depicts the evolution and improvement of these structures and presents and analyses three contemporary long-span structures
Here, I'd put a comma after 'structures' to break it up because of the repetition of 'and'.
it doesn’t seem to show much cohesiveness.- should you be using contractions?
the reader is pointed out - the reader is told/informed or it is pointed out
Then what’s the point of the introduction?- I'm not a great fan of direct questions in such writing. Shouldn't you be telling me rather than asking me? It's OK because you have set it up with 'so far so good', and it is a rhetorical question, but could you end the paragraph without a dircet question?
Besides this minor remark- I'd use criticism
The mentioned projects- The above-mentioned projects
The mentioned projects illustrate the convergence of architecture and engineering in exiting new ways.
Not only do these projects span immense distances,
Should this be a new paragraph? I'd keep them together as the second sentence illustartes the exciting (spelling) new ways of doing things
You mention 3 projects, but don't say anything about the Hangar. Couldn't you give a third example instead of ending on an ellipsis (,…), which I wouldn't recommend.