For a member model in nonlinear structural analysis, a lumped plastic model that idealizes its flexural bending, shear, and axial behaviors by springs with the nonlinear hysteretic model is widely adopted because of its simplicity and transparency compared to the other rigorous finite element methods. On the other hand, a challenging task in its numerical solution is to satisfy the equilibrium condition between nonlinear flexural bending and shear springs connected in series. Since the local forces between flexural and shear springs are not balanced when one or both springs experience stiffness changes (e.g., cracking, yielding, and unloading), the additional unbalanced force due to overshooting or undershooting each spring force is also generated. This paper introduces an iterative scheme for numerical solutions satisfying the equilibrium conditions between flexural bending and shear springs. The effect of equilibrium iteration on analysis results is shown by comparing the results obtained from the proposed method to those from the conventional scheme, where the equilibrium condition is not perfectly satisfied.

A B S T R A C T
1. 서 론
2. 구성방정식 및 수렴계산
    2.1 휨 스프링으로 구성된 부재
    2.2 불평형력 해소를 위한 수렴계산: 시스템 불평형력
    2.3. 휨 스프링과 전단 스프링으로 구성된 부재
    2.4 불평형력 해소를 위한 수렴계산: 부재 불평형력
3. 해석대상 및 방법
    3.1 해석대상
    3.2 해석 방법
4. 해석 결과
    4.1 Case-1: 전단 스프링 유무에 따른 응답 비교
    4.2 Case-2: 시스템 불평형력의 해소 유무에 따른 응답비교
    4.3 Case-3: 부재 불평형력의 해소 유무에 따른 응답비교
5. 결 론
감사의 글
REFERENCES

• 김유석(홍익대학교 건축공학부 부교수) | Kim, Yousok (Associate Professor, School of Architectural Engineering, Hongik University) Corresponding author