钢纤维喷射混凝土配合比试验设计

钢纤维喷射混凝土作永久衬砌，既可加快施工进度，又降低成本，且能显著改善混凝土的抗裂性能、延性、韧性及抗冲击性能，是一种新型复合材料。本文结合工程实例介绍了CF30钢纤维喷射混凝土配合比的整个试验设计过程。     

Experimental investigation of the effect of the bending stiffness of reinforced-concrete piles under lateral load

Conclusions 1. The stress-strain state of the reinforced-concrete-pile/soil system depends on both the elastoplastic properties of the soil, and the pile material.2. The variation in the bending stiffness of the cross section of a reinforced-concrete pile during loading should be accounted for in calculating the lateral load on these piles. Consideration of this factor will make it possible to determine the stress-strain state of the system under consideration more accurately; this will ensure a saving of concrete and reinforcement.Kharkov Institute of Civil Engineers. Kharkov Scientific-Research Institute for the Design and Planning of Industrial Construction. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 9–11, July–August, 1988.     

Behaviours of reinforced-concrete building under tsunami loading

The 26 December 2004 Indian Ocean tsunami caused damage to many buildings and killed a lot of people in several countries that border on the Indian Ocean including Thailand. To understand the behaviour of reinforced-concrete buildings under tsunami loads, a generic one-storey building has been developed from the average values of the structural indices of residential houses in southern Thailand. The generic building has been analysed to capture responses under tsunami hydrodynamic forces. At each inundation depth, the lateral force has been increased until collapse. From results, the resistance of the building was controlled by the shear failure of columns at inundation depths lower than 2.57 m. The lateral resistances controlled by the shear failure were about 258 kN. As the inundation depth increased, locations of loads moved higher and the flexural failure occurred in the columns of the building. At an inundation depth of 3.2 m, the lateral resistance decreased about 50% from that controlled by the shear failure.     

夏季控制商品混凝土坍落度损失的措施

混凝土坍落度是测定混凝土和易性、流动性的重要指标,是混凝土工作度的反映。当混凝土拌合物随着水化反应的不断进行和在外界条件的影响下(如水份蒸发,温度升高等),使水泥颗粒产生凝聚随着时间的推移,拌合物逐渐失去原来具有的流动性,称为混凝土坍落度损失。     

基于SHPB试验的钢纤混凝土损伤研究

通过SHPB试验得到压杆中入射波与透射波应变随时间变化的时程曲线,求得在不同应变率条件下被测混凝土材料的应力与应变的关系,然后对混凝土的损伤因子采用Weibull函数,通过拟合得到了混凝土材料在冲击载荷下损伤因子的变化,确定了影响损伤因子变化的参数.对透射波的测量采用了半导体应变计技术,测量结果表明,半导体应变计技术可以较好的用在较弱的透射波测量.     

混凝土排水管道施工要点

根据现场实际施工的经验积累,总结出了从沟槽开挖、垫层施工、管道铺设、管道气测试、混凝土窨井浇筑、混凝土窨井水测试、土方回填等方面需要注意的施工要点.     

混凝土冻融变形的试验研究

进行了砂浆饱和水试件的水中和空气冻融试验,并通过测量砂浆试件中心的冻融变形和温度变化,以及对所测数据的分析,明确了混凝土的冻结收缩、膨胀变形的发展规律。同时,通过测量试件冻融循环前后动弹性模量的变化,得出相对动弹性模量可以间接地反映试件的残留冻融变形的大小。     

人工气候与恒电流通电法加速锈蚀钢筋混凝土梁的结构性能比较研究

采用人工气候环境和恒电流通电法对钢筋混凝土梁进行加速锈蚀试验,以钢筋混凝土梁底顺筋锈胀裂缝宽度为标准,对钢筋表面锈蚀特征、锈蚀钢筋力学性能、以及锈蚀钢筋混凝土梁的结构性能进行了试验研究与比较分析。由于人工气候环境与恒电流通电法使混凝土内钢筋锈蚀的电化学机理不同,试验结果表明:在混凝土表面顺筋锈胀开裂宽度相同条件下,两种环境引起的钢筋表面锈蚀特征、锈蚀钢筋名义强度和延伸率、锈蚀钢筋混凝土梁承载能力与延性均有明显的差异。人工气候环境模拟自然环境气候过程,并强化了气候因素的老化作用,使混凝土内钢筋锈蚀具有相同的电化学机理,并达到加速锈蚀的目的,将对进一步研究钢筋锈蚀程度对结构性能退化影响具有重要的学术和实际意义。     

RCP钢筋混凝土管检测技术

介绍了RCP钢筋混凝土管的检测项目,从外观质量、几何尺寸、抗压强度、内水压力等方面,阐述了RCP钢筋混凝土管的检测要点,指出钢筋混凝土管的检测评定,对于提高排水管的质量有重要意义。     

