Sourcing problem for construction industry

In construction projects, availability of required material at right time at the project site is crucial to complete the project on time and within the budget. The construction project could be delayed for several reasons and this may disrupt supplies. In this work we assume that enough supply may not be available on time if the project delayed excessively unless the project manager has special supply contracts with the suppliers. Usually suppliers react in two ways towards change in delivery dates; either they may increase the price or provide a limited quantity on the negotiated price. In this work we discuss both the cases and provide solution approaches. The efficiency of the approaches is verified using randomly generated data sets.