平面杆系结构内力包络图仿真优化与编程

讨论受任意集中力、集中力偶和线性分布力等复杂移动荷载作用下的平面杆系结构内力包络图仿真优化技术。借助平面杆系结构分析软件Vsap2011,分析了单元截面离散方式和荷载移动步长对内力包络图求解精度的影响。研究表明:为了获得较高的内力包络图求解精度,对于移动荷载经过的单元,截面必须按步细分;对于活载任意布置的单元,截面必须在荷载作用点之间再插入足够多的分点;对于不受荷载的单元,两端刚结的必须按距离细分,而含有一个以上铰结点的不必细分。此外,在步长接近或相差不大的情况下,如果步长既能整除荷载队列的间距,又能整除载荷载通过单元的长度,那么就可以提高内力包络图的求解精度。如果将单元长度和荷载队列间距的最大公约数作为步长,既可获得较高的内力包络图求解精度,又可大大节省计算机时。

Simulation optimization and programming of internal force envelope in plane skeletal structures

The optimal simulation of the internal force envelope in the plane skeletal structures subjected to complex moving loads was discussed,including arbitrary concentrated force,concentrated couple and linearly distributed force and etc.The plane skeletal structures analyzing software Vsap2011 was used to deal with the effects of the discrete form of element section and the moving step length of load on the solving precision of internal force envelope.The results show that in order to obtain higher solving precision of internal force envelope,the cross section of elements passed by mo-ving loads must be divided by steps,and the cross section of elements of irregularly arranged live loads must be inserted further with enough dividing points between the action points of loads,and the cross section of elements without loads must be divided by defined interval when both ends are rigid-jointed and should not be divided when more than one point are hinged-jointed.It also can be concluded that when the steps are similar,the solving precision of internal force envelope can be improved if the step can be exactly divided by the distance of load queues and the length of element passed by moving loads.Furthermore,besides the improved solving precision,the computer time can be greatly saved when the step is used as greatest common divisor between the length of elements passed by moving loads and the distance of moving load queues.