Abstract: In recent years, lots of large-scale, complex, and “beyond-limit” building structures have been constructed both at home and abroad， most of which are irregular structures. In designing practice, we often encounter the problems out of the scope of regulations or the problems not specified in pertinent codes. The existing standards cannot be applied to these problems, and they are also lack of clear goals, evidence and methods for the problems. Under these circumstances, aiming at a series of large engineering projects of (ARUP) engineering consulting company in China, this paper introduces the solutions of the problems by engineering mechanics.