Use of Crescent Shaped Braces for Controlled Seismic Design of Ductile Structures

作     者：Tomaso Trombetti Giada Gasparini Stefano Silvestri Ilaria Ricci 

作者机构：Department of Structural Engineering University of Bologna Italy 

出 版 物：《Journal of Civil Engineering and Architecture》 (土木工程与建筑（英文版）)

年 卷 期：2011年第5卷第10期

页      面：890-902页

学科分类：070801[理学-固体地球物理学] 07[理学] 08[工学] 081402[工学-结构工程] 0708[理学-地球物理学] 081304[工学-建筑技术科学] 0813[工学-建筑学] 0814[工学-土木工程] 

主　　题：Horizontal-resisting element horizontal-resisting system stiffness strength ductility crescent-shaped braces performance objectives. 

摘      要：It is known that the seismic response of a structural system is highly influenced, in addition to the earthquake input, by the dynamic characteristics of the system itself. This paper presents an approach for the identification of the characteristics of the structural system resisting to horizontal loads which enables to satisfy given seismic performance objectives. This is achieved by considering a total conceptual separation between the structural systems resisting to vertical and horizontal loads. The proposed approach is first briefly developed in general within a Performance-Based Seismic Design （PBSD） framework and then fully applied to the case study of a five-storey steel building structure. It is composed of three basic steps： （1） identification of the fundamental characteristics which should be possessed by the horizontal resisting system to satisfy a multiplicity of performance objectives, （2） development of a peculiar horizontal resisting system composed of ＂crescent shaped braces＂ which are specifically calibrated to satisfy given performance objectives, （3） verification, by means of appropriate time-history analyses, of the seismic performances achieved. In detail, the horizontal resisting system is calibrated to satisfy a multiplicity of performance objectives through the identification of an ＂objectives curve＂, in the Force-Displacement diagram, of the mechanical characteristics of the structure. The calibration is obtained by methods/tools borrowed either from Direct Displacement-Based Design （DDBD） or Force-Based Design （FBD）, depending on the specific performance objective to be imposed. The applicative example has been carried out with reference to three performance objectives and has led to the identification of a horizontal resisting system composed of special bracing elements capable of realizing a sort of properly-calibrated seismic isolation called crescent-shaped braces. The results obtained through non-linear dynamic analyses have shown th