OpenSees Commands to Create Brick Elements

The Eight Node Brick Element

 

element Brick8N  eletag? node1? node2? node3? node4? node5? node6? node7?
                 node8? matTag?  bf1? bf2? bf3? massDens?

The Brick8N element is the standard eight node three dimensional element implemented based on tensor operation. The arguments to construct the element are its tag, eletag, eight nodes ordered according to Figure 1, the material tag, matTag, the body forces, bf1, bf2, bf3, and the mass density, massDens. By default, \(3\times 3 \times 3\) integration points are used. Users will be able to specify number of integration points very soon.

The valid queries to a Brick8N element when creating an ElementRecorder are “force,” “stiffness,” “stress,” “pq,” “pqall,” “gausspoint,” “plastic” or “plasticGPC.” For “stress” output, the six stress components from each Gauss point are output by the order: \(\sigma_x\), \(\sigma_y\), \(\sigma_z\), \(\tau_{xy}\), \(\tau_{xz}\), \(\tau_{yz}\). The stresses can also be output in \(p\) and \(q\) format by using query “pq,” where \(p\) is the hydrostatic pressure, while \(q\) is the equivalent deviatoric stress. In this case, the stress state at one gauss point is printed in the \(pq\) format. If the stress states at all gauss points need to be printed, use the query “pqall.” For “gausspoint,” the coordinates of all Gauss points are printed out. For “plastic,” the equivalent deviatoric plastic strain from each Gauss point is output in the same order as the coordinates are printed. But the coordinates have to be output separated. If one needs to output the gauss point coordinates together with the plastic strain, the query “plasticGPC” needs to be used.

{#8node width=“9.0cm” style=“margin:auto; display: block; max-width: 75%”}

The Twenty Node Brick Element

 

element Brick20N eletag? node1? node2? node3? node4? node5? node6? node7?
        node8?  node9?  node10?  node11?  node12? node13? node14? node15? 
        node16? node17? node18?  node19?  node20? matTag? bf1?  bf2? bf3? 
        massDens?

The Brick8N element is the standard eight node three dimensional element implemented based on tensor operation. The arguments to construct the element are its tag, eletag, twenty nodes ordered according to Figure 2, the material tag, matTag, the body forces, bf1, bf2, bf3, and the mass density, massDens. By default, \(3\times 3 \times 3\) integration points are used. Users will be able to specify number of integration points very soon.

The valid queries to a Brick20N element when creating an ElementRecorder are “force,” “stiffness,” “stress,” “pq,” “gausspoint,” or “plastic.” For “stress” output, the six stress components from each Gauss point are output by the order: \(\sigma_x\), \(\sigma_y\), \(\sigma_z\), \(\tau_{xy}\), \(\tau_{xz}\), \(\tau_{yz}\). The stresses can also be output in \(p\) and \(q\) format by using query “pq,” where \(p\) is the hydrostatic pressure, while \(q\) is the equivalent deviatoric stress. In this case, the stress state at one gauss point is printed in the \(pq\) format. For “gausspoint,” the coordinates of all Gauss points are printed out. For “plastic,” the equivalent deviatoric plastic strain from each Gauss point is output in the same order as the coordinates are printed.

{#20node width=“9cm” style=“margin:auto; display: block; max-width: 75%”}