EVALUATION OF LOADS AND STRUCTURAL RESISTANCES IN THE LIMIT STATE DESIGN

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In the development of practical aspects of the limit state design, quite a few problems for the load and the structural resistance are to be solved. In this study, (1) the evaluation of limit state for members in steel structure, (2) the dynamic response for both the earthquake and the strong wind, (3) the load combination model are focused to be investigated.The limit state in terms of local buckling and Euler buckling is evaluated with aids of existing experimental results, which are also rearranged in a form of data base with slenderness ratio and width-thickness ratio as major parameters. Such efforts should be continued further for effective uses of the limit state design.Wing response studies are conducted by establishing an analytical model for the sway-torsional vibration. Simulated wing load fluctuations with a specified correlation are used for numerical response analyzes. Seismic response studies consist of two parts, one is the analysis of recorded responses of scaled structure to reveal the collapse process of steel structure and the other is the statistical evaluation of structural behavior for high rise buildings to compute the seismic safety in terms of the second moment reliability.The load combination model is one of important parts of the limit state design. Level crossing rate approaches are developed for combinations of time varying loads, then load factors are numerically obtained as a proposed model. The summation of log-normal random variables is treated to provide a simple load combination example.Finally the definition of limit state design is discussed to increase the rationality of further development. A few future problems are also summarized with an emphasis on the improvement of the probabilistic model of load and the theoretical basis for the target reliability.