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Lateral shear performance of sheathed post-and-beam wooden structures with small panels

《结构与土木工程前沿（英文）》   页码 1117-1131 doi: 10.1007/s11709-023-0939-0

摘要： Sheathed post-and-beam wooden structures are distinct from light-wood structures. They allow for using sheathing panels that are smaller (0.91 m × 1.82 m) than standard-sized panels (1.22 m × 2.44 m or 2.44 m × 2.44 m). Evidence indicates that nail spacing and panel thickness determine the lateral capacity of the wood frame shear walls. To verify the lateral shear performance of wood frame shear walls with smaller panels, we subjected 13 shear walls, measuring 0.91 m in width and 2.925 m in height, to a low-cycle cyclic loading test with three kinds of nail spacing and three panel thicknesses. A nonlinear numerical simulation analysis of the wall was conducted using ABAQUS finite element (FE) software, where a custom nonlinear spring element was used to simulate the sheathing-frame connection. The results indicate that the hysteretic performance of the walls was mainly determined by the hysteretic performance of the sheathing-frame connection. When same nail specifications were adopted, the stiffness and bearing capacity of the walls were inversely related to the nail spacing and directly related to the panel thickness. The shear wall remained in the elastic stage when the drift was 1/250 rad and ductility coefficients were all greater than 2.5, which satisfied the deformation requirements of residential structures. Based on the test and FE analysis results, the shear strength of the post-and-beam wooden structures with sheathed walls was determined.

关键词： post-and-beam wooden structures with sheathed walls     low reversed cyclic loading     bearing capacity     stiffness     numerical simulation    

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An enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxialloading conditions

Mohammad Reza AZADI KAKAVAND, Ertugrul TACIROGLU

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1531-1544 doi: 10.1007/s11709-020-0675-7

摘要： Some of the current concrete damage plasticity models in the literature employ a single damage variable for both the tension and compression regimes, while a few more advanced models employ two damage variables. Models with a single variable have an inherent difficulty in accounting for the damage accrued due to tensile and compressive actions in appropriately different manners, and their mutual dependencies. In the current models that adopt two damage variables, the independence of these damage variables during cyclic loading results in the failure to capture the effects of tensile damage on the compressive behavior of concrete and vice-versa. This study presents a cyclic model established by extending an existing monotonic constitutive model. The model describes the cyclic behavior of concrete under multiaxial loading conditions and considers the influence of tensile/compressive damage on the compressive/tensile response. The proposed model, dubbed the enhanced concrete damage plasticity model (ECDPM), is an extension of an existing model that combines the theories of classical plasticity and continuum damage mechanics. Unlike most prior studies on models in the same category, the performance of the proposed ECDPM is evaluated using experimental data on concrete specimens at the material level obtained under cyclic multiaxial loading conditions including uniaxial tension and confined compression. The performance of the model is observed to be satisfactory. Furthermore, the superiority of ECDPM over three previously proposed constitutive models is demonstrated through comparisons with the results of a uniaxial tension-compression test and a virtual test.

关键词： damage plasticity model     plain concrete     cyclic loading     multiaxial loading conditions    

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Seismic response of precast reinforced concrete wall subjected to cyclic in-plane and constant out-of-planeloading

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1128-1143 doi: 10.1007/s11709-021-0753-5

摘要： This paper provides insight into the seismic behavior of a full-scale precast reinforced concrete wall under in-plane cyclic loading combined with out-of-plane loading replicated by sand backfill to simulate the actual condition of basement walls. The tested wall exhibited flexural cracks, owing to the high aspect ratio and considerable out-of-plane movement due to lateral pressure from the backfill. The wall performed satisfactorily by exhibiting competent seismic parameters and deformation characteristics governed by its ductile response in the nonlinear phase during the test with smaller residual drift. Numerical analysis was conducted to validate experimental findings, which complied with each other. The numerical model was used to conduct parametric studies to study the effect of backfill density and aspect ratio on seismic response of the proposed precast wall system. The in-plane capacity of walls reduced, while deformation characteristics were unaffected by the increase in backfill density. An increase in aspect ratio leads to a reduction in in-plane capacity and an increase in drift. Curves between the ratio of in-plane yield capacity and design shear load of walls are proposed for the backfill density, which may be adopted to determine the in-plane yield capacity of the basement walls based on their design shear.

