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UBC Theses and Dissertations

A contribution to computer aided design evaluation of steel structures Leung, Y. C.


The engineer mostly uses in his work scientific knowledge, which is described in codified observations and abstractions from reality, and he may occasionally discover and research such knowledge. Other knowledge is largely uncodified, such as experimental patterns, e.g. technologies (physical procedures), and methodologies (mental procedures). These experimental patterns will become in future more and more accessible to the engineer, as they will be increasingly codified and scientifically described. One of the objectives of the reported research is to contribute towards this goal. In the first part of this thesis general considerations to the design and fabrication of steel structures are presented. Reasons for the decline of growth rates in Western industrialized countries are briefly discussed and the transition from Machine Age to Systems Age is being explained. A shift of emphasis in the engineering field is noted from the area of analysis to synthesis. The needs for more tools and computerized aids for the structural engineer for synthesis is pointed out. The main objective of this thesis is to develop an efficient and realistic method to evaluate a particular structural steel design by means of the fabrication and erection costs. The cost is broken down into cost of material and cost of labour. Emphasis is placed on the evaluation of the latter. For the time being, the cost of material is estimated based on the total weight of the structure and a current unit cost. Realizing that the estimation of the labour cost of a steelstructure based on weight is not satisfactory, the construction works are broken down into basic activities. The labour time required for each activity is summed and with the current labour rate, the cost of labour is obtained. The method which is proposed in this thesis is intended to be used either by the steel fabricator to evaluate a particular design, or by the engineering consultants to guide him to an economic solution. A structural data file containing the fabrication and erection details of the structure is setup and a program is written to calculate the fabrication/erection cost of the structure based on the information in this data file and the cost data base of the fabricator. Due to the variation in facilities and setup of the fabricators, each one will have his own cost data base. Changes in the design of a structure can be made by altering the structural data file and the fabrication/erection cost of the structure will be calculated automatically by the computer. This would allow interactive optimization of a design to be carried out in a short time which is often what a fabricator has in preparing a tender. The fabricator will then be able to propose alterations to the design of the structure with reduction of costs. Due to the time limitations, the portion of work on erection costs has not been completed.

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