6156 eng reportzib 0 -- 2016-12-22 -- In this paper, we compare several approaches for the problem of gas network expansions using loops, that is, to build new pipelines in parallel to existing ones. We present different model formulations for the problem of continuous loop expansions as well as discrete loop expansions. We then analyze problem properties, such as the structure and convexity of the underlying feasible regions. The paper concludes with a computational study comparing the continuous and the discrete formulations. 1438-0064 urn:nbn:de:0297-zib-61564 Ralf Lenz Ralf Lenz Robert Schwarz 16-67 eng uncontrolled Mixed Integer Nonlinear Programming deu uncontrolled Gas Network Applications deu uncontrolled Expansion Planning OPERATIONS RESEARCH, MATHEMATICAL PROGRAMMING Mathematical Optimization Lenz, Ralf MODAL-GasLab MODAL-Gesamt Applied Optimization https://opus4.kobv.de/opus4-zib/files/6156/ZR-16-67.pdf