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Triaxial elastoplastic damage constitutive model of unreinforced clay brick masonry wall

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Earthquake Engineering and Engineering Vibration 2023年第1期22卷 157-172页

作者： Wu Biye dai junwu Bai Wen Yang Yongqiang Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina EarthquakeAdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China

Due to differences in the properties of composition materials and construction techniques,unreinforced masonry is characterized by low strength,anisotropy,nonuniformity,and low ductility.In order to accurately simulate the mechanical behavior of unreinforced brick masonry walls under static and dynamic loads,a new elastoplastic damage constitutive model was proposed and the corresponding subroutine was developed based on the concrete material constitutive model.In the proposed constitutive model,the Rankine strength theory and the Drucker-Prager strength theory were used to define the tensile and compressive yield surface function of materials,respectively.Moreover,the stress updating algorithm was modified to consider the tensile plastic permanent deformation of masonry materials.To verify the accuracy of the proposed constitutive model,numerical simulations of the brick masonry under monotonic and cyclic uniaxial tension and compression loads were carried out.Comparisons among the numerical and theoretical and experimental results show that the proposed model can properly reflect the masonry material mechanical properties.Furthermore,the numerical models of four pieces of masonry walls with different mortar strengths were established.Low cyclic loadings were applied and the results show that the proposed constitutive model can properly simulate the wall shear failure characteristics,and the force-displacement hysteretic curves obtained by numerical simulation are in good agreement with the tests.Overall,the proposed elastic-plastic damage constitutive model can simulate the nonlinear behavior of unreinforced brick masonry walls very well,and can be used to predict the structural response of masonry walls.

关键词： brick masonry elastoplastic model calibration parameters numerical simulation damage variable

Numerical simulation on the seismic performance of retrofitted masonry walls based on the combined finite-discrete element method

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Earthquake Engineering and Engineering Vibration 2023年第3期22卷 777-805页

作者： Wu Biye dai junwu Jin Huan Bai Wen Chen Bowen Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China Guangdong University of Petrochemical Technology Maoming 525000China

Due to the long construction life,improper design methods,brittle material properties and poor construction techniques,most existing masonry structures do not perform well during earthquakes.The retrofitting method using an external steel-meshed mortar layer is widely used to retrofit existing masonry buildings.Assessing the seismic performance of masonry walls reinforced by an external steel-meshed mortar layer reasonably and effectively is a difficult subject in the research field of masonry structures.Based on the combined finite-discrete elements method,the numerical models of retrofitted brick walls with four different masonry mortar strengths by an external mortar layer are established.The shear strength of mortar and the contact between the retrofitted mortar layer and the brick blocks are discussed in detail.The failure patterns and load-displacement curves of the retrofitted brick walls were obtained by applying low cycle reciprocating loads to the numerical model,and the bearing capacity and the failure mechanism of the retrofitted walls were obtained by comparing the failure patterns,ultimate bearing capacity,deformability and other aspects with the tests.This study provides a basis for improving the seismic strengthening design method of masonry structures and helps to better assess the seismic performance of masonry structures after retrofitting.

关键词： masonry wall external steel-meshed mortar layer combined finite-discrete element method hysteretic curve ultimate bearing capacity

Finite element analysis of an all-steel buckling-restrained brace

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Earthquake Engineering and Engineering Vibration 2022年第4期21卷 1119-1135页

作者： Jiang Tao dai junwu Yang Yongqiang Bai Wen Pang Hui Liu Rongheng Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChinaEarthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China

Typical all-steel buckling-restrained braces(BRBs)usually exhibit obvious local buckling,which is attributed to the lack of longitudinal restraint to the rectangle core plate.To address this issue,all-steel BRBs are proposed,in which two T-shaped steel plates are adopted as the minor restraint elements to restrain the core plate instead of infilled concrete or mortar.In order to investigate the factors that characterize the hysterical responses of this device,different finite element(FE)models are developed for the specific context.The FE models are developed based on nonlinear finite element software,which incorporate continuum(shell or brick)elements,large displacement,and deformation formulations.In these FE models,two different steel constitutive models are adopted to precisely reproduce the cyclic response of the BRB component.Meanwhile,comparisons between the numerical and experimental results are conducted to validate the effectiveness and accuracy of the robust FE model.The agreements between experimental observations and numerical predictions demonstrate that the FE method could be utilized for in depth parametric analysis.Furthermore,BRBs with detailed configurations can provide excellent hysteretic behavior and seismic performance through the optimal design process.

