Fermo - bridge

Startup package for prefabricated concrete girder – bridge construction


New features in FERMO bridge construction

With version 23, in addition to the regular adaptations to run under Windows and the authoritative standards, additional enhancements are available in FERMO, which make the use of the program application more versatile:

Basic functions

  •     Bending capacity due to NM-interaction for required reinforcement req As, req A
  •     Flexural capacity due to NM-interaction with existing reinforcement / minimum reinforcement
  •     Strain check with existing reinforcement associated with the design combinations
  •     Shear capacity due to V-T-VT interaction with linear stress resultants and own reinforcement material for the Web
  •     Composite joint reinforcement with own reinforcement material for bond reinforcement
  •     Additional design sections with detailed output of design results
  •     Tensile force cover diagram available Zs + Zp ≥ req Zs + Zp
  •     Summary of existing and required reinforcement including minimum reinforcement

Subsequent prestressing

  •     Different prestressing steel materials per layer


  •     Verification against fatigue of longitudinal reinforcement and prestressing steel Level 2
  •     Verification against fatigue of concrete pressure level 2
  •     Verification against fatigue of the tension struts (transverse or stirrup reinforcement)
  •     Check against fatigue of compression struts
  •     Verification against fatigue of the composite joint


  •     Limitation of concrete compressive stresses I / II


FERMO – Precast girder for building- and bridges

The basic modules " building construction " and " bridge construction " contain all options that are at least required for a prestressed concrete girder in building or bridge construction. The possible extensions are independent of each other; i.e. they can be added individually. Furthermore, it is possible to add the modules from structural building towards bridge or from bridge towards building structures.



Concrete girder Basic Module

The reinforced concrete design is carried out uniaxial. In detail, the following tasks can be solved with FERMO:

  • homogenous rectangular, T-beam, slab and H-sections with variable web and flange thicknesses as well as upstand beam and V cross sections with or without bulge
  • typed symmetric and non-symmetric cross-sections in longitudinal direction
  • arbitrary, variable cross-section layout including cross-section offsets
  • single symmetric, in special cases also asymmetric cross-section shapes, are possible but are designed uniaxial
  • subsequently applied in-situ concrete slab – i.e. composite cross-sections
  • varying, statically determinate systems: factory support, transport support, assembly support, auxiliary support and final support
  • maximum of 8 analysis moments along the timeline from the factoring up to the end of the lifecycle
  • linear stress resultants and deformations with automatic consideration of the effective slab widths
  • alternative consideration of normal strength concretes (up to C50/60), high strength concretes (C55/67 up to C 100/115), ultra-high strength concrete (UHC140)
  • reinforcement (up to B550), high strength reinforcement (SAS670)
  • edge related single reinforcement or distributed reinforcement
  • multi-layer reinforcement for single reinforcement and single-layer reinforcement for distributed reinforcement
  • Fixed, inner and variable, outer reinforcement layers that can be set either automatically or user-defined minimum requirements for the concrete cover and durability
  • minimum requirements for the concrete cover and durability
  • fixed or elastic support with automatic calculation of the spring constants
  • reliable generation of the design combinations with the aid of load case attributes
  • automatic generation of load cases by copying or copying with a certain distance
  • single loads, line loads, trapezoidal loads and triangular loads, temperature loads and support settlement
  • loads can be arranged centric or eccentric
  • linear stress resultant calculation with automatic generation of all design combinations
  • optional consideration of the minimum restraint, direct / indirect support
incl. Design of Load Capacity
  • complete bearing capacity analyses in the ULS for the permanent, accidental and earthquake situation
  • minimum and ductility reinforcement for building construction and earthquake
  • minimum and robustness reinforcement for bridge construction
  • minimum reinforcement due to construction regulations
  • bending bearing capacity due to normal force / moment interaction
  • combination of the bending reinforcement under consideration of the minimum reinforcement
  • shear bearing capacity due to V-T-VT interaction with linear stress resultants
  • flange connecting reinforcement
  • composite joint reinforcement
  • tabular fire protection for decisive combination of actions (quasi-permanent, frequent)
  • additional analysis sections
  • summary of the existing and required reinforcement
  • summary of the material consumption (bill of quantities)
incl. Modul Design – Bridge Construction
  • basics for bridges according to EN 1990 appendix A2 and corresponding national basics for the general building construction, respectively, structural engineering according to EN 1990 appendix A1 and corresponding national annexes for DE, AT, SK/CZ and UK
  • live loads according to EN 1991-1
  • complete reinforced concrete and prestressed concrete design according to DIN 1045-1, EN 1992 1 and corresponding national annexes for DE, AT, SK/CZ and UK
  • specification of the longitudinal reinforcement as single or distributed reinforcement
  • annexes for DE, AT, SK/CZ and UK
  • bridge live loads according to EN 1991-2
  • complete reinforced concrete and prestressed concrete design according to DIN Fachbericht 102, EN 1992 2 and corresponding national annexes for DE, AT, SK/CZ and UK
  • input of the longitudinal reinforcement only as distributed reinforcement
  • damage equivalent coefficients for the fatigue load model for road bridges
  • main tensile stresses SL
incl. Module Stressing Bed prestressing
  • single-level prestressing
  • database with all common prestressing methods in the stressing bed
  • quick and easy input of the tendons with / without stripping
  • concrete strain and prestressing steel strain trajectories
  • prestressed concrete design under consideration of creep, shrinkage and short-term relaxation due to heat treatment
  • transmission and anchorage lengths
  • anchorage analysis of the stressing bed prestressing
  • tensile force coverage graphic for reinforcing and prestressing steel
  • bursting reinforcement for pretensioned tendons
incl. Module Design of Details
  • circular / rectangular recesses and notches at the girder ends
  • design of geometric discontinuity areas for small and large opening (recesses) according to DAfStb Heft 399/599 and DAfStb Heft 459
  • post design for openings really close to each other <  0,8 * h
  • design of geometric discontinuity areas for offset supports (notches)
incl. Module Serviceability Design
  • complete serviceability analyses in the SLS
  • reinforcement of the crack width for slim and thick structural members
  • minimum reinforcement due to the run-off of the hydration heat in the in-situ concrete slab
  • decompression analysis, if prestressing exists
  • limitation of the concrete compressive stresses II
  • limitation of the reinforcing and prestressing steel stresses II
  • limitation of the crack width (direct and indirect method)
  • limitation of the main tensile stresses in bridge construction
  • limitation of the sagging to leff/250 (span) and to leff/100 (lever arm) in condition II (cracked state)
  • limitation of the deflection difference in condition II (cracked state) to leff/500
  • length changes and support rotation
  • deformations optionally for quasi-permanent, frequent or rare combination of actions (CoA)
incl. Module Fatigue Design
  • analysis against fatigue of the longitudinal reinforcement and the prestressing steel
  • analysis against fatigue of the shear reinforcement and stirrups
  • calculation of the fatigue strength by specifying the number of load cycles
  • consideration of the dynamic factor in building construction
  • consideration of the damage equivalent coefficients in bridge construction
  • main tensile stresses FLS



The FERMO prestressing girder in bridge construction is a powerful design program for precast and concrete composite girders and has the following special features:

  • Consistent program concept with overview at a glance
  • Program interface can be adapted for specific tasks
  • For both simple and complex engineering tasks in building and industrial construction
  • Configurable output for a wide range of requirements from pre-design up to the final inspection phase incl. detail output at user defined sections
  • Component-oriented load transfer with reliable transfer and organisation scheme

The best of both worlds

The combination of the prefabricated girder programs RTfermo and FETT is carried out in 2 stages through the successor program FERMO: RTfermo will be discontinued at the end of 2018 and FETT at the end of 2019. RTfermo will remain in product maintenance until 2019 and FETT until 2020.

The modular concept for FERMO corresponds in the broadest sense to the one of FETT, in which the use of high-performance concrete and the fire protection design was integrated into the reinforced concrete base module.


Cover Picture: RIB Software SE, NL CZ: Libor Svejda


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