竹集成材單向偏壓構(gòu)件力學(xué)性能分析與試驗(yàn)研究
發(fā)布時(shí)間：2019-01-28 20:07
【摘要】：竹集成材是由原竹經(jīng)工業(yè)化加工而成,在物理性能上優(yōu)越于傳統(tǒng)木材、綠色環(huán)保方面優(yōu)于混凝土、砌體等傳統(tǒng)建筑材料的一種具有發(fā)展?jié)摿Φ男滦徒ㄖ牧稀Ｄ壳?對(duì)于竹集成材的研究仍不夠成熟,多數(shù)研究主要針對(duì)材料的基本力學(xué)性能和構(gòu)件軸心受壓性能、抗彎性能等,對(duì)于竹集成材柱偏心受壓性能的研究幾乎沒有。在實(shí)際結(jié)構(gòu)工程中,極少有理想的軸心受壓構(gòu)件,即使是按軸心受壓設(shè)計(jì)的構(gòu)件,也會(huì)因偶然的橫向荷載、支座條件不理想或施工制作的偏差等情況而出現(xiàn)附加彎矩。因此,研究竹集成材偏壓構(gòu)件基本力學(xué)性能顯得十分有意義。本文首先通過試驗(yàn)研究了材料的軸向拉壓力學(xué)性能,結(jié)果表明：竹集成材抗拉強(qiáng)度為119.19 MPa,彈性模量為10.02GPa;抗壓強(qiáng)度為51.41MPa,彈性模量為8.71GPa,比例極限為34.43MPa。軸拉破壞為脆性破壞,應(yīng)力-應(yīng)變呈線性關(guān)系;軸壓破壞為塑性破壞,應(yīng)力-應(yīng)變初始呈線性關(guān)系,隨后呈明顯的非線性關(guān)系。軸壓應(yīng)力-應(yīng)變曲線可分為兩個(gè)階段：小變形彈性階段和大變形塑形階段。文章根據(jù)此現(xiàn)象采用分段函數(shù)對(duì)竹集成材單軸向拉壓應(yīng)力-應(yīng)變關(guān)系建立數(shù)學(xué)模型。受拉和受壓的比例階段均采用直線,受壓的塑性段采用二次拋物線,模型與試驗(yàn)曲線吻合良好。其次,參考《木結(jié)構(gòu)試驗(yàn)方法標(biāo)準(zhǔn)》設(shè)計(jì)了三種不同的長細(xì)比竹集成材構(gòu)件,研究其在不同初始偏心距下的力學(xué)性能。分析發(fā)現(xiàn)：當(dāng)初始偏心距一定時(shí),隨著長細(xì)比的增加,變形增大,承載力降低；當(dāng)長細(xì)比一定時(shí),隨著初始偏心距的增加,承載力逐漸減小,變形逐漸增加,二階彎矩增加。三種不同長細(xì)比試件,在偏心荷載作用下,最終都會(huì)因?yàn)閭?cè)向位移很大而出現(xiàn)類似于受彎破壞,且破壞出現(xiàn)于受拉側(cè)。但在整個(gè)變形過程中,試件截面始終保持水平,符合平截面假定,而試件的變形曲線與二次多項(xiàng)式函數(shù)吻合良好。最后,對(duì)竹集成材的偏壓承載力作理論分析。根據(jù)不同模量理論,推導(dǎo)出竹集成材偏壓破壞時(shí)撓曲線符合二次多項(xiàng)式函數(shù)；結(jié)合試驗(yàn)現(xiàn)象,以破壞時(shí)拉壓邊緣是否達(dá)到極限應(yīng)變?yōu)槠茐臏?zhǔn)則,提出大偏壓和小偏壓兩種分析模型,并對(duì)小偏壓下側(cè)向撓度進(jìn)行修正,求出不同長細(xì)比的試件端部的等效軸力和彎矩。通過試驗(yàn)值與理論值對(duì)比發(fā)現(xiàn),兩者吻合良好。
[Abstract]:Bamboo agglomerated timber is a new type of building material with development potential, which is made from raw bamboo after industrialized processing, and is superior to traditional building materials such as concrete, masonry and so on in terms of physical properties and environmental protection. At present, the research of bamboo timber is still not mature, most of the research mainly focus on the basic mechanical properties of materials, axial compression performance of members, bending performance, and so on, but there is almost no research on eccentric compression performance of bamboo timber columns. In the actual structural engineering, there are few ideal axial compression members, even the members designed according to the axial compression, but also due to accidental lateral load, support conditions are not ideal or the construction of the deviation of the situation such as additional bending moment. Therefore, it is of great significance to study the basic mechanical properties of the composite members. In this paper, the axial tensile and compressive mechanical properties of the bamboos were studied by means of experiments. The results showed that the tensile strength of the bamboos was 119.19 MPa, and the elastic modulus was 10.02 GPA. The compressive strength is 51.41 MPA, the elastic modulus is 8.71 GPA, and the proportional limit is 34.43 MPA. The axial tensile failure is brittle, the stress-strain is linear, the axial compression failure is plastic, the initial stress-strain is linear, and the nonlinear relationship is obvious. The stress-strain curve of axial compression can be divided into two stages: elastic stage of small deformation and plastic stage of large deformation. According to this phenomenon, a mathematical model of uniaxial stress-strain relationship of bamboo agglomerated timber was established by using piecewise function. The proportional stage of tension and compression adopts straight line, and the plastic segment of compression adopts quadratic parabola, and the model agrees well with the test curve. Secondly, according to the Standard of Wood structure Test method, three different kinds of timber components with aspect ratio are designed and their mechanical properties under different initial eccentricity are studied. It is found that when the initial eccentricity is constant, the deformation increases and the bearing capacity decreases with the increase of the slenderness ratio, and with the increase of the initial eccentricity, the bearing capacity decreases gradually, the deformation increases and the second moment increases with the increase of the slenderness ratio. Under eccentric load, three kinds of specimens with different slenderness ratios will eventually be subjected to bending failure due to the large lateral displacement, and the damage will occur on the tension side. However, in the whole deformation process, the section of the specimen is always horizontal, which accords with the assumption of the plane section, and the deformation curve of the specimen is in good agreement with the quadratic polynomial function. Finally, the theoretical analysis of the eccentric bearing capacity of bamboo timber is made. According to the theory of different moduli, the deflection curve of bamboo lumber subjected to biasing failure accords with quadratic polynomial function. According to the experimental phenomenon, two kinds of analytical models, large bias and small bias, are put forward, and the lateral deflection under small bias is corrected by taking the limit strain of tension and compression edge as failure criterion. The equivalent axial force and bending moment at the end of the specimen with different slenderness ratio are obtained. By comparing the experimental values with the theoretical values, it is found that the two are in good agreement with each other.