scholarly journals FEMA P695 methodology for safety margin evaluation of steel moment resisting frames subjected to near-field and far-field records

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Mahdi Heshmati ◽  
Alireza Khatami ◽  
Hamzeh Shakib
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Near Field ◽  
Safety Margin ◽  
Far Field ◽  
Performance Factors ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Nonlinear Static ◽  
Special Moment Resisting Frame

AbstractThis study presents the impact of near-field and far-field earthquakes on the seismic design of Intermediate Moment Resisting Frame (IMRF) and Special Moment Resisting Frame (SMRF) structures through FEMA (Federal Emergency Management Agency) P695 methodology to highlight the importance of probabilistic collapse as well as seismic performance factors of these structures. The purpose of this study is to investigate the collapse performance of steel intermediate and special moment resisting frame systems as the most common structural systems in urban areas in order to assess the seismic performance factors used for the design using nonlinear static and dynamic analysis methods. In this regard, as the representatives of low-rise to high-rise buildings, archetypes with 5-, 10- and 15- story of intermediate and special moment resisting frames are designed and then the nonlinear models are developed in OpenSees software. Nonlinear static analyses are performed to assess the overstrength and ductility of these systems. The effects of near-field and far-field ground motions on these frames are investigated through incremental dynamic analysis. These analyses are performed with 22 far-field and 20 near-field ground motion records using FEMA P695 methodology. The results show that near-field earthquakes have serious impacts on the collapse probability of structures. The superiority of special moment resisting frame over intermediate moment resisting frame is quantified in terms of safety margin and median collapse capacity under both near-field and far-field earthquakes. Finally, the results indicate that the response modification factors introduced in seismic design code are acceptable for intermediate moment resisting frame and special moment resisting frame under far-field ground motions. However, in the near-field sites while SMRF system meets the requirements of FEMA P695 methodology, the IMRF system does not satisfy these criteria.

scholarly journals Characterizing Ground Motions that Collapse Steel Special Moment-Resisting Frames or Make Them Unrepairable

2015 ◽  
Vol 31 (2) ◽  
pp. 813-840 ◽  
Author(s):  
Anna H. Olsen ◽  
Thomas H. Heaton ◽  
John F. Hall
Keyword(s):  
Regression Models ◽  
Ground Motions ◽  
Spectral Acceleration ◽  
Ground Displacement ◽  
Intensity Measures ◽  
Moment Resisting Frame ◽  
Frame Buildings ◽  
Moment Resisting ◽  
Equivalent Frame ◽  
Special Moment Resisting Frame

This work applies 64,765 simulated seismic ground motions to four models each of 6- or 20-story, steel special moment-resisting frame buildings. We consider two vector intensity measures and categorize the building response as “collapsed,” “unrepairable,” or “repairable.” We then propose regression models to predict the building responses from the intensity measures. The best models for “collapse” or “unrepairable” use peak ground displacement and velocity as intensity measures, and the best models predicting peak interstory drift ratio, given that the frame model is “repairable,” use spectral acceleration and epsilon ( ∊) as intensity measures. The more flexible frame is always more likely than the stiffer frame to “collapse” or be “unrepairable.” A frame with fracture-prone welds is substantially more susceptible to “collapse” or “unrepairable” damage than the equivalent frame with sound welds. The 20-story frames with fracture-prone welds are more vulnerable to P-delta instability and have a much higher probability of collapse than do any of the 6-story frames.

scholarly journals On the Seismic Response of Protected and Unprotected Middle-Rise Steel Frames in Far-Field and Near-Field Areas

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Dora Foti
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
Near Field ◽  
Shaking Table ◽  
Far Field ◽  
Base Shear ◽  
Friction Dampers ◽  
Steel Moment Resisting Frames ◽  
Damage Indices ◽  
Moment Resisting

Several steel moment-resisting framed buildings were seriously damaged during Northridge (1994); Kobe (1995); Kocaeli, Turkey (1999), earthquakes. Indeed, for all these cases, the earthquake source was located under the urban area and most victims were in near-field areas. In fact near-field ground motions show velocity and displacement peaks higher than far-field ones. Therefore, the importance of considering near-field ground motion effects in the seismic design of structures is clear. This study analyzes the seismic response of five-story steel moment-resisting frames subjected to Loma Prieta (1989) earthquake—Gilroy (far-field) register and Santa Cruz (near-field) register. The design of the frames verifies all the resistance and stability Eurocodes’ requirements and the first mode has been determined from previous shaking-table tests. In the frames two diagonal braces are installed in different positions. Therefore, ten cases with different periods are considered. Also, friction dampers are installed in substitution of the braces. The behaviour of the braced models under the far-field and the near-field records is analysed. The responses of the aforementioned frames equipped with friction dampers and subjected to the same ground motions are discussed. The maximum response of the examined model structures with and without passive dampers is analysed in terms of damage indices, acceleration amplification, base shear, and interstory drifts.

