北深沟大桥钢管混凝土泵送顶升施工技术

介绍北深沟大桥钢管拱混凝土灌注施工工艺、方法和技术要点,并介绍该桥自密实微膨胀高性能钢管混凝土配制的设计思路、技术要求。     

自密实堆石混凝土在水库重建工程中的应用

自密实堆石混凝土具有高密实、水化温升小、工艺简单、能极大地降低对人工技术水平的要求、施工效率高、易于现场质量控制、工期短等特点,国内的重大项目中很多用到了自密实混凝土,并取得了良好的收效。本文通过分析自密实堆石混凝土的各项性能以及长坑三级水库枢纽工程的具体结构特点,将自密实堆石混凝土应用在长坑三级水库的重建工程中,给出了工程设计的具体方案、配合比设计以及施工流程。     

高速铁路无砟轨道自密实混凝土施工研究

板式无砟轨道是一种全新的铁路轨道结构形式,它不同于传统有砟轨道,无须轨枕、散粒体碎石道床等结构支撑.自密实混凝土是板式无砟轨道结构的关键工程材料,其灌注施工质量直接决定板式无砟轨道结构整体质量.结合郑济铁路河南段现场施工经验,探讨了自密实混凝土和配制要求,总结了高速铁路无砟轨道自密实混凝土施工要点,希望对同类工程施工有一定参考和借鉴.     

不同水胶比自密实混凝土的强度及波速测试研究

设计了4种不同水胶比(0.52、0.48、0.44、0.40)自密实混凝土试件(N1、N2、N3、N4),分别在不同养护龄期(7、14、28、56、84、112 d)时进行超声波速与抗压强度的测试,得出强度与波速随龄期增长的变化规律,并根据其变化规律作回归分析,获得合适龄期内两者的函数关系。结果表明:试件抗压强度随养护龄期延长而增加,增长速率逐渐下降;在一定龄期内,强度与波速存在密切的内在联系,又因不同水胶比的试件波速增长速率不同,故回归方程不同;水胶比为0.52的自密实混凝土以幂函数拟合性最好,水胶比为0.48、0.40自密实混凝土则以指数函数最优,而对于水胶比为0.44的自密实混凝土,线性函数最佳;建立无损模拟曲线方程,可为预测适用本地区低水胶比自密实混凝土强度提供理论支持,也为检测加固工程中自密实混凝土质量问题提供了数据支撑。     

矩形钢管混凝土柱施工工艺质量控制分析

以某工程为例,通过矩形钢管混凝土柱设计、施工的工程实践,对泵送顶升浇筑法和柱顶直接抛落法的适用条件、施工特点、质量控制要点进行对比分析。结果表明,矩形钢管混凝土柱高抛工艺实施过程中钢柱未产生有害变形,钢柱焊缝未发现开裂现象,板壁未屈服变形,柱内混凝土的强度也达到了设计要求,具有较好的安全性和可行性。     

低强度自密实混凝土在竖向薄型构件中施工质量控制

目前国内外低强度自密实混凝土的应用较少。本文通过低强度自密实混凝土在工程实体竖向构件中的应用实践,提出了解决施工质量问题的控制措施。     

基于创新试验培养大学生综合能力

混凝土配合比设计试验是土木类教学中必不可少的传统实验,忽视了学生实践和创新等综合能力的培养。自密实混凝土作为混凝土的一种新技术,在配合比设计方面与普通混凝土存在较大差别,文章分析了自密实混凝土配合比设计概念,并结合自密实混凝土配合比创新实验项目分析了大学生如何在解决新问题的过程中提高综合能力,总结了创新实验项目的成效和体会。     

CRTSⅢ型板式无砟轨道自密实混凝土恒压灌注工艺研究

以武咸城际铁路工程为背景,对自密实混凝土恒压灌注工艺在CRTSⅢ型板式无砟轨道结构中的应用进行了研究,阐述了自密实混凝土恒压灌注工艺的工艺流程,并对该施工方法提出改进方案,自密实混凝土的成功应用对于CRTSⅢ型板式无砟轨道结构的成功具有十分重要的意义,该技术的应用可以对今后相关工程提供一些借鉴。     

自密实超早强高性能混凝土试验研究

为满足修补混凝土自密实的要求,利用高效复合减水剂增塑和超细复合粉煤灰改善胶凝材料级配等有效措施,尽可能降低新拌混凝土屈服剪应力,使混凝土拌合物达到自密实所需要的流动性,在大量试验的基础上确定了自密实混凝土的配比参数．针对超早强的性能要求,通过胶砂试验,在多种化学外加剂中,选取早强剂A作为超早强水泥混凝土的外加剂,并确定其合理的掺量,同时在此基础上对自密实超早强高性能混凝土的配制技术进行优化,试验结果表明:选用高效减水剂、早强剂A、普通硅酸盐水泥可配制出1d的抗折强度达3．0 MPa以上,2d抗折强度达4．0MPa以上,自密实性能好,30min后混凝土拌合物坍落度损失小的自密实超早强高性能混凝土,能够满足对混凝土路面进行快速修补、无需振捣的要求．     

新型钢管混凝土支架的设计与分析

针对现有钢管混凝土支架不能多级耗能让压的现状，研制了一种能够多级耗能协同让压的新型钢管混凝土支架。通过对新型钢管混凝土支架结构的设计与分析、支架拼装工艺及工作过程的研究，表明该新型支架能够较好地适用于复杂地质环境条件下的巷道支护工程，具有一定的应用前景。     

