selected code profile.

01 / DEFINITION

Section typologies

Each typology has its own parameters: webs and haunches for a box girder, cantilevers for a PSI-DP slab, ribs for a PSI-DN, trapezoids for a beam. The free contour accepts polygons, openings and spreadsheet import.

01Single-cell box girderInclined webs, haunches, bottom slab
02PSI-DP slabSolid slab with cantilevers
03PSI-DN ribbed slabRibs and deck slab
04Precast beamPrecast or VIPP beams: trapezoids and precast table
05U beam / troughFootbridges and trough decks
06Inverted T or LPrecast beams with bottom flange
07Double-tee unitPretensioned strands
08Hollow-core slabCores and strands
09Free contourPolygon, openings, import

01Passive steel

Place bars one by one, along a segment or an arc, paste them from a spreadsheet, or generate layers around the perimeter with a set cover and spacing. Clashes with ducts and the contour are flagged.

  • XY, segment, arc, import
  • Perimeter: cover, spacing, clashes
  • Required areas applied to layers

02Tendons and strands

Pick the tendon type (4T15S to 19T15S, T15S or T12.5 strands), pre- or post-tensioned, bonded or not. Lay them out in rows, segments, arcs or by import. Ducts are deducted from the concrete; touching ducts are merged.

  • Tendon catalogue and duct diameters
  • Pre- or post-tensioning, bond
  • Families and cover zone σenr

03Bundled examples

Six complete projects ship with the app: geometry, tendons, materials, stages and combinations. Each load creates an editable copy and leaves your saved models untouched.

  • 56 m box girder, PSI-DP, PSI-DN
  • Trough footbridge, 38 m VIPP beam
  • Two-cell free contour

02 / STAGES

Stages, combinations and variants

The construction stages describe the section’s history: stressing, permanent and variable loads, prestress losses. SLS and ULS combinations build on this history.

Stages
G, P or Q actions, stressing of a tendon family, fractions of instantaneous or deferred losses, choice of section (net, inst., long-term).
Combinations
They start from the virgin section, the end of a stage sequence or one of its stages. Variable actions do not carry over from one combination to the next.
Variants
EC2: Pk,inf and Pk,sup. BPEL: P1 = 1.02 P0 − 0.8 ΔP and P2 = 0.98 P0 − 1.2 ΔP. Crossed with Gmin and Gmax, they give states a to d.
topbottom−8−7−6−5−4−3−2−101 · G1 + P2 · G23 · Lossesσc [MPa]min −6.13max −1.24
Bottom fibreTop fibrePk,infPk,sup
StageBottomTop
Pk,infPk,supPk,infPk,sup
1 · G1 + PSelf-weight and stressing of the 15 12T15S tendons−3.83−6.13−3.46−3.16
2 · G2Superstructures−2.04−4.33−4.84−4.53
3 · LossesDeferred losses, long-term homogenised section−1.24−3.35−4.94−4.66

Bundled PSI-DP 18 / 28 / 18 m, central mid-span: cumulative extreme fibre stresses, phasing PH1, SLS characteristic.

03 / ANALYSES

Seven analyses

Stages and combinations, with their variants, feed every analysis. Concrete, passive steel and tendons are reported separately.

UNCRACKED SECTION ANALYSIS

Elastic analysis, concrete in tension included.

The whole section works, concrete in tension included. For every stage and every combination: σc in the concrete, σenr in the tendon cover zone, σs in passive steel, σp and Δσp in the tendons.

  • Isocolours and diagram
  • σc, σenr, σs, σp, Δσp
  • Cumulative or increments
SBP / 01
σc,min −7.41σc,max −3.24
−7.41σc [MPa]−3.24
σc,min
−7.41MPa
σc,max
−3.24MPa
σs,max
−5.9MPa
σp,max
1173MPa

26 m trough footbridge, EC2 · PH1, end of stage 3 · SLS characteristic, Pk,inf · compression negative

04 / VALIDATION

Results compared with published calculation notes.

The SBP engine is checked on cases with a published solution, replayed with the same assumptions.

760+automated tests
88published stresses replayed on a box girder
6published references

Relative differences, same assumptions.

CaseQuantityRef.SBPDifference
Box girderNet area [m²]Net area [m²]5.86925.86920.00 %
Box girderNet inertia Iy [m⁴]Net inertia Iy [m⁴]2.83832.83820.00 %
Box girderσc bottom fibre, SLS QP [MPa]σc bottom fibre, SLS QP [MPa]8.46538.46540.00 %
Rectangleσc bottom fibre, cracked [MPa]σc bottom fibre, cracked [MPa]8.73808.73990.02 %
RectangleNeutral axis, cracked [m]Neutral axis, cracked [m]0.218910.218790.05 %
Rectangleσp tendon, ULS [MPa]σp tendon, ULS [MPa]1356.51356.50.00 %
34 m VIPP beamNet area [m²]Net area [m²]0.70040.70040.00 %
34 m VIPP beamσ bottom fibre, G1 + P1 [MPa]σ bottom fibre, G1 + P1 [MPa]−4.822−4.8220.00 %

Excerpt. Box girder and rectangle: Cerema CDS notes. VIPP beam: Sétra guide.

Box girder · SLS QP stresses over the depthMax difference 0.0002 MPa
0246810−2.0−1.5−1.0−0.50.0σc [MPa]z [m]Gmax PmaxGmax PminGmin PmaxGmin Pmin
SBPPublished values
Four variants Gmin/Gmax × Pmin/Pmax, stresses at the contour vertices, compression positive.

05 / EXPORT

PDF calculation report

Inputs, stages, combinations and every selected analysis, with figures and tables of extreme stresses. The full report for the bundled 56 m box girder runs to 24 pages.

  • Section, materials, bars and tendons
  • Stages, combinations, variants a–d
  • Extreme stresses per state and material
56 m box girder · report generated by SBP, page 156 m box girder · report generated by SBP, page 356 m box girder · report generated by SBP, page 2

Pricing

Free trial, then a one-time purchase.

Try SBP free for 7 days or 20 analyses, then buy it once: every analysis, PDF export and future update, with no subscription and no account. The VIPP tutorial is available without a purchase.

Free trial

7 daysor 20 analyses

Whichever comes first. Full access during the trial, no charge.

One-time purchase

Launch price
$24.99

Regular price $49.99

Every analysis and PDF export.

  • Unlimited analyses and PDF exports
  • Updates included
  • No subscription
  • No account
Download on the App Store

Launch price $24.99, then $49.99. Apple confirms the local price and currency before purchase.

Single payment, nothing renews. Restore the purchase with the same Apple Account.

A question about SBP?SBP supportContact us

Reinforced concrete sections: see SBA

SBA provides reinforced concrete section analyses under EC2, SIA 262 and BAEL 91. App interface in French.

SBA : Béton armé