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Sensitivity analysis of the deterioration of concrete strength in marine environment to multiple corrosive

《结构与土木工程前沿(英文)》 2023年 第17卷 第2期   页码 175-190 doi: 10.1007/s11709-021-0791-z

摘要: The corrosion degradation behavior of concrete materials plays a crucial role in the change of its mechanical properties under multi-ion interaction in the marine environment. In this study, the variation in the macro-physical and mechanical properties of concrete with corrosion time is investigated, and the source of micro-corrosion products under different salt solutions in seawater are analyzed. Regardless of the continuous hydration effect of concrete, the damage effects of various corrosive ions (Cl, SO42, and Mg2+, etc.) on the tensile and compressive strength of concrete are discussed based on measurement in different salt solutions. The sensitivity analysis method for concrete strength is used to quantitatively analyze the sensitivity of concrete strength to the effects of each ion in a multi-salt solution without considering the influence of continued hydration. The quantitative results indicate that the addition of Cl can weaken the corrosion effect of SO42 by about 20%, while the addition of Mg2+ or Mg2+ and Cl can strengthen it by 10%–20% during a 600-d corrosion process.

关键词: sensitivity analysis     concrete strength     corrosion deterioration     multi-ion interaction     marine environment    

Effect of environment change on the strength of cement/lime treated clays

Takenori HINO, Rui JIA, Seiji SUEYOSHI, Tri HARIANTO

《结构与土木工程前沿(英文)》 2012年 第6卷 第2期   页码 153-165 doi: 10.1007/s11709-012-0153-y

摘要: The field strengths of cement/lime treated clays were investigated in the Ariake Sea costal lowlands. The deposition environment of the investigation location is reconstructed and compared to the present ground environment. The mechanism of the ground environment change and its effect on the strength of cement/lime treated soil are discussed. The strength development of improved soil using cement and lime in different curing environments was investigated in the laboratory for studying the effect of environment change on the strength also. It has been found that the strength deterioration of improved soil in deep mixing method is due to 1) the ground environment change due to the secondary oxidation which results in low pH value and high organic content, and 2) the formations of the porous structures result from the elution of the calcium ions. Also, it has been found that the initial strength increase of the improved soil is related to the dissolved silica and that the dissolution of the silica in clay minerals needs long time. When examining the long-term strength for preventing strength degradation, the effect of environmental change has to be considered. The importance of measuring pH and oxidation-reduction potential (ORP) of the ground for cement/lime solidification method is explained.

关键词: soil solidification     ground environment     strength deterioration     pH     oxidation-reduction potential (ORP)     silica    

Environmental deterioration of farmlands caused by the irrational use of agricultural technologies

Xubin Pan,Zhongkui Luo,Yongbo Liu

《环境科学与工程前沿(英文)》 2016年 第10卷 第4期 doi: 10.1007/s11783-016-0865-7

摘要: Without considering the ecosystem-dependence of agricultural production, irrational use of agricultural technologies could bring only short-term economic benefits but leave long-term environmental deterioration. If some agricultural lands have to be abandoned because of these technologies such as chemical films or groundwater depletion, it will aggravate the burden of remaining lands for maintaining or enhancing production. Thus, agricultural production should be a part of public services, requiring the consideration of interests of different stakeholders and sustainability.

关键词: agricultural film     groundwater exploitation     food security     environmental cost    

基于全寿命劣化分析的海底盾构隧道管片安全保障对策研究

刘四进,何川,孙齐,封坤

《中国工程科学》 2017年 第19卷 第6期   页码 52-60 doi: 10.15302/J-SSCAE-2017.06.008

摘要:

管片接头是海底盾构隧道衬砌结构的薄弱环节,在海水的高压力与腐蚀环境的持续耦合作用下,其劣化性能严重影响整个海底盾构隧道衬砌结构的安全。本文在分析既有管片接头侵蚀劣化研究成果的基础上,引入隧道服役时间因素,建立可实现海水压力渗透与氯离子侵蚀的管片接头全寿命侵蚀劣化分析模型,分析了全寿命周期(100年)内海底隧道管片接头的渐进式侵蚀劣化规律,重点研究了海水压力与氯离子浓度对管片接头侵蚀劣化及钢筋锈蚀的影响,并基于全寿命周期内的侵蚀劣化分析,提出保障海底盾构隧道管片衬砌结构长期安全的最经济、最合理的对策。

