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Theoretical modeling of steel reinforced ECC column under eccentric compressive loading

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Science China(Technological Sciences) 2015年第5期58卷 889-898页

作者： PAN JinLong GU Jie CHEN JunHan Key Laboratory of concrete and Prestressed concrete Structures of Ministry of Education Southeast University

Fiber reinforced cementitious composites(ECC) are a class of advanced composites with strain hardening and multiple cracking behaviors. Substitution of concrete with ECC can significantly improve the seismic resistance and durability of the infrastructures. In this paper, it is proposed to use ECC as the matrix of frame columns for improving its load carrying capacity, ductility, and avoiding the brittleness of concrete. Based on the assumption of plane remaining plane and constitutive models of materials, theoretical models for calculating the load-carrying capacity of the steel reinforced ECC columns under small and large eccentric compression are proposed. With the parameters of the constitutive models from the existing experimental data, the relationship between ultimate axial load and moment capacities is also derived with the proposed models. To verify the validity of the proposed theoretical models, finite element analysis with the software of ATENA is conducted to simulate the mechanical behavior of the steel reinforced ECC columns under eccentric compressive loading. The calculation results from the theoretical models show good consistency with the simulated results, indicating that the proposed models are feasible and reliable for design. Finally, based on the theoretical models, the effect of the ultimate tensile strain and compressive strength of ECC, longitudinal reinforcement ratio on the load carrying capacity of the steel reinforced ECC column are comprehensively studied.

关键词： compressive reinforced ultimate durability constitutive reinforcement tensile columns carrying calculating

Seismic behavior and mechanism analysis of innovative precast shear wall involving vertical joints

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Journal of Central South University 2015年第4期22卷 1536-1547页

作者：孙建邱洪兴 Key Laboratory of concrete and Prestressed concrete Structures of Ministry of Education (Southeast University)

To study the seismic performance and load-transferring mechanism of an innovative precast shear wall(IPSW) involving vertical joints, an experimental investigation and theoretical analysis were successively conducted on two test walls. The test results confirm the feasibility of the novel joints as well as the favorable seismic performance of the walls, even though certain optimization measures should be taken to improve the ductility. The load-transferring mechanism subsequently is theoretically investigated based on the experimental study. The theoretical results show the load-transferring route of the novel joints is concise and definite. During the elastic stage, the vertical shear stress in the connecting steel frame(CSF) distributes uniformly; and each high-strength bolt(HSB)primarily delivers vertical shear force. However, the stress in the CSF redistributes when the walls develop into the elastic-plastic stage. At the ultimate state, the vertical shear stress and horizontal normal stress in the CSF distribute linearly; and the HSBs at both ends of the CSF transfer the maximum shear forces.

关键词： precast shear wall vertical joint seismic behavior high-strength bolt connecting steel frame

Structural condition assessment of long-span suspension bridges using long-term monitoring data

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Earthquake Engineering and Engineering Vibration 2010年第1期9卷 123-131页

作者： Deng Yang~+,Ding Youliang~(++) and Li Aiqun~§Key Laboratory of concrete & Prestressed concrete Structures of Ministry of Education,Southeast University,Nanjing 210096,China PhD Student ++ Assistant Professor ~§Professor Key Laboratory of concrete & Prestressed concrete Structures of Ministry of Education Southeast University Nanjing China

This paper focuses on developing an online structural condition assessment technique using long-term monitoring data measured by a structural health monitoring system. The seasonal correlations of frequency-temperature and beam-end displacement-temperature for the Runyang Suspension Bridge are performed, first. Then, a statistical modeling technique using a six-order polynomial is further applied to formulate the correlations of frequency-temperature and displacement-temperature, from which abnormal changes of measured frequencies and displacements are detected using the mean value control chart. Analysis results show that modal frequencies of higher vibration modes and displacements have remarkable seasonal correlations with the environmental temperature and the proposed method exhibits a good capability for detecting the micro damage-induced changes of modal frequencies and displacements. The results demonstrate that the proposed method can effectively eliminate temperature complications from frequency and displacement time series and is well suited for online condition monitoring of long-span suspension bridges.

