Civil Engineering Reference
In-Depth Information
10.3.2 Truss Elements
A truss element is a linear element with two nodes at its ends that connects two
nodes of a mesh arbitrarily positioned in space (Fig. 10.8, left). By a truss element
only normal forces (compression and tension) but no shear forces and bending mo-
ments can be transferred.
Figure 10.8
Truss and spring elements
As an example, truss elements are able to simulate the sealing installed between the
shotcrete membrane and the internal lining of a tunnel. Also the effect of rock anchors,
whether pre-stressed or not, may be simulated using truss elements (Section 10.5.4).
10.3.3 Spring Elements
Spring elements (Fig. 10.8, right) are used to simulate predetermined nodal displace-
ments (Section 10.5.1) or a continuous elastic support of the computation section de-
pending on the selected spring constant.
Like truss elements spring elements are linear elements with two nodes at their ends.
Often only one of the two end nodes coincides with a node of a three-dimensional ele-
ment, whereas the other end node lies outside the system and is joined to a fixed support
point (Fig. 10.8, right).
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