Disaster response operations are critical for decreasing the devastating impacts that result in casualties and property damages. Since these operations require cooperation in dynamic and complex situations, the responding organizations require a solid organizational structure collectively. This article introduces computational designs and evaluations of alternative organizational structures for disaster responses to resolve the disconnections between resource demands and supplies. In particular, this research consists of (1) organizational structure designs with two optimization techniques, (2) agent-based simulations that virtually replicate disaster response contexts, and (3) social network analysis to interpret the relations between the structures and the performances from the network perspectives. We applied this approach to log records of Hurricane Katrina, and our evaluations suggest that alternative organizations would improve operation outcomes, that is, increase the successful resource delivery counts and reduce a number of organizational conflicts. This computational approach could be further utilized in designing and evaluating organizations under complex and dynamic situations.