外文翻譯---芳綸纖維筋混凝土梁的抗彎效應(yīng)之?dāng)?shù)值研究

1、<p><b>　　畢業(yè)設(shè)計(jì)/論文</b></p><p>　　外 文 文 獻(xiàn) 翻 譯</p><p>　　系　 別 城市建設(shè)學(xué)院 </p><p>　　專 業(yè) 班 級 </p><p>　　姓　 名 </

2、p><p>　　評 分 </p><p>　　指 導(dǎo) 教 師 </p><p><b>　　華中科技大學(xué)</b></p><p><b>　　2011 年3月</b></p>

3、;<p>　　芳綸纖維筋混凝土梁的抗彎效應(yīng)之?dāng)?shù)值研究</p><p>　　本文介紹了芳綸纖維筋混凝土梁的抗彎效應(yīng)。通過三維非線性有限元分析和迭代截面分析及實(shí)驗(yàn)驗(yàn)證，預(yù)測芳綸纖維筋混凝土梁構(gòu)件預(yù)應(yīng)力性能?；炷亮簽楹喼Я汉蛦握{(diào)加載直至發(fā)生故障?；炷亮旱慕孛嫘阅転椋号浣盥?.15％-0.36％，Ig / Icr 比率25比77，其中Ig / Icr分別為總慣性和打擊時(shí)刻慣性。實(shí)驗(yàn)對受測梁施予各種預(yù)應(yīng)力

4、以評估荷載與位移的負(fù)荷對比、中性軸深度、有效慣性力矩的變化以及橫梁變形，同時(shí)也測試了現(xiàn)有設(shè)計(jì)方案的適用性和預(yù)測方程。鋼筋混凝土水平梁的抗彎曲性能，如開裂荷載，產(chǎn)生應(yīng)變的鋼筋混凝土梁中性軸和深度有顯著影響。諸如Ig / Icr比的斷面性能是影響鋼筋混凝土梁包括變形指數(shù)在內(nèi)的變形特征的一項(xiàng)重要性能參數(shù)。文章還對改善現(xiàn)有設(shè)計(jì)方案提出了建議。</p><p>　　增強(qiáng)聚酯混凝土是傳統(tǒng)的鋼筋結(jié)構(gòu)一種很有前景的替代品，廣泛用

5、于民用。使用玻璃鋼的好處包括重力強(qiáng)度比較好，無腐蝕性和無磁性，具有良好的化學(xué)抗疲勞性、長期維護(hù)成本低、現(xiàn)場反應(yīng)快等優(yōu)點(diǎn)。該復(fù)合材料可用于代替?zhèn)鹘y(tǒng)的鋼筋混凝土。鋼筋混凝土構(gòu)件可能遭受腐蝕破壞，導(dǎo)致混凝土構(gòu)件承載能力不足。為了減少了鋼材腐蝕，可能需要較高的維修費(fèi)用。增強(qiáng)聚脂鋼筋混凝土無腐蝕性，從而可以克服這些問題。通常情況下，鋼筋混凝土和聚酯混凝土在實(shí)踐中使用。一般不會推薦使用聚酯混凝土，因?yàn)樗趬A性環(huán)境下強(qiáng)度會退化，在持續(xù)荷載下鋼筋混凝土

6、容易斷裂。通常情況下，鋼筋混凝土的拉伸強(qiáng)度與增強(qiáng)聚脂鋼筋混凝土相當(dāng)，一般是1200至2100兆帕，而前者的模量一般來說較后者低40％，鋼筋混凝土的成本大約是增強(qiáng)聚脂鋼筋混凝土的35％左右?？紤]到增強(qiáng)聚脂鋼筋混凝土應(yīng)用的初始成本高，所以推薦鋼筋混凝土復(fù)合材料作為混凝土構(gòu)件，此外，它引起人們的特別關(guān)注還因?yàn)槠淠Ａ康汀?</p><p>　　不同于鋼筋混凝土構(gòu)件，增強(qiáng)聚脂鋼筋混凝土梁不會因長度問題出現(xiàn)變形，除非發(fā)生故障

7、。和鋼材的低模量相比，增強(qiáng)聚脂鋼筋混凝土的低模量，可能會使其預(yù)應(yīng)力梁的撓度增大。相應(yīng)地，現(xiàn)有文獻(xiàn)大多數(shù)是關(guān)于增強(qiáng)聚脂鋼筋混凝土構(gòu)件在負(fù)載彎曲的兩個(gè)獨(dú)特性能方面。通過比較鋼筋混凝土梁和鋼預(yù)應(yīng)力梁承載能力，發(fā)現(xiàn)了鋼筋混凝土梁承載能力的潛力。Lees and Burgoyne對鋼筋混凝土梁彎曲效應(yīng)和芳綸纖維筋混凝土粘結(jié)效果做了研究。Toutanji和Saafi評估了鋼筋混凝土梁的失效模式及可塑性。研究發(fā)現(xiàn)，鍵粘結(jié)充分時(shí)較無粘結(jié)，荷載變形極限低