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU531.3
本文編號(hào)：2417275
[Abstract]:Bamboo agglomerated timber is a new type of building material with development potential, which is made from raw bamboo after industrialized processing, and is superior to traditional building materials such as concrete, masonry and so on in terms of physical properties and environmental protection. At present, the research of bamboo timber is still not mature, most of the research mainly focus on the basic mechanical properties of materials, axial compression performance of members, bending performance, and so on, but there is almost no research on eccentric compression performance of bamboo timber columns. In the actual structural engineering, there are few ideal axial compression members, even the members designed according to the axial compression, but also due to accidental lateral load, support conditions are not ideal or the construction of the deviation of the situation such as additional bending moment. Therefore, it is of great significance to study the basic mechanical properties of the composite members. In this paper, the axial tensile and compressive mechanical properties of the bamboos were studied by means of experiments. The results showed that the tensile strength of the bamboos was 119.19 MPa, and the elastic modulus was 10.02 GPA. The compressive strength is 51.41 MPA, the elastic modulus is 8.71 GPA, and the proportional limit is 34.43 MPA. The axial tensile failure is brittle, the stress-strain is linear, the axial compression failure is plastic, the initial stress-strain is linear, and the nonlinear relationship is obvious. The stress-strain curve of axial compression can be divided into two stages: elastic stage of small deformation and plastic stage of large deformation. According to this phenomenon, a mathematical model of uniaxial stress-strain relationship of bamboo agglomerated timber was established by using piecewise function. The proportional stage of tension and compression adopts straight line, and the plastic segment of compression adopts quadratic parabola, and the model agrees well with the test curve. Secondly, according to the Standard of Wood structure Test method, three different kinds of timber components with aspect ratio are designed and their mechanical properties under different initial eccentricity are studied. It is found that when the initial eccentricity is constant, the deformation increases and the bearing capacity decreases with the increase of the slenderness ratio, and with the increase of the initial eccentricity, the bearing capacity decreases gradually, the deformation increases and the second moment increases with the increase of the slenderness ratio. Under eccentric load, three kinds of specimens with different slenderness ratios will eventually be subjected to bending failure due to the large lateral displacement, and the damage will occur on the tension side. However, in the whole deformation process, the section of the specimen is always horizontal, which accords with the assumption of the plane section, and the deformation curve of the specimen is in good agreement with the quadratic polynomial function. Finally, the theoretical analysis of the eccentric bearing capacity of bamboo timber is made. According to the theory of different moduli, the deflection curve of bamboo lumber subjected to biasing failure accords with quadratic polynomial function. According to the experimental phenomenon, two kinds of analytical models, large bias and small bias, are put forward, and the lateral deflection under small bias is corrected by taking the limit strain of tension and compression edge as failure criterion. The equivalent axial force and bending moment at the end of the specimen with different slenderness ratio are obtained. By comparing the experimental values with the theoretical values, it is found that the two are in good agreement with each other.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU531.3
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