高强度混凝土的耐火性能研究

高强度混凝土（HSC）具有强度高，空隙率低，抗渗性好，耐久性好等优点，在建筑工程特别是高层建筑中被广泛采用。但是，与普通混凝土相比，高强混凝土的耐火性能较差，特别是火灾中的抗爆裂性能较差。本文从工程应用的角度出发．结合国外的研究成果，对高强混凝土（HSC）的耐火性能进行探讨，将为高强度混凝土抗火设计提供参考。     

在桥梁工程中高性能混凝土抗压强度影响因素探讨

高性能混凝土被认为是在高强混凝土基础上的发展和提高,也可以说是对高强混凝土的进一步完善。但是将高性能混凝土（HPC）与高强混凝土（HSC）混为一谈是不确切的。高性能混凝土不仅可以用天然材料构成制品,而且可以采用大量的工业废料制成复合性能的高强混凝土,如具有高强度、耐磨损、抗高温且在寒冷、低温冻融循环下性能不变、徐变小、硬度高,低透水性或不透水等性能。本文结合京沪高速常州至无锡段高性能混凝土的使用情况,评价时速350km／h客运专线中高性能混凝土的强度状况。     

钢管高强混凝土轴压柱耐炎极限的试验研究

通过对5个圆形截面钢管高强度混凝土（以下简称钢管高强混凝土）柱的耐火试验，研究钢管高强混凝土柱在标准温升曲线下的力学性能和耐火极限。试验研究结果表明，钢管高强混凝土柱具有较好的耐火性能，在柱子外围只需进行适应的防火涂料保护，即可达到《高层民用建筑设计防火规范》（GB50045-95）对柱结构所要求的耐火极限。     

高强轻骨料混凝土配合比设计及性能研究

本文对高强对轻骨料混凝土的配合比进行分析,使用松散体积法计算轻骨料混凝土的水泥用量、水灰比、砂率等基准配合比。并对比分析高强轻骨料混凝土与普通混凝土的高强性能、抗震性能、抗裂性能、耐久及耐火性能。     

高温环境下高强度混凝土剩余强度的神经网络预测模型

<正>沙特国王大学土木工程系学者研究了高强混凝土(HSC)在高温(或火灾)下的性能。通过开展大量火灾试验,建立了基于人工神经网络(ANN)的混凝土受热后剩余抗压强度预测模型,并将其应用于HSC结构抗火设计。利用该模型对数据进行分析,可以找出具有统计学意义的敏感变量,     

不同受火方式下混凝土柱耐火性能的试验研究

通过5根高强混凝土柱和2根普通混凝土柱的足尺明火试验,考察了不同受火方式对混凝土柱破坏形态、轴向变形和耐火极限的影响。结果表明:(1)非四面受火柱的耐火极限较四面受火柱有很大提高,同时三面受火柱的耐火极限小于两面受火柱;(2)相同受火方式和相同轴压比下高强混凝土柱的耐火极限远低于普通混凝土柱;(3)相同受火方式下大轴压比普通混凝土柱的耐火极限可能小于中等轴压比的高强混凝土柱。在实际结构的抗火设计中,合理考虑受火方式、混凝土强度等级和轴压比的影响是十分必要的。     

高强混凝土平板耐火试验

近年来,高强混凝土用于建筑物及其他混凝土结构日益广泛,同时高强混凝土的耐火性能也成为人们所关心的问题,用于建筑物的各种材料,一般都具有一定的耐火要求,以往耐火试验中所规定的各种数据,均是指抗压强度在5kN/cm~2以下的普通混凝土。据有关方面报导:掺入二氧化硅灰粉的超高强混凝土(抗压强度达17.5kN/cm~2,而实际上是不含粗骨料的砂浆)在高温作用下发生爆裂。     

聚丙烯纤维对高性能混凝土耐火性能影响研究综述

高性能混凝土工作性能好,耐久性好,其成本与同级高强混凝土相比更为经济,但是在火灾作用下,会产生爆裂、剥落。高性能混凝土的耐火性能是一个值得重视的问题,工程实践中往往掺入一定量有机纤维,改善高性能混凝土的耐火性能。文章分析混凝土高温爆裂机理,总结了在聚丙烯纤维对高性能混凝土的高温性能、耐久性能的影响研究成果,为深入研究聚丙烯纤维高性能混凝上的耐火性能提供参考依据。     

活性粉末混凝土的耐久性研究

对配制的活性粉末混凝土(RPC)进行了耐久性研究。得到RPC混凝土在热养护后14d内强度有倒缩现象,并存在着较大的化学收缩和干缩。RPC混凝土水胶比为0.21时,抗氯离子渗透能力要比高强度(HSC)混凝土水胶比为0.25时的大得多,RPC混凝土的抗化学侵蚀能力要比HSC混凝土大。RPC混凝土具有抗液氮冻融的能力。     

高强混凝土的耐火性能

就国内外的研究结果,总结普通高强混凝土、钢纤维高强混凝土和聚丙烯高强混凝土高温后的强度和耐久性、渗透性能恶化的规律。综合阐述高强混凝土的耐火性能,并深入探讨高强混凝土高温爆裂机理,影响爆裂的主要因素及防治方法,并对高强混凝土耐火性能的研究方向提出建议。     

