scholarly journals Extension of The Improved Upper-Bound Pushover Analysis For Seismic Assessment of Steel Moment Resisting Frames With Setbacks

Author(s):  
Abdallah Yacine Rahmani ◽  
Mohamed Badaoui ◽  
Nouredine Bourahla ◽  
Rita Bento

Abstract Pushover analysis technique is a key tool for the performance-based seismic design that has been largely adopted in the new generation of seismic codes. Therefore, more precise and reliable performance predictions are highly demanded. Improved upper-bound (IUB) pushover analysis is one of the advanced nonlinear static procedures (NSPs) that has been recently developed. This procedure estimates adequately the response of regular and tall buildings. In this study, IUB is extended to assess the seismic response of irregular buildings with setbacks. To this end, an adjustment of the IUB lateral load distribution is implemented by integrating a third mode of vibration to control the response of these complex buildings. Fifteen multi-storey steel frames with different types of setbacks including a reference structure are used to test the accuracy of the proposed procedure by comparing its results to those from other NSPs and the nonlinear time history analysis (NLHA). The findings show the superior capacity of the extended IUB in predicting the seismic response of buildings with different levels and types of setbacks.

2018 ◽  
Vol 162 ◽  
pp. 04019 ◽  
Author(s):  
Sardasht Sardar ◽  
Ako Hama

Numerous recent studies have assessed the effect of P-Delta on the structures. This paper investigates the effect of P-Delta in seismic response of structures with different heights. For indicating the effect of P-Delta, nonlinear static analysis (pushover analysis) and nonlinear dynamic analysis (Time history analysis) were conducted by using finite element software. The results showing that the P-Delta has a significant impact on the structural behavior mainly on the peak amplitude of building when the height of the structures increased. In addition, comparison has been made between concrete and steel structure.


2013 ◽  
Vol 405-408 ◽  
pp. 1674-1677
Author(s):  
Bo Yu ◽  
Di Liu ◽  
Lu Feng Yang

Peak displacement is one of the most important parameters for the performance based seismic design of bridge structure, while the peak displacement is often significantly impacted by the P-Δ effect. In this study, the influence of the P-Δ effect on the statistics of peak displacement of bridge structure was quantificationally investigated based on a series of nonlinear time-history analysis. The bridge structure was idealized as the single degree of freedom (SDOF) system and the hysteretic behaviour was represented by the improved Bouc-Wen model. The statistic analysis was implemented based on the inelastic dynamic responses of the SDOF system under 69 selected earthquake records. The results show that the P-Δ effect has significant impact on the mean and dispersion of peak displacement of bridge structures, especially if the normalized yield strength and the natural vibration period are small.


2009 ◽  
Vol 25 (3) ◽  
pp. 583-605 ◽  
Author(s):  
Wei Chiang Pang ◽  
David V. Rosowsky

This paper presents a direct displacement design (DDD) procedure that can be used for seismic design of multistory wood-framed structures. The proposed procedure is applicable to any pure shear deforming system. The design procedure is a promising design tool for performance-based seismic design since it allows consideration of multiple performance objectives (e.g., damage limitation, safety requirements) without requiring the engineer to perform a complex finite element or nonlinear time-history analysis of the complete structure. A simple procedure based on normalized modal analysis is used to convert the code-specified acceleration response spectrum into a set of interstory drift spectra. These spectra can be used to determine the minimum stiffness required for each floor based on the drift limit requirements. Specific shear walls can then be directly selected from a database of backbone curves. The procedure is illustrated on the design of two three-story ATC-63 archetype buildings, and the results are validated using nonlinear time-history analysis.


