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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    

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    

Seismic behavior of cantilever wall embedded in dry and saturated sand

Sanku KONAI, Aniruddha SENGUPTA, Kousik DEB

《结构与土木工程前沿(英文)》 2020年 第14卷 第3期   页码 690-705 doi: 10.1007/s11709-020-0615-6

摘要: The embedded cantilever retaining walls are often required for excavation to construct the underground facilities. Significant numbers of numerical and experimental studies have been performed to understand the behavior of embedded cantilever retaining walls under static condition. However, very limited studies have been conducted on the behavior of embedded retaining walls under seismic condition. In this paper, the behavior of a small scale model embedded cantilever retaining wall in dry and saturated sand under seismic loading condition is investigated by shake table tests in the laboratory and numerically using software FLAC2D. The embedded cantilever walls are subjected to sinusoidal dynamic motions. The behaviors of the cantilever walls in terms of lateral displacement and bending moment are studied with the variation of the two important design parameters, peak amplitude of the base motions and excavation depth. The variation of the pore water pressures within the sand is also observed in the cases of saturated sand. The maximum lateral displacement of a cantilever wall due to seismic loading is below 1% of the total height of the wall in dry sand, but in case of saturated sand, it can go up to 12.75% of the total height of the wall.

关键词: embedded cantilever wall     shake table test     FLAC2D     seismic loading     saturated and dry sand    

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    

enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxial loading

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    

Geotechnical forensic investigation of a slope failure on silty clay soil—A case study

Mohammad Abubakar NAVEED, Zulfiqar ALI, Abdul QADIR, Umar Naveed LATIF, Saad HAMID, Umar SARWAR

《结构与土木工程前沿(英文)》 2020年 第14卷 第2期   页码 501-517 doi: 10.1007/s11709-020-0610-y

摘要: Qila Bala Hisar is one of the noteworthy places of Peshawar, Khyber Pakhtunkhwa. The fort was constructed on a filled ground during the 18th century and it was renovated several times by the occupants ever since. Recently, due to an earthquake of magnitude 7.3, the upper part of the south-western wall of the fort collapsed. The collapse of the wall was attributed to the failure of the retained slope. This research was undertaken to characterize the slope material, study causal factors of failure and evaluate remedial strategy. The investigation involved conventional field and laboratory testing and geophysical investigation using electrical resistivity technique to evaluate the nature of stratum. Also, X-ray Diffraction and Scanning Electron Microscopy was used to study the slope material at a molecular level to evaluate the existence of swelling potential. The analysis has shown that excessive seepage of water caused by the poor maintenance of runoff and sewage drains is the causal factor triggered by the seismic event. A remedial strategy involving soil nails, micro piles and improvement of the surface drainage is recommended.

关键词: forensic geotechnical investigation     slope failure     slope analysis     finite element method     numerical analysis     seismic loading     Qila Bala Hisar    

Reconsideration on the effect of nitrogen on mixed culture polyhydroxyalkanoate production toward high organic loading

Zhiqiang Chen, Lizhi Zhao, Ye Ji, Qinxue Wen, Long Huang

《环境科学与工程前沿(英文)》 2019年 第13卷 第4期 doi: 10.1007/s11783-019-1135-2

摘要:

Effect of nitrogen on mixed culture PHA production was reconsidered.

Enrichment history of PHA accumulating culture was discussed.

Higher PHA content and biomass growth were achieved in presence of nitrogen.

Enrichment strategy toward higher PHA accumulation was investigated.

Microbial community succession in PHA accumulation phase was investigated.

关键词: Polyhydroxyalkanoate (PHA)     Organic loading rate     Nitrogen content     Biomass growth     Enrichment history    

Effect of loading rate on shear strength parameters of mechanically and biologically treated waste

《环境科学与工程前沿(英文)》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1595-7

摘要:

● Mechanical behavior of MBT waste affected by loading rate was investigated.

