鋼管混凝土柱沖擊動力響應(yīng)的等效單自由度方法研究
發(fā)布時間：2018-10-04 19:10
【摘要】：鋼管混凝土結(jié)構(gòu)憑借承載力高、抗震性能優(yōu)越、施工簡便等諸多優(yōu)點在工程項目中得到廣泛應(yīng)用。作為承重構(gòu)件的鋼管混凝土柱如果遭受到橫向沖擊等偶然荷載作用,將會造成重大的人員傷亡和財產(chǎn)損失。本文先采用LS-DYNA有限元軟件對軸壓作用下的鋼管混凝土柱的抗沖擊性能展開研究,然后基于等效單自由度方法,計算鋼管混凝土柱的沖擊動力響應(yīng)。研究內(nèi)容如下:1.根據(jù)試驗結(jié)果,驗證了 LS-DYNA軟件計算的可靠性。然后建立了兩種不同鋼管壁厚的構(gòu)件有限元模型。計算結(jié)果發(fā)現(xiàn),當(dāng)沖擊高度較小時,在一定的軸壓比范圍內(nèi),適當(dāng)施加軸力能夠提高鋼管混凝土構(gòu)件的抗沖擊性能;當(dāng)沖擊高度較大時,即使在較小的軸壓比范圍內(nèi),軸力的存在也會急劇削弱鋼管混凝土構(gòu)件的抗沖擊性能。2.從仿真結(jié)果可以看出,軸壓作用下的鋼管混凝土柱的沖擊力時程曲線一般分為具有平臺段和沒有平臺段兩種形式,為了便于等效單自由度方法的計算,按照沖量相等的原則將實際復(fù)雜的沖擊力時程曲線簡化為矩形脈沖和三角形脈沖形式,在一定情況下得到的位移誤差較小。3.推導(dǎo)了軸壓作用下鋼管混凝土柱受跨中沖擊等效單自由度體系的運動微分方程,并給出了矩形脈沖和三角形脈沖荷載的位移響應(yīng)通解。采用等效單自由度方法計算了各種仿真工況的位移響應(yīng),對比位移最大值發(fā)現(xiàn),當(dāng)沖擊速度較小時,一般可以將沖擊力時程簡化成矩形脈沖荷載,此時得到的最大位移值與LS-DYNA的仿真結(jié)果誤差較小;當(dāng)沖擊速度較大時,一般需要將沖擊力時程簡化成三角形脈沖荷載,此時計算結(jié)果的誤差比矩形脈沖相對較大;在小軸壓范圍內(nèi),軸壓比增大時,誤差會減小;增加鋼管厚度,結(jié)構(gòu)產(chǎn)生的位移減小,誤差也減小。
[Abstract]:Concrete filled steel tube (CFST) structure is widely used in engineering projects by virtue of its high bearing capacity, superior seismic performance and easy construction. Concrete-filled steel tubular columns as load-bearing members will cause heavy casualties and property losses if they are subjected to accidental loads such as lateral impact. In this paper, the impact resistance of concrete-filled steel tubular columns under axial compression is studied by using LS-DYNA finite element software, and then the impact dynamic response of concrete filled steel tubular columns is calculated based on the equivalent single-degree-of-freedom method. The research is as follows: 1. According to the experimental results, the reliability of LS-DYNA software calculation is verified. Then two kinds of finite element models of steel tube with different wall thickness are established. The results show that when the impact height is small and the axial compression ratio is within a certain range, the proper application of axial force can improve the impact resistance of concrete-filled steel tubular members, and when the impact height is large, even in a small axial compression ratio range, The impact resistance of concrete filled steel tubular (CFST) members will be greatly weakened by the existence of axial force. From the simulation results, it can be seen that the impact time history curve of concrete-filled steel tubular columns under axial compression is generally divided into two forms: the stage section and the non-platform section. In order to facilitate the calculation of the equivalent single-degree of freedom method, According to the principle of equal impulse, the actual complex time history curve of impact force is simplified into rectangular pulse and triangular pulse, and the displacement error is smaller. 3. The differential equations of motion of concrete-filled steel tubular columns under axial compression are derived and the displacement responses of rectangular and triangular impulsive loads are given. The displacement response of various simulation conditions is calculated by using the method of equivalent single degree of freedom. By comparing the maximum displacement with the maximum displacement, it is found that when the impact velocity is small, the time history of impact force can be simplified into rectangular pulse load. When the impact velocity is large, the time history of impact force should be simplified as triangular pulse load, and the error of the calculated result is larger than that of rectangular pulse. In the small axial compression range, when the axial compression ratio increases, the error will decrease, and the displacement and error of the structure will decrease with the increase of the steel tube thickness.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU398.9
[Abstract]:Concrete filled steel tube (CFST) structure is widely used in engineering projects by virtue of its high bearing capacity, superior seismic performance and easy construction. Concrete-filled steel tubular columns as load-bearing members will cause heavy casualties and property losses if they are subjected to accidental loads such as lateral impact. In this paper, the impact resistance of concrete-filled steel tubular columns under axial compression is studied by using LS-DYNA finite element software, and then the impact dynamic response of concrete filled steel tubular columns is calculated based on the equivalent single-degree-of-freedom method. The research is as follows: 1. According to the experimental results, the reliability of LS-DYNA software calculation is verified. Then two kinds of finite element models of steel tube with different wall thickness are established. The results show that when the impact height is small and the axial compression ratio is within a certain range, the proper application of axial force can improve the impact resistance of concrete-filled steel tubular members, and when the impact height is large, even in a small axial compression ratio range, The impact resistance of concrete filled steel tubular (CFST) members will be greatly weakened by the existence of axial force. From the simulation results, it can be seen that the impact time history curve of concrete-filled steel tubular columns under axial compression is generally divided into two forms: the stage section and the non-platform section. In order to facilitate the calculation of the equivalent single-degree of freedom method, According to the principle of equal impulse, the actual complex time history curve of impact force is simplified into rectangular pulse and triangular pulse, and the displacement error is smaller. 3. The differential equations of motion of concrete-filled steel tubular columns under axial compression are derived and the displacement responses of rectangular and triangular impulsive loads are given. The displacement response of various simulation conditions is calculated by using the method of equivalent single degree of freedom. By comparing the maximum displacement with the maximum displacement, it is found that when the impact velocity is small, the time history of impact force can be simplified into rectangular pulse load. When the impact velocity is large, the time history of impact force should be simplified as triangular pulse load, and the error of the calculated result is larger than that of rectangular pulse. In the small axial compression range, when the axial compression ratio increases, the error will decrease, and the displacement and error of the structure will decrease with the increase of the steel tube thickness.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU398.9
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