Is it allowed to write a paper using another's framework? I am an undergraduate, and I recently found myself interested in a topic in economics, and there is a famous article, his framework including something like "model, negotiation, uncertainty...etc."
Is it okay to use his framework with my model (improved upon his), to analyze the situations the author mentioned in his paper? 

To be clear, I mentioned many times in my paper about using the author's framework, and not only my model is different, I also added quite a lot extensions of my own. Also, I did not copy his words, just the situations he analyzed, for example, the model with uncertainty, the model with negotiation, etc.

But, is it allowed or common to analyze my model using other's framework? (most sections' names in my paper are identical to the original author's paper, for example, I used "model, negotiation, uncertainty...etc." as well.
Of course, as long as you say clearly it's his and don't suggest it is your own. As a tip, make also clear what your part of the framework/model is, and how it differs from the original.