How to change complex chain line string to line string?

@Srikanth b, 

I believe I understand your question, and after some digging I found the answer here. 

https://communities.bentley.com/products/microstation/w/microstation__wiki/15322/convert-lines-into-single-linestring

Create Complex Chain with Simplified Geometry

- activate Create Complex Chain command

- switch ON the option Simplify Geometry

- set the method to either Manual or Automatic

Follow the prompts to create the chain.

If the final chain only consists of lines and linestrings, the result will be a linestring.

This method seemed to work for me. I hope it helps someone else out even though your query is stale.