ABSTRACT
Long-span frames and roofs are widely used worldwide as they provide large internal spaces without obstructions. In designing long-span roofs for structural safety, the traditional design method faces many difficulties, such as unknown buckling effective length. This new and advanced Direct Analysis (DA) method of design shows and takes many advantages for structural safety and cost saving in terms of construction and maintenance. In this chapter, the DA considering P-Δ and P-δ effects as well as initial imperfections is proposed for the design of long-span roofs, and assumption of effective length is no longer required. The application of this concept of second order analysis to design of practical structures without an assumption of effective length appears to be new and unique, especially on the aspects of design at construction stages accounting for construction sequence. Key considerations for the construction of long-span structures by DA are first reported. The planning of subdivision roof panels, a lifting procedure, a temporary support system, and offloading sequences for load transfer from a temporary support system to the permanent structure is guided by DA such that an economic design and safe construction can be developed and achieved. A constructed long-span single-layer roof structure in Macau is used to demonstrate the validity, practicality, accuracy, and reliability of the proposed method and is taken as an example of successful joint work for advanced design by academicians and engineers in practice.