Seismic performance of reinforced concrete ductile moment-resisting frame buildings located in different seismic regions

1992 ◽  
Vol 19 (4) ◽  
pp. 688-710 ◽  
Author(s):  
T. J. Zhu ◽  
W. K. Tso ◽  
A. C. Heidebrecht
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Ground Motions ◽  
Base Shear ◽  
High Rise ◽  
Moment Resisting Frame ◽  
Short Period ◽  
Frame Buildings ◽  
Moment Resisting ◽  
Seismic Regions

Seismic areas in Canada are classified into three categories for three different combinations of acceleration and velocity seismic zones (Za < Zv, Za = Zv, and Za > Zv), and ground motions in different zonal combination areas are expected to have different frequency characteristics. The National Building Code of Canada specifies different levels of seismic design base shear for short-period buildings located in areas with different zonal combinations. The specification of seismic design base shear for long-period buildings is directly tied to zonal velocity, irrespective of seismic zonal combination. This paper evaluates the seismic performance of both high-rise long-period and low rise short-period reinforced concrete ductile moment-resisting frame buildings located in seismic regions having Za < Zv, Za = Zv, and Za > Zv. Two frame buildings have 10 and 18 storeys were used as structural models for high-rise buildings, while a set of four-storey buildings were used to represent low-rise buildings. All buildings were designed to the current Canadian seismic provisions and concrete material code. Three groups of earthquake records were selected as representative ground motions in the three zonal combination regions. The inelastic responses of the designed buildings to the three groups of ground motions were analyzed statistically. The results indicate that the distribution of inelastic deformations is significantly different for high-rise frame buildings situated in seismic regions with Za < Zv, Za = Zv, and Za > Zv. Inelastic deformation is concentrated in the lower storeys for high-rise buildings located in Za < Zv areas, whereas significant inelastic deformation can develop in the upper storeys for high-rise buildings situated in Za > Zv regions. The use of three different levels of seismic design base shear for short-period structures improves the consistency of ductility demands on low-rise buildings situated in the three different zonal combination regions. Despite the use of appropriate design base shears for different seismic regions, the ductility demands for these low-rise buildings are relatively high. To avoid excessive ductility demands, it is suggested that the seismic strengths for low-rise short-period buildings should not be significantly reduced from their elastic design base shears. Key words: earthquake, ground motion, seismic, design, reinforced concrete, frame buildings, beams, columns, ductility.

scholarly journals Kajian Perilaku Struktur Portal Beton Bertulang Tipe SRPMK dan Tipe SRPMM

2018 ◽  
Vol 1 (3) ◽  
Author(s):  
Nur Laeli Hajati ◽  
Rizki Noviansyah
Keyword(s):  
Seismic Design ◽  
Structural Systems ◽  
Final Project ◽  
Moment Resisting Frame ◽  
Performance Point ◽  
Earthquake Resistant ◽  
Moment Resisting ◽  
Frame System ◽  
Special Moment Resisting Frame ◽  
The City

ABSTRACTMoment Resisting Frame System (SRPM) is one of the earthquake resistant structural systems that is often used in Indonesia. SRPM is classified into three types are Ordinary Moment Resisting Frame System (SRPMB), Intermediate Moment Resisting Frame System (SRPMM), and Special Moment Resisting Frame System (SRPMK). In this final project, the structure of the building is modeled with SRPMM and SRPMK in areas with high seismicity (Seismic Design Category D) in the city of Yogyakarta, then compared the behavior of the structure between the two models. The result of this research is SRPMM which its purpose for medium earthquake area, can still give good performance which is indicated by fulfillment of design requirement, performance when performance point is in Immadiate Occupancy condition up to Life Safe, and give good ductility value when Collapse occurred.Keywords: intermediate moment resisting frame system, special moment resisting frame system, performance point, ductilityABSTRAKSistem Rangka Pemikul Momen (SRPM) adalah salah satu sistem struktur penahan gempa yang sering digunakan di Indonesia. SRPM dibagi menjadi tiga jenis yaitu Sistem Rangka Pemikul Momen Biasa (SRPMB), Sistem Rangka Pemikul Momen Menengah (SRPMM), dan Sistem Rangka Pemikul Momen Khusus (SRPMK). Dalam tugas akhir ini struktur gedung dimodelkan dengan SRPMM dan SRPMK pada wilayah dengan tingkat kegempaan tinggi (Kategori Desain Seismik D) dikota Yogyakarta, kemudian dibandingkan perilaku struktur antara kedua model tersebut. Hasil dari penelitian ini adalah SRPMM yang peruntukannya untuk wilayah gempa sedang, tetap dapat memberikan kinerja cukup baik yang ditunjukkan dengan terpenuhinya persyaratan-persyaratan desain, kinerja pada saat performance point berada pada kondisi Immadiate Occupancy sampai dengan Life Safe, serta memberikan nilai daktilitas yang baik ketika terjadi keruntuhan.Kata kunci: SRPMM, SRPMK, performance point, daktilitas.

