• Steel and Composite Structures
• /
• 제25권1호
• /
• pp.1-17
• /
• 2017

Seismic performance of hybrid steel frames defined as mixture of rigid and semi-rigid connections is investigated in this paper. Three frames with 10, 15 and 20 stories are designed with fully rigid connections and then with 4 patterns for semi-rigid connection placement, some of beam to column rigid connections would turn to semi-rigid. Each semi-rigid connection is considered with 4 different moment capacities and all rigid and semi-rigid frames consisting of 51 models are subjected to 5 selected earthquake records for nonlinear analysis. Maximum story drifts, roof acceleration and base shear are extracted for those 5 earthquake records and average values are obtained for each case. Based on numerical results for the proposed hybrid frames, story drifts remain in allowable range and the reductions in the maximum roof acceleration of 22, 29 and 25% and maximum base shear of 33, 31 and 54% occur in those 10, 15 and 20-story frames, respectively.

• 한국강구조학회 논문집
• /
• 제12권4호통권47호
• /
• pp.375-385
• /
• 2000

6층 비가새 및 20층 가새 철골구조물에서 기하 비선형, 재료 비선형, 접합부 비선형을 고려할 때 극한 횡하중에 대해 요구되는 접합부 연성도를 파악하였다. 재료 비선형을 고려하기 위하여 단면 모멘트-곡률 관계는 Fiber 모델을 이용하고 부재 강성행렬은 유연도 선형분포 해석모델을 이용하여 유도하였다. 강접합부를 반강접합부로 대체한 6층 구조물의 접합부 연성도는 강접합부인 경우 보다 적었고 20층 구조물에서 요구되는 반강접합부 연성도는 전단접합부의 경우와 거의 같고 강접합부는 전단접합부나 반강접합부에 비하여 큰 연성도가 필요하였다.

• 한국강구조학회 논문집
• /
• 제8권4호통권29호
• /
• pp.121-131
• /
• 1996

Semi-rigid frames are frames for whcih the connections joining the beam and column are neither fully rigid nor perfectly pinned. In reality, all steel frames are semi-rigid in nature as all connections exhibit a certain degree of flexibility under loads. For semi-rigid frmaed structures, it is tended to reduce more rigidity of the member for the nonlinear behavior of connections and the P-delta effects of framed structure. To predict the actual behavior of semi-rigid steel frames, a more realistic analysis methods which explicitly takes into account the effect of connection flexibility should be used. In this research, the effect of connection flexibility in the semi-rigid structure has been investigated. To predict the response of flexibility connected frames, the algorithm of semi-rigid steel frame is developed using connection model having nonlinear spring on end of beam.

• Steel and Composite Structures
• /
• 제34권5호
• /
• pp.625-641
• /
• 2020

The realistic modeling of the beam-column semi-rigid connection in steel frames attracted the attention of many researchers in the past for the seismic analysis of semi-rigid frames. Comparatively less studies have been made to investigate the behavior of steel frames with semi-rigid connections under different types of earthquake. Herein, the seismic behavior of semi-rigid steel frames is investigated under both far and near-field earthquakes. The semi-rigid connection is modeled by the multilinear plastic link element consisting of rotational springs. The kinematic hysteresis model is used to define the dynamic behavior of the rotational spring, describing the nonlinearity of the semi-rigid connection as defined in SAP2000. The nonlinear time history analysis (NTHA) is performed to obtain response time histories of the frame under scaled earthquakes at three PGA levels denoting the low, medium and high-level earthquakes. The other important parameters varied are the stiffness and strength parameters of the connections, defining the degree of semi-rigidity. For studying the behavior of the semi-rigid frame, a large number of seismic demand parameters are considered. The benchmark for comparison is taken as those of the corresponding rigid frame. Two different frames, namely, a five-story frame and a ten-story frame are considered as the numerical examples. It is shown that semi-rigid frames prove to be effective and beneficial in resisting the seismic forces for near-field earthquakes (PGA ≈ 0.2g), especially in reducing the base shear to a considerable extent for the moderate level of earthquake. Further, the semi-rigid frame with a relatively weaker beam and less connection stiffness may withstand a moderately strong earthquake without having much damage in the beams.

• 한국농공학회지
• /
• 제40권1호
• /
• pp.78-87
• /
• 1998

In this study, semi-rigid light-weight framed structures analysis model (SERIFS) was developed by advancing the LEIFS model. This model enables us to analyze simultaneous effects of large deflection and semi-rigid connection by computing unbalanced load occurring in the process of repeated loading through equalization of bending moments and torsion. This model is also able to handle the effect of the semi-rigid connection and large deflection by modifying the elastic stiffness matrix using moment-rotation behavior of connection. Moment-rotation behavior of the semi-rigid connection was adopted from the experimental results of load-vertical displacement of frame element In conclusion, this model achieves to analyze the nonlinear and large deflection behavior on the semi-rigid and light-weight steel frame connection.

