Fatigue performance of lightweight steel–concrete–steel sandwich systems

This paper investigates the static and fatigue strength behavior of a composite sandwich system, which consists of a lightweight concrete core sandwiched in between two steel plates and interconnected by J-hook connectors. For this purpose, fibre-reinforced lightweight concrete, of density less than 1450 kg/m3, and novel J-hook connectors that are capable of resisting tension and shear have been developed. Fatigue tests were carried out to study the fatigue behaviour of sandwich beams by varying the maximum applied load and load range. It is found that maximum applied load and load range affect fatigue performance independently. The maximum applied load has a significant effect on fatigue performance when the difference between it and the load range is large. Test evidence shows that considering only the load range, without taking into account the maximum applied load, may over-predict the fatigue life of the sandwich structural system. Finally, a three-parameter fatigue design equation, taking into account both the load range and maximum applied load, is proposed based on regression analysis of test data.