含结构惯性载荷作用桁架结构的弯曲应力及其控制

BENDING STRESSES AND THEIR CONTROLS FOR TRUSSES WITH STRUCTURAL INERTIA LOAD

结构惯性载荷所占成分较大的桁架结构,需考虑其对杆单元弯曲应力的影响及其控制。针对该问题,可用桁架结构分析方法求解杆内轴向应力,再用受横向均布载荷梁的分析方法求解杆内最大弯曲应力,将两者相加以确定杆内最大总应力。继而,采用控制细长比的方法,以控制横向惯性载荷引起的最大弯曲应力,并讨论相应的屈曲条件以确定许用轴向压应力。运用应力比法对多工况下应力约束桁架结构进行最轻化设计,以含惯性载荷作用的3杆和10杆桁架结构优化为例,验证该控制最大弯曲应力方法的必要性与有效性。

When an inertia load constitutes a significant component of the loads in a truss, its effect on the bending stress in a bar element and how to control must be considered. For the problem, the analysis method for trusses was used to solve the axial stresses in the bars. And, the analysis method for a beam with uniformly distributed load is discussed to solve the maximum bending stress in a bar element. The two-component stresses are added to determine the total maximum stress in a bar. Then, it is proposed to use a method for controlling the slenderness ratio, to control the maximum bending stress caused by an inertia load. And, the corresponding buckling conditions are discussed to determine the allowable axial compressive stress. For example, the stress ratio method is used to minimize the truss mass under stress constraints for multiple loadings. And, a three-bar and a tenbar truss with an inertia load are used to verify that the method for controlling the maximum bending stress is necessary and effective.