A displacement/damage controlled (DDC) seismic design method for composite (steel/concrete) frames, consisting of circular concrete-filled steel tube (CFT) columns and composite beams (steel beams connected with concrete floor slabs) is developed in this study. The proposed seismic design method controls displacement and damage in a direct way for all seismic performance levels including the one near collapse. Through empirical expressions this method can estimate the inter-storey drift ratio (IDR) of a designed structure and evaluate the damage index (DI) of critical members for a given seismic intensity. A reduced number of design iterations is achieved while the computationally demanding non-linear time-history analysis can be avoided. The necessary empirical expressions of the design method are derived by means of statistical and sensitivity analysis of a large response databank consists of IDR and DI that cover all the way from elastic behavior to final global dynamic instability. This response databank is created by performing extensive parametric incremental dynamic analyses of many composite framed structures of the kind considered here under many seismic motions and different soil types. Design examples reveal that the DDC design method successfully estimates the targeted IDR for the desired seismic performance level as well as controls the DI in critical beam-to-column joints in order to avoid a soft-storey failure mechanism or partial loss of structure. Compared to all steel framed structures, the composite frames considered here exhibit a better seismic performance with beams and columns exhibiting a lower DI. The low-damage performance of composite frames is mainly emphasized as the number of storeys increases, while both the IDR and DI tend to fall within lower performance levels than those of the corresponding all steel frames for the same seismic intensity.

本研究开发了一种复合（钢/混凝土）框架的位移/损伤控制（DDC）抗震设计方法，该方法由圆形钢管混凝土柱（CFT）和复合梁（与混凝土楼板相连的钢梁）组成。所提出的抗震设计方法可以直接控制所有地震性能水平的位移和破坏，包括接近崩溃的水平。通过经验表达式，该方法可以估算设计结构的层间漂移比（IDR），并评估给定地震强度下关键构件的破坏指数（DI）。设计迭代次数减少了，同时可以避免计算量大的非线性时间历史分析。通过对包括IDR和DI在内的大型响应数据库进行统计和敏感性分析，得出了设计方法的必要经验表达式，这些数据库涵盖了从弹性行为到最终全局动态不稳定性的所有方式。该响应数据库是通过在许多地震运动和不同土壤类型下对此处考虑的许多这种复合框架结构进行广泛的参数增量动态分析而创建的。设计实例表明，DDC设计方法成功地估算了所需抗震性能水平的目标IDR，并控制了关键的梁到柱节点的DI，从而避免了软层破坏机制或结构的部分损失。与所有钢框架结构相比，此处考虑的复合框架表现出更好的抗震性能，而梁和柱的DI更低。随着层数的增加，复合框架的低损伤性能主要被强调，而在相同的地震烈度下，IDR和DI的性能水平往往低于相应的所有钢框架。