DETERMINATION OF DYNAMIC FORCES IN BRIDGES. PRELIMINARY TESTS ON A REDUCED SCALE MODEL

The measurements on existing railway bridges made up to the present by the Specialists Committee have shown that it is difficult to derive laws of general application from these tests. Individual parameters of available bridges cannot be modified without influencing the other properties. It was therefore suggested that similar tests should be made on reduced scale models, on which each parameter can be altered independently to within wide limits. For the solution of static problems tests on reduced scale models have proved their value for years. In order to provide the possibility for dynamic measurements, several questions had still to be solved. For this reason a preliminary test was made, a description of which is supplied in this report. The first part also contains theoretical data, from which the time scale and the speed were determined. It seems that there may be a dynamic similarity when both the reduced scale model and the actual bridge perform the same number of vibrations during the passing of a vehicle. The tests were made on a bridge model of plexiglas with a span of 1.20 m. A two-axled vehicle which could pass over the model at various speeds by means of two runways served as moving load. The weight of the vehicle could be varied and amounted to 5.0 kg, 8.1 kg and 11.1 kg respectively. Wherever possible, the tests were made in accordance with the directives of the D23 Specialists Committee in charge of railway bridges. The results of the various test series were represented in diagrams according to various points of view. They concerned test runs at identical initial conditions and test runs with different vehicle weights and ballast of the model. On the basis of these preliminary tests it may be concluded that the dynamic effects can be studied from reduced scale models. In order to obtain a confirmation of the conditions of similarity some supplementary tests are required. It is suggested that further tests should be planned, during which comparative measurements on an existing bridge, on a reduced scale model corresponding to a real structure and mathematical investigations of the same bridge are to be made.

• Supplemental Notes:
  • Restrictions on the use of this document are contained in the explanatory material.
• Corporate Authors:

  International Union of Railways

  Office of Research and Experiments
  Utrecht,   Netherlands 
• Publication Date: 1962-3

Media Info

• Features: Appendices;
• Pagination: 22 p.

Subject/Index Terms

• TRT Terms: Axle load force; Bridge design; Bridges; Defects; Dynamic tests; Stresses; Structural design; Wheels
• Uncontrolled Terms: Dynamic analysis
• Old TRIS Terms: Axle loadings; Bridge stresses; Question d23; Wheel flat spots
• Subject Areas: Bridges and other structures; Railroads; Vehicles and Equipment;

Filing Info

• Accession Number: 00052834
• Record Type: Publication
• Source Agency: International Union of Railways
• Report/Paper Numbers: D23/RP 6/E Intrm. Rpt
• Files: TRIS
• Created Date: Jul 8 1994 12:00AM