关键词： structural health monitoring modal frequency beam-end displacement temperature seasonal correlation suspension bridge

Design and experimental verification of a new multi-functional bridge seismic isolation bearing

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第12期13卷 904-914页

作者： Chen-xi XING Hao WANG Ai-qun LI Ji-rong WU MOE Key Laboratory of concrete and Prestressed concrete Structures Southeast UniversityNanjing 210096China

A new multi-functional bridge seismic isolation bearing(MFBSIB) is designed and its mechanical model is developed in this *** an upper sliding device and a lower energy dispassion isolation device effectively,the new MFBSIB can adjust the deformation caused by temperature,vehicle breaks,and concrete creep,etc.,in addition to dissipating *** switch of 'slide-isolation' is achieved and the efficiency of both upper and lower parts is validated through experiment with a *** shear performance curve established in this paper is verified to be efficient in describing the mechanical characteristics of the bearing through *** is proved through both numerical calculation and experimental analysis that the new MFBSIB is endowed with enough vertical rigidity,good energy dissipation ability,stable overall performance,and good realization in expected *** performance is slightly influenced by shear stress,while affected by vertical pressure,loading frequency,slide limit,etc.,*** results could provide reference for study and application of the new MFBSIB.

关键词： Seismic isolation bearing Sliding device Finite element analysis Model experiment Bridge

Fatigue monitoring and analysis of orthotropic steel deck considering traffic volume and ambient temperature

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Science China(Technological Sciences) 2013年第7期56卷 1758-1766页

作者： SONG YongSheng DING YouLiang Key Laboratory of concrete and Prestressed concrete Structures of Ministry of Education Southeast University

Fatigue has gradually become a serious issue for orthotropic steel deck used for long-span bridges. Two fatigue effects, namely number of stress cycles and equivalent stress amplitude, were introduced as investigated parameters in this paper. Investigation was focused on their relationships with traffic volume and ambient temperature by using 7-months fatigue monitoring data of an actual bridge. A fatigue analytical model considering temperature-induced changes in material property of asphalt pavement was established for verifying these relationships. The analysis results revealed that the number of stress cycles and equivalent stress amplitude showed a linear correlation with the traffic volume and ambient temperature, respectively, and that the rib-to-deck welded joint was much more sensitive to the traffic volume and ambient temperature than the rib-to-rib welded joint. The applicability of the code-recommended model for fatigue vehicle loading was also discussed, which revealed that the deterministic vehicle loading model requires improvement to account for significant randomness of the actual traffic conditions.

关键词： fatigue orthotropic steel deck structural health monitoring finite element model temperature traffic volume

Influence of local geometric parameters on fatigue performance of orthotropic steel deck

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Journal of Central South University 2014年第5期21卷 2091-2099页

作者：宋永生丁幼亮 Key Laboratory of concrete and Prestressed concrete Structures of Ministry of Education(Southeast University)

Fatigue has become critical issue for bridge with orthotropic steel *** of stress cycle and equivalent stress amplitude were adopted as two investigated fatigue *** presented from fatigue monitoring comparison of two series-lined bridges,three local geometric parameters of steel box girder have significant influence on fatigue performance of two welded *** are thickness of longitudinal ribs(Tr),longitudinal spacing of transverse floor plate(Sc)and longitudinal truss(LT).Fatigue analytical models were created for parametric study of fatigue effects under wheel ***,three local parameters have exhibited insignificant influence on number of stress *** with Tr and Sc,configuration of LT has brought about foremost effect on the equivalent stress *** equivalent stress amplitude of rib-to-deck and rib-to-rib welded joints,the influence regions of LT are respectively longitudinal strap and quadrate with the geometric length of 600 *** attention ought to be paid for local stiffen structure on fatigue performance of orthotropic steel deck in fatigue design and monitoring.

