The Seismic Performance And Damage Analysis Of BRB Frame Structure Based On Improved Pushover Method

Earthquake is one of the most serious natural disasters in human society, which has caused a lot of houses collapsed. To reduce the impact of earthquakes on structures, it is important to take vibration-control measures, in which the BRB is an effective way. BRBs have strong lateral stiffness and strength, and also act as the "fuse" role in structures. During the earthquake, they can reduce damage to the main structure through dissipating seismic energy, promoting the seismic performance of the whole structure. Because of BRBs’ nonlinear properties, they will have a relatively large impact on the dynamic characteristics and the dynamic response of the primary structure, and also make the analysis of energy dissipation complex. Based on the comparison of current seismic analysis methods of BRB, results show that the elastic-plastic static method are convenient and easy to implement, but due to the traditional method of pushover has limitations, making the results of their analysis are not accuracy enough. Therefore, focus on improving the BRB frame structure pushover method based on the target displacement of cyclic loading pushover method, and based on this method damage analysis method of BRB frame structure is proposed. First of all, this paper discusses the development and research status of pushover method, and specifically introduces the principle of pushover method, different lateral force loading pattern, and several common methods of pushover. Calculating of the target displacement based on the displacement coefficient method has been introduced in detail, and the selection of some of the calculation parameters is suggested. Then the displacement coefficient is combined with capacity spectrum method to put forward a simple calculation method for the effective damping ratio of BRB structure-the cyclic loading pushover method. And implementation steps of this method are given in SAP2000. Then a case study is carried out in SAP2000, and results of this method are compared with those of time history analysis to verify its feasibility. Example in this article is a five-storey concrete frame designed by YJK structure design software, which is reinforced by BRB on the basis. The rationality of the brace layout has been verified. In the process of calculation, the plastic hinge is defined according to thecross section analysis through XTRACT program and beam reinforcement given by YJK software, which is more accurate that defined by default parameters in SAP2000. Results of proposed method are at accordance with those of time history analysis, showing the feasibility of this method.Finally, based on the proposed pushover method and existed damage model, this paper put forward an improved damage analysis method, which can be used as a simple method for seismic performance analysis. According to acquired damage indexes, one can determine the damaged conditions of structure by inferring to relational table of the damage index.