2006 Volume 57 Issue 5 Pages 395-403
The facility layout problem (FLP) is defined as needing to find an optimal layout with respect to the minimization of material handling costs (MHC) between departments. An elevator (ELV) is a necessity for multi-floor FLPs in order to transfer materials between departments on different floors, and the ELV location significantly influences MHC. While there are some multi-floor layout techniques that consider the ELV location, they have many problems. For example, there is a technique where the ELV is located within a department. In this paper, a new multi-floor facility layout technique is proposed, in which the detailed locations of input/output (I/O) points are determined in addition to departments and ELVs, using an integrated approach of combinatorial optimization and mathematical programming. In this technique, ELVs can be located in free positions without overlapping with departments. I/O points are also optimized within a defined range, but not using conventional ways. The proposed algorithm is based on Simulated Annealing. The objective function is the minimization of MHC between the I/O points of departments along the aisle with the shortest distance. The results of computational experiments show the effectiveness of the proposed algorithm.