To intergrate finite elements Into CAD enviroment, design oriented structure of the finite element program is desirable. For this purpose a program called CFEP has been developed. Generation of geometry data is independently treated in the program to ease the modification of property or loading data. By conveniently handling the large number of load cases with various load combinations, and by comprehensively reporting the results through inclusive output for the multiple analyses, the program greatly facilitates the design process. Interfacing with interactive graphic post-processor, the results of analyses and final designed values are obtained in a compact and comprehensive manner. The paper also describes necessary tasks for developing such program on the economical microcomputer. Sample output of printed and graphical form well illustrates the procedure.

This paper presents an expert system approach to solve preliminary bridge design problems. The system employs a forward chaining inference strategy to 1) choose the appropriate superstructure types and construction methods and 2) use the solutions chosen in 1) to determine a list of ranked alternatives. The basic information used in the selection is collected from various sources. Due to the uncertainties presented in the information collected, Fuzzy sets are used to handle these uncertainties in the system. Finally to approve this system some applications are made to select superstructure types and construction methods of them.

The planar effects on the concrete pavements Is mainly due to the concrete shrinkage, subgrade friction, and thermal expansion or contraction. A complete understanding of analytical behavior of concrete pavement requires the development of computer model, stiffness matrix and equivalent nodal load matrices due to the effects mentioned above. A computer program, INPLANE II, has been written to evaluate the planar effects on concrete pavements. The planar effects determine to what degree the joint open and also help In determining factors which affect the joint stiffnesses and structural behavior of concrete Pavements.

The current load combination criteria for design of nuclear power plant structures are not based on the probability-based design concept but rely on the conventional design concept. In this paper, a load combination criteria for design of NPP coin-tainment structures are proposed based on a FEM-based random vibration analysis. More accurate reliability analyses under various dynamic loads such as earthquake loads were made possible by incorporating the FEM and random vibration theory, which is different from the conventional reliability analysis method. In this paper, the load factors for the design of NPP structures in Korea are proposed by considering appropriate fond combination criteria for design.

Live load data in domestic office buildings have been collected in a systematic manner. Based on surveyed data, equivalent uniformly distributed load intensities, which produce the same load effect as the actual spatially varying live load, have been obtained for various structural members(such as slab, beam, column, etc.). Influence surface method has been employed to compute load effects under real live load, inclucing beam moment, slab moment as well as axial force and moments in column. The results have been examined to find probabilistic characteristics and relationship between influence area and load intensity(or coefficient of variation). The results were also compared with other survey results and found to be reasonable.

An extended model for the assessment of fatigue reliability of steel structures In the presence of residual stresses Is developed. The model explicitly Includes the uncertainties of the lean stress and residual stress in terms of the zero-mean equivalent stress-range. It Is assumed that the fatigue life of welded Joints follows the Weibull distribution. Based on the numerical illustrations, It Is shown that the probability of fatigue fat lure and the allowable stress-range for fatigue design could be significantly affected by the presence of residual stresses. This effect may be represented through the mean stress at the welded joints.

Recent trends in design standards development have encouraged the use of probabilistic limit sate design concepts. Reliability analysis adopted in those advanced countries have the potentials that they afford for symplifying the design Process arid placing it on a consistent reliability based for various construction materials. This study is proposed in the reliability analysis of plane frame structures using second-order moment method(Level-II they). Lind-Hasofer's minimum distance method is use in the derivation of an mathematical algorithm as well as an determination of Correlation cofficients, reliability index and total reliability index depending on the multiple failure modes. In addition. This study is employed as a practical tool for the approximate reliability analysis. Results of the numerincal analysis showed that the difference between the reliability index of the failure probability of the multiple failure modes and the total reliability index of the failure probability with the simultaneous failure modes deviated nearly 3∼10% depending on tile performance functions.

In order to take account of the statistical properties of random variables used in the structural analysis, the conventional approach usually adopts the safety factor based on past experiences for the qualitative assessment of structural safety problem. Recently, new approach based on the probabilistic concept has been applied to the assessment of structural safety in order to circumvent the difficulties of the conventional approach in choosing the appropriate safety factor. Thus, computer program called "Probabilistic finite element method" is developed by incorporation the probabilistic concept into the conventional matrix method in order to investigate the effects of the random variables on the final output of the structural analysis. From the comparison of some examples, it can be concluded that the PFEM developed in this study deals with consistently with the uncertainty of random variables and provides the rational tool for the assessment of structural safety of plane frame.

Methods for the estimation of the coefficient matrices in the equation of motion for a linear multi-degree-of-freedom structure arc studied. For this purpose, the equation of motion is transformed into an auto-regressive and moving average with auxiliary input (ARMAX) model. The ARMAX parameters are evaluated using several methods of parameter estimation; such as toe least squares, the instrumental variable, the maximum likelihood and the limited Information maximum likelihood methods. Then the parameters of the equation of motion are recovered therefrom. Numerical example is given for a 3-story building model subjected to an earthquake exitation.

Through a series of analyses of specific structures it is shown that incremental collapse may be the critical design criterion and that shakedown analysis can be used as a design tool. Using shakedown analysis technique, a nonlinear structural optimization program has been developed. This incorporates : (ⅰ) design constraints on elastic stresses and deflections ; (ⅱ) constraints for the prevention of incremental collapse and soft story failure ; and (ⅲ) the constraint on the fundamental period of structure. A five-step design procedure is proposed by using this program to obtain the optimum design that satisfies all the requirements of comprehensive earthquake-resistant design.

On this condition of steel bridge member having a crack, occasionaly it is improssible to measure of stress history and to extract test specimen. Under this situation, tried to estimate remaining service life from statistical data on traffic and existing results of fatigue test without measuring of stress history and fatigue test. The main results are as following (1) Stress history of simple beam estimated from Montecallo simulation method with probabilistic model of traffic can be use to estimate remaining fatigue life instead of measuring of stress history. (2) In such a case measuring of remaining fatigue life at bridge member haying a crack, influences of RMS model and RMC model on fatigue crack growth rate are not differ without difference of applied stress range. (3) Application of cut off method may be overestimate remaining fatigue life.

Until recently post-processing of finite element model has been Heavily relied on expensive graphic peripheral devices. For this reason many engineers and researchers can not afford to access to the graphics. with the aid of inexpensive personal computers very econmical post-processor graphics program called MICRO-POST has been developed in conjunction with low-cost printers and plotters. Model geometry or results of analysis for the unlimitted meshes either produced by mainframe or microcomputer can be easily and economi-call presented in a number of different graphic devices. The paper presents the procedure obtaining the device the independent graphics, and the structure and functions of the program. It also describes a new error-preventive dialogue type input technique to control the plot operation in an interactive manner. Through the post-processing examples for the general purpose finite element programs, it demonstrates the usefulness of the program.