2011 ◽  
Vol 243-249 ◽  
pp. 3889-3892 ◽  
Author(s):  
Tian Li Wang ◽  
Qing Ning Li ◽  
Hai Jun Yin

In order to analyze seismic response of the curved ramp bridge, this paper selected a single curved ramp bridge in a multilevel junction system as its research object. Considering the piers, beams, bearings and expansion joints simulation, it respectively built the calculating models for a curved ramp bridge and a corresponding linear one. Using nonlinear time history analysis, the paper contrasts seismic response of the curved ramp bridge with that of the linear one in several different seismic inputs. Finally the seismic response characteristic of a curved ramp bridge is put forward.


2013 ◽  
Vol 671-674 ◽  
pp. 782-785
Author(s):  
Bin He ◽  
Jin Lai Pang ◽  
Cheng Qing Liu

For the lack of research in the longitudinal frame of prefabricated structure for its weak lateral stiffness, pushover analysis is conducted to evaluate the seismic performance of a fabricated concrete frame. Based on case study, the strengthening strategies with viscous dampers are analyzed. In view of the undesirable drift distribution and failure mode in the existing building, it is believed that arrangement of dampers should be designed to attain a uniform drift distribution. Based on the nonlinear time history analysis method, the strategy of damper allocation in vertical direction of the structure is investigated .Results indicate that a proper design might be attained based on the property of existing system, leading to a uniform drift distribution and better seismic performance.


2021 ◽  
Vol 6 (2) ◽  
pp. 98
Author(s):  
Ilham Ilham

ABSTRAKPenggunaan bresing tahan tekuk dapat menjadi solusi atas kebutuhan struktur tahan gempa di Indonesia. Disipasi energi pada elemen bresing tahan tekuk dilakukan melalui kinerja plastifikasi bagian inti bresing akibat beban tarik dan tekan. Penelitian ini berisi kajian kinerja dari bangunan rangka baja beraturan dengan bresing tahan tekuk (BRB) dengan variasi level ketinggian lantai yaitu 3 lantai, 8 lantai dan 15 lantai. Analisis struktur 3D dilakukan dengan dua prosedur analisis yaitu modal pushover dan nonlinear time history pada program ETABS. Hasil analisis menunjukkan bahwa pemilihan elemen BRB sangat mempengaruhi kinerja struktur, yang terlihat dari pola drift yang terjadi. Untuk struktur beraturan dengan berbagai ketinggian, tingkat kinerja struktur dengan BRB cukup baik, yaitu Immediate Occupancy (IO) akibat beban gempa rencana. Plastifikasi hanya terjadi pada BRB, dan kelelehan pada balok mulai terbentuk sampai mekanisme keruntuhan terjadi. Hasil modal pushover dengan nonlinear time history pada bangunan 15 lantai yang cukup mirip menunjukkan bahwa modal pushover dapat digunakan untuk memprediksi kinerja struktur BRB yang beraturan.Kata kunci: kinerja struktur, bresing tahan tekuk, immediate occupancy, modal pushover, nonlinear time history ABSTRACTBuckling restrained braces (BRB) can be an alternative solution for earthquake resistant steel structure in Indonesia. The energy dissipation for buckling restrained elements is conducted through yielding of the core due to tension or compression forces. This study presents an evaluation of the structural performance of steel structures with BRB varying in heights, 3-story, 8-story and 15-story. The 3D structural analysis was carried out with ETABS software using 2 methods, Modal Pushover and Nonlinear Time History. The results shows that the selection of BRB elements greatly affected the structural performance, showed by the drift pattern. For regular structures with variation in heights, structures with BRB behaved satisfactory under the design load with the performance level of Immediate Occupancy (IO). Yielding was limited to BRB members, and afterwards the yielding occurred on beams until collapse. The results of modal pushover and time history analysis for 15-story structure are similar, thus modal pushover can be used to predict the performance of regular structural system with BRB.Keywords: structural performance, buckling restrained brace, immediate occupancy, modal pushover analysis, nonlinear time history analysis


Author(s):  
Gareth J. Morris ◽  
Andrew J. Thompson ◽  
James N. Dismuke ◽  
Brendon A. Bradley

