Journal of the Computational Structural Engineering Institute of Korea (한국전산구조공학회논문집)

Computational Structural Engineering Institute of Korea (한국전산구조공학회)
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Seismic Behavior of a Bridge with Pile Bent Structures Subjected to Multi-Support Excitation

다지점 가진에 의한 단일형 현장타설말뚝 교량의 지진거동

  • Sun, Chang-Ho (Department of Civil and Environmental Engineering, University of Ulsan) ;
  • Ahn, Sung-Min (Kunhwa Engineering and Consulting) ;
  • Kim, Ick-Hyun (Department of Civil and Environmental Engineering, University of Ulsan)
  • 선창호 (울산대학교 건설환경공학부) ;
  • 안성민 (건화엔지니어링 철도구조사업부) ;
  • 김익현 (울산대학교 건설환경공학부)
  • Received : 2019.11.08
  • Accepted : 2019.11.18
  • Published : 2019.12.31
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Abstract

It is important to ensure the seismic safety of pile-bent bridges constructed in areas with thick soft ground consisting of various soil layers against seismic motion in these layers. In this study, several synthetic seismic waves that are compatible with the seismic design spectrum for rock sites were generated, and the ground acceleration history of each soil layer was obtained based on ground analyses. Using these acceleration histories, each soil layer was modeled using equivalent linear springs, and multi-support excitation analyses were performed using the input motion obtained at each soil layer. Due to the nonlinear behavior of the soft soil layers, the intensity of the input ground motion was not amplified, which resulted in the elastic behavior of the bridge. In addition, inputting the acceleration history obtained from a particular layer simultaneously into all the ground springs reduced the response. Therefore, the seismic performance of this type of bridge might be overestimated if multi-excitation analysis is not performed.

연약지반이 두껍고 다양한 지층으로 구성된 지역에 건설되는 단일형 현장타설말뚝 교량은 다양한 지층을 통해서 단일형 말뚝으로 입력되는 지반운동에 대해서 내진안전성을 확보하는 것이 중요하다. 본 연구에서는 설계지반운동에 부합되는 다수의 인공합성지진을 생성하여 이를 암반의 입력지반으로 하여 지반해석을 수행하여 각 지층에서의 지반가속도이력을 산정하였다. 이 가속도이력을 이용하여 각 지층의 지반을 등가스프링으로 모델화하고, 각 지층에서의 가속도시간이력을 입력지반운동으로 하는 다지점 가진 지진해석을 수행하였다. 연약층의 비선형거동특성으로 입력지반운동의 세기는 크게 증폭되지 않아서 교량은 탄성영역 내에서 거동하였다. 한편, 특정 지층에서 산정된 가속도이력을 모든 지반스프링에 동시에 입력하면 응답이 감소하였다. 따라서, 다지점가진 해석을 수행하지 않으면 이러한 형식의 교량의 내진성능을 과대평가할 수 있다.

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References

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