关键词： steel BRB T-shaped steel finite element model optimal design hysteretic behavior

Multiscale confinement nitridation in molybdenum carbide for efficient hydrogen production

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Journal of Energy Chemistry 2024年第7期94卷 61-69页

作者： Liming dai Chenchen Fang Xiaoyuan Zhang Xuefeng Xu Xuanxuan Chen Xinyue Zong Xueming Hu Wenyao Zhang Liang Xue Pan Xiong Yongsheng Fu Jingwen Sun junwu Zhu Key Laboratory for Soft Chemistry and Functional Materials Ministry of EducationNanjing University of Science and TechnologyNanjing 210094JiangsuChina

The molybdenum carbide(Mo_(2)C)has been regarded as one of the most cost-efficient and stable electrocatalyst for the hydrogen evolution reaction(HER)by the virtue of its Pt-like electronic structures.However,the inherent limitation of high density of empty valence band significantly reduces its catalytic reactivity by reason of strong hydrogen desorption resistance.Herein,we propose a multiscale confinement synthesis method to design the nitrogen-rich Mo_(2)C for modulating the band structure via decomposing the pre-coordination bonded polymer in a pressure-tight tube sealing system.Pre-bonded c/N-Mo in the coordination precursor constructs a micro-confinement space,enabling the homogeneous nitrogenization in-situ happened during the formation of Mo_(2)C.Simultaneously,the evolved gases from the precursor decomposition in tube sealing system establish a macro-confinement environment,preventing the lattice N escape and further endowing a continuous nitridation.Combining the multiscale confinement effects,the nitrogen-rich Mo2C displays as high as 25%N-Mo concentration in carbide lattice,leading to a satisfactory band structure.Accordingly,the constructed nitrogen-rich Mo_(2)C reveals an adorable catalytic activity for HER in both alkaline and acid solution.It is anticipated that the multiscale confinement synthesis strategy presents guideline for the rational design of electrocatalysts and beyond.

关键词： Molybdenum carbide Hydrogen evolution reaction Multiscale confinement synthesis Valence band modulation Nitrogen doping

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曲线轨道式隔震装置的结构优化与应用研究

中南大学学报（自然科学版） 2024年第1期55卷 355-364页

作者：赵守江柏文戴君武故宫博物院北京100009 中国地震局工程力学研究所地震工程与工程振动重点实验室黑龙江哈尔滨150080 地震灾害防治应急管理部重点实验室黑龙江哈尔滨150080

针对浮放物体的防震保护需求,研发出一款基于新型抗侧移组件的曲线轨道式隔震装置。阐述它的构造特点和运行机制,并依据结构原理制作模型,通过试验与理论对比来检验模型的运行质量进而验证方案的可行性。然后结合雨花阁内文物来设计样机... 详细信息

针对浮放物体的防震保护需求,研发出一款基于新型抗侧移组件的曲线轨道式隔震装置。阐述它的构造特点和运行机制,并依据结构原理制作模型,通过试验与理论对比来检验模型的运行质量进而验证方案的可行性。然后结合雨花阁内文物来设计样机,采用多条楼面波进行样机的振动台试验,测试其隔震效果。最后探讨建筑滤波效应对该类隔震装置设计的影响。研究结果表明:曲线轨道式隔震装置经优化后不仅零部件功能清晰,结构简单易加工,而且具备整体性强、运行质量高以及后期可扩展等优势。试验模型的零部件能充分发挥各自功能,尤其是抗侧移组件极大提高了模型的稳定性和可靠性,理论分析与试验结果吻合良好。结合案例所设计的样机虽具有较好的隔震性能,但限于非线性双自由度的结构特点,重复试验的响应结果存在差异,工程应用中应予以重视。当楼面波不易获取且隔震装置周期远离建筑自振周期时,依据楼面加速度放大系数,将调幅后的原始波作为隔震装置设计依据是可行的且结果偏保守。

关键词：曲线轨道式隔震装置振动台试验浮放物体滤波效应

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新型万向球摆式隔震装置的设计与应用

地震工程与工程振动 2024年第2期44卷 89-97页

针对浮放物体防震保护的迫切需求,研发了一款基于万向球的摆式隔震装置。首先介绍了它的构造特征与运行原理,并以某陈列佛塔为对象进行方案设计,利用有限元软件模拟万向球与圆盘间的接触关系,评估该装置的承载能力;然后通过试验验证了... 详细信息