关键词: 盾构隧道     安全保障     劣化分析     离子侵蚀     管片接头    

Evaluating the material strength from fracture angle under uniaxial loading

Jitang FAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 288-293 doi: 10.1007/s11709-018-0480-8

摘要: The most common experimental methods of measuring material strength are the uniaxial compressive and tensile tests. Generally, shearing fracture model occurs in both the tests. Compressive strength is higher than tensile strength for a material. Shearing fracture angle is smaller than 45° under uniaxial compression and greater than 45° under uniaxial tension. In this work, a unified relation of material strength under uniaxial compression and tension is developed by correlating the shearing fracture angle in theory. This constitutive relation is quantitatively illustrated by a function for analyzing the material strength from shear fracture angle. A computational simulation is conducted to validate this theoretical function. It is full of interest to give a scientific illustration for designing the high-strength materials and engineering structures.

关键词: strength     fracture     mechanics    

Evaluating effect of chloride attack and concrete cover on the probability of corrosion

Sanjeev Kumar VERMA, Sudhir Singh BHADAURIA, Saleem AKHTAR

《结构与土木工程前沿(英文)》 2013年 第7卷 第4期   页码 379-390 doi: 10.1007/s11709-013-0223-9

摘要: Corrosion of reinforced concrete (RC) structures is one of the significant causes of deterioration of reinforced concrete (RC) structures. Chlorination is a major process governing the initiation and advancement of the injurious corrosion of steel bars. Now, several researches on the chlorination of concrete structures have been ongoing around the world. Present article reviews several recently performed chlorination studies, and from results of a field survey evaluates the effect of chloride content on the probability of corrosion and the influence of concrete compressive strength on the chloride content and penetration, also evaluates the effect of concrete cover over the chloride content of the RC structures at rebar depth and on the probability of corrosion.

关键词: concrete     chloride     reinforcement     corrosion     deterioration     cover    

The effects of interfacial strength on fractured microcapsule

Luthfi Muhammad MAULUDIN, Chahmi OUCIF

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 353-363 doi: 10.1007/s11709-018-0469-3

摘要: The effects of interfacial strength on fractured microcapsule are investigated numerically. The interaction between crack and microcapsule embedded in mortar matrix is modeled based on cohesive approach. The microcapsules are modelled with variation of core-shell thickness ratio and potential cracks are represented by pre-inserted cohesive elements along the element boundaries of the mortar matrix, microcapsules core, microcapsule shell, and at the interfaces between these phases. Special attention is given to the effects of cohesive fracture on the microcapsule interface, namely fracture strength, on the load carrying capacity and fracture probability of the microcapsule. The effect of fracture properties on microcapsule is found to be significant factor on the load carrying capacity and crack propagation characteristics. Regardless of core-shell thickness ratio of microcapsule, the load carrying capacity of self-healing material under tension increases as interfacial strength of microcapsule shell increases. In addition, given the fixed fracture strength of the interface of microcapsule shell, the higher the ratio core-shell thickness, the higher the probability of microcapsules being fractured.

关键词: interfacial strength     cohesive elements     microcapsule     core-shell thickness ratio     fracture properties    

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    

The strength–dilatancy characteristics embraced in hypoplasticity

Zhongzhi FU, Sihong LIU, Zijian WANG

《结构与土木工程前沿(英文)》 2013年 第7卷 第2期   页码 178-187 doi: 10.1007/s11709-013-0191-0

摘要: The strength-dilatancy characteristics of frictional materials embraced in the hypoplastic model proposed by Gudehus and Bauer are investigated and compared with the revised model suggested by Huang. In the latter the deviatoric stress in the model by Gudehus and Bauer is replaced by a transformed stress according to the stress transformation technique proposed by Matsuoka. The flow rule, the failure state surface equation and the strength-dilatancy relationship embraced in both models are derived analytically. The performance of the two hypoplastic models in reproducing the relationship between the peak strength and the corresponding dilation rate under triaxial compression, plane compression and plane shearing are then extensively investigated and compared with experimental results and with the predictions made by particular classical stress-dilatancy theories. Numerical investigations show that the performance in reproducing the strength-dilatancy relationship is quite satisfactory under triaxial compression stress state in both models and the predictions made by the transformed stress based model are closer to the results obtained from classical stress-dilatancy theories for plane compression and plane shearing problems.

