en Optimization Techniques Optimization Techniques پژوهشي Research Natural disasters and crisis are inevitable and each year impose&nbsp;destructive effects on human as injuries and damage to property. In natural&nbsp; disasters and after the outbreak of the crisis, demand for logistical goods&nbsp;and services increase. Effective distribution of emergency aid could have a&nbsp;significant role in minimizing the damage and fatal accident. In this study, a&nbsp;three-level relief chain including a number of suppliers in fixed locations, candidate&nbsp;distribution centers and affected areas at certain points are considered.&nbsp;For this purpose a mixed integer nonlinear programming model is proposed for&nbsp;open transportation location routing problem by considering split delivery of&nbsp;demand. In order to solve a realistic problem, foregoing parameters are considered&nbsp;as fuzzy in our proposed mode. The objectives of the proposed model&nbsp;include total cost minimization, minimization of the maximum travel time of<br> vehicles and minimization of unmet demands. In order to solve the problem&nbsp;of the proposed model, fuzzy multi-objective planning is used. For efficiency&nbsp;and effectiveness of the proposed model and solution approach, several numerical&nbsp;examples are studied. Computational results show the effectiveness and&nbsp;efficiency of the model and the proposed approach. location-routing model, Optimization, mixed integer nonlinear programming, network 483 496 http://ijiepr.iust.ac.ir/browse.php?a_code=A-10-1168-2&slc_lang=en&sid=1 Shadan Sadighbehzadi shadan_behzadi@yahoo.com 180031947532846005556 180031947532846005556 No depatrment of mathematics, qazvin branch, iau Zohreh Moghaddas moghaddas.sahar@gmail.com 180031947532846005557 180031947532846005557 No depatrment of mathematics, qazvin branch, iau Amirreza Keyghobadi a.kyghobadi@ctbiau.ac.ir 180031947532846005558 180031947532846005558 Yes depatrment of management, central tehran branch, iau Mohsen vaez-ghasemi mohsen.vaez@gmail.com 180031947532846005559 180031947532846005559 No depatrment of mathematics, rasht branch, iau