关键词： precast wall     basement wall     out-of-plane response     quasi-static test     sand backfill     seismic parameters    

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Numerical evaluation of group-pile foundation subjected to cyclic horizontal load

Youngji JIN, Xiaohua BAO, Yoshimitsu KONDO, Feng ZHANG,

《结构与土木工程前沿（英文）》 2010年 第4卷 第2期   页码 196-207 doi: 10.1007/s11709-010-0021-6

摘要： In this paper, three-dimensional (3D) finite element analyses of a real-scale group-pile foundation subjected to horizontal cyclic loading are conducted using a program named DBLEAVES. In the simulations, nonlinear behaviors of ground and piles are described by subloading model and the axial-force dependent model (AFD model) which considered the axial-force dependency in the nonlinear moment-curvature relations. In order to consider the influence of an effective stress path on the prediction of the group-pile foundation, the analyses are conducted within the framework of the soil-water coupling method with finite-difference and finite-element regime. The material parameters of soils are determined based on conventional triaxial drained compression tests on undisturbed and remolded specimens. The applicability of the proposed numerical method is encouraging, and therefore, it is quite confident to say that the method can be used to predict the mechanical behaviors of group-pile foundation to a satisfactory accuracy, particularly with the effective stress analysis.

关键词： group-pile foundation     real-scale cyclic loading test     three-dimensional finite element method (3D-FEM)     soil-water coupling analysis     undisturbed and remolded specimens    

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Compressive and cyclic flexural response of double-hooked-end steel fiber reinforced concrete

Demewoz W. MENNA; Aikaterini S. GENIKOMSOU; Mark F. GREEN

《结构与土木工程前沿（英文）》 2022年 第16卷 第9期   页码 1104-1126 doi: 10.1007/s11709-022-0845-x

摘要： Recent developments on high-performance double-hooked-end steel fibers have enhanced the wide applications of steel fiber reinforced concrete (SFRC). This study presents the compressive properties and the cyclic flexural performance of the SFRC that were experimentally examined. Three different double-hooked-end steel fibers at 0.25%, 0.5%, 0.75%, and 1% volume fractions were considered. All fiber types had similar length to diameter ratios, while the first two fiber types had similar anchorage mechanisms (4D) and tensile strength and the third type had different anchorage mechanism (5D) and a higher tensile strength. The increased volumetric ratio of the fibers increased the post-peak compressive strain (ductility), the tensile strength, and the cyclic flexural strength and cumulative energy dissipation characteristics of the SFRC. Among the 4D fibers, the mixtures with the larger steel fibers showed higher flexural strength and more energy dissipation compared to the SFRCs with smaller size fibers. For 1% steel fiber dosage, 4D and 5D specimens showed similar cyclic flexural responses. Finally, a 3D finite element model that can predict the monotonic and cyclic flexural responses of the double-hooked-end SFRC was developed. The calibration process considered the results obtained from the inverse analysis to determine the tensile behavior of the SFRC.

关键词： steel fiber reinforced concrete     fiber geometry     cyclic loading     energy dissipation     finite element modeling     inverse analysis    

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Displacement-based seismic design of high-strength concrete frame columns

ZHANG Guojun, LIU Jianxin, LU Xilin

《结构与土木工程前沿（英文）》 2008年 第2卷 第1期   页码 93-101 doi: 10.1007/s11709-008-0006-x

摘要： Based on the testing results of 108 high-strength concrete columns under constant axial loading and horizontal cyclic loading, the relations between the drift ratio at yield, the maximum displacement drift, the limiting displacement drift, the ductility ratio of testing columns and shear span-to-depth ratio, axial compression ratio, confining reinforcement characteristic values, the ratio of cover area to confined core area as well as longitudinal reinforcement ratio are discussed in this paper. Then the relations between limiting displacement drifts and axial compression ratio, confining reinforcement characteristic values and the ratio of cover area to confined core area are analytically regressed. Subsequently the relations between confining reinforcement characteristic values and axial compression ratio, the limiting displacement drift, and the practical formula used to calculate confining reinforcement characteristic values are put forward. In the end the minimum confining reinforcement characteristic values in the dense hoop regions of high-strength concrete columns are presented by comparatively analysis, and compared with ones in the design code (GB 50010-2002, P. R. China).