针对浮放物体防震保护的迫切需求,研发了一款基于万向球的摆式隔震装置。首先介绍了它的构造特征与运行原理,并以某陈列佛塔为对象进行方案设计,利用有限元软件模拟万向球与圆盘间的接触关系,评估该装置的承载能力;然后通过试验验证了内部阻尼机构力学模型的准确性,采用时程分析法检验了该装置在8度极罕遇地震作用下的隔震效果,并与传统滑动摩擦摆的减震性能进行了对比。结果表明,该隔震装置不仅结构简单、性能可靠,而且具有摩擦系数低,起滑加速度阈值小,阻尼灵活可调的特点。装置中的点面接触具有一定的承载能力,能够满足设计需求。端部设置黏滞阻尼器的阻尼机构表现出明显的速度相关性,阻尼力会随速度的增大而增大。该装置隔震性能良好,在满足位移限值的情况下达到了设定的隔震目标,而且相比于传统型,在位移和加速度响应均需兼顾的情况下,通过合理调整阻尼机构的性能参数,该装置在各地震工况中能够取得更优的综合隔震效果。

关键词：摆式隔震装置万向球阻尼机构浮放物体丝杠

Novel uniaxial concrete constitutive model considering bond-slip effect

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Earthquake Engineering and Engineering Vibration 2020年第3期19卷 649-668页

作者： Liu Yongbin dai junwu Yang Yongqiang Jiang Tao Institute of Engineering Mechanics China Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Engineering and Engineering Vibration China Earthquake AdministrationHarbin 150080China

A uniaxial concrete constitutive model considering the bond-slip effect is proposed and its finite element analysis(FEA)implementation on a fiber section of a beam-column element is presented.The tension-stiffening,crackclosing,crack-opening,cyclic degradation of the tensile capacity of reinforced concrete are modeled,which reveals the significance of energy dissipation resulting from bond slip during crack opening and closing under cyclic loading.The model is based on a simplified mechanical concept in a smeared manner and verified through quasi-static test results of X-type slender RC columns.The FEA results using a common concrete model with no consideration of bond slip present significant pinching when predicting the hysteretic loop of slender columns,which is not consistent with the test results and underestimates the capacity of energy dissipation of cracking during cyclic load.The results obtained with the proposed model show good agreement with the test results,which can reflect the degradation of stiffness and strength as well as the energy dissipation of the crack opening and closing due to the bond slip effect.Considering its simplicity and computational efficiency,it is more applicable for analyzing large-scale structures than other methods that consider the bond-slip effect,especially for slender columns,such as those used in cooling towers and subjected to seismic excitation.

关键词： concrete constitutive columns

Shake table tests of suspended ceilings to simulate the observed damage in the M_s 7.0 Lushan earthquake, China

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 239-249页

作者： Wang Duozhi dai junwu Qu Zhe Ning Xiaoqing Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake Administration

Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.

关键词： suspended ceiling Lushan earthquake Wenchuan earthquake shake table test wall closure acoustic mineral fiber panel

Study of a new-type of steel buckling-restrained brace

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Earthquake Engineering and Engineering Vibration 2020年第1期19卷 239-256页

作者： Jiang Tao dai junwu Yang Yongqiang Liu Yongbin Bai Wen Institute of Engineering Mechanics China Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Engineering and Engineering Vibration of China Earthquake Administration Harbin 150080China

The rectangle core plate of all-steel buckling-restrained braces(BRBs) usually exhibit obvious local buckling, due to the lack of longitudinal restraint from the encasing tube. To eliminate the undesirable effects, a novel steel BRB is proposed. In this new-type steel BRB, two T-shaped steels are adopted as the minor restraint elements to restrain the core plate instead of infilled concrete or mortar. Meanwhile, the ingot-iron material with low yielding strength and high elongation is applied to the steel core to study the mechanical properties of steel BRBs. To validate the theoretical requirements for the width-to-thickness ratio of the steel core and the thickness of angle steel, quasi-static tests of eight specimens were conducted. The tests focused on the energy dissipation capacity and failure modes of the proposed steel BRBs. Nonlinear finite element analysis was also carried out to validate the experimental results. Both the aforementioned results imply that appropriately designed steel BRBs can meet the performance requirements for BRB components.

关键词： steel BRB T-shaped steel Ingot-iron energy dissipation capacity failure modes nonlinear fi nite element analysis