• Steel and Composite Structures
• /
• 제18권6호
• /
• pp.1405-1421
• /
• 2015

Semi-rigid connections are the actual behavior of beam-to-column connections in steel frames. However, the behavior of semi-rigid connections is not taken into account for the simplicity in the conventional analysis and design of steel frames. A computer-based analysis and design has been studied for the three-dimensional steel frames with semi-rigid connections. The nonlinear analysis which includes the effects of the flexibility of connections is used for this study. It is designed according to the buckling and combined stress constraints under the present loading after the joint deformations and the member end forces of the space frame are determined by the stiffness matrix method. The semi-rigid connection type is limited to the top and bottom angles with a double web angle connection. The Frye-Morris polynomial model is used to describe the non-linear behavior of semi-rigid connections. Various design examples are presented to demonstrate the efficiency of the method. The results of design and analysis of unbraced semi-rigid frames are compared to the results of unbraced rigid frames under the same design requirements.

• 한국강구조학회 논문집
• /
• 제21권5호
• /
• pp.483-492
• /
• 2009

소성영역에서 부재의 강성감소, 휨효과 및 잔류응력의 영향을 고려하면서 극한 한계상태에서 강골조의 거동을 평가하기 위해 개선 소성 힌지법을 이용하여 평면강골조의 비선형해석을 실시하고, 강접 및 반강접 평면강골조의 다양한 모델에 대한 수치해석을 통하여 거동을 평가하는데 목적이 있다. 그리고 상용프로그램을 이용한 해석결과를 이용하여 반강접율의 변화에 따른 골조의 거동을 분석한다.

• 한국강구조학회 논문집
• /
• 제22권4호
• /
• pp.313-324
• /
• 2010

본 연구에서는 반강접 접합부 배치에 따른 구조물 거동특성을 파악하기 위하여 KBC2005 건축구조설계기준으로 비가새 5층 철골 구조물을 설계하여 모든 접합부를 완전 강접합부와 반강접 접합부로 이상화한 경우 그리고 반강접 접합부를 수직배치 및 수평배치한 경우에 대하여 비탄성 시간이력 구조해석을 실시하였다. 철골 보 및 기둥의 모멘트-곡률 관계는 화이버모델을 이용하여 확인하였으며 반강접 접합부의 모멘트-회전각 관계는 3-매개변수 파워모델 그리고 철골 보, 기둥 및 접합부의 이력거동은 3-매개변수 모델을 이용하여 나타내었다. 4개 지진파에 대한 재현주기 2400년 위험수준에 해당하는 최대지반가속도와 5% 층간변위에 대한 푸쉬오버 구조해석의 최대밑면전단력 발생 최대지반가속도에 대하여 시간이력 구조해석을 실시하여 밑면전단력, 지붕층 변위, 층간변위, 접합부 요구연성도, 기둥, 보 및 접합부의 최대휨모멘트 그리고 소성힌지 분포 등을 확인하였다. 반강접 접합부를 수직적으로 외부에 배치할수록 최대밑면전단력과 층간변위는 감소하며, 수평적으로 상부층에 배치할수록 접합부 요구연성도가 감소하였다. 푸쉬오버 구조해석과 시간이력 구조해석에서 최대층간변위 발생 위치가 다르고 크기는 푸쉬오버 구조해석에서 과대평가되었다. 밑면전단력, 층간변위 및 접합부 요구연성도를 위한 가장 바람직한 반강접 접합부 배치는 수직적으로 외부에 배치하는 것이다.

• Steel and Composite Structures
• /
• 제4권6호
• /
• pp.453-469
• /
• 2004

In this article, a genetic algorithm based optimum design method is presented for non-linear steel frames with semi-rigid connections. The design algorithm obtains the minimum weight frame by selecting suitable sections from a standard set of steel sections such as European wide flange beams (i.e., HE sections). A genetic algorithm is employed as optimization method which utilizes reproduction, crossover and mutation operators. Displacement and stress constraints of Turkish Building Code for Steel Structures (TS 648, 1980) are imposed on the frame. The algorithm requires a large number of non-linear analyses of frames. The analyses cover both the non-linear behaviour of beam-to-column connection and $P-{\Delta}$ effects of beam-column members. The Frye and Morris polynomial model is used for modelling of semi-rigid connections. Two design examples with various type of connections are presented to demonstrate the application of the algorithm. The semi-rigid connection modelling results in more economical solutions than rigid connection modelling, but it increases frame drift.

• 한국공간구조학회논문집
• /
• 제3권1호
• /
• pp.35-46
• /
• 2003

Conventional analysis and design of steel structures are performed using the assumption of a either fully rigid or pinned. However, every steel connection lies in between fully rigid and pinned connection. So, It is important to consider the connection for steel structure design. In this paper Computer-based second-order elastic analysis is used to calculate one story two bay and two story three bay for steel structures with semi-rigid connection. Genetic Algorithms(GAs) and Sequential Unconstrained Minized Technique(SUMT) dynamic programming is used to the method for optimum design of steel structures. The efficiency and validity of the developed continuous and discrete optimum design algorithm was verified by applying the algorithm to optimum design examples.