某建筑CFG桩复合地基沉降机理分析与加固处理

分析了福州市某建筑吹填土CFG桩复合地基沉降机理,通过方案比选,提出采用钢管混凝土桩加固建筑物基础的处理方案;详细介绍了钢管混凝土桩数量及布置、桩身构造设计、施工流程及工艺要求等;监测结果表明,采用钢管混凝土桩进行基础加固,对控制建筑物沉降效果显著。     

Three-dimensional nonlinear analysis of creep in concrete filled steel tube columns

INTRODUCTION Creep is an internal characteristic of concrete under long-term load. A long time has elapsed since the first discovery of concrete creep in 1907 by Hatt. Many researches have been devoted to this complex problem ever since. However, despite major suc-cesses, the creep phenomenon is still far from being fully understood, even though the phenomenon has occupied some of the best minds in the field, such as Glanville, Dischinger, Troxell, Pickett, Neville, etc. Creep phenome…     

Influence of Axial Load Ratio on Shear Behavior of Through-Diaphragm Connections of Concrete-Filled Square Steel Tubular Columns

Nonlinear finite element analysis and parametric studies were carried out to study the influence of axial load ratio on the shear behavior of the through-diaphragm connections of concrete-filled square steel tubular columns. The analysis reveals that smaller axial load ratio can improve the shear bearing capacity and ductility while larger axial load ratio will decrease the shear behavior of the through-diaphragm connections. The parametric studies indicate that the axial load ratio should be limited to less than 0.4 and its influence should be considered in the analysis and design of such connections.     

Application of compactness detection to complicated concrete-filled steel tube by ultrasonic method

An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study. Because of the particularity of the complicated concrete-filled steel tubular column, the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column. According to the results of the plane detection method and embedded sounding pipe method, the cementing status of steel tube and concrete can be concluded, which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.     

Flexural Capacity Formula of Diaphragm-Through Joints of Concrete-Filled Square Steel Tubular Columns

Finite element analysis and parametric studies were performed to investigate the flexural capacity of the panel zone of diaphragm-through joints between concretefilled square steel tubular columns and H-shaped steel beams.Through the comparisons of failure modes,load–displacement curves,and bearing capacity,it was found that the flexural capacity of the panel zone of diaphragmthrough joints was determined by the tensile action and influence of the web of H-shaped steel beams,and the axial load should be taken into account.The steel tube and the diaphragm were the major parts of the joint that resisted the bending moment.The contribution of in-filled concrete had little influence on the flexural capacity of the panel zone of the joint and could be neglected.According to the results of these numerical studies,a formula that considered the influence of the web of H-shaped steel beams and the axial load was developed based on the yield lines in the diaphragm and the steel tube.The results of the proposed formula were in good agreement with the numerical data of this investigation.     

摩擦摆支座在钢管混凝土拱桥中减震效果研究

以跨度为120m的刚性拱肋柔性系杆的下承式钢管混凝土拱桥为分析模型,利用摩擦摆减震隔震支座对简支体系的桥跨结构进行减震研究,运用MIDAS有限元软件模拟多维人工地震波输入以检验摩擦摆系统的减震效果。分析结果证明了在大跨度钢管混凝土拱桥中应用摩擦摆隔震支座系统的有效性。     

钢纤维混凝土施工技术与质量控制

结合现浇钢纤维混凝土工程的实例，介绍了钢纤维混凝土，提出了施工技术与质量控制的措施。     

Seismic behavior of diaphragm-through connections of concrete-filled square steel tubular columns and H-shaped steel beams

Based on the introductions of a type of diaphragm-through connection between concrete-filled square steel tubular columns (CFSSTCs) and H-shaped steel beams,a finite element model of the connection is developed and used to investigate the seismic behavior of the connection.The results of the finite element model are validated by a set of cyclic loading tests.The cyclic loading tests and the finite element analyses indicate that the failure mode of the suggested connections is plastic hinge at the beam with inelastic rotation angle exceeding 0.04 rad.The suggested connections have sufficient strength,plastic deformation and energy dissipation capacity to be used in composite moment frames as beam-to-column rigid connections.     

Analysis and behaviour of FRP-confined short concrete columns subjected to eccentric loading

Fibre-reinforced polymer （FRP） composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete （RC） columns. To design FRP jackets safely and economically, the behaviour of such columns should be predicted first. This paper is concerned with the analysis and behaviour of FRP-confined RC circular and rectangular short columns subjected to eccentric loading. A simple design-oriented stress-strain model for FRP-confined concrete in a section analysis was first proposed. The accuracy was then proved by two test data. Following that, a parametric study including amount of FRP confinement, FRP strain capacity, unconfined concrete strength and shape of column section is provided. Some conclusions were obtained at the end of the paper. The work here will provide a comprehensive understanding of the behaviour of FRP-confined concrete columns. The simplicity of the model also enables a simple equivalent stress block to be developed for direct use in practical design.     

运用5M1E分析法实现超高钢骨制柱质量达优

运用5M1E分析法,指出钢骨柱的混凝土浇筑质量不高与钢骨混凝土柱垂直度难以控制是导致钢骨混凝土柱施工质量缺陷的首要问题。通过制定柱垂直度与轴线控制的措施,采用自密实性混凝土浇筑,有效解决了钢骨及钢筋密集布置无法振捣和混凝土浇筑难的问题,实现钢骨混凝土柱轴线位置和垂直度达到设计目标,无漏浆、无色差、无麻面,保证良好的外观质量,经检验为优质结构。