Member definition as X-Brace or K-Brace

Dear SACS User,

I aware there is a feature to perform X-Brace or K-Brace at SACS.

however if I model it manually, do I need to define that the brace is X-Brace or K-Brace even though I have manually made the braces looks like X-Brace however I define the member as standard? 

How the concept of X-Brace or K-Brace works?

thanks