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Seismic spatial effects on long-span bridge response in nonstationary inhomogeneous random fields

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Earthquake Engineering and Engineering Vibration 2005年第1期4卷 75-82页

作者：林家浩张亚辉赵岩 State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116023 ChinaProfessor Chongqing Communications Research & Design Institute Chongqing 400067 ChinaAssociateProfessor State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116023 China Chongqing Communications Research & Design Institute Chongqing 400067 China Post-doctor

The long-span bridge response to nonstationary multiple seismic random excitations is investigated using the PEM (pseudo excitation method). This method transforms the nonstationary random response analysis into ordinary direct dynamic analysis, and therefore, the analysis can be solved conveniently using the Newmark, Wilson-9 schemes or the precise integration method. Numerical results of the seismic response for an actual long-span bridge using the proposed PEM are given and compared with the results based on the conventional stationary analysis. From the numerical comparisons, it was found that both the seismic spatial effect and the nonstationary effect are quite important, and that both stationary and nonstationary seismic analysis should pay special attention to the wave passage effect.

关键词： earthquake nonstationary random vibration multiple excitation long-span bridge

Experimental study on flutter stability of a long-span bridge subject to wind-rain actions

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Science China(Technological Sciences) 2013年第8期56卷 2089-2098页

作者： XIN DaBo LI Hui OU JinPing WANG Liang CHEN DongYing School of Civil Engineering Harbin Institute of Technology School of Civil & Hydraulic Engineering Dalian University of Technology School of Construction Engineering Heilongjiang Institute of Technology

Based on the free vibration test method for extracting flutter derivatives,an experiment on flutter stability of a long-span bridge under simultaneous actions of wind and rain was carried out in a wind tunnel.A separated twin-box girder section model was employed as the *** flutter derivatives and critical flutter wind speed of this girder subject to both wind and rain(with various rainfall intensities,wind speeds and attack angles)were obtained,then the flutter stability of the bridge influenced by rainfall was *** results showed that the flutter derivatives of this bridge depend on the angles of attack of wind flow in the wind and rain ***,rainfall has great effect on three flutter derivatives(H2*,H4* and A4*)and has less effect on other three flutter derivatives(H1*,H3* and A3*).With the increasing rainfall density,the critical flutter velocity first increases and then *** density of rainfall has the effect of increasing mass,stiffness and damping on bridge decks,and higher density of rainfall has the effect of random inhomogeneous impact on bridge decks.

关键词： flutter long-span bridge simultaneous actions of wind and rain wind tunnel test

longitudinal force in continuously welded rail on long-span tied arch continuous bridge carrying multiple tracks

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Journal of Central South University 2015年第5期22卷 2001-2006页

作者：闫斌戴公连郭文华徐庆元 School of Civil Engineering Central South University National Engineering Laboratory for High Speed Railway Construction (Central South University)

Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube(CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a(77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail(CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind *** show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.

关键词： railroad bridge long-span bridge tied arch continuous beam continuously welded rail track-bridge interaction

Some important aspects of wind-resistant studies on long-span bridges

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Science China(Technological Sciences) 2012年第12期55卷 3334-3343页

作者： GU Ming State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

In recent years many long-span bridges have been or are being constructed in the world, especially in China. Wind loads and responses are the key factors for their structural design. This paper introduces some important achievements of wind-resistant studies of the author's research team on long-span bridges. First, new concepts and identification methods of aerodynamic derivatives and aerodynamic admittances were proposed. Then mechanical and aerodynamic control strategies and methods of wind-induced vibrations of long-span bridges were the great concerned problems, and valuable achievements were presented. Especially, great efforts which have been theoretically and experimentally made on rain-wind induced vibration of cables of cable-stayed bridges were described. Finally, some new progresses in computation wind engineering were introduced, and a new method for simulating an equilibrium boundary layer was put forward as well.

关键词： long-span bridge aerodynamic derivative and admittance flutter and buffeting control rain-wind induced vibration ofstay cable computation wind engineering equilibrium boundary layer

Seismic spatial effects on dynamic response of long-span bridges in stationary inhomogeneous random fields

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Earthquake Engineering and Engineering Vibration 2004年第2期3卷 171-180页

作者：林家浩张亚辉赵岩 State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116023China Professor State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116023China Associate Professor State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116023China Post-doctor

The seismic analysis of long-span bridges subjected to multiple ground excitations is an important problem. The conventional response spectrum method neglects the spatial effects of ground motion,and therefore may result in questionable *** random vibration approach has been regarded as more ***,so far, computational difficulties have not yet been satisfactorily *** this paper,an accurate and efficient random vibration approach—pseudo excitation method (PEM),by which the above difficulties are overcome,is *** has been successfully used in the three dimensional seismic analysis of a number of long-span bridges with thousands of degrees of freedom and dozens of *** numerical results of a typical bridge show that the seismic spatial effects~ particularly the wave passage effect,are sometimes quite important in evaluating the safety of long-span bridges.

