نوع مقاله : یادداشت فنی
گروه مهندسی سازه، دانشگاه آزاد اسلامی واحد اهر
عنوان مقاله [English]
Bracing increases frame stiffness and reduces lateral displacement, due to transverse forces, but reduces frame ductility in comparison with moment resistant frames. A cable is known as a flexible element that can only undergo tension forces and has no compression strength. Using tension only elements within the bracing system of structures has created the idea of using cables as part of the lateral bracing system. In the present research, a new cable bracing is proposed. Different moment resistant frames with and without bracing, together with the proposed bracing, were analyzed and compared. Under the lateral load effect, the moment resistant frame shows the most displacement, compared to the same frame equipped with bracing. By adding the x-bracing cables to the moment resistant frame, displacements are reduced considerably, depending on the size of the cable diameter, due to additional stiffness by the cables. Adding a square plate in the intersection of the x-bracing cables (proposed bracing) show that the displacements are reduced compared with x-bracing cables, although the displacements were less than those obtained from the moment resistant frame. The results also showed that using x- bracing cables as a continuous form, gave more displacements compared to x- bracing cables used at each frame cell. By adding a square plate in the intersection of the x-bracing cables, the displacements are increased, while displacements are reduced by increasing cable diameter. In frames braced with cables, including the one proposed, increasing cable diameter causes an increase in cable axial load. Finally, the results show that the behavior of the proposed bracing is somehow between the behavior of the x-braced and the moment resistant frames. By choosing different cable diameter and a square shaped plate for the proposed bracing, the results tend towards either the x-bracing or the moment resistant frame. Only one of the two braces in the x-bracing cables acts under tension; while all cables are under tension in the proposed bracing.