ارايه‌ي يك مدل تحليلي براي تخصيص كمّي ريسك در پروژه هاي ساخت

Analytical Model for Quantitative Risk Allocation in Construction Projects

تخصيص ريسك معمولاً در اسناد مناقصه و توسط كارفرما انجام مي شود. كارفرمايان معمولاً بدون درنظرگرفتن شرايط عوامل حاضر در قرارداد، مسيوليت اكثر ريسك ها را به پيمانكار واگذار مي‌كنند كه اين عمل، تاثيرات منفي در هزينه هاي طرفين قرارداد مي گذارد. اين پژوهش با ارايه‌ي مدلي بر مبناي نظريه‌ي چانه‌زني، رفتار بازيكنان در مرحله‌ي مذاكره براي تخصيص كمّي ريسك، كه شبيه به رفتار بازيكنان در يك بازي است، را مدل‌سازي مي‌كند و تخصيص ريسك منصفانه بين كارفرما و پيمانكار را انجام مي دهد. براي رسيدن به اين منظور، ابتدا پيامدهاي هزينه‌يي كارفرما و پيمانكار در درصدهاي مختلف تخصيص ريسك تعيين مي شود. سپس با درنظرگرفتن بازه‌ي مشترك موجود بين درصدهاي تخصيص ريسك قابل قبول براي كارفرما و پيمانكار، چانه‌زني بر سر ميزان منفعت به‌وجودآمده انجام مي شود. براي ارايه‌ي قابليت هاي مدل پيشنهادي، تخصيص كمّي ريسك در يك پروژه‌ي خط لوله و براي ريسك تورم انجام شده است.

Risk allocation is commonly defined by the owner through tender documents. The clients commonly transfer the responsibility of most of the risks to contractors. This one-sided attitude regarding risk allocation, however, probably has unfavorable effects on both client and contractor costs. This research presents a model based on the bargaining game theory, in which the behavior of contracting parties in quantitative risk allocation negotiation processes is modeled. Bargaining is a situation in which players have a common interest to cooperate, but have conflicts on how to cooperate exactly. The most important characteristics of the theory are that the results are determined under perfect information, by rational players, with positive discount rates, having a realistic bargaining protocol, immediate settlement, and a unique equilibrium with no time loss. In order to perform the quantitative risk allocation, the client and contractor costs (payoffs) are determined at different percentages of risk allocation. Having determined the client and contractor payoffs, the common interval between the players’ acceptable risk allocation percentage is determined. The bargaining process is then done between the client and contractor to share the benefits. The fuzzy inference system is used to determine the size of the playersʹ discount factor, based on the values of different influencing factors. The size of the discount factor plays an important role in the final results, and in reaching an equitable agreement. The proposed approach models the realistic behavior of contracting parties in the risk allocation negotiation process, which is similar to the players’ behavior in a game, and determines a desirable and equitable risk allocation strategy between the client and contractor. To evaluate the performance of the proposed method, it is employed in a pipeline project, and a quantitative risk allocation is performed for the inflation risk, as one of the most important identified risks.