Is sierpenski's triangle considered to be a computational model? I was reading about sierpenski's triangle and i found that it is similar to pascal's Triangle, which can show coefficients in binomial expansion,  also rule 90 from ECA.

If Sierpenski's triangle can show coefficients in binomial expansion, and was simulated by other two systems {Pascal's Triangle} and {Rule 90} does that means it is a computationa model ?

What about rule 110, which is proved to be universal, is it a computational model also?
I would not call Sierpenski's triangle a computational model.  A computational model should be a system that has a way to compute something.  This means there needs to be a way to supply an input, and a way that the system does something with that input to compute something.  Sierpenski's triangle is a single thing (a single set), and it is fixed -- there is no way to supply different inputs and get a different output.

For similar reasons, I would not call Pascal's triangle a computational model.

However, I would call rule 90 a computational model.  There are standard ways of providing an input and computing stuff (e.g., the input bitstring is interpreted as a row, and then successive rows are derived using the cellular automaton rules, which is interpreted as a computation).  Similarly, I would call rule 110 a computational model.  Or, more generally, I might call cellular automata a computational model, and rule 90 and rule 110 as two instances of cellular automata.