关键词： seismic response random vibration multiple excitation long-span bridge

bridge vibration under complex wind field and corresponding measurements: A review

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第3期9卷 339-362页

作者： Enbo Yu Guoji Xu Yan Han Peng Hu Jamie F.Townsend Yongle Li School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China School of Civil Engineering Changsha University of Science and TechnologyChangsha 410114China

Due to increased demands in transportation development,bridge construction has been extended to areas with complex wind *** addition to common flow features such as high wind speeds and strong turbulence intensity,in coastal areas,bridges are likely to be exposed to non-stationary and non-Gaussian high-speed wind fields during hurricane *** built in mountainous regions will experience varying wind directions,incident angles of attack(AOA),and wind speed variation due to undulating *** complex wind fields are challenging to the bridge engineering community to which accurate calculation methods and suppression measures for bridge vibration are urgently *** this paper,state-of-the-art research results are introduced through three categories:(a)the distinctive characteristics of complex wind fields in offshore and mountainous areas,(b)the categories of wind-induced vibrations for bridges,and(c)the suppression measures employed in engineering *** now,the studies regarding the coupled bridge vibration in complex wind fields have made considerable progress,but a richer database of actual wind measurement results and more efficient simulation methods still need to be further established.

关键词： Complex wind field long-span bridge Vibration suppression Buffeting VIV Flutter

Experimental research on daily deformation monitoring of steel box girder bridge based on BDS/GPS

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High Technology Letters 2018年第3期24卷 272-278页

作者：陈健 Yue Dongjie Liu Zhiqiang Zhu Shaolin Chen Hao School of Earth Science and Engineering Hohai University

In order to investigate the feasibility of BDS/GPS in the deformation monitoring of long-span bridges,analysis and research on aspects like number of visible satellites,PDOP value and monitoring precision are carried out. To analyze daily deformation characteristics of steel box girder bridge,observation data for 48 consecutive hours is computed by self-programmed software. Experiment results show that the monitoring-points on the bridge demonstrate obvious periodicity and recoverability in vertical and horizontal directions,meanwhile,changes in the elevation direction are relatively stable. The deformation-monitoring results of BDS/GPS combination system and GPS single system show good consistency. However,in a complex environment of the bridge,especially under the condition that satellite signals are severely affected,the advantages of BDS/GPS combination over GPS single system are more obvious.

关键词： dynamic deformation monitoring BDS/GPS baseline solution daily repeatability long-span bridge

Theoretical research on structural damage alarming of long-span bridges using wavelet packet analysis

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Journal of Southeast University(English Edition) 2005年第4期21卷 459-462页

作者：丁幼亮李爱群缪长青东南大学土木工程学院南京210096

The state equation and observation equation of the structural dynamic systems under various analysis scales are derived based on wavelet packet analysis. The time-frequency properties of structural dynamic response under various scales are further formulated. The theoretical analysis results reveal that the wavelet packet energy spectrum （WPES） obtained from wavelet packet decomposition of structural dynamic response will detect the presence of structural damage. The sensitivity analysis of the WPES to structural damage and measurement noise is also performed. The transfer properties of the structural system matrix and the observation noise under various analysis scales are formulated, which verify the damage alarming reliability using the proposed WPES with preferable damage sensitivity and noise robusticity.

关键词： structural damage alarming wavelet packet analysis wavelet packet energy spectrum long-span bridge

Dynamic Deformation Monitoring for long-span bridges under Construction and EMD De-noising Method

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Journal of Civil Engineering and Architecture 2016年第7期10卷 853-859页

作者： Shengxiang Huang Chao Kang Wen Zhang School of Geodesy and Geomatics Wuhan University Wuhan 430079 China Collaborative Innovation Center for Geospatial Technology Wuhan 430079 China

Construction progress of long-span bridge is complicated and the quality control is strict. Any disadvantage during construction may potentially affect the internal forces and deck alignments after it is open to traffic. To exactly evaluate the periodic alignments, internal forces and safety, geometrical and physical monitoring are needed during construction. This study aims at the requirement of dynamic geometric monitoring during Sutong bridge construction, and introduces the realization and observing schemes of the self-developed GPS real-time dynamic geometrical deformation monitoring system. Affected by wind load and construction circumstance, GPS （global positioning system） monitoring signal contains a variety of noise. And the useful signal can be extracted from the signal after de-noising the noises. A de-noising method based on EMD （empirical mode decomposition） model is introduced here to process the bridge dynamic monitoring data, and with the wavelet threshold de-noising method are compared. The result shows that the EMD method has good adaptability, is free from the choice of wavelet bases and the number of decomposition layer. The method is an effective de-noising method for dynamic deformation monitoring to large-span bridges.

关键词： long-span bridge construction period dynamic deformation monitoring empirical mode decomposition de-noising.