Nonlinear response history analysis (NLRHA), or so-called “nonlinear time history analysis”, is adopted by practicing structural engineers who implement performance-based seismic design and/or assessment procedures. One important aspect in obtaining reliable output from the NLRHA procedure is the input ground motion records. The underlying intention of ground motion selection and amplitude-scaling procedures is to ensure the input for NLRHA is representative of the ground shaking hazard level, for a given site and structure. The purpose of this paper is to highlight the salient limitations of the ground motion selection and scaling requirements in Sections 5.5 and 6.4 of the New Zealand (NZ) loading standard NZS 1170.5 (2004). From a NZ regulatory perspective; there is no specific framework for seismic hazard analysis and ground motion selection (thus self-regulation is the current norm). In contrast, NZS 1170.5 contains many prescriptive requirements for scaling and applying records which are challenging to satisfy in practice. Also discussed within, there are implications for more modern guidance documents in NZ, such as the 2017 “Assessment Guidelines” for existing buildings, which cite NZS 1170.5, a standard which is at least 16 years old (draft issued in 2002). To emphasize the above issues with NZS 1170.5, this paper presents a summary of the more contemporary approaches in the US standards ASCE 7-16 (new buildings) and ASCE 41-17 (existing buildings), along with some examples of the more stringent US requirements for Tall Buildings.


Author(s):  
Kanthi Srirengan ◽  
Partha Chakrabarti ◽  
Rupak Ghosh

Two novel methods namely the Dominant Modes method and the All Modes method to predict the seismic-pushover load for the jacket-type structures are presented. Both of these methods are based on the linear superposition of the modal reactions. As a preliminary evaluation, the linear elastic response of a jacket structure subjected to seismic-pushover loads is compared with that obtained from the response spectrum analysis. Furthermore, the nonlinear inelastic behavior obtained from the seismic-pushover analysis is compared with that obtained from the nonlinear time-history analysis, for a portal frame subjected to El Centro earthquake motion. When more than one mode is dominant in an excitation direction, both the linear elastic and the nonlinear inelastic responses obtained using the loads generated from the All Modes method are representative of the reference solutions.


Author(s):  
Paata Rekvava

A method is presented for the evaluation of the seismic reliability function of realistic structural systems. The method is based on a preliminary simulation involving three-dimensional nonlinear time history analysis of the soil-interface-building system. The design procedure is performed to establish the probabilistic characterization of the demands on the structure, followed by the solution of system reliability problem with correlated demands and capacities. The Structural behavior is evaluated by means of the methodology of Performance-Based Seismic Design (PBSD). This study has taken into account the stochastic nature of the spatial ground motion in Tbilisi region. The method is demonstrated with an application to a 3D RC Buildings subjected to seismic excitation for the specified hazard at the site. The developed method and obtained results can be used in seismic risk study for new buildings of examined type under design, as well as for existing RC buildings of old generation for future seismic activity.


2013 ◽  
Vol 40 (7) ◽  
pp. 644-654 ◽  
Author(s):  
Nikolas Kyriakopoulos ◽  
Constantin Christopoulos

The seismic performance of a typical 1960s Type 2 construction steel moment-resisting frame hospital structure designed only for lateral wind loads was investigated. The structure was found to have a soft first storey and displayed large P–Δ sensitivities. An experimental program determined that the connections had considerable inherent ductility and were stable up to 2.0% interstorey drift, despite not having been designed for a ductile cyclic response. The structure was numerically modelled using advanced strength degradation considerations. A nonlinear time-history analysis was conducted using Montreal and Vancouver ground motions and the structure’s performance was found to be inadequate under the considered design hazard levels. Retrofits were proposed for the two orthogonal frames using a performance-based approach and supplemental damping, rather than local interventions to increase the ductility of these connections, and the performance of the final retrofit designs were investigated numerically to confirm that the desired performance levels were achieved.


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