Understanding and Analysing Trusses

trusses are everywhere they are used in bridges antenna towers cranes even in parts of the International Space Station and for good reason they allow us to create strong structures while using materials in a very efficient and cost-effective way so what exactly is a truss it is essentially a rigid structure made up of a collection of

straight members but that's not a complete definition there are two important assumptions we need to be able to make for a structure to be considered as a truss first we need to be able to assume that all the joints in the structure can be represented by a pinned connection meaning that members are free

to rotate at the joints the members of a truss are often rigidly connected using what is known as a gusset plate but if the center lines of all the members at a joint intersect at the same point like they do here it's reasonable to assume that the joint behaves like a pin connection the second assumption we need

to be able to make is that loads are only ever applied at the joints of the truss we never have loads acting in the middle of a member for example because all joints are pinned the members cannot carry bending moments they can only carry axial loads this simplifies the analysis of a truss significantly each

member has to be in equilibrium so the forces acting at each end of a member must be equal and opposite each member is either in tension or in compression these assumptions are what differentiate a truss from a frame [Music] unlike trusses frames don't necessarily have pin joints and so members can carry bending moments a frame can also have

loads applied directly to its members