According to the geometry of the bistatic translational invariant SAR,the paper derived a precise bistatic SAR range equation which was consisted of a equivalent monostatic range and a range compensation term and might precisely described the bistatic range history.

By experiments,this paper analyses and corrects the imaging process of the actual DSA system based on the "equivalent single energy"model,and the results indicate the validity of this method.

the calculating concept was guoted,which of the internal force of the bent structuer in space,when analysing the internal force onsuch as the unit of the complex bent structuer,the relation between the equivalent element length and the assigning modulus,in order to get the certain reckoning and electricity calculating means,and verify by the fact that the example is in progress.

For an actual compos?ite girder bridge, three dimensional stresses were analyzed using the equivalent plate element, and the results of the analysis were compared with data from a load test.