The growing world population, climate-damaging emissions and increasing scarcity of re- sources pose major problems for the construction industry. Solutions are being sought to build with less material and thus reduce emissions. The Collaborative Research Center 1244 at the University of Stuttgart has been investigating these problems in a multidisci- plinary team since 2017. The main focus is on realizing savings in material and emissions with the help of adaptive structures. In this context, the first adaptive high-rise building D1244 was realized at the University of Stuttgart [1]. The design of high-rise buildings is dominated by stiffness, rather than strength. The same is true for bridges. Thus, these structures show great potential concerning the use of adaptive elements. By integrating adaptivity into the design process of new bridges, significant amounts of material can be saved [2]. For existing bridges, retrofitting can be realized using adaptive elements, as deformations are more accessible to adaptation than forces. Equipping bridges with adaptive elements promises a more cost-effective and environmentally friendly solution to increase the durability than building new bridges. This contribution investigates a steel tied-arch bridge in the north of Germany. It experiences limit violations of displacements and excitation of governing natural frequencies from increased loading scenarios due to the new train generation of ICE3. To investigate this issue, a numerical model of the bridge is set up. The retrofitting approach is to actuate the hangers. In the model, this is achieved by a superposition of the actual load case with a temperature loading in the hangers. This model is transformed into an optimization problem with the objective of keeping the actuation effort (i.e., the resulting normal forces in the hangers from the temperature load) as low as possible with respect to the displacement limits and stress limits of the used steel. Other, potentially disadvantageous effects such as the slacking of passive hangers due to the effect of neighboring active hangers are also investigated. REFERENCES [1] L. Blandini, W. Haase, S. Weidner, M. B¨ohm, T. Burghardt, D. Roth, O. Sawodny and W. Sobek. D1244: Design and Construction of the First Adaptive High-Rise Experimental Building. Fronters Built Environment., 8:814911, 2022. [2] M. del Mar Corral, L. Todisco, J. M. Soria. Design, construction and testing of a smart under-deck cable-stayed footbridge