In this paper the problem of optimal structure design, subjected to regular lifetime condition for all elements is considered. The author sets up the problem, proposes an iterative method for solving and apply the obtained results to a simple example. | T('p chi CO' h(>c Journal of Mechanics, NCNS'l' of Vietnam T. XVII, 1995, No 2 (28- 33) ON THE PROBLEM OF OPTIMAL STRUCTURE DESIGN SUBJECTED TO REGULAR LIFETIME CTITERION NGUYEN VAN PHO Hanoi University of Civil Engineering SUMMARY. The objective function of problem of optimal structure design can be choosen differently. For example the objective function can be the weight, the net cost, the regular resistance, the regular reliability, an so on. In this paper the problem of optimal structure design, subjected to regular lifetime condition for all e~ements is considered. The author sets up the problem, proposes an iterative method for solving and apply the obtained results to a simple example. §1. INTRODUCTION Up to now the problem of optimal structure design has been paid attention by many authors [1, 2, 3, . 1 According to the goal the problem is aimed at, the objective function is choosen differently. It's well known that the different structural components or the different parts of a single contruction are generally made of different sorts 6£ materials, having different load conditions, suffering from different erosion environment, etc. Therfore these components or parts have their resistance capacity decreasing upon the time with different laws and different intensities. As a result, the lifetime (the untilisation time) of the structural components will not be the same. To get security in the exploitation one has recourse to the way replacing or strengthening. It is regrettable, however, that some parts of a construction can not be replaceable or their are too expensive, moreover the resulted stoppage of exploitation is unacceptable by the manager, because of heavy economic loss. Thiss gives 'rise to the problem of designing different parts of a construction, which have the same or likely the same lifetime. These are called constructions with regular lifetime. The problem of regular lifetime is a class of optimization problems. Here the .