关键词: Mechanically and biologically treated waste     Landfill     Triaxial test     Loading rate     Axial strain     Shear strength parameter    

Axisymmetric loading on nanoscale multilayered media

《结构与土木工程前沿(英文)》 2023年 第17卷 第1期   页码 152-164 doi: 10.1007/s11709-022-0895-0

摘要: Multilayered nanoscale structures are used in several applications. Because the effect of surface energy becomes nontrivial at such a small scale, a modified continuum theory is required to accurately predict their mechanical behaviors. A Gurtin–Murdoch continuum model of surface elasticity is implemented to establish a computational scheme for investigating an elastic multilayered system under axisymmetric loads with the incorporation of surface/interface energy. Each layer stiffness matrix is derived based on the general solutions of stresses and displacements obtained in the form of the Hankel integral transform. Numerical solutions to the global equation, which are formulated based on the continuity conditions of tractions and displacements across interfaces between layers, yield the displacements at each layer interface and on the top surface of the multilayered medium. The numerical solutions indicate that the elastic responses of multilayered structures are affected significantly by the surface material properties of both the top surface and interfaces, and that they become size dependent. In addition, the indentation problem of a multilayered nanoscale elastic medium under a rigid frictionless cylindrical punch is investigated to demonstrate the application of the proposed solution scheme.

关键词: functionally graded layer     Gurtin–Murdoch surface elasticity     multilayered medium     size dependency     stiffness matrix    

Data-driven approach to solve vertical drain under time-dependent loading

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 696-711 doi: 10.1007/s11709-021-0727-7

摘要: Currently, the vertical drain consolidation problem is solved by numerous analytical solutions, such as time-dependent solutions and linear or parabolic radial drainage in the smear zone, and no artificial intelligence (AI) approach has been applied. Thus, in this study, a new hybrid model based on deep neural networks (DNNs), particle swarm optimization (PSO), and genetic algorithms (GAs) is proposed to solve this problem. The DNN can effectively simulate any sophisticated equation, and the PSO and GA can optimize the selected DNN and improve the performance of the prediction model. In the present study, analytical solutions to vertical drains in the literature are incorporated into the DNN–PSO and DNN–GA prediction models with three different radial drainage patterns in the smear zone under time-dependent loading. The verification performed with analytical solutions and measurements from three full-scale embankment tests revealed promising applications of the proposed approach.

关键词: vertical drain     artificial neural network     time-dependent loading     deep learning network     genetic algorithm     particle swarm optimization    

Comparison and harmonization of building wind loading codes among the Asia-Pacific Economies

Yaojun GE, Shuyang CAO, Xinyang JIN

《结构与土木工程前沿(英文)》 2013年 第7卷 第4期   页码 402-410 doi: 10.1007/s11709-013-0230-x

摘要: This paper reviews wind loading codes and standards in the Asia-Pacific Region, in particular in the 15 countries and areas. A general description of wind loading model is given as a famous wind loading chain described by four variables including velocity pressure, exposure factor, pressure coefficient, and gust response factor. Through the APEC-WW Workshops and the extensive calculations for three examples of low, medium and high rise buildings, these four important variables of wind loads are evaluated and compared with statistical parameters, mean values and coefficients of variation. The main results of the comparison show some differences among the 15 economies, and the reasons and further incorporation are discussed and suggested.

关键词: wind loading     codification     velocity pressure     exposure factor     pressure coefficient     gust response factor    

Effect of strata restraint on seismic performance of prefabricated sidewall joints in fabricated subway

《结构与土木工程前沿(英文)》 2023年 第17卷 第5期   页码 763-779 doi: 10.1007/s11709-023-0917-6

摘要: A disadvantage of the conventional quasi-static test method is that it does not consider the soil restraint effect. A new method to test the seismic performance of prefabricated specimens for underground assembled structures is proposed, which can realistically reflect the strata restraint effect on the underground structure. Laboratory work combined with finite element (FE) analysis is performed in this study. Three full-scale sidewall specimens with different joint forms are designed and fabricated. Indices related to the seismic performance and damage modes are analyzed comprehensively to reveal the mechanism of the strata restraint effect on the prefabricated sidewall components. Test results show that the strata restraint effect effectively improves the energy dissipation capacity, load-bearing capacity, and the recoverability of the internal deformation of the precast sidewall components. However, the strata restraint effect reduces the ductility of the precast sidewall components and aggravates the shear and bending deformations in the core region of the connection joints. Additionally, the strata restraint effect significantly affects the seismic performance and damage mode of the prefabricated sidewall components. An FE model that can be used to conduct a seismic performance study of prefabricated specimens for underground assembled structures is proposed, and its feasibility is verified via comparison with test data.

关键词: underground structures     precast sidewall specimen     seismic test method     bearing capacity     energy dissipation capacity     plastic deformation    

Solution to economic dispatch problem with valve-point loading effect by using catfish PSO algorithm

K. MURALI,T. JAYABARATHI

《能源前沿(英文)》 2014年 第8卷 第3期   页码 290-296 doi: 10.1007/s11708-014-0305-y

摘要: This paper proposes application of a catfish particle swarm optimization (PSO) algorithm to economic dispatch (ED) problems. The ED problems considered in this paper include valve-point loading effect, power balance constraints, and generator limits. The conventional PSO and catfish PSO algorithms are applied to three different test systems and the solutions obtained are compared with each other and with those reported in literature. The comparison of solutions shows that catfish PSO outperforms the conventional PSO and other methods in terms of solution quality though there is a slight increase in computational time.