关键词: strength     dilatancy     hypoplasticity     frictional materials    

Slender reinforced concrete shear walls with high-strength concrete boundary elements

《结构与土木工程前沿(英文)》 2023年 第17卷 第1期   页码 138-151 doi: 10.1007/s11709-022-0897-y

摘要: Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词: slender walls     high-strength concrete     rectangular and barbell-shaped walls     cold joints    

碱硅酸反应与碱碳酸盐反应

唐明述

《中国工程科学》 2000年 第2卷 第1期   页码 34-40

摘要:

碱集料反应(AAR)可分为两类,即碱硅酸反应(ASR)与碱碳酸盐反应(ACR)。二者的共同点是与碱发生的化学反应可导致混凝土中集料的体积增大,从而可能使混凝土甚至整个建筑物或构筑物发生膨胀开裂。文章着重从膨胀过程和机理以及岩石的结构特征探讨二者的特性与差异。ASR类型岩石具有碱活性的前提条件是较低的二氧化硅结晶完整度。只有隐晶质、微晶质、玻璃质或发生过应变的二氧化硅才会具有较高的化学活性,导致混凝土破坏。通过系统研究证实,对碱碳酸盐反应,虽然结晶的完整程度以及白云石(CaCO3·MgCO3)分子式中Ca/Mg比也将影响其与碱反应的速率,但起决定作用的是白云石晶体的尺寸及其在岩石中的分布状态和被基质包围的紧密程度。从微观结构得出的这些特征将有助于加深对碱集料反应膨胀机理的认识。文中还介绍了形成活性白云石的地质环境和碱硅酸反应与碱碳酸盐反应的区分方法。

关键词:     集料     硅酸     碳酸盐     混凝土开裂     机理    

Calculation methods of the crack width and deformation for concrete beams with high-strength steel bars

Jianmin ZHOU, Shuo CHEN, Yang CHEN

《结构与土木工程前沿(英文)》 2013年 第7卷 第3期   页码 316-324 doi: 10.1007/s11709-013-0211-0

摘要: Three groups of concrete beams reinforced with high-strength steel bars were tested, and the crack width and deformation of the specimens were observed and studied. To facilitate the predictions, two simplified formulations according to a theory developed by the first author were proposed. The advantages of the formulations were verified by the test data and compared with several formulas in different codes.

关键词: concrete beam     high-strength steel bar     crack width     deformation    

Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

Hakan T TURKER

《结构与土木工程前沿(英文)》 2022年 第16卷 第8期   页码 1017-1028 doi: 10.1007/s11709-022-0871-8

摘要: The effect of size on the biaxial flexural strength (BFS) of Portland cement mortar was investigated by using the recently proposed triangular plate method (TPM). An experimental program was conceived to study the size effect by keeping a constant water-cement ratio of 0.485, cement-sand ratio of 1:2.75, and using unreinforced triangular mortar plates of five different thicknesses and seven different side lengths. The BFS of the produced specimens was tested, and variations of BFS depending on specimen thickness and side length were determined. The results indicated that increases in triangular plate specimen side length and specimen thickness led to a decrease in the BFS of Portland cement mortar. The effect of specimen length increase on BFS was more significant than on the effect of the specimen thickness. The variations in specimens’ thickness indicated a deterministic Type I size effect, while the variations in specimens’ length showed an energetic-statistical Type I size effect.

关键词: testing     apparatus & methods     plain concrete     tensile properties     biaxial flexural strength     triangular plate method    

Structure improvement and strength finite element analysis of VHP welded rotor of 700°C USC steam turbine

