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Real-time reliability assessment based on acceleration monitoring for bridge

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Science China(Technological Sciences) 2016年第8期59卷 1294-1304页

作者： ZHANG LiYe SUN LiMin SHANG ZhiQiang state key laboratory for disaster reduction in civil eng.neering Tongji University Shanghai 200092 China

Bridge health monitoring （BHM） has become increasingly significant in the life-cycle of the structure such as maintenance, repair and rehabilitation. It is necessary to use BHM information efficiently to assess the working conditions of the bridge. The main objective of this study is to develop an effective method and establish a framework for the real-time reliability assessment based on BHM acceleration information. The first-passage probability and its further development have been proposed to as- sess the reliability probability. The first-passage probability shows the probability of that a scalar process exceeds a designated threshold during a given time interval. The advantage of the proposed method is the assessment of the real-time reliability probability based on the monitoring information during an assessment reference period. Furthermore, the velocity data and displacement data are calculated from the acceleration monitoring data using the relationships between their power spectral density （PSD） functions. The real-time reliability assessment of Donghai Bridge, which is the first large scale cross-sea bridge in China, demonstrates that the proposed method is efficient and effective.

关键词： real-time reliability first passage monitoring information power spectral density (PSD) Donghai Bridge

Grouping response method for equivalent static wind loads based on a modified LRC method

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Earthquake eng.neering and eng.neering Vibration 2012年第1期11卷 107-119页

作者： Zhou Xuanyi Gu Ming Li Gang state key laboratory of disaster reduction in civil eng.neering Tongji UniversityShanghai 200092China

Wind loading is one of the most important loads for controlling the design of large-span roof structures. Equivalent static wind loads, which can generally aim at determining a specific response, are widely used by structural designers. A method for equivalent static wind loads applicable to multi-responses is proposed in this paper. A modified load- response-correlation （LRC） method corresponding to a particular peak response is presented, and the similarity algorithm implemented for the group response is described. The main idea of the algorithm is that two responses can be put into one group if the value of one response is close to that of the other response, when the structure is subjected to equivalent static wind loads aiming at the other response. Based on the modified LRC, the grouping response method is put forward to construct equivalent static wind loading. This technique can simultaneously reproduce peak responses for some grouped responses. To verify its computational accuracy, the method is applied to an actual large-span roof structure. Calculation results show that when the similarity of responses in the same group is high, equivalent static wind loads with high accuracy and reasonable magnitude of equivalent static wind distribution can be achieved.

关键词： large-span roof equivalent static wind loads modified LRC method grouping response similarityalgorithm

Seismic analysis of a LNG storage tank isolated by a multiple friction pendulum system

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Earthquake eng.neering and eng.neering Vibration 2011年第2期10卷 253-262页

作者： Zhang Ruifu Weng.Dagen Ren Xiaosong state key laboratory for disaster reduction in civil eng.neering Tongji University Shanghai 200092 China

The seismic response of an isolated vertical, cylindrical, extra-large liquefied natural gas （LNG） tank by a multiple friction pendulum system （MFPS） is analyzed. Most of the extra-large LNG tanks have a fundamental frequency which involves a range of resonance of most earthquake ground motions. It is an effective way to decrease the response of an isolation system used for extra-large LNG storage tanks under a strong earthquake. However, it is difficult to implement in practice with common isolation bearings due to issues such as low temperature, soft site and other severe environment factors. The extra-large LNG tank isolated by a MFPS is presented in this study to address these problems. A MFPS is appropriate for large displacements induced by earthquakes with long predominant periods. A simplified finite element model by Malhotra and Dunkerley is used to determine the usefulness of the isolation system. Data reported and statistically sorted include pile shear, wave height, impulsive acceleration, convective acceleration and outer tank acceleration. The results show that the isolation system has excellent adaptability for different liquid levels and is very effective in controlling the seismic response of extra-large LNG tanks.

