Experimental dynamic characterization of a new composite glubam-steel truss structure

The main characteristics of an original bamboo-steel composite truss structure are presented in this work. Specifically, the considered system is a spatial truss structure whose upper chord and diagonal bars are made by glubam elements whereas its lower chord is made by steel members with a hollow cross-section. This novel structural system has been conceived to build roofs and low/mid-span bridges (for example, footbridges), in such a way to ensure easy and rapid construction, efficient use of the constituent materials, low manufacturing costs and good environmental sustainability. A prototype spatial truss beam for laboratory tests is initially described by providing details about geometry, connections and materials properties. The results obtained from dynamic experimental tests are then discussed. In particular, the dynamic response under ambient vibrations and the free-decay response of this truss structure have been recorded and analyzed in order to estimate its modal properties. Design values of the viscous damping ratio for glubam truss structures with steel bolted connections are finally recommended. The numerical assessment of the human-induced vibration serviceability conditions for footbridges built by means of this structural system is finally performed.