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![]() However, there has been little discussion about the differences in seismic performance. The building code provides detailed design requirements for each of the MD-CBF bracing configurations. Similarly, in the X-bracing configuration, there are no unbalanced vertical forces in the beams, but the columns are designed to resist large axial forces when the braces have yielded and buckled. ![]() This results in smaller beams compared to the V- or inverted V- bracing configurations. Due to the symmetrical geometry of the M-XBF configuration, the unbalanced forces from the floor above and below cancel each other out (if the braces are of the same size). Similarly, the beams in the M-XBF system must be capacity designed for the yielding and buckling of the braces. To prevent the structure from losing total stiffness, the top story braces of the SZBF are capacity designed to resist the combined unbalanced vertical loads when all the braces yielded and buckled. SZBF uses zipper columns placed between the braces to transfer the unbalanced vertical forces to higher stories. ![]() To mitigate the unbalanced force demand in the beam, the suspended zipper braced frame (SZBF) was proposed by Yang et al. This makes the beams in the V- or inverted V- bracing configurations of the MD-CBF very large. In the V- or inverted V- bracing configurations, the beam must be designed to be continuous between columns and capable of resisting the maximum unbalanced vertical and horizontal loads when the braces below (inverted V) or above (V) the beam has buckled and yielded. The configurations include: inverted V-braced (I-VBF), V-braced (VBF), X-braced (XBF), and Multistory-X-braced (M-XBF).Īccording to CSA-S16-14, the probable tensile and compressive resistance of bracing members shall be taken as Equations (1, 2), respectively. Multiple MD-CBF configurations have been pre-qualified by the CSA S16-14 ( CSA, 2014). On the other hand, the LD-CBF is targeted to be used for locations with less earthquake shaking, where the ductility requirement of the braces can be relaxed. ![]() The MD-CBF is targeted to be used in high seismic zones, where the SFRS is designed to have enhanced ductility through yielding of the steel braces, while the beams and columns are capacity designed to resist the maximum load produced by the braces. In the Canadian steel building code, CSA S16-14 ( CSA, 2014), there are two types of steel CBFs: (1) moderate ductile concentrically braced frame (MD-CBF) and (2) limited ductile concentrically braced frame (LD-CBF). This type of SFRS is effective in providing the stiffness and strength needed to resist earthquake forces. Steel concentrically braced frame (CBF) is a seismic force resisting system (SFRS) commonly used in seismic zones around the world. The results show that the different bracing configurations play an important role in sizing the structural members, which impacts the initial material usage and the overall life cycle cost of the building. Detailed structural responses, initial costs, and life cycle costs of the prototype building with five different bracing configurations were systematically compared. Five different bracing configurations were designed according to the National Building Code of Canada and CSA S16 standard. In this study, the impact of the bracing configuration on the seismic response of a five-story prototype office building located in Vancouver, Canada, is systematically examined. These codes provide detailed design requirements for the structural members and connections, but no guidance is provided in selecting the best bracing configuration for the design. Several bracing configurations have been proposed in different building codes worldwide. This type of structural system utilizes steel braces to provide the stiffness and strength needed to dissipate earthquake energy. 2Department of Civil Engineering, University of British Columbia, Vancouver, BC, CanadaĬoncentrically braced frame (CBF) is an effective and prevalent seismic force resisting system which is commonly used in low-rise buildings.1International Joint Research Laboratory of Earthquake Engineering, Tongji University, Shanghai, China.Yang 1,2 *, Hediyeh Sheikh 2 and Lisa Tobber 2
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