Assessment of The Design and Performance of Primary and Secondary Seismic Members Of Reinforced Concrete Dual System

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


From recent earthquake experiences, buildings with structural walls do have satisfactory performance against collapse. However, this is not always true for dual structures composed of both structural walls and frames resisting seismic actions. This begs for a detailed study on the performance of dual structures. Some studies show that the elastic response of dual buildings is mainly governed by the wall response and the frame contribution could be neglected, which then makes them a secondary seismic member. This scenario is reversed while the members are within their inelastic nature. These variations make it difficult to select and identify primary and secondary members based on stiffness limitation specified in codes which is only based on the linear response of the members. Without clearly identifying the distinction between these members in a structure, and without clearly knowing the boundary between these seismic members it is difficult to follow the simplified approaches of analysis in practice, in which lateral load is resisted by some selected and properly detailed members. Hence, to address the effect of considering frames as secondary seismic members in RC wallframe system, comparative analysis among sample dual system buildings has been carried out in the following thesis work. Efforts have been made to evaluate the overall seismic performance of the buildings using non-linear push over analysis method. For each building under study two cases are examined. In the first case frames and shear walls are designed and detailed as primary seismic members. In the second case however, frames are designed as secondary seismic members and shear walls are designed and detailed to be primary seismic resistance contributors. The results of non-linear push over analysis were obtained for each case in the form of capacity curves, global yielding point and performance point, plastic hinge formation patterns, and base shear distribution among frames and walls. The observation of these results shows that the overall seismic resistance capacity of buildings reduces when frames are considered as secondary seismic members. In conclusion of this study; in RC wall-frame dual system, it is important to design both frames and walls as primary seismic members. In addition, frames take up larger bases shear in the inelastic range than what is estimated in the linear analysis, which makes it incorrect to regard these members as secondary seismic members according to most building codes specification of base shear resistance proportion between primary and secondary members. To minimize the effect of neglecting frames as secondary members, the stiffness limitation specified in code should be revised.



Reinforced Concrete, Seismic Members, Reinforced Concrete Dual System