88 M. Abdelnour and V. Zabel Lateral member bending of the bottom chord related to global lateral bending (125.93 Hz, num. 126.12 Hz) Vertical member bending of the bottom chord related to global vertical bending (140.75 Hz, num.: 143.59 Hz) Fig . 9. 6 Identified local vibrations that are coupled to global mode shapes of selected compression members and corresponding frequencies Lateral member bending of the top chord related to global lateral bending (127.46 Hz, num. 126.12 Hz) Vertical member bending of the top chord related to global vertical bending (139.72 Hz, num.: 143.59 Hz) Fig . 9. 7 Identified local vibrations that are coupled to global mode shapes of selected tension members and corresponding frequencies local members, the modal strain energy is used to choose which frequencies to consider where the bending deformation is activated. The high number of degrees of freedom of a space frame structure, reflected in the numerical model, indicates that a higher maximal model order should be considered in a parametric modal identification than commonly necessary if continuous systems such as bridges, towers, or floors are investigated. Acknowledgments The authors would like to express sincere gratitude to the Priority Program SPP 2255 “Kulturerbe Konstruktion” for the initiation of the research project “DENKRAUM” with special thanks to the German Research Foundation (DFG) for the financial support. References 1. Maes, K., Peeters, J., Reynders, E., Lombaert, G., De Roeck, G.: Identification of axial forces in beam members by local vibration measurements. J. Sound Vib. 332 , 5417–5432 (2013) 2. Li, S., Reynders, E., Maes, K., De Roeck, G.: Vibration-based estimation of axial force for a beam member with uncertain boundary conditions. J. Sound Vib. 332(4), 795–806 (Feb. 2013). https://doi.org/10.1016/j.jsv.2012.10.019 3. Rebecchi, G., Tullini, N., Laudiero, F.: Estimate of the axial force in slender beams with unknown boundary conditions using one flexural mode shape. J. Sound Vibr. (2013)., [Online]. Available: https://doi.org/10.1016/j.jsv.2013.03.018 4. Luong, T.M.H.: Identification of the State of Stress in Iron and Steel Truss Structures by Vibration–Based Experimental Investigations. BTU Cottbus-Senftenberg/Bauhaus University in Weimar, Cottbus/Weimar (2018) 5. Warnaar, D.B., Mcgowan, P.E.: Effects of local vibrations on the dynamics of space truss structures. In: Proc. of AIAA Dynamics Specialists Conf., pp. 868–875, Monterey (1987) 6. Brehm, M., Zabel, V., Bucher, C.: An automatic mode pairing strategy using an enhanced modal assurance criterion based on modal strain energies. J. Sound Vib. 329 , 5375–5392 (2010) 7. Rainieri, C., Fabbrocino, G.: Influence of model order and number of block rows on accuracy and precision of modal parameter estimates in stochastic subspace identification. Int. J. Lifecycle Perform. Eng. 1(4), 317–334 (2014)
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