Energy-based Design Method for Passive Energy Dissipative Bracing Systems

In this study an energy-based method for the design of passive Energy Dissipative Bracing (EDB) systems is presented, as a retrofit technique for existing reinforced concrete (RC) buildings. A comprehensive literature overview concerning the design of hysteretic bracing systems based on various design philosophies, such as force-, displacement- or energy-based, is provided. The efficiency of the proposed method is validated by comparing the proposed methodology with two design procedures selected in the literature, applied to three RC frames. The results showed that the proposed method is more effective in avoiding the damage concentration at a single story and in distributing the additional strength provided by the EDBs proportionally to the hysteretic energy demand along the structure height. The validity of each procedure is compared based on non-linear static and non-linear dynamic analyses.

Hysteretic Energy Demands in Multi-Degree-of-Freedom Systems Subjected to Earthquakes

Reliable estimation of energy demands imposed on a structure by a design ground motion is a key component of energy-based design. Although several studies have been conducted to quantify the energy demands in single-degree-of-freedoms systems, few have focused on multi-degree-of-freedom systems. This study aims to build on the knowledge from previous studies on multi-degree-of-freedom systems with special focus on the distribution of hysteretic energy demands among the components of the structure. Nonlinear response history analyses conducted under ground motion sets representing three different hazard levels show that the total input and hysteretic energy demands of multi-degree-of-freedom systems can be accurately estimated from equivalent single-degree-of-freedom systems for low- and medium-rise buildings. The distribution of hysteretic energy demands over the height of the multistory structures has been shown to vary significantly from ground motion to ground motion. Analyses results also show that the relative strength of adjoining beams and columns has a significant influence on the hysteretic energy demand distribution. On the other hand, the energy distribution is relatively insensitive to the damping model used in the analysis of the multi-degree-of-freedom system.