关键词： horizontal cyclic     longitudinal reinforcement     design     loading     constant    

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Start-up of PN-anammox system under low inoculation quantity and its restoration after low-loading rate

Guoliang Zhang, Liang Zhang, Xiaoyu Han, Shujun Zhang, Yongzhen Peng

《环境科学与工程前沿（英文）》 2021年 第15卷 第2期 doi: 10.1007/s11783-020-1324-z

摘要： Abstract • PN-A was start-up under low inoculation amount and a higher NRR was achieved. • PN-anammox system was successfully restored by aggressive sludge discharge. • Increase in granular sludge was the important factor to rapid recovery. • Enrichment of AOB and AnAOB in granular sludge favors the stable operation. Partial nitritation (PN)-anaerobic ammonium oxidation (anammox) is a promising pathway for the biological treatment of wastewater. However, the destruction of the system caused by excessive accumulation of nitrate in long-term operation remains a challenge. In this study, PN-anammox was initialized with low inoculation quantity in an air-lift reactor. The nitrogen removal rate of 0.71 kgN/(m3·d) was obtained, which was far higher than the seed sludge (0.3 kgN/(m3·d)). Thereafter, excess nitrate build-up was observed under low-loading conditions, and recovery strategies for the PN-anammox system were investigated. Experimental results suggest that increasing the nitrogen loading rate as well as the concentration of free ammonium failed to effectively suppress the nitrite oxidation bacteria (NOB) after the PN-anammox system was disrupted. Afterwards, effluent back-flow was added into the reactor to control the up-flow velocity. As a result, an aggressive discharge of sludge that promoted the synergetic growth of functional bacteria was achieved, leading to the successful restoration of the PN-anammox system. The partial nitritation and anammox activity were in balance, and an increase in nitrogen removal rate up to 1.07 kgN/(m3·d) was obtained with a nitrogen removal efficiency of 82.4% after recovery. Besides, the proportion of granular sludge (over 200 mm) increased from 33.67% to 82.82%. Ammonium oxidation bacteria (AOB) along with anammox bacteria were enriched in the granular sludge during the recovery period, which was crucial for the recovery and stable operation of the PN-anammox system.

关键词： PN-anammox     Granular sludge     Excess nitrate build-up     Recovery strategy for partial nitrification     Aggressive discharge of sludge    

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Experimental study on slender buckling-restrained knee braces with round steel bar cores

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 99-121 doi: 10.1007/s11709-022-0875-4

摘要： This study aimed to investigate a novel slender buckling-restrained knee brace damper (BRKB) for welded and weld-free steel framing systems. The proposed BRKB adopts steel bar cores connected by a central coupler and restrained by tube buckling restrainers with a cover tube supporter. The advantages of the proposed damper include easy assembly compared to conventional buckling restrained braces, and high architectural flexibility for the retrofitting of large-span weld-free or welded steel moment-resisting systems. Specifically, by increasing the number of contraction allowances, undesirable failure mechanisms that are global instability and local buckling of the restrainer ends can be effectively suppressed because the more uniform plastic deformation of the core bar can be achieved longitudinally. In this study, displacement-controlled compression and cyclic loading tests were carried out to investigate the deformation capacities of the proposed BRKBs. Structural performance metrics associated with both loading tests, such as strength capacities, strains at the cover tubes and buckling restrainers, and hysteretic behaviors of the proposed damper under cyclic loads, were measured and discussed. Test results revealed that the geometrical characteristics of the cover tubes and adopted contraction allowances at the dampers play essential roles in their load-bearing capacities.

关键词： weld-free beam-to-column connections     moment-resisting frame     cyclic and compression loading tests     buckling-restrained knee brace     cover tube    

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地震波荷载作用下类岩石试样波形传播和裂纹扩展数值模拟研究 Article

张晓平, 张旗, 刘泉声, 肖锐铧

《工程（英文）》 2022年 第17卷 第10期   页码 140-150 doi: 10.1016/j.eng.2021.09.023

摘要：

地震之后伴随的余震在地震诱发滑坡灾害中起着重要作用。主震中已对岩体造成了不同程度的损伤，这使得余震过程中岩体裂纹进一步发展和相互交互贯通过程更复杂。为了探究地震波荷载对类岩石试样破裂失稳过程的影响，通过采用基于颗粒元黏结模型（bonded-particle model, BPM）的数值方法，研究了在两个正交方向上循环地震波加载作用下的波传播规律和裂纹扩展过程。结果表明，由于计算试样尺寸（76 mm × 152 mm）远小于地震波纵波波长，试样内未观察到波的透射和反射现象；加载产生的裂纹均为微张拉裂纹，重复轴向地震波加载不能使微张拉裂纹进一步扩展；只有当加载方向由轴向变为侧向，再由侧向变为轴向时，裂纹才会进一步扩展并最终导致试样破坏。本文揭示了在地震波反射作用及余震作用下，大量滑坡灾害发生的内在机理。

