Duzkale, A K (2013) Reducing uncertainty in bid preparation phase of cost estimating for structural steel. PhD thesis, Catholic University of America, USA.
Abstract
Uncertainties are encountered in bid selection, bid document review, and quantity takeoff stages of the bid preparation phase of cost estimating for structural steel. Comparison of the bid candidate projects' objectives is often challenging due to differing units in addition to project selection factors being tangible or intangible. Although the Analytical Hierarchy Process (AHP) is an effective decision aid, shortcomings of the method are found by researchers. The purpose of the research is to investigate the efficiency of the AHP in bid selection decision-making and to develop a method that avoids mistakes in assigning judgment values per Saaty's fundamental scale of absolute numbers. Proposed solutions are validated by simulation with 10,000 iterations. Contributions are: (1) The developed algorithm converts objective values to Saaty's scale values correctly by comparing the objectives, (2) a modified AHP yields correct decisions, (3) AHP is modified to be used for bid selection. Since quantities of cost items are extracted from the bid documents, investigation of bid document uncertainties is vital. The aim of the research is to explore, explain, and expose the bid document uncertainties that cause: (1) Under- or over-estimations of quantities, (2) disruptions leading to laborious takeoff processes, and (3) increasing lack of takeoff automaticity. Quantity takeoffs of school projects are performed. Contributions are: (1) A C-I-V-I-L uncertainty classification is formed, (2) eighty-four types of minor uncertainty are discovered and explained to improve the quantity takeoff accuracy by increasing the estimators' awareness, (3) a framework of information flow errors based on known and unknown information links between project bid agents is designed to explicate the causes of uncertainty. Cost estimation of structural steel requires estimators to envisage the connection elements of framing. Assigning percentage values for connection elements causes inaccurate quantities. A steel uncertainty model (SUM) is developed to provide more accurate quantity takeoff and increase the accuracy of pricing. Inputs of the model are based on the material properties provided by the AISC Manual of Steel Construction. Validation of model results is achieved by actual bill of materials results of the steel detailing software from the completed projects. Contributions include increasing the accuracy of quantity takeoff and bid prices, creating a steel uncertainty model, and minimizing the takeoff duration by eliminating tedious tasks.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Thesis advisor: | Lucko, G |
| Uncontrolled Keywords: | accuracy; duration; efficiency; uncertainty; cost estimation; estimating; pricing; estimator; analytical hierarchy process; simulation |
| Index terms: | pricing, judgment, efficiency, estimation, investigation, project selection, duration, analytical hierarchy process, cost estimating, material property, framing, accuracy, information flow, documents, estimator, validation, decision-making, bid preparation, estimating, agent, steel construction |
| Subjects: | value management, dispute resolution, data collection methods, profession, financial and cost management, professional development, material properties and characteristics, performance management, information systems, decision analysis, project controls, practitioner, economic analysis, bidding, conceptual models, structural engineering, decision-making and optimization |
| Topics: | Quality Management, Legal Issues, Project Management, Engineering Principles, Procurement, Risk Management, Digital Applications, Time Control, Research Practice, Construction Materials, Information Management, Business Strategy, Cost Management, Roles and Professions |
| Descriptive scope: | 3 PCA |
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