• 한국지진공학회논문집
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• 제18권2호
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• pp.95-103
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• 2014

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.

• Structural Engineering and Mechanics
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• 제47권1호
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• pp.119-129
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• 2013

Nonlinear Static Procedures (NSPs) have been developed as a practical tool to estimate the seismic demand of structures. Several researches have accomplished to minimize errors of NSPs, namely pushover procedures, in the Nonlinear Time History Analysis (NTHA), as the most exact method. The most important issue in a typical pushover procedure is the pattern and technique of loading which are extracted based on structural dynamic fundamentals. In this paper, the coefficients of modal force combination is focused involving a meta-heuristic optimization algorithm to find the optimum load pattern which results in a response with minimum amount of errors in comparison to the NTHA counterpart. Other parameters of the problem are based on the FEMA recommendations for pushover analysis of building structures. The proposed approach is implemented on a high-rise 20 storey concrete moment resisting frame under three earthquake records. In order to demonstrate the effectiveness and robustness of the studied procedure the results are presented beside other well-known pushover methods such as MPA and the FEMA procedures, and the results show the efficiency of the proposed load patterns.

• Structural Engineering and Mechanics
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• 제83권2호
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• pp.229-244
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• 2022

This paper investigates the seismic performance of buildings designed using DDBD (Direct Displacement based Design) and FBD (Force based Design) approaches from the probabilistic viewpoint. It aims to estimate the collapse capacity of structures and assess the adequacy of seismic design codes. In this regard, (i) IDA (Incremental Dynamic Analysis) curves, (ii) interstory drift demand distribution curves, (iii) fragility curves, and (iv) the methodology provided by FEMA P-695 are applied to examine two groups of RC moment resistant frame buildings: 8-story structures with different plans, to study the effect of different span arrangements; and 3-, 7- and 12-story structures with a fixed plan, to study the dynamic behavior of the buildings. Structural modeling is performed in OpenSees software and validated using the results of an experimental model. It is concluded that increasing the building height would not significantly affect the response estimation of IDA and fragility curves of DDBD-designed structures, while the change in span arrangements is effective in estimating responses. In the investigation of the code adequacy, unlike the FBD approach, the DDBD can satisfy the performance criteria presented in FEMA P-695 and hence provide excellent performance.

• Steel and Composite Structures
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• 제42권1호
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• pp.59-74
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• 2022

This study introduces a general reliability-based, performance-based design framework to design frames regarding their uncertainties and user-defined design goals. The Iterative-R method extracted from the main framework can designate a proper R (i.e., response modification factor) satisfying the design goal regarding target reliability index and pre-defined probability of collapse. The proposed methodology is based on FEMA P-695 and can be used for all systems that FEMA P-695 applies. To exemplify the method, multiple three-dimensional, four-story steel special moment-resisting frames are considered. Closed-form relationships are fitted between frames' responses and the modeling parameters. Those fits are used to construct limit state functions to apply reliability analysis methods for design safety assessment and the selection of proper R. The frameworks' unique feature is to consider arbitrarily defined probability density functions of frames' modeling parameters with an insignificant analysis burden. This characteristic enables the alteration in those parameters' distributions to meet the design goal. Furthermore, with sensitivity analysis, the most impactful parameters are identifiable for possible improvements to meet the design goal. In the studied examples, it is revealed that a proper R for frames with different levels of uncertainties could be significantly different from suggested values in design codes, alarming the importance of considering the stochastic behavior of elements' nonlinear behavior.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.436-442
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• 2022

Hurricanes and tornadoes are the most destructive natural disasters in some central and southern states. Thus, storm shelters, which can provide emergency protections for low-rise building residents, are becoming popular nowadays. Both FEMA and ICC have published a series of manuals on storm shelter design. However, the authors found that the materials for related products in the market are heavyweight and hard to deliver and install; renovations are necessary. The authors' previous studies found that lightweight and high-performance composite materials can withstand extreme wind pressure, but some building codes are designated in wind-borne debris areas. In these areas, wind debris can reach greater than 100 mph speed. In addition, the impact damage on the composite materials is an increasing safety issue in many engineering fields; some can cause catastrophic results. Therefore, studying composite structures subjected to wind debris impact is essential. The finite element models are set up using the software Abaqus 2.0 to conduct the simulations to observe the impact resistance behavior of the carbon fiber composite sandwich panels. The selected wood debris models meet the FEMA requirements. The outcome of this study is then employed in future lab tests and compared with other material models.

