The OpenSees shell element library has been enriched by 2 new entries developed by ASDEA Software: the quadrilateral ASDShellQ4 and triangular ASDShellT3 shell elements.
Regarding the platebending part, they represent thick (sheardeformable) ReissnerMindlin plates. As is known, low order elements can exhibit transverseshear locking in the thin plate limit. To overcome this problem, the MITC4 and MITC3 formulations are used.
As for the membrane part, both use special formulations (AGQ6I for ASDShellQ4 and ANDeS for ASDShellT3) to improve the inplane bending behavior even with very coarse discretization.