發(fā)布時(shí)間：2018-03-01 11:36

  本文關(guān)鍵詞： FRP約束混凝土 本構(gòu)關(guān)系 受壓斷裂能 斷裂 粘聚區(qū)模型 剝離　出處：《大連理工大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：在鋼筋混凝土結(jié)構(gòu)的服役過程中,由于年限、周圍環(huán)境影響等原因,其結(jié)構(gòu)性能出現(xiàn)退化。主要的表現(xiàn)有承載能力與剛度的降低、延性降低。另外一方面,隨著對(duì)結(jié)構(gòu)安全等級(jí)認(rèn)識(shí)的提高,一些按照原有規(guī)范設(shè)計(jì)的結(jié)構(gòu)物已經(jīng)不能適應(yīng)新規(guī)范的要求。此外,結(jié)構(gòu)使用用途的改變也有可能造成既有結(jié)構(gòu)不能滿足使用要求。這些問題導(dǎo)致結(jié)構(gòu)需要進(jìn)行拆除重建或者加固改造。由于纖維增強(qiáng)復(fù)合材料具有輕質(zhì)高強(qiáng)、耐腐蝕等優(yōu)點(diǎn),近年來大量應(yīng)用于加固工程結(jié)構(gòu)的各種構(gòu)件尤其是梁、柱。各國(guó)研究人員對(duì)FRP加固結(jié)構(gòu)的性能進(jìn)行了大量的實(shí)驗(yàn)與理論研究,取得諸多成果。本文在前人研究的基礎(chǔ)上,重點(diǎn)對(duì)FRP約束混凝土的本構(gòu)關(guān)系以及FRP加固混凝土梁的斷裂及FRP混凝土界面剝離過程進(jìn)行了分析。得到了以下結(jié)果： (1)修正了Lam和Teng基于設(shè)計(jì)的應(yīng)力-應(yīng)變關(guān)系。首先通過Jefferson的混凝土破壞面方程推導(dǎo)了FRP約束混凝土的強(qiáng)度預(yù)測(cè)模型。該模型直接僅需混凝土單軸抗壓強(qiáng)度以及FRP拉斷應(yīng)變；推導(dǎo)了基于損傷的應(yīng)變公式。在強(qiáng)度與應(yīng)變預(yù)測(cè)模型的基礎(chǔ)上,提出了修正的Lam和Teng應(yīng)力-應(yīng)變模型。與搜集的試驗(yàn)數(shù)據(jù)比較表明,對(duì)于強(qiáng)度模型,本文模型與Rousakis和Karabinis模型、Wu和Zhou模型與試驗(yàn)數(shù)據(jù)吻合最好；對(duì)于應(yīng)變模型,本文模型、Wu等模型與Teng等模型與試驗(yàn)數(shù)據(jù)吻合最好。進(jìn)一步比較表明,本文提出的修正的Lam和Teng模型能夠很好地表達(dá)結(jié)構(gòu)的整體行為。本模型可用于實(shí)際構(gòu)件截面的應(yīng)力分析。 (2)在Suzuki等以及Teng等工作的基礎(chǔ)上,基于受壓斷裂能的概念,提出了一種確定基于分析FRP約束混凝土應(yīng)力-應(yīng)變關(guān)系的數(shù)值方法。與試驗(yàn)結(jié)果比較表明,該方法與試驗(yàn)結(jié)果整體吻合良好。另外,分別對(duì)強(qiáng)約束小破壞應(yīng)變、弱約束小破壞應(yīng)變、弱約束大破壞應(yīng)變?nèi)N情況研究了試件長(zhǎng)度對(duì)FRP約束混凝土應(yīng)力-應(yīng)變關(guān)系的影響。分析結(jié)果表明,對(duì)于強(qiáng)約束類型FRP約束混凝土,其應(yīng)力-應(yīng)變關(guān)系不需要考慮試件長(zhǎng)度的影響；對(duì)于弱約束類型FRP約束混凝土,其應(yīng)力-應(yīng)變關(guān)系必須考慮試件長(zhǎng)度的影響。 (3)提出了一種斷裂力學(xué)方法來模擬FRP加固梁的斷裂與FRP-混凝土界面剝離過程。該方法采用虛擬裂縫模型模擬混凝土的斷裂過程,采用粘聚區(qū)模型模擬FRP混凝土界面的剝離,采用應(yīng)力強(qiáng)度因子疊加原理與權(quán)函數(shù)方法建立了整體控制方程與裂縫口張開位移協(xié)調(diào)方程。通過本課題組的試驗(yàn)數(shù)據(jù)驗(yàn)證了本方法的有效性。另外,還對(duì)影響梁承載能力的各個(gè)因素進(jìn)行了詳細(xì)的研究。研究結(jié)果表明,初始縫高比、梁高、混凝土強(qiáng)度等級(jí)對(duì)FRP加固混凝土梁的第一峰值荷載影響較大,FRP的厚度與高度對(duì)FRP加固混凝土梁的第二峰值荷載影響較大。研究還表明,相對(duì)于FRP厚度,FRP的寬度對(duì)FRP加固混凝土的承載能力影響更大。
[Abstract]:During the service of reinforced concrete structures, the performance of reinforced concrete structures is degraded due to the years of service and the influence of the surrounding environment. The main performance is the reduction of bearing capacity and stiffness, and the decrease of ductility. On the other hand, With the improvement of the level of structural safety, some structures designed according to the original code can no longer meet the requirements of the new code. The change in the use of the structure may also cause the existing structure to fail to meet the operational requirements. These problems lead to the need for demolition, reconstruction or reinforcement of the structure. Because fiber reinforced composites have the advantages of light weight, high strength, corrosion resistance, etc. In recent years, a large number of members, especially beams and columns, have been used in strengthening engineering structures. Many experimental and theoretical studies have been carried out on the performance of FRP reinforced structures by researchers from all over the world, and many achievements have been obtained. The constitutive relation of