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A new methodology for energy-based seismic design of steel moment frames 被引量:2
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作者 Mebrahtom Gebrekirstos Mezgebo Eric M. Lui 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第1期131-152,共22页
A procedure is proposed whereby input and hysteretic energy spectra developed for single-degree-of-freedom (SDOF) systems are applied to multi-degree-of-freedom (MDOF) steel moment resisting frames. The proposed p... A procedure is proposed whereby input and hysteretic energy spectra developed for single-degree-of-freedom (SDOF) systems are applied to multi-degree-of-freedom (MDOF) steel moment resisting frames. The proposed procedure is verified using four frames, viz., frame with three-, five-, seven- and nine-stories, each of which is subjected to the fault- normal and fault-parallel components of three actual earthquakes. A very good estimate for the three- and five-story frames, and a reasonably acceptable estimate for the seven-, and nine-story frames, have been obtained. A method for distributing the hysteretic energy over the frame height is also proposed. This distribution scheme allows for the determination of the energy demand component of a proposed energy-based seismic design (EBSD) procedure for each story. To address the capacity component of EBSD, a story-wise optimization design procedure is developed by utilizing the energy dissipating capacity from plastic hinge formation/rotation for these moment frames. The proposed EBSD procedure is demonstrated in the design of a three-story one-bay steel moment frame. 展开更多
关键词 energy-based seismic design hysteretic energy distribution MDOF systems steel moment frames story-wise optimization design
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Effectiveness of two conventional methods for seismic retrofit of steel and RC moment resisting frames based on damage control criteria 被引量:3
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作者 Seyed Bahram Beheshti Aval Hamed Sadegh Kouhestani Lida Mottaghi 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第3期537-555,共19页
This study investigates the efficiency of two types of rehabilitation methods based on economic justification that can lead to logical decision making between the retrofitting schemes. Among various rehabilitation met... This study investigates the efficiency of two types of rehabilitation methods based on economic justification that can lead to logical decision making between the retrofitting schemes. Among various rehabilitation methods, concentric chevron bracing(CCB) and cylindrical friction damper(CFD) were selected. The performance assessment procedure of the frames is divided into two distinct phases. First, the limit state probabilities of the structures before and after rehabilitation are investigated. In the second phase, the seismic risk of structures in terms of life safety and financial losses(decision variables) using the recently published FEMA P58 methodology is evaluated. The results show that the proposed retrofitting methods improve the serviceability and life safety performance levels of steel and RC structures at different rates when subjected to earthquake loads. Moreover, these procedures reveal that financial losses are greatly decreased, and were more tangible by the application of CFD rather than using CCB. Although using both retrofitting methods reduced damage state probabilities, incorporation of a site-specific seismic hazard curve to evaluate mean annual occurrence frequency at the collapse prevention limit state caused unexpected results to be obtained. Contrary to CFD, the collapse probability of the structures retrofitted with CCB increased when compared with the primary structures. 展开更多
关键词 steel and RC moment resisting frames seismic retrofitting collapse probability concentric chevron bracing(CCB) cylindrical friction damper (CFD)
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Optimal seismic retrofit model for steel moment resisting frames with brittle connections 被引量:1
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作者 Hyo Seon Park Se Woon Choi Byung Kwan Oh 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第4期835-847,共13页
Based on performance-based seismic engineering, this paper proposes an optimal seismic retrofit model for steel moment resisting frames(SMRFs) to generate a retrofit scheme at minimal cost. To satisfy the acceptance... Based on performance-based seismic engineering, this paper proposes an optimal seismic retrofit model for steel moment resisting frames(SMRFs) to generate a retrofit scheme at minimal cost. To satisfy the acceptance criteria for the Basic Safety Objective(BSO) specified in FEMA 356, the minimum number of upgraded connections and their locations in an SMRF with brittle connections are determined by evolutionary computation. The performance of the proposed optimal retrofitting model is evaluated on the basis of the energy dissipation capacities, peak roof drift ratios, and maximum interstory drift ratios of structures before and after retrofitting. In addition, a retrofit efficiency index, which is defined as the ratio of the increment in seismic performance to the required retrofitting cost, is proposed to examine the efficiencies of the retrofit schemes derived from the model. The optimal seismic retrofit model is applied to the SAC benchmark examples for threestory and nine-story SMRFs with brittle connections. Using the retrofit efficiency index proposed in this study, the optimal retrofit schemes obtained from the model are found to be efficient for both examples in terms of energy dissipation capacity, roof drift ratio, and maximum inter-story drift ratio. 展开更多
关键词 steel moment resisting frame performance-based seismic engineering optimal seismic retrofit EVOLUTIONARYCOMPUTATION
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Structural failure analysis with CMS-based ground motion selection using innovative cost function and weight factors
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作者 Delbaz Samadian Imrose B.Muhit Nashwan Dawood 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第4期899-918,共20页
The selection and scaling of ground motion records is considered a primary and essential task in performing structural analysis and design.Conventional methods involve using ground motion models and a conditional spec... The selection and scaling of ground motion records is considered a primary and essential task in performing structural analysis and design.Conventional methods involve using ground motion models and a conditional spectrum to select ground motion records based on the target spectrum.This research demonstrates the influence of adopting different weighted factors for various period ranges during matching selected ground motions with the target hazard spectrum.The event data from the Next Generation Attenuation West 2(NGA-West 2)database is used as the basis for ground motion selection,and hazard de-aggregation is conducted to estimate the event parameters of interest,which are then used to construct the target intensity measure(IM).The target IMs are then used to select ground motion records with different weighted vector-valued objective functions.The weights are altered to account for the relative importance of IM in accordance with the structural analysis application of steel moment resisting frame(SMRF)buildings.Instead of an ordinary objective function for the matching spectrum,a novel model is introduced and compared with the conventional cost function.The results indicate that when applying the new cost function for ground motion selection,it places higher demands on structures compared to the conventional cost function.Moreover,submitting more weights to the first-mode period of structures increases engineering demand parameters.Findings demonstrate that weight factors allocated to different period ranges can successfully account for period elongation and higher mode effects. 展开更多
