This study presents a dry precast concrete (PC) beam-column connection, and its target seismic performance level is set to be emulative to the reinforced concrete (RC) intermediate moment resisting frame system specified in ACI 318 and ASCE 7. The key features include self-sustaining ability during construction with the dry mechanical splicing method, enabling emulative connection performances and better constructability. Test specimens with code-compliant seismic details were fabricated and tested under reversed cyclic loading, which included a PC beam-column connection specimen with dry connections and an RC control specimen. The test results showed that all the specimens failed in a similar failure mode due to plastic deformations in beam members, while the hysteretic response curve of the PC specimen showed comparable and emulative performances compared to the RC specimen. Seismic performance evaluation was quantitatively addressed, and on this basis, it confirmed that the presented system can fully satisfy all the required performance for the intermediate RC moment resisting frame.
This paper is the sequel of a companion paper (I. Performance Evaluation) evaluating the relation between the seismic performance of steel intermediate moment frames (IMFs) and the rotation capacity of connections. The evaluation revealed that the seismic performance of IMFs having the required minimum rotation capacity suggested in the current standards did not meet the seismic performance criteria presented in FEMA 695. Therefore, thepresent study evaluates the causes of the vulnerable seismic performance for steel IMFs and proposes alternatives to satisfy the seismic performance suggested in FEMA 695. To that goal, the results of nonlinear analysis, which are the pushover analysis and the incremental dynamic analysis, are examined and evaluated. As a result, high-rise IMF systems are seen to have the lower collapse margin ratio after connection fracture than row-rise IMF systems and, the actual response isfound to compared tothedesign drift ratio acting on design load design. Finally, the minimum design load values are proposed to meet the seismic performance suggested in FEMA 695 for IMF systems having vulnerable seismic performance.
The current AISC341-10 standard specifiesa value of 0.02 radian for the minimum rotation capacity of connections for the intermediate steel moment frame system. However, despite of the advances realized in the domains of performance evaluation method and analysis method, research onthe minimum rotation capacity of the intermediate steel moment frame systemsatisfying the seismic performance has not been conducted in detail. In this study, the intermediate moment frame systemisdesigned with respect to current standards and the seismic performance in accordance with the rotational capacity of connections is evaluated using the seismic performance evaluation method presented in FEMA-P695. The minimum rotation capacity of intermediate steel moment frames required to satisfy seismic performance as well as the major design values affecting the seismic performance of moment frame areestimated. To that goal, the design parameters are selected and various target frames are designed. The analysis models of the main nonlinear elements are also developed for evaluating seismic performance. The resultsshow that the 20-story structure doesnot meet the seismic performance even if it satisfies the rotation capacity of 0.02 radian.
In current seismic design code, steel moment frames are classified into ordinary, intermediate, and special moment frames. In the case of special moment frames which have large R-factor, economic design is possible by reducing the design lateral force. However, there is difficulty for practical application due to constraints such as strong column-weak beam requirement. This study evaluated if steel intermediate moment frame could maintain enough seismic capacity when the R-factor is increased from 4.5 to 6. As for the analytical models, steel moment frames of 3 and 5 stories were categorized into four performance groups according to seismic design category. Seismic performances of the frames were evaluated through the procedure based on FEMA P695. FEMA P695 utilizes nonlinear static analysis(pushover analysis) and nonlinear dynamic analysis(incremental dynamic analysis, IDA). In order to reflect the characteristics of Korean steel moment frames on the analytical model, the beam-column connection was modeled as weak panel zone where the collapse of panel zone was indirectly considered by checking its ultimate rotational angle after an analysis is done. The analysis result showed that the performance criteria required by FEMA P695 was satisfied when R-factor increased in all the soil conditions except SE.
최근 초고층 건물의 수가 증가하면서 건축 및 토목 구조물의 내진 및 내풍 설계의 중요성이 점차 강조되고 있다. 본 연구에서는 중력하중을 지지하는 대상 구조물에 대하여 지진하중 및 풍하중의 작용 전후를 비교하고 그 영향을 요구 강재량으로 평가 하였다. 본 연구에서는 서로 다른 높이를 갖는 다수의 철골 중간모멘트 골조를 대상으로 내진 및 내풍 설계를 수행하여 높이에 따른 영향을 평가 하였다. 본 연구를 진행함에 있어 평면의 형상은 SAC Project (Gupta and Krawinker, 1999)를 참고하였다. 3, 6, 9, 12, 15층 총 5가지 높이의 구조물에 대하여 해석을 진행하였으며 층고는 4m로 하였다. 사용한 지진하중은 등가정적해석법을 이용하여 정적 지진하중을 사용하였고 풍하중은 KBC2009에 따른 정적 풍하중을 사용하였다. 각각의 대상구조물의 강재량을 비교해본 결과, 구조물의 높이가 증가함에 따라 풍하중과 지진하중의 영향이 커지는 경향을 보이고, 풍하중 영향의 증가폭이 더 빠르게 커짐을 알 수 있다. 이는 높이가 높아질수록 지진하중에 대한 고려와 함께 풍하중에 의한 효과를 고려해야할 필요가 있음을 의미한다.