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Strengthening of the panel zone in steel moment-resisting frames
Abedini, Masoud,Raman, Sudharshan N.,Mutalib, Azrul A.,Akhlaghi, Ebrahim Techno-Press 2019 Advances in computational design Vol.4 No.4
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.
Song, Taeksun,Song, Seung-Eun,Raman, Sahadevan,Anaya, Mauricio,Husson, Robert N. American Society for Microbiology 2008 Journal of Bacteriology Vol.190 No.6
<B>ABSTRACT</B><P>Mycobacterial SigE and SigH both initiate transcription from the <I>sigB</I> promoter, suggesting that they recognize similar sequences. Through mutational and primer extension analyses, we determined that SigE and SigH recognize nearly identical promoters, with differences at the 3′ end of the −35 element distinguishing between SigE- and SigH-dependent promoters.</P>
An improved polynomial model for top -and seat- angle connection
P. Prabha,V. Marimuthu,S. Arul Jayachandran,S. Seetharaman,N. Raman 국제구조공학회 2008 Steel and Composite Structures, An International J Vol.8 No.5
The design provisions for semi-rigid steel frames have been incorporated in codes of practice for steel structures. In order to do the same, it is necessary to know the experimental moment-relative rotation (M-θr) behaviour of beam-to-column connections. In spite of numerous publications and collection of several connection databases, there is no unified approach for the semi-rigid design of steel frames. Amongst the many connection models available, the Frye-Morris polynomial model, with its limitations reported in the literature, is simple to adopt at least for the linear design space. However this model requires more number of connection tests and regression analyses to make it a realistic prediction model. In this paper, 3D nonlinear finite element (FE) analysis of beam-column connection specimens, carried out using ABAQUS software, for evaluating the M-θr behaviour of semi-rigid top and seat-angle (TSA) bolted connections are described. The finite element model is validated against experimental behaviour of the same connection with regard to their moment-rotation behaviour, stress distribution and mode of failure of the connections. The calibrated FE model is used to evaluate the performance of the Frye-Morris polynomial model. The results of the numerical parametric studies carried out using the validated FE model have been used in proposing modifications to the Frye-Morris model for TSA connection in terms of the powers of the size parameters.