关键词 weighted objective function ground motion selection steel moment resisting frame hazard analysis
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Numerical simulation of the seismic behavior of self-centering steel beam-column connections with bottom flange friction devices 被引量:3
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作者 Guo Tong Song Lianglong Zhang Guodong 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2011年第2期229-238,共10页
A new type of steel moment resisting frame with bottom flange friction devices (BFFDs) has been developed to provide self-centering capacity and energy dissipation, and to reduce permanent deformations under earthqu... A new type of steel moment resisting frame with bottom flange friction devices (BFFDs) has been developed to provide self-centering capacity and energy dissipation, and to reduce permanent deformations under earthquakes. This paper presents a numerical simulation of self-centering beam-column connections with BFFDs, in which the gap opening/closing at the beam-column interfaces is simulated by using pairs of zero-length elements with compression-only material properties, and the energy dissipation due to friction is simulated by using truss elements with specified hysteretic behavior. In particular, the effect of the friction bolt bearing against the slotted plate in the BFFDs was modeled, so that the increase in lateral force and the loss of friction force due to the bolt bearing could be taken into account. Parallel elastic-perfectly plastic gap (ElasticPPGap) materials in the Open System for Earthquake Engineering Simulation (OpenSees) were used with predefined gaps to specify the sequence that each bolt went into the bearing and the corresponding increase in bending stiffness. The MinMax material in OpenSees is used to specify the minimum and maximum values of strains of the ElasticPPGap materials. To consider the loss of friction force due to bok bearing, a number of parallel hysteretic materials were used, and the failure of these materials in sequence simulated the gradual loss of friction force. Analysis results obtained by using the proposed numerical model are discussed and compared with the test results under cyclic loadings and the seismic loading, respectively. 展开更多
关键词 numerical simulation post tensioned SELF-CENTERING moment resisting steel frame bottom flange frictiondevice bolt bearing
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Selection and modification of ground motion records using Newmark-Hall spectrum as target spectrum for long-period structures 被引量:1
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作者 Fu Jianyu Wang Dongsheng +1 位作者 Zhang Rui Chen Xiaoyu 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第1期117-134,共18页
Input ground motions have significant impacts on the uncertainty of structural responses in time-history analysis.In this study,records were selected and scaled for the evaluation of mean structural responses accordin... Input ground motions have significant impacts on the uncertainty of structural responses in time-history analysis.In this study,records were selected and scaled for the evaluation of mean structural responses according to the target spectrum.The Newmark-Hall spectrum is closely related to seismic response of short,medium and long-period structures,so it was taken as the target spectrum here.The nonlinear time-history analyses of 9-story and 20-story steel moment-resisting frame structures were carried out as examples.They represent medium and long-period buildings,respectively.Three target spectra with risk of 50%,10%and 2%probabilities for exceedance in 50 years were calculated by the average Newmark-Hall spectrum method for three ground motion sets developed in the SAC Steel Project.The predicted structural mean responses of these Newmark-Hall spectra were compared with those calculated by the average spectral acceleration method for the same record set.It is found that both methods have similar accuracy for estimating the structural mean response.However,the method proposed herein is more effective in reducing the variability of the structural responses.Also,the proposed method is more advantageous for the time-history analysis of long-period structures or structures with more severe nonlinear responses under strong seismic excitations. 展开更多
关键词 time-history analysis selection and modification of ground motions target spectrum Newmark-Hall spectrum steel moment resisting frame structure
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Meta databases of steel frame buildings for surrogate modelling and machine learning-based feature importance analysis
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作者 Delbaz Samadian Imrose B.Muhit +1 位作者 Annalisa Occhipinti Nashwan Dawood 《Resilient Cities and Structures》 2024年第1期20-43,共24页
Traditionally,nonlinear time history analysis(NLTHA)is used to assess the performance of structures under fu-ture hazards which is necessary to develop effective disaster risk management strategies.However,this method... Traditionally,nonlinear time history analysis(NLTHA)is used to assess the performance of structures under fu-ture hazards which is necessary to develop effective disaster risk management strategies.However,this method is computationally intensive and not suitable for analyzing a large number of structures on a city-wide scale.Surrogate models offer an efficient and reliable alternative and facilitate evaluating the performance of multiple structures under different hazard scenarios.However,creating a comprehensive database for surrogate mod-elling at the city level presents challenges.To overcome this,the present study proposes meta databases and a general framework for surrogate modelling of steel structures.The dataset includes 30,000 steel moment-resisting frame buildings,representing low-rise,mid-rise and high-rise buildings,with criteria for connections,beams,and columns.Pushover analysis is performed and structural parameters are extracted,and finally,incorporating two different machine learning algorithms,random forest and Shapley additive explanations,sensitivity and explain-ability analyses of the structural parameters are performed to identify the most significant factors in designing steel moment resisting frames.The framework and databases can be used as a validated source of surrogate modelling of steel frame structures in order for disaster risk management. 展开更多
关键词 Surrogate models Meta database Pushover analysis steel moment resisting frames Sensitivity and explainability analyses Machine learning
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