Unusual Methods for Deflection Measurements


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Title: Unusual Methods for Deflection Measurements

Author(s): M. Ladner

Publication: Special Publication

Volume: 88


Appears on pages(s): 165-180

Keywords: bridges (structures); deflection; load tests (struc-tural); -measurement; prestressed

Date: 11/1/1985

The measurement of the vertical displacement during the load testing of a structure are of great importance. Therefore different methods have been developed for that purpose. For static load tests the wire supported method is normally used in Switzerland by the Swiss Federal Laboratories for Materials Testing and Research (EMPA). When this method cannot be applied because of the inaccessibility of a reference point the water levelling method can then be employed. When only local deflections of a bridge deck under a concentrated load are to be determined, then the horizontal wire levelling method may be used. If also the level of a bridge relative to a fixed point, e .g . relative to the abutment, is to be established, the electronic levelling system may then be applied. In this paper, a short description of each of these methods is given. In addition to- this, some of the aspects how errors can be eliminated are also discussed.