Jinyuan SHI,Zhicheng DENG,Yong WANG,Yu YANG

《能源前沿(英文)》 2016年 第10卷 第1期   页码 88-104 doi: 10.1007/s11708-015-0387-1

摘要: The optimized structure strength design and finite element analysis method for very high pressure (VHP) rotors of the 700°C ultra-super-critical (USC) steam turbine are presented. The main parameters of steam and the steam thermal parameters of blade stages of VHP welded rotors as well as the start and shutdown curves of the steam turbine are determined. The structure design feature, the mechanical models and the typical position of stress analysis of the VHP welded rotors are introduced. The steady and transient finite element analysis are implemented for steady condition, start and shutdown process, including steady rated condition, 110% rated speed, 120% rated speed, cold start, warm start, hot start, very hot start, sliding-pressure shutdown, normal shutdown and emergency shutdown, to obtain the temperature and stress distribution as well as the stress ratio of the welded rotor. The strength design criteria and strength analysis results of the welded rotor are given. The results show that the strength design of improved structure of the VHP welded rotor of the 700°C USC steam turbine is safe at the steady condition and during the transient start or shutdown process.

关键词: 700°C ultra-super-critical unit     steam turbine     very high pressure rotor     structure strength design     strength design criteria     finite element analysis    

An experimental study on the flexural behavior of heavily steel reinforced beams with high-strength concrete

Yasser SHARIFI, Ali Akbar MAGHSOUDI

《结构与土木工程前沿(英文)》 2014年 第8卷 第1期   页码 46-56 doi: 10.1007/s11709-014-0237-y

摘要: In recent years, an emerging technology termed high-strength concrete (HSC) has become popular in construction industry. Present study describes an experimental research on the behavior of high-strength concrete beams in ultimate and service state. Six simply supported beams were tested, by applying comprising two symmetric concentrated loads. Tests are reported in this study on the flexural behavior of high-strength reinforced concrete (HSRC) beams made with coarse and fine aggregate together with Microsilica. Test parameter considered includes effect of being compressive reinforcement. Based on the obtained results, the behavior of such members is more deeply reviewed. Also a comparison between theoretical and experimental results is reported here. The beams were made from concrete having compressive strength of 66.81–77.72 N/mm and percentage reinforcement ratio ( / ) in the range of 0.56% – 1.20%. The ultimate moment for the tested beams was found to be in a good agreement with that of the predicted ultimate moment based on ACI 318-11, ACI 363 and CSA-04 provisions. The predicted deflection based classical formulation based on code provisions for serviceability requirements is found to underestimate the maximum deflection of HSC reinforced beams at service load.

关键词: high-strength concrete (HSC) members     flexural behavior     reinforced concrete     experimental results     ultimate moment    

标题 作者 时间 类型 操作

Sensitivity analysis of the deterioration of concrete strength in marine environment to multiple corrosive

期刊论文

Effect of environment change on the strength of cement/lime treated clays

Takenori HINO, Rui JIA, Seiji SUEYOSHI, Tri HARIANTO

期刊论文

Environmental deterioration of farmlands caused by the irrational use of agricultural technologies

Xubin Pan,Zhongkui Luo,Yongbo Liu

期刊论文

基于全寿命劣化分析的海底盾构隧道管片安全保障对策研究

刘四进,何川,孙齐,封坤

期刊论文

Evaluating the material strength from fracture angle under uniaxial loading

Jitang FAN

期刊论文

Evaluating effect of chloride attack and concrete cover on the probability of corrosion

Sanjeev Kumar VERMA, Sudhir Singh BHADAURIA, Saleem AKHTAR

期刊论文

The effects of interfacial strength on fractured microcapsule

Luthfi Muhammad MAULUDIN, Chahmi OUCIF

期刊论文

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

期刊论文

The strength–dilatancy characteristics embraced in hypoplasticity

Zhongzhi FU, Sihong LIU, Zijian WANG

期刊论文

Slender reinforced concrete shear walls with high-strength concrete boundary elements

期刊论文

碱硅酸反应与碱碳酸盐反应

唐明述

期刊论文

Calculation methods of the crack width and deformation for concrete beams with high-strength steel bars

Jianmin ZHOU, Shuo CHEN, Yang CHEN

期刊论文

Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

Hakan T TURKER

期刊论文

Structure improvement and strength finite element analysis of VHP welded rotor of 700°C USC steam turbine

Jinyuan SHI,Zhicheng DENG,Yong WANG,Yu YANG

期刊论文

An experimental study on the flexural behavior of heavily steel reinforced beams with high-strength concrete

Yasser SHARIFI, Ali Akbar MAGHSOUDI

期刊论文