2D Soil structure interaction (ssi)

Dear fellower, 

i want to know if is possible to define the Perfect Matched layer (PML) in 2D analysis where only shell elements exist? i tried MAT 230, but the error message told me that MAT230 can be only used to solid elements. Or is there any other solution to model it in 2D structure? because 2d anaylsis saves a tons of computing time. 

Thanks in advance, 

Dest regards, 

Yuan