COMPUTER-AIDED' PROCESSING OF STRUCTURAL DESIGN SPECIFICATIONS

Abstract

Checking a structural design against an accepted set of design constraints is an integral part of the design process. The complexity of implementing a design process as a computer program is largely attributable to the form of presentation of the design constraints by the various codes and specifications. In this study a separation of the con-straint checking activity in the overall computer-aided design process is suggested. The development of a general-purpose processor for checking design constraints is discussed. The processor accepts design constraints in the form of Decision Logic Tables. The processor is general-purpose in the sense that it is capable of using any set of design constraints provided in the form of decision tables. The program handles the large volUme of data involved by: (a) conditionally executing subsequenttables only when the data generated by latter tables is -actually required and found undefined at that.time; and (b) grouping data through ingredient and dependent relations aswell as mutually exclu-- sive sets. 2 Conditional execution of tables saves not only on wasteful data input but also economizes on execution time. It involves suspending execution of a table under processing at a given time if an undefined data element is encountered and starting execution of another table leading to the evalua-tion of the undefined data element. Conditional execution is implemented by recursive use of the same program segment. A general provision to recycle the constraint checking process by changing only a few design parameters and/or for alternate design approaches has been provided by requiring input of only such data elements which are different from the previous cycle. External input of a parameter for recycling successfully eradicates all effects of its previous value, regardless of depth, and leaves all unaffected data unchanged, thereby significantly reducing input and recalcu-lation. The concepts of the constraint checking process have been applied on the 1969 AISC Specification. Examples have been solved for illustration.