关键词： LNG tank earthquake isolation bearing

Simulation of roof snow loads based on a multi-layer snowmelt model:Impact of building heat transfer

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Building Simulation 2024年第6期17卷 907-932页

作者： Xuanyi Zhou Heng.Chen Yue Wu Tiange Zhang state key laboratory of disaster reduction in civil eng.neering Tongji UniversityShanghai200092China

To investigate the impact of building heat transfer on roof snow loads,roof snow loads and snow load thermal coefficients from 61 Chinese sites over a period of 50 years are simulated based on basic meteorological data such as temperature,humidity,wind speed,and precipitation,and a multi-layer snowmelt model considering the building heat ***,the accuracy of the multi-layer snowmelt model is validated using the data of observed ground snow load and roof snow melting *** relationship between meteorological conditions,snow cover characteristics,and thermal coefficients of snow loads in three representative sites is then ***,the characteristics of thermal coefficients in each zone are analyzed by combining them with the statistical results of meteorological data from 1960 to 2010,and the equations of thermal coefficients in different zones on indoor temperatures and roof heat transfer coefficients are fitted ***,the equations in this paper are compared with the thermal coefficients in the main snow load *** results indicate that the snowmelt model using basic meteorological data can effectively provide samples of roof snow *** the cold zone where the snow cover lasts for a long time and does not melt easily,the thermal coefficients of the snow loads on the heating buildings are lower than those in the warm zone due to the long-term influence of the heat from inside the *** coefficients are negatively correlated with indoor temperatures and roof heat transfer *** the indoor temperature is too low or the roof insulation is good,the roof snow load may exceed the ground snow *** thermal coefficients for heated buildings in the main snow load codes are more conservative than those calculated in this paper,and the thermal coefficients for buildings with lower indoor temperatures tend to be smaller.

关键词： snowmelt model roof snow load building heat transfer thermal coefficient load code

Effects of riverbed scour on seismic performance of high-rise pile cap foundation

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Earthquake eng.neering and eng.neering Vibration 2010年第4期9卷 533-543页

作者： Han Zhenfeng.Ye Aijun Fan Lichu state key laboratory for disaster reduction of civil eng.neering Tongji University Shanghai 200092 China

To explore the seismic performance of a high-rise pile cap foundation with riverbed scour, a finite element model for foundations is introduced in the OpenSees finite element framework. In the model, a fiber element is used to simulate the pile shaft, a nonlinear p-y element is used to simulate the soil-pile interaction, and the p-factor method is used to reflect the group effects. A global and local scour model is proposed, in which two parameters, the scour depth of the same row of piles and the difference in the scour depth of the upstream pile and the downstream pile, are included to study the influence of scour on the foundation. Several elasto-plastic static pushover analyses are performed on this finite element model. The analysis results indicate that the seismic capacity （or supply） of the foundation is in the worst condition when the predicted deepest global scout depth is reached, and the capacity becomes larger when the local scour depth is below the predicted deepest global scout depth. Therefore, to evaluate the seismic capacity of a foundation, only the predicted deepest global scout depth should be considered. The method used in this paper can be also applied to foundations with other soil types.

关键词： riverbed scour high-rise pile cap pile group fiber element seismic capacity pushover p-y element

Numerical Simulation of a New 3D Isolation System Designed for a Facility with Large Aspect Ratio

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Computer Modeling in eng.neering & Sciences 2019年第9期120卷 759-777页

作者： Ying Zhou Peng.Chen state key laboratory of disaster reduction in civil eng.neering Shanghai200092China

This paper proposes a novel three-dimensional(3D)isolation system for facilities and presents the numerical simulation approach for the isolated system under earthquake excitations and impact effect using the OpenSees(Open System for Earthquake eng.neering Simulation)software frame *** 3D isolators combine the quasi-zero stiffness(QZS)system in the vertical direction and lead rubber bearing in the horizontal *** the large aspect ratio of the isolated facility,linear viscous dampers are designed in the vertical direction to diminish the overturning *** vertical QZS isolation system is characterized by a cubic force-displacement relation,thus,no elements or materials can model this mechanic behavior in the existing finite element *** study takes advantage of the open source feature of the OpenSees to create a new material to represent the mechanic properties of the QZS *** the user-defined material is combined with the rubber isolator element to model the 3D *** different soil types and input magnitudes,six sets of natural seismic records and artificial waves and half sine pulses are selected as the input excitations.A finite element model for the 3D isolated facility is established based on the combined element and the simulation is performed to calculate the time history *** numerical simulation reveals the flexibility of the OpenSees to deal with new eng.neering problems,and the results prove that the new 3D isolation system can have an optimal isolation effect in both horizontal and vertical *** maximum acceleration response at the top of the facility is below the target limit,and the maximum deformation and the overturning motion of the isolation system can be controlled in a safe range.

