期刊名称：Archiwum Fotogrametrii, Kartografii i Teledetekcji
印刷版ISSN：2083-2214
出版年度：2001
卷号：1
期号：11
语种：Polish
出版社：Main Board of Association of Polish Surveyors
摘要：Interest in natural thermal phenomena,which occur in bridges,has been lasting from the thirties. However,field measurements o f real objects have been performed very seldom. Therefore experimental verification o f theoretical works becomes very important. An attempt concerning such investigations was performed within the Research Project KBN (the Committee o f Scientific Research) no 7 T07E 012 15 .Development o f methodology’ o f determination o f thermal deformations o f steel bridges’' at the Institute of Road and Bridges o f the Warsaw University o f Technology. Analysis o f climatic conditions in Poland allowed to select a region characterised by the extreme distribution o f annual and daily temperatures. Such requirements were met by the area o f the city o f Przemyśl. Two bridges were selected for measurements and tests within this area: one plate girder road object with an integrated pier o f 152.9 m expansion,and the second object,a railway flyover with an ortotropowym channel cut-walk o f 20 m expansion. Measurements o f temperatures and spatial deformations,made by means o f electronic meters,with the use o f a photogrammetric method,were performed in January and July o f 1999 and 2000. A concept o f differential measurements was assumed as an initial method for designing photogrammetric measurements. For that purpose photographs were taken from stable positions,with repeatable external orientation photogrammetric cameras. Due to considerable time intervals o f successive registration,this condition was approximately met in practice. This allowed to perform observations according to the temporary stereogramme mode,for which only changes o f external orientation ofphotographs,resulting from the method o f restoration ofpositions and utilisation o f the (JMK-IO low stability camera,were determined. Observations were performed by means o f an analytical stereo-plotter. with the use of a specialised procedure o f measurements performed according to the mode o f temporary stereogrammes Each o f measured objects was registered by means o f a net o f coherent photographs,in order to allow equal determination o f co-ordinates o f investigated points. In practice,photogrammetric models,which describe particidar geometric features o f investigated bridges,were reconstructed with the accuracy o f m_\ my mz - i. 2mm Values o f deformations,determined by means o f the photogrammetric method (with an exception o f the component perpendicular to the axis o f the investigated bridge) have met expectations o f "road experts ".