8、。格雷斯和賽義德對預(yù)應(yīng)力混凝土梁進(jìn)行測試，包括碳玻璃鋼粘結(jié)和無粘結(jié)筋的結(jié)合，增加梁變形。</p><p>　　雖然_Soudki等已作出大量研究鋼筋預(yù)應(yīng)力梁構(gòu)件與FRP預(yù)應(yīng)力梁構(gòu)件的特性，人們對于玻璃鋼預(yù)應(yīng)力梁彎曲仍然缺乏了解。舉例來說，這種梁的彎曲性能，取決于玻璃鋼預(yù)應(yīng)力筋和截面特性，由于玻璃鋼復(fù)合材料應(yīng)力破裂現(xiàn)象，F(xiàn)RP筋預(yù)應(yīng)力上限也低于鋼筋主要是Concrete Institute在FRP筋預(yù)應(yīng)力強(qiáng)度可能存

9、在著因隨個(gè)案而變的情況； 然而，目前還沒有發(fā)現(xiàn)人們對于這項(xiàng)重要研究需要。</p><p>　　本文在強(qiáng)化數(shù)值研究的基礎(chǔ)上，介紹了粘結(jié)芳綸纖維混凝土預(yù)應(yīng)力梁的彎曲響應(yīng)強(qiáng)度與增強(qiáng)特點(diǎn)；運(yùn)用三維有限元法分析（FEA）和非線性迭代進(jìn)行截面分析，預(yù)測了芳綸纖維預(yù)應(yīng)力構(gòu)件彎曲性。</p><p>　　研究選擇了三個(gè)實(shí)驗(yàn)方案以驗(yàn)證建模方法。特別值得一提的是，選定的梁包括Ig / Icr 比率超過25，其

10、中Ig / Icr分別為總慣性和打擊時(shí)刻慣性，所獲得的計(jì)算量基于一段完全破裂部分，這在檢測玻璃鋼混凝土結(jié)構(gòu)經(jīng)常使用。</p><p>　　本文對芳綸纖維筋混凝土彎梁預(yù)應(yīng)力進(jìn)行了數(shù)值研究并且進(jìn)行了實(shí)驗(yàn)驗(yàn)證。受測梁為輕加強(qiáng)型（ρ＜0.4％），Ig / Icr的比例高達(dá) 77，這是芳綸纖維的典型應(yīng)用特點(diǎn)。該研究的重點(diǎn)是評估芳綸纖維預(yù)應(yīng)力構(gòu)件的彎曲響應(yīng)，尤其是各種預(yù)應(yīng)力水平性能?？偨Y(jié)如下： </p><

11、;p>　　芳綸纖維筋預(yù)應(yīng)力水平顯著影響著梁的開裂荷載，但研究沒有發(fā)現(xiàn)會影響極限荷載。由于設(shè)計(jì)方案為輕加強(qiáng)型（即張力控制部分）。芳綸纖維張力變化受關(guān)鍵區(qū)域（靠近中跨區(qū)）撓距控制，而不是受影響臨近千斤頂端張力變化預(yù)應(yīng)力水平的影響。 當(dāng)Ig / Icr的比率下降時(shí)，預(yù)應(yīng)力水平往往影響服務(wù)狀態(tài)深度中性軸的變化。目前用來預(yù)測中性軸有效深度的ACI440.4R - 04方程可以用于檢測芳綸纖維預(yù)應(yīng)力構(gòu)件。</p>&l

12、t;p>　　梁截面特性，如Ig / Icr比率，對目前用來預(yù)測有效力矩的ACI440.4R - 04方程有顯著的影響。ACI440.4R – 04方法在Ig / Icr= 25檢測梁時(shí)非常有效，而當(dāng)梁Ig / Icr比大于55時(shí)，由于預(yù)測了剛性變形，該方法會高估有效力矩。當(dāng)Ig / Icr的比值小于55時(shí)，ACI440.1R - 06方法對混合配筋構(gòu)件預(yù)應(yīng)力進(jìn)行了合理的預(yù)測？。Yost 等(Yost et al. , 2003)

13、所提出的實(shí)驗(yàn)公式可以很好地預(yù)測有效力矩，而由此產(chǎn)生的Bischoff法修改后可以用來測試玻璃鋼預(yù)應(yīng)力梁。Ig / Icr的比值一直決定芳綸纖維預(yù)應(yīng)力構(gòu)件的偏轉(zhuǎn)特性，直到發(fā)生開裂，但是，預(yù)應(yīng)力水平在服務(wù)狀態(tài)時(shí)是更的主導(dǎo)因素。</p><p>　　提高可塑性時(shí)ACI440.4R - 04現(xiàn)行規(guī)則應(yīng)予修訂，把臨界撓度考慮在內(nèi)。研究表明，芳綸纖維筋的預(yù)應(yīng)力水平應(yīng)限制為最高40％以滿足ACI- 318變形需求。