关键词： 3D isolation quasi-zero stiffness OpenSees facility large aspect ratio

Construction of homogeneous loading functions for elastoplastic damage models for concrete

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Science China(Physics,Mechanics & Astronomy) 2014年第3期57卷 490-500页

作者： ZHANG Ji LI Jie School of civil eng.neering Tongji University state key laboratory for disaster reduction in civil eng.neering

Over the past 2 decades,tight restriction has been imposed on streng.h criteria of concrete by the combination of plasticity and damage in one *** present study aims at constructing plastic/damage loading functions for elastoplastic damage models for concrete that can perform more satisfactorily in 3D stress *** streng.h criteria of concrete are reorganized according to their simplest representations as Cartesian,cylindrical,mixed cylindrical-Cartesian,and other forms,and the homogeneity of loading functions *** is found that under certain supplementary conditions from physical meanings,an unambiguous definition of the cohesion in a streng.h criterion,which is demanded in an elastoplastic damage model,is usually available in an explicit or implicit form,and in each case the loading function is still *** apply and validate the presented theory,we construct the respective homogeneous damage and plastic loading functions and implant them into some widely used elastoplastic damage models for concrete,and their performances in triaxial compression prove to have improved significantly.

关键词： concrete streng.h theory damage plasticity loading function

Seismic design and analysis of a high-rise self-centering wallbuilding:Case study

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Frontiers of Structural and civil eng.neering 2023年第11期17卷 1690-1706页

作者： Ying ZHOU Rui WANG Yiqiu LU state key laboratory of disaster reduction in civil eng.neering College of Civil EngineeringTongji UniversityShanghai 200092China

Post-tensioning self-centering walls are a well-developed and resilient ***,despite extensive research,the application of this technology has previously been limited to low-rise buildings.A ten-story selfcentering wall building has now been designed and constructed using the state-of-art design methodologies and construction detailing,as described in this *** building is designed in accordance with direct displacement-based design methodology,with modification of seismic demand due to relevant issues including higher-mode effects,second order effects,torsional effects,and flexural deformation of wall *** sections are designed with external energydissipating devices of steel dampers,and seismic performance of such designed self-centering walls is evaluated through numerical *** is the first eng.neering project that uses self-centering walls in a high-rise *** seismic design procedure of such a high-rise building,using self-centering wall structures,is comprehensively reviewed in this work,and additional proposals are put *** of construction detailing,including slotted beams,flexible wall-to-floor connections,embedded beams,and damper installation,is *** demonstration project promotes the concept of seismic resilient structures and contributes to the most appealing city planning strategy of resilient cities at *** paper could be a reference for industry eng.neers to promote the self-centering wall systems worldwide.

关键词： self-centering wall post-tensioned precast concrete wall seismic resilient structure high-rise building seismic design eng.neering practice

Independent cover meshless particle method for complex geotechnical eng.neering

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Frontiers of Structural and civil eng.neering 2018年第4期12卷 515-526页

作者： Jianqiu WU Yongchang CAI state key laboratory of disaster reduction in civil eng.neering College of Civil EngineeringTongji UniversityShanghai 200092China

A new Independent Cover Meshless Particle (ICMP) method is proposed for the analysis of complex geotechnical eng.neering. In the ICMP method, the independent rectangular cover regardless of the shape of the analysis model is employed as the influence domain of each discrete node, the general polynomial is employed as the meshless interpolation function of the independent nodal cover, and the Cartesian Transformation Method (CTM) is used for the numerical integration of the nodal covers cut by material interfaces, joints, cracks and faults. The present method has a simple formulation and a low computational cost, and is easy for the numerical analysis and modeling of complex geotechnical eng.neering. Several typical numerical examples are presented to demonstrate the accuracy and robustness of the proposed method.

关键词： meshless method particle method independent cover CTM geotechnical eng.neering