Experimental measurement of dynamic properties of composite slabs from frequency response

Nowadays, in order to increase the live load bearing capacity and provide large-scale cost savings associated with construction projects, using structures with a lower dead load and higher strength is extremely common throughout the world. This issue causes structures to be highly susceptible to vibration and, as a consequence, meeting vibration serviceability dominates design criteria. Hence, identifying dynamic characteristics is crucial to provide a desirable serviceability. Recently, unfilled steel-concrete composite decks with perfobond rib shear connectors are used in buildings and bridges as a novel structural system. A little amount of research has been reported till date on the dynamic characteristics of this structural system. Thus, this study focuses on the dynamic characteristics of unfilled steel-concrete decks, including normal-weight high-strength concrete (HC) and lightweight high-strength concrete (LHC). Some of the main dynamic characteristics such as damping ratio, natural frequencies, and frequency response functions (FRFs) assessed by means of non-destructive technique (NDT) with hammer excitation. Subsequently, the experimental results in terms of natural frequencies were compared with the finite element model (FEM) predictions. It is concluded that there is good agreement for natural frequencies with difference of less than 13% and consequently the developed FEM model can be used for structural performance prediction and damage detection of composite decks with reliable accuracy. The results show that the damping ratios and natural frequencies of the decks fabricated with LHC (DLHC) and HC (DHC) decreases in comparison to those of decks fabricate with plain concrete (DPC). The most effective mode was the first mode with a damping ratio of almost 0.5% for both DHC and DLHC. DPC and DLHC had approximately similar serviceability, whereas DLHC can be more applicable than DPC due to lower weight.