Forces in an Overdeterminate Truss SE 110.22

Forces in an Overdeterminate Truss

Type: SE 110.22
Name: Forces in an Overdeterminate Truss
Technical Description

  With surplus bars a statically determinate truss becomes internally statically indeterminate. In this case the truss is termed statically overdeterminate. In an overdeterminate truss, the bar forces depend on the elastic properties of the truss and cannot be calculated easily.
  The SE 110.22 experimental setup permits investigation and comparison of statically determinate and statically indeterminate trusses.

  Using the bars and node discs, a statically determinate, single plane truss is first constructed. On installation of a surplus bar the truss becomes overdeterminate. By way of a load application device, straight or inclined forces are applied to the truss, thereby simulating various load cases. The occurring tensile and compressive forces in the bars are recorded by means of strain gauge measurement.
  Computerised evaluation of measured values is provided by measuring amplifier FL 152. The software in FL 152 is used to manage the measurement data and provide graphical representation of the bar forces. The software features a comprehensive help function.

  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.

Learning Objectives / Experiments

- measurement of the bar forces in a statically

  determinate and a statically overdeterminate, single

  plane truss
- distribution of forces in the single plane truss

  dependent on the use of a surplus bar
- dependency of the bar forces on the external

  * magnitude, direction, point of application
- comparison of measurement results with

  mathematical methods
  * method of joints
  * Ritter’s method of sections


- basic principle: measurement of forces using

  strain gauge measurement


* Comparison of forces in statically determinate and

  overdeterminate trusses1
* Bars with strain gauge measurement to measure bar


Available accessories
FL 151 -- Multi-Channel Measuring Amplifier
SE 112 -- Mounting Frame
Alternative products
FL 111 -- Forces in a Simple Bar Structure
SE 110.21 -- Forces in Various Single Plane Trusses
SE 110.44 -- Deformation of Trusses
SE 130 -- Forces in a Howe Truss

[1] investigation of bar forces in statically overdeterminate trusses
[2] surplus bar, longitudinally adjustable
[3] straight and inclined loading possible
[4] load application device with force gauge mountable on different node discs 

[5] measuring point to measure force on each bar
[6] measuring amplifier FL 152 required
[7] GUNT-software in FL 152 to evaluate measured values graphically
[8] storage system to house the components

[9] experimental setup in frame SE 112


Technical Data

Bars: 8
- 5 bars, fixed 300mm
- 2 bars, fixed 424mm
- 1 bar, adjustable 400...450mm
- angle between bars: 30°, 45°, 60°, 90°
- maximum bar force: 500N
- measuring point on each bar
- height of truss max. 270mm
- length of truss max. 500mm
Load application device

- -500...+500N, graduation: 10N
Dial gauge: measurement range: 0...20mm


Dimensions and Weight

LxWxH: 1170x480x178mm (storage system)

Weight: approx. 22kg (total)

Scope of Delivery

1 set of bars
5 node discs
1 load application device

1 dial gauge
1 set of cables
1 storage system with foam inlay
1 set of instructional material

Order Details

022.11022  SE 110.22  Forces in an

                                      Overdeterminate Truss