The design philosophy embodied in this specification is based on the concept of limit state design. Structures are designed and optimization designed taking into consideration the limit states, and two major categories of limit-state are recognized: ultimate and serviceability. The primary considerations in ultimate limit state design are strength and stability, while that in serviceability is deflection. Appropriate load and resistance factors are used so that a uniform reliability is achieved for all steel structures under various loading conditions and the design strength of each structural component should equal or exceed the required strength determined according to the load combinations.
In the STAAD.Pro implementation, members are proportioned to resist the design loads without exceeding the limit states of strength, stability, and serviceability. Accordingly, the most economic section is selected based the least weight criteria as augmented by the designer in specification of allowable member depths, desired section type, or other such parameters. The code checking portion of the program checks whether code requirements for each selected section are met and identifies the governing criteria.
The following sections describe the salient features of the STAAD.Pro implementation of GB 50017-2017. A detailed description of the design process along with its underlying concepts and assumptions is available in the specification document.