Proposed Panel Zone Model for Seismic Design of Steel Moment-Resisting Frames

Recent changes to the United States seismic design provisions permit the use of weak column-strong beam steel moment resisting frames. This design concept has not been used in the past, because it results in plastic hinges in the columns during moderate or extreme earthquakes. This paper shows the results of inelastic dynamic response calculations on a weak column frame and a comparable strong column system. The results show that the ductility demand is much greater for the weak column strong beam framing system with some acceleration records. The required ductility is then compared for the different structural systems and both are compared to the results of experiments. The comparison suggests that the weak column system may not be able to develop the required ductility. The results of this paper should help define the viability and limits in applicability of the weak column system.

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Strengthening of the Panel Zone in Steel Moment Resisting Frames

10.31224/osf.io/dh3ba ◽

2019 ◽

Author(s):

Masoud Abedini ◽

Sudharshan N. Raman ◽

Azrul A. Mutalib ◽

Ebrahim Akhlaghi

Keyword(s):

Structural Engineering ◽

Steel Structures ◽

Inelastic Behavior ◽

Linear Deformation ◽

Rigid Zone ◽

Steel Moment Resisting Frames ◽

Moment Resisting Frames ◽

Panel Zone ◽

Standard Design ◽

Moment Resisting

Rehabilitation and retrofitting of structures designed in accordance to standard design codes is an essential practice in structural engineering and design. For steel structures, one of the challenges is to strengthen the panel zone as well as its analysis in moment-resisting frames. In this research, investigations were undertaken to analyze the influence of the panel zone in the response of structural frames through a computational approach using ETABS software. Moment-resisting frames of six stories were studied in supposition of real panel zone, different values of rigid zone factor, different thickness of double plates, and both double plates and rigid zone factor together. The frames were analyzed, designed and validated in accordance to Iranian steel building code. The results of drift values for six stories building models were plotted. After verifying and comparing the results, the findings showed that the rigidity lead to reduction in drifts of frames and also as a result, lower rigidity will be used for high rise building and higher rigidity will be used for low rise building. In frames with story drifts more than the permitted rate, where the frames are considered as the weaker panel zone area, the story drifts can be limited by strengthening the panel zone with double plates. It should be noted that higher thickness of double plates and higher rigidity of panel zone will result in enhancement of the non-linear deformation rates in beam elements. The resulting deformations of the panel zone due to this modification can have significant influence on the elastic and inelastic behavior of the frames.

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Robustness Assessment of Steel Moment Resisting Frames

The Open Civil Engineering Journal ◽

10.2174/1874149501711010420 ◽

2017 ◽

Vol 11 (1) ◽

pp. 420-433 ◽

Cited By ~ 1

Author(s):

David Cassiano ◽

Carlos Rebelo ◽

Luís Simoes da Silva

Keyword(s):

Seismic Design ◽

Progressive Collapse ◽

Design Criteria ◽

Steel Moment Resisting Frames ◽

Moment Resisting Frames ◽

Long Span ◽

Moment Resisting ◽

Structural Plastic ◽

Steel Mrf ◽

Pushdown Analysis

Nowadays, many buildings with steel Moment Resisting Frames (MRF) are built in seismic zones when seismic codes are at its early stages of development, and as such, these structures are often designed solely to resist lateral wind loads without providing an overall ductile mechanism. On the other hand, current seismic design criteria based on hierarchy of resistance allow enhancing the structural ductility and controlling the structural plastic behaviour. Therefore, seismic design criteria might also be beneficial to improve the structural robustness. In order to investigate this issue for steel MRF, a parametric study based on pushdown analysis and on the Energy Balance Method is described and discussed in the present paper. With this regard, the following cases are examined: (i) MRF not designed for seismic actions and (ii) MRF designed for seismic actions. The investigated parameters are (i) the number of storeys, (ii) the interstorey height, (iii) the span length, (iv) the building plan layout and (v) the column loss scenario. Results show that the low-rise and long span structures are the most prone to progressive collapse and that the elements in the directly affected zone of the wind designed 8 storey structures respond in the elastic range. Structures designed according to the capacity design principles were found to be less robust than wind designed structures that are characterized by strong beams and weak columns. The number of elements above the removed column and size of beam cross section were found to be key parameters in arresting progressive collapse.

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