scholarly journals STUDY OF HIGHER MODE EFFECTS AND LATERAL LOAD PATTERNS IN PUSHOVER ANALYSIS OF STEEL FRAMES WITH STEEL SHEAR WALL

2016 ◽  
Vol 10 (29) ◽  
pp. 13-27 ◽  
Author(s):  
Mohammad Ghanoonibagha ◽  
Mohammad Gol ◽  
Mohammad Ranjbar
Keyword(s):  
Pushover Analysis ◽  
Steel Frames ◽  
Shear Wall ◽  
Lateral Load ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Steel Shear Wall

scholarly journals Evaluation of Modal and FEMA Pushover Procedures Using Strong-Motion Records of Buildings

2005 ◽  
Vol 21 (3) ◽  
pp. 653-684 ◽  
Author(s):  
Rakesh K. Goel
Keyword(s):  
Pushover Analysis ◽  
Strong Motion ◽  
Northridge Earthquake ◽  
Reasonable Estimate ◽  
Modal Pushover Analysis ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Nonlinear Static Procedure ◽  
Nonlinear Static ◽  
Fema 356

The objective of this investigation is to evaluate the FEMA-356 Nonlinear Static Procedure (NSP) and a recently developed Modal Pushover Analysis (MPA) procedure using recorded motions of four buildings that were damaged during the 1994 Northridge earthquake. For this purpose, displacements and drifts from the FEMA-356 NSP and the MPA procedures are compared with the values “derived” from the recorded motions. It is found that the FEMA-356 NSP typically underestimates the drifts in upper stories and overestimates them in lower stories when compared to the recorded motions. Among the four FEMA-356 distributions considered, the “Uniform” distribution led to the most excessive underestimation or overestimation indicating that the need to carefully reevaluate the usefulness of this distribution in the FEMA-356 NSP. Furthermore, FEMA-356 distributions failed to provide accurate estimates of story drifts for a building that satisfied the FEMA-356 criterion for detecting the presence of higher mode effects indicating the need to carefully re-examine this criterion. The MPA procedure, in general, provides estimates of the response that are much closer to the values from the recorded motion compared to those from the FEMA-356 NSP. In particular, the MPA procedure, unlike the FEMA-356 NSP, is able to capture the effects of higher modes. For a building that exhibits dominant effects of “soft” first story, however, neither the MPA procedure nor the FEMA-356 NSP led to reasonable estimate of the response.

On a Process of Rapid Estimation of Seismic Demands for Generic Steel Frame Structures

2005 ◽  
Author(s):  
Chiung-Yueh Lin ◽  
Wei-Zhi Chen ◽  
Tysh-Shang Jan
Keyword(s):  
Pushover Analysis ◽  
Tall Buildings ◽  
Frame Structures ◽  
Seismic Demands ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
History Analysis ◽  
Story Drift ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis

The seismic demands of tall buildings can be evaluated by nonlinear response history analysis with some more representative, site-dependent, earthquakes, or by pushover analysis. However, the process of the evaluation is tedious and time consuming. Therefore, it is desirable to have a simplified process that provides quick and reasonable estimates of seismic demands, especially in the stage of conceptual (preliminary) design. Gupta & Krawinkler (2000) has reached on a process in the estimation of roof and story drift demands for frame structures from the spectral displacement at the first period of the structure, through a series of modification factors, accounting for MDOF effects, inelasticity effects, and P-delta effects. It is found that this process can estimate seismic demands reasonably, provided that no negative post-yield story stiffness exists. Also, the modification factors are uniform or with reasonable dispersion, except for structures dominated by higher mode effects. This study has conducted a similar research by performing simulations on Taiwan code–compliant structures of different heights (2,5,10,20 and 30 stories), located in different seismic zones and subjected to sets of local ground motions. The feature of this study is that the seismic demands are estimated from the SRSS of the elastic, modal roof displacements of the structure, instead of the first mode spectral displacement. The simulation results have shown that the modification factors are more promising — uniform or with more reasonable dispersion — even the structure is dominated by high mode effects. Therefore, it is concluded that the process proposed in this study is a feasible method and the modification factors obtained in this study are useful for local engineer in engineering applications.

scholarly journals Kajian Perbandingan Kinerja Struktur Dinding Geser Komposit Berdasarkan Tingkatan Gedung. (Hal. 20-29)

2019 ◽  
Vol 5 (3) ◽  
pp. 20
Author(s):  
Dimas EL Islamy ◽  
Erma Desmaliana ◽  
Nessa Valiantine Diredja
Keyword(s):  
Steel Plate ◽  
Pushover Analysis ◽  
Shear Wall ◽  
Steel Plate Shear Wall ◽  
Steel Shear Wall ◽  
Wall Shear ◽  
Immediate Occupancy ◽  
Strength And Stiffness ◽  
Spectrum Response ◽  
Composite Steel

