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Frontiers of Structural and Civil Engineering 2020年第1期14卷 169-184页

作者： Elmira SHOUSHTARI msaiid saiidi Ahmad ITANI Mohamed AMOUSTAFA Department of Civil and Environmental Engineering University of NevadaReno NV 89557USA

This paper presents pretest analysis of a shake table test model of a 0.35-scale,two-span,steel plate girder bridge.The objective of pretest analysis was to obtain an insight on the seismic response of the bridge model during the shake table tests.The bridge included seat type abutments,full-depth precast deck panels,and a two-column bent in which columns were pinned to the footing and integral with superstructure.Six accelerated bridge construction connections were incorporated in the bridge model.An analytical model was developed in OpenSees and was subjected to ten input bi-directional earthquake motions including near-fault and far-field records.The overall seismic response of the bridge was satisfactory for all the earthquake records at 100%,150%,and 200%design level.All connections and capacity-protected components remained elastic,and the average ductility capacity surpassed the ductility demand even at 200%design level.Using experimental fragility curves developed for RC bridge columns,it was predicted that there was a probability of 45%that columns would undergo the imminent failure in the last run and a probability of 30%for their failure.

关键词： shake table test accelerated bridge construction steel girder bridge OpenSEES UHPC simple for dead continuous for live

Investigation of effect of near-fault motions on substandard bridge structures

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Earthquake Engineering and Engineering Vibration 2011年第1期10卷 1-11页

作者： Austin Brown M. Saiid saiidi Dynamic Certification Laboratories Department of Civil & Environmental Engineering

The objective of this study was to investigate the effects of near-fault ground motions on substandard bridge columns and piers. To accomplish these goals, several large scale reinforced concrete models were constructed and tested on a shake table using near- and far-field ground motion records. Because the input earthquakes for the test models had different characteristics, three different measures were used to evaluate the effect of the input earthquake. These measures are peak shake table acceleration, spectral acceleration at the fundamental period of the test specimens, and the specimen drift ratios. For each measure, force-displacement relationships, strains, curvatures, drift ratios, and visual damage were evaluated. Results showed that regardless of the measure of input or response, the near-fault record generally led to larger strains, curvatures, and drift ratios. Furthermore, residual displacements were small compared to those for columns meeting current seismic code requirements.

关键词： near-fault reinforced concrete bridge columns dynamic response

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Computational studies on the seismic response of the State Route 99 bridge in Seattle with SMA/ECC plastic hinges

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 149-164页

作者： Jiping GE M.Saiid saiidi Sebastian VARELA School of Urban Construction and Safety Engineering Shanghai Institute of TechnologyShanghai 201418China Department of Civil and Environmental Engineering University of NevadaRenoNV 89557USA Structural Engineering Group Freese and Nichols Inc.Fort WorthTX 76109USA

This paper reports a computational study on the seismic response of a three-span highway bridge system incorporating conventional and novel substructure details for improved seismic performance.The bridge has three continuous spans supported by two single-column piers and integral abutments founded on drilled shafts.It will be the first full-scale highway bridge to use superelastic shape memory alloy bars (SMA)and engineered cementitious composite (ECC)to mitigate column plastic hinge damage and minimize residual displacements after a strong earthquake. A three-dimensional computational model capturing the nonlinear constitutive response of the novel materials and the effects of dynamic soil-structure interaction was developed to assess the seismic response of the bridge in finite-element software OpenSees.Two versions of the same bridge were analyzed and compared,one with conventional cast-in-place reinforced concrete columns,and the other with top plastic hinges incorporating Nickel-Titanium (NiTi)SMA reinforcing bars and ECC.The novel SMA/ECC plastic hinges were found to substantially reduce damage and post-earthquake residual displacements in the bridge substructure,but led to larger maximum drifts relative to the bridge with conventional reinforced concrete plastic hinges.The analysis results suggested that the novel plastic hinges could lead to improved post-earthquake serviceability of bridges after intense earthquakes.

关键词： seismic design analytical simulation near-fault earthquakes shape memory alloy engineered cementitious composite self-centering

Residual drift spectra for RC bridge columns subjected to near-fault earthquakes

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Earthquake Engineering and Engineering Vibration 2021年第1期20卷 193-211页

作者： S.M.Seyed Ardakani M.Saiid saiidi Paul Somerville Department of Civil and Environmental Engineering Ohio Northern University525 S.Main St.AdaOH 45810USA Department of Civil and Environmental Engineering University of NevadaRenoMS 258RenoNV 89557USA AECOM Technology Corporation One California Plaza300 S Grand AvenueLos AngelesCA 90017USA

Permanent displacement of a bridge column can be directly measured during the inspection after near-fault earthquakes.However,the engineer needs to estimate the expected residual drift at the design stage to determine if the bridge seismic performance is satisfactory.The most direct method to estimate the residual displacement is nonlinear response history analysis,which is time consuming and cumbersome.Alternatively,an attractive but indirect method is generating estimated residual displacement spectra that depend on displacement ductility demand,column period,site conditions,and earthquake characteristics.Given the period and the expected displacement ductility demand for the column,the residual drift response spectra curves can be utilized to estimate the residual drift demand.Residual drift spectra that are applicable to RC bridge columns in different parts of the United States were developed based on nonlinear response history analyses using a comprehensive collection of recorded and synthetic near-fault ground motions and were linked to one-second spectral acceleration(S1)of the AASHTO maps.It was also found that the residual drift ratio is below one percent when S1 is less than 0.6 g.

关键词： near-fault earthquake reinforced concrete bridge column residual displacement

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Influence of earthquake ground motion incoherency on multi-support structures

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Earthquake Engineering and Engineering Vibration 2002年第2期1卷 167-180页

作者：杨庆山 M.Saiid saiidi 王航 Ahmad Itani School of Civil Engineering and Architecture Northern Jiaotong University.Beijing.100044.China. Department of Civil Engineering University of NevadaRenoNV89557USA Beijing General Municipal Engineering Design and Research Institute.China Department of Civil Engineering University of Nevada.RenoNV.89557USA

A linear response history analysis method is used to determine the influence of three factors:geometric incoherency,wave-passage,and local site characteristics on the response of lnulti-support structures subjected to differential ground motions.A one-span frame and a reduced model of a 24-span bridge,located in Las Vegas,Nevada are studied,in which the influence of each of the three factors and their combinations are analyzed.It is revealed that the incoherency of earthquake ground motion can have a dramatic influence on structural response by modifying the dynamics response to uniform excitation and inducing pseudo-static response,which does not exist in structures subjected to uniform excitation.The total response when all three sources of ground motion incoherency are included is generally larger than that of uniform excitation.

关键词： earthquake bridges ground motion incoherency wave passage local site characteristics multi-support structures

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公路桥的动力反应

世界地震工程 1982年第Z1期 21-25页

作者： Brucc Douglas Mehdi saiidi James Richardson 何度心

序言桥梁设计者在估计地震力在桥梁上的分布时所遇到的重要问题之一是如何处理土-结构的相互作用。最近在新西兰召开的讨论会指出,这个问题特别与桥梁结构有关,应更加注意。土-结构相互作用问题的重要性,业已

关键词：公路桥桥台中心线阻尼比桥面地震反应加速度记录基本振型振型位移动力反应动力响应

EXAMPLES OF RECENT ADVANCES IN SEISMIC STRUCTURAL TESTS

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EXAMPLES OF RECENT ADVANCES IN SEISMIC STRUCTURAL TESTS