关键词： 地震波     循环荷载     裂纹扩展     黏结模型    

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Joint slip investigation based on finite element modelling verified by experimental results on wind turbine lattice towers

Saleh YAGHOOBI, Ahmad SHOOSHTARI

《结构与土木工程前沿（英文）》 2018年 第12卷 第3期   页码 341-351 doi: 10.1007/s11709-017-0393-y

摘要：

Slippage corresponds to the relative displacement of a bolted joint subjected to shear loads since the construction clearance between the bolt shank and the bolthole at assembly can cause joint slip. Deflections of towers with joint slippage effects is up to 1.9 times greater than the displacements obtained by linear analytical methods. In this study, 8 different types of joints are modelled and studied in the finite element program, and the results are verified by the experimental results which have been done in the laboratory. Moreover, several types of joints have been modelled and studied and load-deformation curves have also been presented. Finally, joint slip data for different types of angles, bolt diameter and bolt arrangements are generated. Thereupon, damping ratios (z) for different types of connections are reported. The study can be useful to help in designing of wind turbine towers with a higher level of accuracy and safety.

关键词： Joint slip     cyclic loading     Finite element modelling     Experimental joint behavior     damping ratios (   

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Fast determination of tobramycin by reversed-phase ion-pair high performance liquid chromatography with

Liang ZHU, Jingkang WANG

《化学科学与工程前沿（英文）》 2013年 第7卷 第3期   页码 322-328 doi: 10.1007/s11705-013-1348-z

摘要： A simple and direct method without a derivation step for routine analysis of tobramycin has been developed. This method used reversed-phase ion-pair high performance liquid chromatography (HPLC) with a refractive index (RI) detector and a C18 column which is stable at pH above 1.00. The presence of 4.50 mg·mL trifluoroacetic acid (TFA) in the mobile phase improved the protonation of tobramycin and the formation of ion-pairs, and thus reduced its hydrophility. This unique separation–detection combination showed good linearity with correlation coefficients 0.9996 in the concentration range of 0.25–2.50 mg·mL . The quantitation limit and detection limit were determined to be 0.23 mg·mL and 0.071 mg·mL , respectively. Tobramycin was recovered in 98.00%, 98.84% and 99.64% for tobramycin solutions at concentrations of 2.25 mg·mL , 1.50 mg·mL and 0.75 mg·mL , respectively. The relative standard deviations for six spiked samples ranged from 0.20% to 2.40%, indicating a good reproducibility of this method.

关键词： tobramycin     aminoglycoside     refractive index detector     high-performance liquid chromatography     ion-pairing    

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Fragility assessment of wood sheathing panels and roof-to-wall connections subjected to wind loading

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 867-876 doi: 10.1007/s11709-021-0745-5

摘要： The performance of the wood-frame buildings after tornadoes has shown that the majority of the wind damage resulted from building envelope failure most typically due to the loss of the roof. To assess the performance and the reliability of low-rise wood-frame residential buildings with a focus on the roofs, fragility analysis can be used to estimate the probability of failure of a roof when constructed with specified nails and sheathing sizes. Thus, this paper examines the fragility of specific types of nails, roof-to-wall (RW) connection details, and sheathing sizes based on the damaged roofs that were previously assessed in the Dunrobin area in Ottawa (Ontario) that was hit with an Enhanced Fujita (EF3) tornado on September 21, 2018. The presented fragility analysis considers four scenarios, including different sheathing and nail sizes. Dead loads, wind loads, and resistance on the sheathing panels were compiled and analyzed to determine the failure of the examined roofs. The eight fragility models suggest that the safest roof sheathing (RS) is the 1.22 m × 1.22 m sheathing panel with 8 d nails, and the safest RW connections is achieved by using H2.5 hurricane clips.

关键词： tornadoes     wind loads     low-rise buildings     fragility analysis     risk assessment     structural failures    

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Isogeometric analysis of coupled thermo-elastodynamic problems under cyclic thermal shock

Asghar AMANI DASHLEJEH

《结构与土木工程前沿（英文）》 2019年 第13卷 第2期   页码 397-405 doi: 10.1007/s11709-018-0473-7

摘要： The isogeometric analysis (IGA) method was extended for the solution of the coupled thermo-elastodynamic equations. The dimensionless formulation was accepted in discretization of the uncoupled and coupled thermoelasticity equations and the Generalized Newmark method was used in the time integration procedure. First, the performance of the proposed method was verified against a two-dimensional benchmark example subjected to constant thermal shock with available exact analytical solutions. Then a two-dimensional half-space benchmark example under thermal shock was solved. Finally, cyclic thermal shock (CTS) loading was applied on the half-space problem. The results dedicated that IGA can be used as a suitable approach in the analysis of the general thermomechanical problems.

