[法律资料]6渐近法.ppt

结构力学Structural mechanics §6-1 引言 foreword 本章小结 conclusion * * 渐 近 法 successive approximation method 渐近法 Chapter 11 successive approximation method 逐次逼近 approach gradually →收敛 convergence →精确解 accurate solution 特点：characteristic ① 不组成求解方程 not form equation 生动形象，重复步骤，易于手算 vivid, repeated step, easy to manual calculation 渐近法 Successive approximation method 力矩分配法 moment distribution method 无剪力分配法 no-shear distribution method 迭代法 iteration method §11-2 力矩分配法的基本原理basic principle of moment distribution method 一、基本概念 basic concept 1、劲度系数(转动刚度)S:stiffness coefficient(rotation stiffness) ——近端（转动端）仅发生单位转角时，引起的近端杆端弯矩。Bar-end moment of near end when only unit angle of rotation appears in near end (rotating end) A A A i A B i B A i B A 2、传递系数C：carry-over coefficient ——当近端有转角时，远端弯距与近端弯距的比值。 the ratio of far-end moment and near-end moment when near end has angle of rotation A A A i A B i B A i B A 远 端 约 束 far-end restriction S C 固 定 fix 0.5 铰 支 hinge 0 滑 动 slip -1 劲度系数S与传递系数C： stiffness coefficient and carry-out coefficient 3、节点不平衡力矩：unbalance moment of joint 4、分配系数：distribution coefficient 5、分配弯矩：distribution moment 6、传递弯矩：carry-out moment (Couple M acted at joint A is distributed to near end of each member by distribution coefficient, and far-end moment is equal to that near-end moment multiplies carry-over coefficient) i14 — 节点转动 moment of Z1 angle when joint rotates 角产生的弯矩 Z 1 M 12 m 于是得(so) 近端弯矩可写为：near-end moment write as ——分配系数 distribution coefficient 分配弯矩distribution moment 固端弯矩 fix-end moment — F M 12 ? 将不平衡力矩变号后按劲度系数大小的比例分配给各近端 reverse the unbalance moment and distribute to every near-end by the proportion of stiffness coefficient — 1 F j M ? F M M 12 12 + = m F F j M M M 12 1 12 12 ) ( + - = ? m 远端弯矩：far-end moment 同理(as same as)： 同理(as same as)： distribute every near-end moment to every far-end by the ratio of carry-out coefficient 归纳:conclusion fix joint, every bar has fix-end bending moment and unbalance moment of joint relax joint, di