混凝土轴压溃裂过程的细观数值试验研究

将混凝土视为由骨料、砂浆以及它们之间的界面过渡区(ITZ)组成的细观复合材料,建立了一种包含零厚度粘结单元在内的有限元模型,将粘结单元嵌入到ITZ中以及砂浆单元的边界上,以形成潜在的裂缝发展路径。利用该模型对已生成的二维混凝土试件进行了单轴压缩的数值试验,获得了试件的应力-应变关系曲线以及试件从微裂纹萌发、裂缝开展到最后压溃破坏过程的裂缝演变状态,得到的宏观裂缝及溃裂形态与轴压物理试验十分相近,得到的力学响应曲线与物理试验也呈现良好的一致性。     

冬季施工条件下混凝土性能试验分析

从冬季施工的角度出发,结合黑龙江地区冬季施工周期较长的实际情况,通过实验室模拟冬季施工条件,得到了不同混凝土强度的增长规律及不同温度下混凝土的抗冻临界强度,并根据标准养生不同龄期的混凝土强度,推算出了混凝土达到抗冻临界强度的时间。     

超声波测试下聚丙烯腈纤维海工混凝土抗侵蚀试验与研究

海工混凝土在海洋环境下的抗侵蚀性能是影响混凝土耐久性的一个重要因素.为研究聚丙烯腈纤维海工混凝土抗侵蚀性及其在受力状态下的工作性态,对聚丙烯腈纤维海工混凝土进行了侵蚀和力学试验.通过用浸烘循环的试验方法模拟海洋环境下混凝土侵蚀过程,并在对其加载时用超声波检测受力状态下混凝土的工作性态.试验结果表明:聚丙烯腈纤维可在海工...     

人工气候环境下混凝土氯离子扩散试验

通过设计的人工气候环境下的混凝土侵蚀试验,分析了24、40、80、120、160 d腐蚀后混凝土的氯离子侵蚀特性,并基于Fick第二定律进行了混凝土扩散参数的拟合。结论表明:人工气候环境下氯离子对混凝土的侵蚀有自然环境下侵蚀的特点,并可得到的扩散系数随时间的关系。     

钢筋混凝土管顶管施工技术

针对过公路段大口径钢筋混凝土管顶管施工难度和特点,结合近年来国内过公路段大口径钢筋混凝土管顶管施工技术,对钢筋混凝土管顶管施工方法和技术进行探讨,以完善钢筋混凝土管顶管施工工艺。     

水库混凝土输水管的防渗加固处理

黄坡水库坝内输水管老化和渗漏严重。分析了管壁产生裂缝的原因，介绍了工程修复加固所选用的材料和施工工序。     

Durability of concrete pipes subjected to combined steam and carbonation curing

A beneficial use of carbonation as an auxiliary curing regime for concrete pipes was studied in an attempt to reduce steam curing time, improve durability performance and explore the possibility of using concrete pipe to sequester carbon dioxide. Durability performance of the carbonated concretes was characterized by carbon uptake, strength gain, pH, calcium hydroxide content, permeability, sorptivity and sulfate and acid resistance. It was found that initial curing using steam is necessary to facilitate carbonation. Although the contribution of early carbonation to strength gain is not noticeable after initial steam curing, the process is unique in promoting enhanced durability performance of concrete. The early carbonation leads to a reduction in calcium hydroxide near the surface while maintaining a pH above the corrosion threshold value at the core. Carbonated concretes also exhibit improved resistance to sulfate attack, water absorption, and chloride ion penetration. A carbon uptake of 9% by cement mass makes concrete pipe an ideal candidate for carbon dioxide capture and storage.     

Elasto-plastic response of orthotropic pipes under bending, pressure and axial force

An elasto-plastic analysis of circular thin-walled pipes in the non-buckled configuration subjected to bending moment, pressure and axial loads is presented. Plastic stress-strain relationships based on Drucker's postulates, Hill's yield criterion and the deformation theory are utilized. The analysis includes orthotropic behaviour with the assumption of a linear strain-hardening material. Results are presented for both isotropic and orthotropic materials.     

混凝土单轴压缩分形损伤演化的CT试验研究

在试验室对混凝土立方体试块进行了单轴压缩试验,完成破坏试验后用断层扫描CT技术研究混凝土立方体试件破坏过程的演化灾变过程,重点利用分形数学理论对混凝土试件的裂缝形成演化过程进行了分析研究,得出了一些有价值的结论。     

非标准混凝土小型空心砌块抗压强度切割检测方法的试验研究

我国目前的砌块强度试验方法标准中,只对标准砌块的抗压强度规定了检测方法。对于工程现场常用的清扫孔砌块、系梁砌块的抗压强度检测还是一项空白,无据可依。通过切割法对清扫孔砌块、系梁砌块的抗压强度检测进行了试验研究,对完善我国砌块产品检验标准具有参考价值。