Fire Endurance of High Strength Concrete Columns

In buildings, fire represents one of the most severe environmental conditions, and therefore, should be properly accounted for in the design of high strength concrete (HSC) structural members. The increased use of HSC in buildings has raised concerns regarding the behavior of such concrete in fire. In particular, spalling at elevated temperatures, as identified in studies by a number of laboratories, is a main concern.In this paper, results from an experimental program on the fire resistance of HSC columns are presented. The factors that influence the thermal and structural behavior of HSC concrete columns under fire conditions are discussed. Data from this study indicate that the type of aggregate, concrete strength, load intensity, and detailing and spacing of ties have an influence on the fire resistance performance of HSC columns. Further, the test results show that tie configuration (bending of ties at 135°, ties and provision of cross ties) and closer tie spacing has a significantly beneficial effect on the fire resistance of HSC columns. The results presented will generate data on the fire resistance of HSC columns, and contribute to identifying the factors that influence the behavior of HSC columns.     

Critical factors governing the fire performance of high strength concrete systems

High strength concrete (HSC), is being increasingly used in a number of building applications, where structural fire safety is one of the major design considerations. Many research studies clearly indicate that the fire performance of HSC is different from that of normal strength concrete (NSC) and that HSC may not exhibit same level of performance (as NSC) in fire. This paper discusses the material, structural and fire characteristics that influence the performance of HSC under fire conditions. Data from earlier experimental and numerical studies is used to illustrate the impact the concrete (material) mix design and structural detailing (design) has on fire performance of HSC systems. An understanding of various factors influencing fire performance will aid in developing appropriate solutions for mitigating spalling and enhancing fire resistance of HSC members.     

掺聚丙烯纤维的高强混凝土高温性能研究

高强混凝土的渗透性很低，高温下可能出现爆裂破坏现象，严重影响混凝土及其内部钢筋的结构安全使用性能。本本通过改变聚丙烯纤维掺量，研究其改善高强混凝土高温爆裂性能，以及高温后高强温凝土吸水率，剩余强度性能及其恢复性能。     

高强、超高强混凝土抗火性研究进展综述

回顾了国内外高强混凝土和超高强混凝土抗火性研究进展,并展望了超高强混凝土(特别是活性粉末混凝土)的下一步研究方向。高强混凝土的高温强度损失与普通混凝土基本类似,但其主要弱点是高温爆裂,可采用聚合物纤维或钢纤维予以抑制。活性粉末混凝土抗火性研究的主要目标应是抑制高温爆裂,减小乃至消除高温爆裂发生的可能性。需要进一步研究宏观断裂性能与微观结构特征,建立活性粉末混凝土抗火性改善的机理,提出确保抗火性的技术途径。     

表面设置防火涂料高强混凝土的高温爆裂

通过4组28d抗压强度为82.6MPa且外包不同厚度非膨胀型隧道防火涂料的高强混凝土试块的高温试验,研究了其爆裂状况随防火涂料厚度的变化情况.结果表明:当防火涂料厚度为20mm时,高强混凝土试块均未发生高温爆裂,试块表面所经历的最高温度仅369～405℃;当防火涂料厚度为10mm时,高强混凝土试块均发生了较剧烈的高温爆裂.与其他方法相比,采用非膨胀型隧道防火涂料不仅可有效抑制高强混凝土的高温爆裂,同时施工方便、适应性好.     

Fire Induced Spalling in High Strength Concrete Beams

A macroscopic finite element model is extended to account for fire induced spalling in high strength concrete (HSC) beams. The model is based on the principles of mechanics and thermodynamics and utilizes pore pressure calculations to predict fire induced spalling in concrete. For validating the model, spalling measurements were made by conducting fire resistance experiments on four normal strength and high strength concrete beams. Spalling predictions from the model are compared with the measured values of spalling at various stages of fire exposure. The validated model is applied to investigate the influence of fire scenario, concrete strength (permeability) and axial restraint on the fire induced spalling and fire response of RC beams. Results from the analysis show that fire scenario, and concrete permeability largely influence the extent of fire induced spalling in concrete beams. Further, it is also shown that the extent of spalling has significant influence on the fire resistance of RC beams.     

An Experimental Investigation on Assessment of Residual Mechanical Performance of Basalt Fiber Reinforced High Strength Concrete at Elevated Temperature

Fire Technology - This research explores the effect of basalt fibers (BFs) added in high strength concrete (HSC) to tailor its mechanical and microstructural response on being exposed to fire....     

Fire behaviour of hollow structural section steel columns filled with high strength concrete

The use of hollow structural section (HSS) steel columns filled with high strength concrete (HSC) is becoming popular due to many advantages they offer. However, whereas the design rules for HSS columns filled with normal strength concrete are well established, there are many uncertainties for HSS columns filled with HSC. Results from numerical studies on the behaviour of HSS columns filled with HSC are presented. The studies were carried out based on both North American and European material properties for HSC and steel. Results show that required fire resistance in HSS columns can be obtained through the use of bar- or steel fibre-reinforcement in HSC.