14、ACI440.4R - 04方法表明可塑性指數(shù)和剖面性能指標(biāo)無關(guān)，而CHBDC方法則受剖面性能指標(biāo)顯著影響。梁Ig / Icr比例高達(dá)77時(shí)不是推薦CHBDC方法高。為使用ACI440.4R - 04方法可塑性指數(shù)極限為2.0。</p><p>　　上述發(fā)現(xiàn)有待更多的實(shí)驗(yàn)加以評估確認(rèn)。 </p><p>　?。ㄗg文來源：http://www.ascelibrary.org ）</p&

15、gt;<p>　　Flexural Response of Concrete Beams</p><p>　　Prestressed with AFRP Tendons: </p><p>　　Numerical Investigation</p><p>　　This paper presents the flexure of concrete be

16、ams prestressed with aramid fiber-reinforced polymer AFRP tendons. Three-dimensional nonlinear finite-element analysis and iterative sectional analysis are conducted to predict the behavior of AFRP-prestressed members, i

17、ncluding experimental validation. The beams are simply supported and monotonically loaded until failure occurs. The sectional properties of the beams include a reinforcement ratio of 0.15% to 0.36% and an Ig / Icr ratio

18、 of 25 to 77, </p><p>　　Fiber-reinforced polymer FRP composites are a promising alter- native to conventional steel reinforcement and widely used for civil structures Bakis et al. 2002 . The benefits of FRP

19、applica- tions include favorable weight-to-strength ratios, noncorrosive and nonmagnetic properties, good chemical and fatigue resis- tance, reduced long-term maintenance costs, and prompt execu- tion on-site Bakis et

20、 al. 2002; Teng et al. 2003; Kim and Heffernan 2008 . The composite materials may be used for pr</p><p>　　Contrary to steel-prestressed concrete members, FRP- prestressed beams do not exhibit yield characte

21、ristics because of the linear behavior of FRPs until failure takes place. The low modulus of FRP composites when compared to that of steel may cause large deflections of FRP-prestressed beams. Correspond- ingly, the majo

22、rity of existing literature is concerned with these two unique aspects of FRP-prestressed members loaded in flex- ure. McKay 1992 examined the potential of concrete beams prestress</p><p>　　tendons to increa

23、se the deformabil- ity of the beams. Grace and Singh 2003 presented a design approach for FRP-prestressed concrete beams with various types of beam sections and highlighted a method to improve ductility of such beam memb

24、ers by including a combination of bonded and unbonded FRP tendons. Zou 2003 studied the deformability of concrete beams prestressed with AFRP or CFRP tendons and con- cluded that excessive deflections of FRP-prestressed

25、beams pro- vided a warning of imminent fail</p><p>　　Although extensive research efforts have been made to exam- ine the behavior of concrete members prestressed with FRP ten- dons Soudki 1998; Lees 2001 , t

26、here is still a dearth of understanding of the flexure of FRP-prestressed beams. For ex- ample, the flexural response of such beams is dependent upon the level of prestress in FRP tendons and sectional properties. The up

27、per limit of FRP tendons for prestressing is well lower than that of steel tendons primarily due to the stress-rupture phenome</p><p>　　To predict the flexural response of concrete beams prestressed with AFR

28、P tendons, two modeling approaches were used: the three-dimensional FEA model using the general-purpose FEA software ANSYS and the nonlinear iterative sectional analysis model. The following summarizes the modeling appro

29、aches.</p><p>　　This paper has presented a numerical investigation regarding the flexure of concrete beams prestressed with AFRP tendons, includ- ing experimental validation. The beams examined were very lig

30、htly reinforced 0.4% and had very high Ig / Icr ratios up to77, which were typical characteristics of AFRP applications. The focus of the research was to evaluate the flexural response of AFRP-prestressed members, in par

31、ticular the effect of various prestressing levels. The following is concluded: The prestr</p><p>　　When the Ig / Icr ratio decreased, prestress levels tended to in- fluence the variation of the neutral axis

32、 depth, particularly for the service state. The present ACI440.4R-04 equation to pre- dict the effective neutral axis depth may be used with an em- pirical constant of 6 for AFRP-prestressed members, rather than a value

33、of 2 that is shown in the present provision, until a better expression is available.</p><p>　　The present ACI440 equations to predict the effective moment of inertia were significantly influenced by the sect

34、ional prop- erties of the beams, such as Ig / Icr ratios. The ACI440.4R-04 approach was reasonable for the beams with Ig / Icr = 25, whereas the approach overestimated the effective moment of inertia for the beams with

35、Ig / Icr ratios greater than 55 so that stiff deflection predictions were achieved. The ACI440.1R-06 approach provided reasonable predictions for nonprestressed member</p><p>　　The present provision of ACI44

36、0.4R-04 concerning the im- provement of deformability i.e., reduce a prestress level in FRP tendons should be revised to include the critical deflec- tion consideration. The research suggests that the prestress level fo

37、r AFRP tendons be limited as low as 40% ultimate to satisfy the ACI-318 deflection requirement.</p><p>　　The ACI440.4R-04 approach showed consistent deformability indices irrespective of the sectional proper

38、ties, whereas the CHBDC approach was significantly affected by the properties. The CHBDC approach may not be recommended for a beam with high Ig / Icr ratios such as 77. A limit of the deformability index for the ACI440.