FRP confined concrete, the fracture of concrete beam strengthened by FRP and the process of FRP concrete interface exfoliation are analyzed in detail. The following results are obtained:. (1) the stress-strain relationship of Lam and Teng based on design is modified. Firstly, the strength prediction model of FRP confined concrete is derived by using the concrete failure surface equation of Jefferson. The model requires only uniaxial compressive strength of concrete and FRP tensile strain directly. The strain formula based on damage is derived. On the basis of strength and strain prediction model, the modified Lam and Teng stress-strain models are proposed. The model agrees well with the experimental data of Rousakis and Karabinis models Wu and Zhou models, and the model Wu et al., Teng model and experimental data of strain model are in good agreement with the experimental data. The further comparison shows that the proposed model is in good agreement with the experimental data. The modified Lam and Teng models proposed in this paper can well express the global behavior of the structure. This model can be used for the stress analysis of the actual member section. 2) based on the work of Suzuki et al and Teng, and based on the concept of compressive fracture energy, a numerical method for determining the stress-strain relationship of concrete confined by FRP is proposed. The method is in good agreement with the experimental results. The influence of specimen length on the stress-strain relationship of FRP confined concrete is studied in three cases of weak constraint and large failure strain. The results show that for FRP confined concrete with strong confinement, The stress-strain relationship does not need to consider the influence of specimen length, but for weakly constrained type FRP confined concrete, the influence of specimen length must be taken into account in the stress-strain relationship. In this paper, a fracture mechanics method is proposed to simulate the delamination process between the fracture and the interface of FRP strengthened beams. The virtual crack model is used to simulate the fracture process of concrete, and the cohesive zone model is used to simulate the exfoliation of the interface of FRP concrete. The stress intensity factor superposition principle and the weight function method are used to establish the integral control equation and the crack opening displacement coordination equation. The validity of the method is verified by the experimental data of our group. The factors that affect the bearing capacity of beams are also studied in detail. The results show that the initial joint height ratio, the beam height, The influence of concrete strength grade on the first peak load of FRP reinforced concrete beam is greater than that of the thickness and height of FRP-strengthened concrete beam. The study also shows that the thickness and height of FRP-strengthened concrete beam have great influence on the second peak load of concrete beam strengthened by FRP. Compared with the thickness of FRP, the width of FRP has more influence on the bearing capacity of concrete strengthened by FRP.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU37

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