44 Identification of Human-Induced Loading Using a Joint Input-State Estimation Algorithm 355 4 6 8 10 −40 −20 0 (a) (b) (c) Time [s] Modal force peri 0 5 10 15 20 0 10 20 30 Frequency [Hz] Modal force 4 4.5 5 5.5 6 6.5 7 7.5 0 200 400 600 800 Time [s] Force [N] Fig. 44.2 Comparison between the identified (green) and simulated (blue) modal load corresponding to fundamental bending mode of the slab: (a) time series and (b) amplitude spectrum of the peri phase (when the pedestrian is on the slab) and (c) the reconstructed foot traces 44.4 Conclusions This contribution uses a state-of-the-art inverse force identification technique to reconstruct the pedestrian-induced load from the resulting vibrational response and a dynamic model of the structure. The experimental study involves a simply-supported concrete slab with a length of 7 m excited by a single pedestrian. The results of the joint input-state estimation algorithm are verified by comparison with the numerically predicted modal load. A good agreement is found between the estimated modal load and the corresponding numerical predictions. Acknowledgements The first author is a post-doctoral fellow of the Research Foundation Flanders (FWO). The financial support is gratefully acknowledged. References 1. Georgakis, C., Ingólfsson, E.: Recent advances in our understanding of vertical and lateral footbridge vibrations. In: Proceedings of the 5th International Footbridge Conference, London, July (2014) 2. Bruno, L., Venuti, F.: Crowd-structure interaction in footbridges: modelling, application to real case-study and sensitivity analysis. J. Sound Vib. 323, 475–493 (2009) 3. Živanovic´, S.: Benchmark footbridge for vibration serviceability assessment under vertical component of pedestrian load. J. Struct. Eng. 138, 1193–1202 (2012) 4. Maes, K., Van Nimmen, K., Lourens, E., Rezayat, A., Guillaume, P., De Roeck, G., Lombaert, G.: Verification of joint input-state estimation for force identification by means of in situ measurements on a footbridge. Mech. Syst. Signal Process. 75, 245–260 (2016) 5. Van Nimmen, K., Maes, K., Van den Broeck, P., De Roeck, G., Lombaert, G.: Inverse identification of pedestrian-induced loads. In: Sas, P., Moens, D., Denayer, H. (eds.) Proceedings of ISMA 2016 International Conference on Noise and Vibration Engineering, Leuven, Sept (2016) 6. Van Nimmen, K., Lombaert, G., Jonkers, I., De Roeck, G., Van den Broeck, P.: Characterisation of walking loads by 3D inertial motion tracking. J. Sound Vib. 333, 5212–5226 (2014) 7. Racic´, V., Pavic´, A., Reynolds, P.: Experimental identification and analytical modelling of walking forces: a literature review. J. Sound Vib. 326, 1–49 (2009) 8. Middleton, C.: Dynamic performance of high frequency floors. PhD thesis, University of Sheffield (2009)
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