关键词： isogeometric analysis     coupled thermo-elastodynamic     dynamic analysis     generalized newmark     cyclic thermal shock    

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Prediction of cyclic large plasticity for prestrained structural steel using only tensile coupon tests

Liang-Jiu JIA, Tsuyoshi KOYAMA, Hitoshi KUWAMURA

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 466-476 doi: 10.1007/s11709-013-0219-5

摘要： Cold-formed steel members, which experience complicated prestrain histories, are frequently applied in structural engineering. This paper aims to predict cyclic plasticity of structural steels with tensile and compressive prestrain. Monotonic and cyclic tests on hourglass specimens with tensile and compressive prestrain are conducted, and compared with numerical simulations using the Chaboche model. Two approaches are taken in the simulation. The first requires only the monotonic tensile test data from the prestrained steels, and the second requires both the monotonic tensile test data from the virgin steel and the prestrain histories. The first approach slightly overestimates the compressive stress for specimens with tensile prestrain, while the second approach is able to accurately predict the cyclic plasticity in specimens with tensile and compressive prestrain.

关键词： cyclic plasticity     prestrain     Chaboche model     mild steel    

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循环双谱及在周期平稳类故障中的应用

苏中元,贾民平,许飞云,胡建中

《中国工程科学》 2006年 第8卷 第9期   页码 57-60

摘要：

论述了未知循环频率的周期平稳信号循环双谱的估计方法；研究了在循环双谱的循环累积量计算中涉及变量的简化存储方法，提出了该变量矩阵是对称阵，通过算法可以三角阵的元素来表述，克服了循环双谱传统估计方法计算量较大的缺陷，提高了运算效率；提出了循环双谱对调相故障信号的分析能力，以及对加性噪声的处理能力，仿真并验证了该方法的有效性，并将其应用于旋转机械状态分析。

关键词： 周期平稳     循环双谱     滞后积    

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标题 作者 时间 类型 操作

Lateral shear performance of sheathed post-and-beam wooden structures with small panels

期刊论文

An enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxialloading conditions

Mohammad Reza AZADI KAKAVAND, Ertugrul TACIROGLU

期刊论文

Seismic response of precast reinforced concrete wall subjected to cyclic in-plane and constant out-of-planeloading

期刊论文

Numerical evaluation of group-pile foundation subjected to cyclic horizontal load

Youngji JIN, Xiaohua BAO, Yoshimitsu KONDO, Feng ZHANG,

期刊论文

Compressive and cyclic flexural response of double-hooked-end steel fiber reinforced concrete

Demewoz W. MENNA; Aikaterini S. GENIKOMSOU; Mark F. GREEN

期刊论文

Displacement-based seismic design of high-strength concrete frame columns

ZHANG Guojun, LIU Jianxin, LU Xilin

期刊论文

Start-up of PN-anammox system under low inoculation quantity and its restoration after low-loading rate

Guoliang Zhang, Liang Zhang, Xiaoyu Han, Shujun Zhang, Yongzhen Peng

期刊论文

Experimental study on slender buckling-restrained knee braces with round steel bar cores

期刊论文

地震波荷载作用下类岩石试样波形传播和裂纹扩展数值模拟研究

张晓平, 张旗, 刘泉声, 肖锐铧

期刊论文

Joint slip investigation based on finite element modelling verified by experimental results on wind turbine lattice towers

Saleh YAGHOOBI, Ahmad SHOOSHTARI

期刊论文

Fast determination of tobramycin by reversed-phase ion-pair high performance liquid chromatography with

Liang ZHU, Jingkang WANG

期刊论文

Fragility assessment of wood sheathing panels and roof-to-wall connections subjected to wind loading

期刊论文

Isogeometric analysis of coupled thermo-elastodynamic problems under cyclic thermal shock

Asghar AMANI DASHLEJEH

期刊论文

Prediction of cyclic large plasticity for prestrained structural steel using only tensile coupon tests

Liang-Jiu JIA, Tsuyoshi KOYAMA, Hitoshi KUWAMURA

期刊论文

循环双谱及在周期平稳类故障中的应用

苏中元,贾民平,许飞云,胡建中

期刊论文