Research on determining the aseismic performance level of reinforced concrete building

In seismic design based on performance, seismic performance level is determined based on failure state of the building and seismic design objective is set according to the importance of the buildings. In many countries, they calculate the seismic reaction of the buildings with the use of structural design programs to check the aseismic performance through the nonlinear static analysis method. In this paper, we established seismic performance levels and aseismic design objective to design on the basis of design objective according to the three levels in Seismic Design Code of Building, DPR Korea, 2010. Keyword: failure, performance, seismic, aseismic, design Received 15 July 2021|Revised 22 August 2021 | Accepted 26 August 2021


Introduction
Since the idea about seismic design based on performance was suggested, many researches and experiments have been taken place. FEMA 273/274 [3,4] suggested seismic design objective relying on performance level of structural and non-structural members and the main methods of deciding seismic performance of buildings with the use of nonlinear static analysis(Pushover) to evaluate the seismic performance.
ATC40 [2] reported the main principle of capacity spectrum method and the method to evaluate the seismic performance and described the evaluation method according to usage and failure state. With the development of seismic design theories, we can design on the economic standard considering the importance of the buildings and evaluate aseismic performance of buildings under various earthquake technically.

2~3%
Most of the building is in elastoplastic behaviour, the building is not destructed though in elastoplastic concentration behavior. However it is difficult to repair.   Table 2 shows the classification according to the importance of the buildings and the design seismic strength of the buildings according to the local seismic strength. The rest of buildings of class 1,2 and 4 -7 6 7 (6 at ground of class1)

Class 4
Secondary buildings which is little damaged,buildings to two stories and public and industrial building with the height of two stories ---7 (not consider) Note: buildings of class 4 can be applied by seismic measure lower than normal seismic one and buildins of class 2 can be reinforced concrete buildings or steel structure of good seismic performance which can be applied by proper seismic measureof the rules according to the local seismic strength.

Decision of seismic performance according to Seismic Design Code of Building of our country
Generally, seismic performance can be classified by destructive state of the structures. Failure state can be divided into 5 levels (non-destructive state, slight destructive state, medium destructive state, serious destructive state, collapse) on basis of earlier studies and experimental data to decide the seismic performance level of the structures based on it.

1) Destructive state of the structures
(1) Non-destructive state Most structural members are in elastic behavior in this state, so it is called "regular operation". About 5 percent of structural members has ductile behavior with slight cracks and the rest of them works in elastic behavior. In this state, most of the members reach elastoplastic deformation limit and the building collapse locally or completely. It is impossible to repair and it endangers lives.

2) Decision of seismic performance level and design objectives
Seismic performance levels of reinforced concrete buildings can be determined as follows on basis of failure state of the structure [1].  Note: g is acceleration of gravity.
Seismic design objectives of reinforced concrete buildings can be determined as follows on basis of seismic strengths and seismic performance levels. Slight earthquake Seismic design objective ① is one that the building is in performance level 1 under strong earthquake and can be used instantly, and can be applied to the very important buildings (Table   1). In our country, this objective is applied to the buildings of the first class in classification of buildings in our country.
Seismic design objective ② is one that the building remains in performance level 1 under normal earthquake and has slight failures under strong earthquake, and can be applied to the buildings of the second class in classification of buildings in our country (Table 2).
Seismic design objective ③ is one that the building remains in performance level 1 with nondestructive state under slight earthquake and is in medium stage of failure, and can be applied to the buildings of the third class in classification of buildings in our country (Table 3).
Seismic design objective ④ is one that slight failure occurs under slight earthquake and the building is in performance level 4 under normal earthquake, can be applied to the buildings of the fourth class in classification of buildings in our country (Table 4).
Seismic design objective ⑤ is one that requires life safety under normal earthquake and the building collapses under strong earthquake, and generally can be applied to the buildings which do not need to consider earthquake ( Table 5).
As is shown, we can estimate the failure state of the buildings under earthquake to guarantee the building more scientifically when we classify the seismic performance levels of reinforced concrete building in to five and design according to it.

Conclusion
Calculation of story drift of the structure and decision of the structural performance levels is important for seismic design. In this essay, we decided the performance levels of the reinforced concrete structures and seismic design objective according to performance.
We laid the foundation of seismic design on the basis of performance by deciding performance levels of reinforced concrete structure considering the importance of the buildings.