element disp

liujinlong · Post by **liujinlong** » Sat Jul 21, 2007 5:40 pm

hi everyone, i want to get the displacement reaction of the midpoint of a truss element, (i have tried to divide the element to two elements,but it was defeated),anyone can give me some advice? or an example? thanks a lot!

pejman_opensees · Post by **pejman_opensees** » Sun Jul 22, 2007 8:27 pm

Truss element is moment free. When you add a node in the middle of the structurally stable problem, it becomes unstable because of occurence of mechanism. One solution( which is not the best one) is to get help from two end nodes of the element. As truss element displaces and rotates linearly in the space, using simple geometric rules you can obtain the displacement of the mid-length by recording the end nodes displacements.