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SE 130 Forces in a Howe truss



  • Measurement of bar forces on a single plane truss, Howe type
  • Measurement of bar forces by strain gauges
  • External load may be applied at different angles


Technical Description

As light-weight structures offering a high degree of rigidity, trusses are employed in the construction of halls, bridges, cranes, pylons and masts. Trusses are bar structures in which the bars are subjected to compression or tension loading, but not to bending.

The SE 130 setup provides experiments on single plane trusses with a high degree of measurement accuracy and computerised result readout based on software. The ready assembled truss is mounted horizontally on a frame. The bars are joined by a “hinged” connection, using node discs. Consequently, our truss can be considered as an ideal truss. The external force is generated with the aid of a threaded spindle. The force can be applied in various directions and at various points.

The forces occurring on the truss bars are recorded by strain gauges. All strain gauge measuring points are housed together in a connection box. From there, they are connected to the measuring amplifier FL 151. The software is used to manage the measurement data and provide graphical representation of the bar forces. The software features a comprehensive help function.

An additional truss is available to extend the scope of the experiment: SE 130.01, Warren type.

The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objectives / Experiments
- measurement of the bar forces in a single plane truss, Howe type
- dependency of bar forces on the external force
   * magnitude, direction, point of application
- comparison of measurement results with mathematical and graphical methods * method of joints
   * Ritter’s method of sections
   * Cremona diagram
- basic principle: measurement of forces using strain gauges


[1] investigation of bar forces in a single plane, statically determinate truss
[2] ready assembled Howe truss
[3] frame for horizontal experimental setup
[4] any straight and inclined load cases possible
[5] fine adjustment of load force
[6] low-friction knife-edge bearing
[7] 2 bearings for vertical forces, 1 bearing for horizontal forces
[8] pre-balanced strain gauge connection box with connection to measuring amplifier FL 151
[9] measuring amplifier FL 151 required
[10] software in FL 151 to evaluate measurement data

Technical Data
Truss: Howe type 
- bar cross-section: 10x3mm, stainless steel
- bar lengths: 115,5, 200, 231mm
- external loading: max. 600N
- bars: 13, of which 7 with strain gauge full bridges
Load application device with force gauge
- tensile force: max. 2kN
- stroke: 30mm
Node discs: 8
Angle between bars: 30°, 45° 

Dimensions and Weight
LxWxH: 1220x620x250mm (frame)
LxWxH: 850x265x15mm (Howe truss)
Weight: approx. 43kg

Scope of Delivery
1 frame
1 Howe truss
1 load application device
1 strain gauge connection box
1 ribbon cable
1 set of instructional material

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