本文選題：UHTCC + 壓縮疲勞��； 參考：《浙江大學(xué)》2015年碩士論文

【摘要】：混凝土是用量最大、用途最廣的建筑材料,其疲勞失效問題研究對(duì)橋梁、道路、高層、海洋工程等都具有重要意義,以往多數(shù)研究結(jié)果表明,加入纖維有益于改善混凝土的抗疲勞性能。以微觀力學(xué)和斷裂力學(xué)為指導(dǎo)的UHTCC (Ultra High Toughness Cementitious Composites),具有超高的韌性和優(yōu)異的裂縫控制能力。當(dāng)前,國內(nèi)外UHTCC疲勞研究主要集中在彎曲疲勞性能上,為了全面研究其疲勞性能,本文在靜載實(shí)驗(yàn)的基礎(chǔ)上,進(jìn)行一系列等幅壓縮疲勞實(shí)驗(yàn),研究應(yīng)力水平、頻率對(duì)UHTCC壓縮疲勞性能的影響。 研究疲勞裂縫擴(kuò)展、纖維破壞情況,發(fā)現(xiàn)壓縮疲勞破壞斷面可分為疲勞源區(qū)、過渡區(qū)和類靜態(tài)破壞區(qū)。疲勞源區(qū)存在纖維較少等缺陷,最先開裂后因反復(fù)摩擦而呈“黑色”,斷面上纖維因嚴(yán)重?cái)D壓而變形；類靜態(tài)破壞區(qū)形成于試件疲勞失效前的極短時(shí)間內(nèi),所受應(yīng)力較高,纖維拔出比例大、纖維完整性好。 通過不同應(yīng)力水平壓縮疲勞實(shí)驗(yàn),得到壓縮S-N曲線,線性回歸的壓縮疲勞強(qiáng)度為0.688,與普通混凝土、鋼纖維混凝土相比,處于較高水平。不同頻率壓縮疲勞實(shí)驗(yàn)表明,隨著頻率降低,疲勞壽命降低,但在一定的頻率范圍內(nèi)(包含0.5Hz-2Hz),頻率對(duì)壓縮疲勞壽命影響較小。以往實(shí)驗(yàn)結(jié)果顯示,普通混凝土和鋼纖維混凝土的壓縮疲勞破壞變形與靜態(tài)曲線下降段相應(yīng)應(yīng)力水平處的變形相近,而本文實(shí)驗(yàn)結(jié)果表明,UHTCC壓縮疲勞破壞變形明顯大于靜態(tài)曲線下降段相應(yīng)應(yīng)力水平處的變形。 本文通過實(shí)驗(yàn)發(fā)現(xiàn)了UHTCC壓縮疲勞破壞變形的特點(diǎn),并探究了UHTCC壓縮疲勞破壞過程和機(jī)理,所做工作對(duì)于建立UHTCC壓縮疲勞模型,進(jìn)而推動(dòng)其工程應(yīng)用,都具有重要意義。
[Abstract]:Concrete is the most widely used building material. The research on fatigue failure of concrete is of great significance to bridges, roads, high-rise buildings, ocean engineering, etc.The addition of fiber is beneficial to improve the fatigue resistance of concrete.UHTCC Ultra High Toughness Cementitious compositions, which is guided by micromechanics and fracture mechanics, has high toughness and excellent fracture control ability.At present, the domestic and foreign UHTCC fatigue research is mainly focused on the bending fatigue performance. In order to study its fatigue performance comprehensively, a series of constant amplitude compression fatigue experiments are carried out on the basis of static load experiments to study the stress level.The effect of frequency on the compressive fatigue properties of UHTCC.The fatigue crack propagation and fiber failure are studied. It is found that the compressive fatigue failure section can be divided into fatigue source region, transition zone and quasi-static failure zone.There are some defects in the fatigue source area, such as less fiber, "black" after cracking and repeated friction, and deformation of the fiber on the section due to severe compression. The quasi-static failure zone is formed in the very short time before fatigue failure of the specimen, and the stress is relatively high.Fiber pullout ratio is large, fiber integrity is good.The compression S-N curve was obtained by the compression fatigue experiments of different stress levels. The compressive fatigue strength of linear regression is 0.688, which is higher than that of ordinary concrete and steel fiber reinforced concrete (SFRC).Different frequency compression fatigue experiments show that the fatigue life decreases with the decrease of frequency, but in a certain frequency range (including 0.5Hz-2Hz), the frequency has little effect on the compressive fatigue life.The experimental results show that the compressive fatigue failure deformation of ordinary concrete and steel fiber reinforced concrete is similar to that of the corresponding stress level in the descending section of the static curve.The experimental results show that the compressive fatigue failure deformation of UHTCC is obviously larger than that of the corresponding stress level in the descending section of the static curve.In this paper, the characteristics of UHTCC compression fatigue failure deformation are found through experiments, and the process and mechanism of UHTCC compression fatigue failure are explored. The work done is of great significance for the establishment of UHTCC compression fatigue model and the promotion of its engineering application.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU528

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 高淑玲;徐世p，

本文編號(hào)：1757072