Evaluation of the MPA Procedure for Estimating Seismic Demands: RC-SMRF Buildings

2008 ◽  
Vol 24 (4) ◽  
pp. 827-845 ◽  
Author(s):  
Hugo Bobadilla ◽  
Anil K. Chopra
Keyword(s):  
Ground Motions ◽  
Pushover Analysis ◽  
Cyclic Behavior ◽  
Hysteretic Model ◽  
Practical Application ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Special Moment Resisting Frame

The modal pushover analysis (MPA) procedure is extended for analysis of reinforced concrete special moment resisting frame (RC-SMRF) buildings, after demonstrating that the theory, assumptions, and approximations underlying this procedure are valid for such systems. The principal extension of the procedure is in the hysteretic model for modal SDF systems, chosen as the peak-oriented model to represent the global monotonic and cyclic behavior of such buildings, characterized by deterioration of stiffness and strength under cyclic deformation. The median seismic demands for 4-, 8-, 12-, and 20-story RC-SMRF buildings—designed to comply with current codes—due to an ensemble of 78 ground motions scaled to four intensity levels were computed by MPA and nonlinear RHA, and compared. It is demonstrated that, even for the most intense ground motions that deform the buildings far into the inelastic range, the MPA procedure demonstrates an adequate degree of accuracy that should make it useful for practical application in estimating seismic demands for RC-SMRF buildings. In contrast the FEMA-356 force distributions are inadequate in estimating seismic demands for the 8-, 12-, and 20-story buildings at all excitation intensities, from the weakest that causes response essentially within the linearly elastic range, to the strongest that drives the buildings far into the inelastic range.

scholarly journals Evaluation of Modified Fish-Bone Model for Estimating Seismic Demands of Irregular MRF Structures

2018 ◽  
Author(s):  
Amin Haghighat ◽  
Ashkan Sharifi
Keyword(s):  
Ground Motions ◽  
Fish Bone ◽  
Seismic Demands ◽  
Error Measure ◽  
Ductility Demand ◽  
Earthquake Records ◽  
Moment Resisting Frame ◽  
Different Types ◽  
Story Drift ◽  
Moment Resisting

This paper evaluates the accuracy of the Modified Fish-Bone (MFB) model for estimating the maximum inter-story drift ratio of irregular moment resisting frame (MRF) structures. To make this model applicable to irregular MRF structures, some modifications are made to the MFB formula. In order to evaluate the accuracy of the MFB model, several irregular frames with different types of irregularities are considered when subjected to different ground motions with different intensities. A local and a global error measure are defined and they are calculated for different frame models subjected to different earthquake records. The effects of different irregularities, ductility demand and frame height on the accuracy of the MFB model are investigated. Based on the results obtained from this evaluation, two simple and effective approaches are suggested to improve the MFB models.

scholarly journals Seismic Fragility Analysis of Mid-Story Isolation Buildings

2021 ◽  
Keyword(s):  
Fragility Curves ◽  
Ground Motions ◽  
Near Field ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Plastic State ◽  
Far Field ◽  
Analysis Method ◽  
Isolation System ◽  
Isolation Layer

Abstract. Seismic fragility analysis is essential for seismic risk assessment of structures. This study focuses on the damage probability assessment of the mid-story isolation buildings with different locations of the isolation system. To this end, the performance-based fragility analysis method of the mid-story isolation system is proposed, adopting the maximum story drifts of structures above and below the isolation layer and displacement of the isolation layer as performance indicators. Then, the entire process of the mid-story isolation system, from the initial elastic state to the elastic-plastic state, then to the limit state, is simulated on the basis of the incremental dynamic analysis method. Seismic fragility curves are obtained for mid-story isolation buildings with different locations of the isolation layer, each with fragility curves for near-field and far-field ground motions, respectively. The results indicate that the seismic fragility probability subjected to the near-field ground motions is much greater than those subjected to the far-field ground motions. In addition, with the increase of the location of the isolation layer, the dominant components for the failure of mid-story isolated structures change from superstructure and isolation system to substructure and isolation system.

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