• 한국지진공학회논문집
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• 제28권4호
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• pp.165-170
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• 2024

This study investigated the impact of soil-structure interaction on multi-degree-of-freedom structures using the shallow-foundation Winkler model, known as the BNWF model. The model's period was determined through eigenvalue analysis and compared to results obtained from FEMA's formula. Results indicated that considering the soil, the structure's period increased by up to 8.7% compared to the fixed-base model, aligning with FEMA's calculations. Furthermore, with adequate ground acceleration, roof displacement increased by 3.4% to 3.8%, while base shear decreased by 4% to 10%. However, roof displacement and base shear increased in some earthquake scenarios due to spectral shape effects in regions with extended structural periods. Foundation damping effects, determined through the foundation's moment-rotation history, grew with higher ground acceleration. This suggests that accounting for period elongation and foundation damping can enhance the seismic design of multi-degree-of-freedom structures.

• 콘크리트학회논문집
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• 제25권3호
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• pp.271-281
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• 2013

구조형식별로 구조물의 안정성 확보를 위해 KBC2009에 새로이 도입된 높이제한에 따라, 내진설계범주D에 해당되는 60 m 이상의 RC 구조물을 계획할 경우 특수전단벽을 의무적으로 사용해야 한다. 그러나 특수전단벽의 엄격한 횡보강 배근상세는 시공성 및 경제성에 부정적 영향을 미칠 것으로 예상된다. 그래서 이 연구에서는 현 규준에 따른 특수전단벽보다 완화된 배근 상세를 갖는 특수전단벽을 제안하고, 특수전단벽과의 성능 비교를 위하여 각각 두 개의 실험체를 제작하고 횡방향 반복 하중실험을 실시하였다. 또한 그 실험 결과를 반영한 보통전단벽, 특수전단벽, 완화된 특수전단벽 구조시스템의 해석모델을 설계하여 FEMA P695에 따른 방법론으로 내진성능평가를 실시하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.233-238
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• 2000

The purpose of this study is to outline the analysis procedure for evaluating the performance of moment resisting steel frames. For this purpose, three ordinary moment resisting frames are designed in compliance to UBC 1994. The evaluation is performed by nonlinear static procedures using two analytical models. Only one analytical model using panel element can reflect the panel zone deformation explicitly. The limit values in FEMA 273 are used as guidelines of predicted demand parameters by which the performance of OMRFs may be assessed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.565-570
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• 2001

Base shear and roof drift relation was acquired from experiment of 3 story ordinary moment resisting frame which was designed using gravity loads. To evaluate the dynamic behavior of the frame, analytical model was generated from experimental result. Dynamic analysis was performed using the analytical model subjected to earthquake ground motions with 500, 1000, and 2400 years of return period. And capacity spectrum method was adopted to find the performance points of the frame. Both dynamic analysis and CSM showed that the performance of the frame meet the life safety objectives suggested by FEMA 273 and ATC 40.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.373-376
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• 2006

There are representative two performance evaluation methods for performance-based design(PBD) of reinforced concrete structures by the nonlinear static analysis, one method includes the capacity spectrum method(CSM) suggested in ATC-40(996) and the other is the displacement coefficient method(DCM) in FEMA-273(1997). The objective of this paper is to compare and verify two methods and suggest the displacement-based design for new performance evaluation of reinforced concrete structures.