【作者】 陈莹；

【导师】 周东华；

【作者基本信息】 昆明理工大学 ， 结构工程， 2008， 硕士

【摘要】 压弯构件在轴力和弯矩的共同作用下,其截面形心应变和曲率会产生耦合作用,本文的主要内容就是研究压弯构件的弹塑性问题。首先,在材料非线性问题中,单元刚度矩阵和结构整体刚度矩阵都要随节点位移而不断变化,这不能用线弹性方法解决,而需要经过多次迭代逼近才能得到真实解。本文利用不同的迭代方法编制了解决非线性弹性问题和弹塑性问题的程序,利用程序对算例进行模拟,比较了这几种迭代方法的结果和收敛速度。并按分层法计算了纯弯状态下单一材料的极限承载力。其次,在对压弯构件弹塑性分析中,作者在计算过程中推导了弹塑性状态下截面的刚度矩阵,单元刚度矩阵,提出了一种在迭代过程中对单元刚度矩阵的新的修正方法,截面内力的计算方法,并考虑了单元左右截面曲率的不同,使得左右截面内力不同的算法。按照上述思路编制出压弯构件的非线性程序,并与有限元软件ANASY的计算结果进行对比,论证压弯构件单元刚度矩阵地正确性,以及程序的正确性。最后,按分级加变形方法编制了恒定轴力下钢筋混凝土截面弯矩一曲率关系的计算机程序,模拟出定轴力弯矩与曲率的关系图。对分级加变形方法的改进是按增量一迭代混合法编制了变化轴力下钢筋混凝土截面非线性分析程序,其中截面刚度矩阵采用有限元虚位移原理方法建立,此程序有效模拟了钢筋混凝土截面上的轴力随弯矩变化的情况。更多还原

【Abstract】 During combined action of axial force and bending moment, the strain and the curvature of the section centroid of beam-columns meeting bring coupling acting forth, the elasto-plastic problem of beam-columns was mianly concerned in this paper.to begin with, during material nonlinearity problem, both element stiffness matrix and structure stiffness matrix is varied with the nodal displacement, this problem can’ t be solved by linear elasticity approach, it’ s verity solution will gotten after repeated iterations. different alternative manners are used to compile routines to solve the nonlinear elasticity and elasto-plastic problem in this paper. the routines are used to the simulation of some reckon case.the outcome and the rapidity of convergence of different alternative manners are compared. the ultimate bearing pressure of the singleness material during simple bending stat was calculated by the the method of stratification.Secondly, during elasto-plastic analysis of beam-columns, both sectional stiffness matrix and element stiffness matrix were derived in elastic-plastic behavior, a new amend means of element stiffness matrix in the process of iteration was proposed. the difference of section curvature and internal force in the left and right section of the element was taked into account. nonlinear program of beam-columns was compiled according to aforesaid clue, and the result was compared with the finite element program ANSYS, the validity of element stiffness matrix and program was argumented.Finally, the program of bending moment-curvature relation of reinforced concrete section was compiled according to the bleeding deformation method, and the bending moment-curvature relational graph was simulated. to improve the bleeding deformation method, a increment- iteration alligation method was used to compile nonlinear program of reinforced concrete section in varied axial force, the section stiffness matrix was established according to the finite element virtual displacement theory, the state of axial force varied according to bending moment on reinforced concrete section was effective simulated by this program in this paper.更多还原