ABSTRAKSalah satu metode untuk meminimalisir simpangan horizontal yang terjadi akibat gaya gempa pada struktur adalah dengan pemasangan dinding geser. Dinding geser mampu memberikan kekuatan dan kekakuan pada struktur gedung. Pada teknologi terkini, dinding geser komposit pelat baja mampu menggabungkan kelebihan dan mengkompensasi kekurangan dinding geser beton dan pelat baja.  Tujuan penelitian ini adalah untuk mengetahui efektifitas penggunaan dinding geser komposit terhadap tingkatan struktur gedung. Penelitian ini dilakukan pada tiga pemodelan struktur gedung dengan jumlah lantai yaitu 10 lantai, 20 lantai, dan 30 lantai dengan menggunakan metode respon spektrum dan analisis beban dorong. Hasil penelitian menunjukkan bahwa simpangan atap yang terjadi pada struktur dengan dinding geser lebih kecil dibandingkan struktur tanpa dinding geser. Berdasarkan analisis beban dorong, penggunaan dinding geser komposit pelat baja dengan tebal 110 mm untuk tiga pemodelan berada pada tingkatan yang sama yaitu IO (immediate Occupancy) yangmana kekuatan dan kekakuan pada gedung hampir sama dengan kondisi sebelum terjadi gempa.Kata kunci: dinding geser komposit pelat baja, respon spektrum, analisis beban dorong, simpangan horizontal ABSTRACTOne of the method to minimize the displacement of structure affected by earthquake is by using shear wall. Shear wall can influence the ductility and stiffness to the structure. On the most recent technology, composite steel plate shear wall can combining the advantages and compensate the disadvantages  of concrete and steel shear wall. This study was conducted by using three models buildings with 10 story, 20 story, and 30 story with spectrum response methods and pushover analysis. The result of this study shows that  drift’s roof on structure using shear wall is smaller than the structure without one. Based on pushover analysis, when structure using shear wall with thickness 110 mm for three models are the same level in immediate occupancy which strength and stiffness in buildings is almost the same as the condition before earthquake.Keywords: composite steel plate shear wall, respons spectrum, pushover analysis, displacement

Comparison of steel frames with RWS and WFP beam-to-column connections through seismic fragility analysis

2020 ◽  
pp. 136943322097728
Author(s):  
Haoran Yu ◽  
Weibin Li
Keyword(s):  
Limit State ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Fragility Analysis ◽  
Structural Safety ◽  
Seismic Fragility ◽  
Fe Modelling ◽  
Collapse Resistance ◽  
Seismic Collapse ◽  
Probabilistic Seismic Demand

Reduced web section (RWS) connections and welded flange plate (WFP) connections can both effectively improve the seismic performance of a structure by moving plastic hinges to a predetermined location away from the column face. In this paper, two kinds of steel frames—with RWS connections and WFP connections—as well as different frames with welded unreinforced flange connections were studied through seismic fragility analysis. The numerical simulation was conducted by using multiscale FE modelling. Based on the incremental dynamic analysis and pushover analysis methods, probabilistic seismic demand analysis and seismic capability analysis were carried out, respectively. Finally, combined with the above analysis results, probabilistic seismic fragility analysis was conducted on the frame models. The results showed that the RWS connection and WFP connection (without double plates) have little influence on reducing the maximum inter-storey drift ratio under earthquake action. RWS connections slightly reduce the seismic capability in non-collapse stages and improve the seismic collapse resistance of a structure, which exhibits good structural ductility. WFP connections can comprehensively improve the seismic capability of a structure, but the seismic collapse resistance is worse than that of RWS connections when the structure has a large number of storeys. The frame with WFP connections has a lower failure probability at every seismic limit state, while the frame with RWS connections sacrifices some of its structural safety in non-collapse stages to reduce the collapse probability.

Determination of seismic design forces by equivalent static load method

2003 ◽  
Vol 30 (2) ◽  
pp. 287-307 ◽  
Author(s):  
JagMohan Humar ◽  
Mohamed A Mahgoub
Keyword(s):  
Seismic Design ◽  
Static Load ◽  
Base Shear ◽  
Uniform Hazard Spectra ◽  
Uniform Hazard Spectrum ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Equivalent Static Load ◽  
Adjustment Factors ◽  
Mode Vibration

In the proposed 2005 edition of the National Building Code of Canada (NBCC), the seismic hazard will be represented by uniform hazard spectra corresponding to a 2% probability of being exceeded in 50 years. The seismic design base shear for use in an equivalent static load method of design will be obtained from the uniform hazard spectrum for the site corresponding to the first mode period of the building. Because this procedure ignores the effect of higher modes, the base shear so derived must be suitably adjusted. A procedure for deriving the base shear adjustment factors for different types of structural systems is described and the adjustment factor values proposed for the 2005 NBCC are presented. The adjusted base shear will be distributed across the height of the building in accordance with the provisions in the current version of the code. Since the code-specified distribution is primarily based on the first mode vibration shape, it leads to an overestimation of the overturning moments, which should therefore be suitably adjusted. Adjustment factors that must be applied to the overturning moments at the base and across the height are derived for different structural shapes, and the empirical values for use in the 2005 NBCC are presented.Key words: uniform hazard spectrum, seismic design base shear, equivalent static load procedure, higher mode effects, base shear adjustment factors, distribution of base shear, overturning moment adjustment factors.

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