Lines of influence on the Gerber beam (SE110.12)

Lines of influence on the Gerber beam (SE110.12)

articulated beam with two cantilever beams and a suspended beam as an example of a typical bridge



  • Many bridges are executed as Gerber beams. Bridges are subjected to moving loads.
  • Consequently, it is important to take these moving loads into account in the design process.
  • To that end, the so-called lines of influence are determined.
  • Lines of influence describe static reactions to a moving load, such as the internal reactions of the beam or support reactions.
  • The lines of influence are determined by way of method of sections and the conditions of equilibrium, in the same way as the bending moment diagram for a static load for example.
  • A Gerber beam is an articulated beam, in the case of SE 110.12with two cantilever beams and a suspended beam between them.
  • Two supports support each cantilever beam.
  • The suspended beam is mounted on articulated supports on each of the cantilever beam arms.
  • As a result, the entire beam is statically determinate.
  • The cantilever beam supports are equipped with force gauges which indicate the support reactions.
  • Single loads and a moving load are provided to place load on the beam.
  • This means the beam can be subjected to point or distributed loads, or to a moving load.
  • The force gauges indicate the effect of a moving load directly in the support reactions.
  • The supports are movable.
  • All the component elements of the experiment are clearly laid-out and housed securely in a storage system.
  • The complete experimental setup is arranged in the frame SE 112.

Technical Details:


  1. investigation of the lines of influence in a statically determinate Gerber beam under different loading
  2. Gerber beam comprising 2 cantilever beams and 1 suspended beam
  3. suspended beam mounted by articulated supports on cantilever beams
  4. beam subjected to moving load or loaded down by single loads
  5. 4 movable supports with force gauge
  6. storage system to house the components
  7. experimental setup in frame SE 112

Technical Data:


  • total length: 1220mm
  • cantilever beam length: 503mm
  • suspended beam length: 250mm

Force gauge: ±50N


  • 24x 5N
  • 12x 1N
  • moving load: 10+20N

Dimensions & Weight:

  • L x W x H: 1170x480x178mm (storage system)
  • Weight: approx. 40kg (total)


Learning Objectives/Experiments:

  • familiarisation with a Gerber beam
  • application of the method of sections and the conditions of equilibrium to calculate the support forces for
  • point load
  • distributed load
  • moving load
  • determination of the internal reactions under static load
  • shear force curve
  • bending moment diagram
  • determination of the lines of influence under moving load
  • comparison of the calculated and measured reactions for static and moving load

Scope of Delivery:

  • 1 Gerber beam (2 cantilever beams + 1 suspended beam)
  • 4 supports with force gauge
  • 1 moving load
  • 1 set of weights
  • 1 storage system with foam inlay
  • 1 set of instructional material


  • direct indication of reactions
  • lines of influence for different load cases


Required: SE 112 Mounting frame


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