Structural Influencing Coefficient Of Eccentrically K-braced Steel Frames

As a kind of structure material, the steel has nicer ductility compared with concrete and brick. As long as the right structure system and the proper node style are selected, the steel structure appears excellent ductility and energy-dissipation ability, when it gets into elastic-plastic state under strong earthqake. For that reason, the design-value of earthquake action of the steel structure should be lower than that of the concrete or brick structure. Compared with many abroad codes for seismic design, code for Seismic Design of Buildings (GB50011-2001) takes the same design value of earthquake action and the same value of R coefficient (2.8125) without taking account of the differences of the structural systems, which is unreasonable and causes the higher design-value for the steel structure.In this paper, 12 eccentrically K-braced steel frames (including different story numbers, different span numbers and different span) are analyzed to get the value of structural influencing coefficient of each example, by Pushover method. A typical ecccentrically K-braced steel frame is given to introduce the detailed steps to determine the proper R value.According to the analysis of 12 eccentrically K-braced steel frames, the result indicates that the earthquake action design value of eccentrically K-braced steel frame which is designed according to the Code (GB50011-2001) is higher than the value it really bears. It is suggested to reduce the design value of earthquake action. Moreover, basing on the analysis of 12 examples and data processing, variation regularities of structural coefficient, ductility coefficient, over-strength coefficient and displacement amplification coefficient are acquired.