关键词: economic dispatch (ED)     valve point loading     catfish particle swarm optimization (PSO)     optimization    

Effects of green roof damping and configuration on structural seismic response

《结构与土木工程前沿(英文)》   页码 1133-1144 doi: 10.1007/s11709-023-0959-9

摘要: Sustainable structures are critical for addressing global climate change. Hence, their structural resilience or ability to recover from natural events must be considered comprehensively. Green roofs are a widely used sustainable feature that improve the environment while providing excellent occupant amenity. To expand their usage, their inherent damping and layout sensitivity to seismic performance are investigated in this study. The soil of a green roof can serve as a damper to dissipate the energy generated by earthquakes or other dynamic events. Results of preliminary analysis show that a green roof soil can increase localized damping by 2.5% under both dry and saturated conditions. Based on these findings, nonlinear time-history analyses are conducted on a three-story building in SAP2000 to monitor the structural behavior with and without a green roof. The increased damping in the green roof soil is beneficial to the structural performance, i.e., it reduces the building displacement and acceleration by 10% and 12%, respectively. Additionally, certain configurations are more effective and beneficial to the structural response than others, which suggests the possibility of design optimization. Based on the findings of this study, new methods of modeling and considering green roofs in structural design are established.

关键词: green infrastructure     green roof     structural resilience     seismic design    

Performance-based seismic assessment of a historical masonry arch bridge: Effect of pulse-like excitations

《结构与土木工程前沿(英文)》   页码 855-869 doi: 10.1007/s11709-023-0972-z

摘要: Seismic analysis of historical masonry bridges is important for authorities in all countries hosting such cultural heritage assets. The masonry arch bridge investigated in this study was built during the Roman period and is on the island of Rhodes, in Greece. Fifteen seismic records were considered and categorized as far-field, pulse-like near-field, and non-pulse-like near-field. The earthquake excitations were scaled to a target spectrum, and nonlinear time-history analyses were performed in the transverse direction. The performance levels were introduced based on the pushover curve, and the post-earthquake damage state of the bridge was examined. According to the results, pulse-like near-field events are more damaging than non-pulse-like near-field ground motions. Additionally the bridge is more vulnerable to far-field excitations than near-field events. Furthermore, the structure will suffer extensive post-earthquake damage and must be retrofitted.

关键词: masonry arch bridges     seismic behavior     modal properties     pulse-like records     nonlinear time history analysis    

标题 作者 时间 类型 操作

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

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

ZHANG Guojun, LIU Jianxin, LU Xilin

期刊论文

Seismic behavior of cantilever wall embedded in dry and saturated sand

Sanku KONAI, Aniruddha SENGUPTA, Kousik DEB

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

enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxial loading

Mohammad Reza AZADI KAKAVAND, Ertugrul TACIROGLU

期刊论文

Geotechnical forensic investigation of a slope failure on silty clay soil—A case study

Mohammad Abubakar NAVEED, Zulfiqar ALI, Abdul QADIR, Umar Naveed LATIF, Saad HAMID, Umar SARWAR

期刊论文

Reconsideration on the effect of nitrogen on mixed culture polyhydroxyalkanoate production toward high organic loading

Zhiqiang Chen, Lizhi Zhao, Ye Ji, Qinxue Wen, Long Huang

期刊论文

Effect of loading rate on shear strength parameters of mechanically and biologically treated waste

期刊论文

Axisymmetric loading on nanoscale multilayered media

期刊论文

Data-driven approach to solve vertical drain under time-dependent loading

期刊论文

Comparison and harmonization of building wind loading codes among the Asia-Pacific Economies

Yaojun GE, Shuyang CAO, Xinyang JIN

期刊论文

Effect of strata restraint on seismic performance of prefabricated sidewall joints in fabricated subway

期刊论文

Solution to economic dispatch problem with valve-point loading effect by using catfish PSO algorithm

K. MURALI,T. JAYABARATHI

期刊论文

Effects of green roof damping and configuration on structural seismic response

期刊论文

Performance-based seismic assessment of a historical masonry arch bridge: Effect of pulse-like excitations

期刊论文