tailieunhanh - A method for technical diagnosis of construction

In the present article the author advances a diagnosis method of structures ditl'erent from the above, we expect that the advanced method could avoid some difficult inherent with the solution of inverse problem. | Vietnam JourniLl of Mechanics, NCST of Vietnam Vol. U, 1999, No 1 (25- 35) A METHOD FOR TECHNICAL DIAGNOSIS OF CONSTRUCTION NGUYEN VAN PHO Hanoi University of Civil Engineering §1. Introduction Nowadays the design of a new construction is no more a hard problem, but it is not the same to the technical diagnosis problem of constructions. The methods, largely used now for the diagnosis problem of construction 1enerally include the following steps: ~ To carry out inspection from the real construction for gathering the needed data by investigations, measurements, experiments, etc. -To model the real construction {scheme of the calculation). - To set up the system of equations for diagnosis. - To solve above the system of equations. ~To evaluate and conclusion. The essence of the above procedure is to solve an inverse (or partly inverse) problem of mechanics [1, 2, 3], therefore the following difficulties often rise:\ -The system of equations is non-linear or transcendent. ~ system of equations of diagnosis has more than one solution (the number eX solutions is finite). - The solutions of system may be unstable due to errors of experimental data. - The system has no solution or an infinity of solutions. Bence up to now there is no yet any program to auspiciously solve the diagnosis problem in the computer, like SAP90 program does for solving the problem \o design a new construction. In the present article the author advances a diagnosis method of structures ditl'erent from the above, we expect that the advanced method could avoid some clit6cukies inherent with the solution of inverse problem. The matter of our method is to solve a sequence of design problems, and to aaJae a comparison between the obtained results so as to deduce the corresponding problem. The similar idea is~used in (4, 5]. 25 For illustration, diagnostic problems of circular and rectangular plates are considered. §2. The contents of the method . The method includes following .