关键词： fatigue effect orthotropic steel deck local detail structural health monitoring finite element analysis wheel load

Prediction of extreme wind velocity at the site of the Runyang Suspension Bridge

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第8期12卷 605-615页

作者： Yang DENG You-liang DING Ai-qun LI Guang-dong ZHOU Key Laboratory of concrete and Prestressed concrete Structures of Ministry of Education Southeast University Nanjing 210096 China

This paper presents a distribution free method for predicting the extreme wind velocity from wind monitoring data at the site of the Runyang Suspension Bridge (RSB), China using the maximum entropy theory. The maximum entropy theory is a rational approach for choosing the most unbiased probability distribution from a small sample, which is consistent with available data and contains a minimum of spurious information. In this paper, the theory is used for estimating a joint probability density function considering the combined action of wind speed and direction based on statistical analysis of wind monitoring data at the site of the RSB. The joint probability distribution model is further used to estimate the extreme wind velocity at the deck level of the RSB. The results of the analysis reveal that the probability density function of the maximum entropy method achieves a result that fits well with the monitoring data. Hypothesis testing shows that the distributions of the wind velocity data collected during the past three years do not obey the Gumbel distribution. Finally, our comparison shows that the wind predictions of the maximum entropy method are higher than that of the Gumbel distribution, but much lower than the design wind speed.

关键词： Extreme wind velocity Maximum entropy theory Probability density function Structural health monitoring(SHM)

Compressive performance of a foam-filled fiber-reinforced grid beetle elytron plate

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Science China(Technological Sciences) 2023年第3期66卷 830-840页

作者： HAO Ning SONG YiHeng CHEN JinXiang HE ChaoChao LI YinSheng Key Laboratory of concrete and Prestressed concrete Structures of the Ministry of Education Southeast UniversityNanjing 211189China

The compressive mechanical properties,failure modes and foam filler strengthening mechanism and effect of a short basalt fiber-reinforced epoxy resin composite grid beetle elytron plate with a polyvinyl chloride(PVC)foam-filled core(GBEPfc)are investigated via compression experiments and the finite element *** results are compared with those of a grid plate(GPfc)with the same wall thickness as the ***,a fully integrated preparation method and process are developed for the GBEPfc,with a material composition that is close to the structure and composition of the *** of more than 20%in the specific compressive strength and specific energy absorption of the GBEPfcrelative to the GPfcare *** foam provides a constraining force for the fiber composite structure;consequently,the trabeculae and honeycomb walls of the core transition from a lower-order deformation that easily occurs to a higher-order deformation that occurs less *** interaction between the core composite structure and PVC foam is *** GBEPfcdeveloped in this paper is simple in structure and easy to prepare,and the material composition is close to biological prototypes and materials used in practical engineerings,which lays a foundation for the application of beetle elytron plates.

关键词： beetle elytron beetle elytron plate foam-filled sandwich plate basalt fiber-reinforced polymer(BFRP) compressive properties

Estimating extreme temperature differences in steel box girder using long-term measurement data

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Journal of Central South University 2013年第9期20卷 2537-2545页

作者：丁幼亮王高新 Key Laboratory of concrete and Prestressed concrete Structures of Ministry of Education (Southeast University)

The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were ***,by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge,the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were *** probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 ***,the temperature difference models in cross-section area were proposed for bridge thermal *** results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are *** the positive and negative temperature differences can be described by the weighted sum of two Weibull *** maximum positive and negative horizontal temperature differences in top plate are 10.30 ℃ and -13.80 ℃,*** the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30 ℃ and-3.70 ℃,*** bridge thermal design,there are two vertical temperature difference models between top plate and bottom plate,and six horizontal temperature difference models in top plate.

关键词： structural health monitoring cable-stayed bridge steel box girder temperature difference extreme value analysis