Load transfer mechanisms in support ropes of flexible rockfall barriers: Geometrical relationships and transmission attenuation

Support ropes of flexible barriers perform dual roles of establishing primary load-transfer pathways and providing attachment points for energy-dissipating devices. Due to the limitations of current measurement methodologies, rope force sensors are usually installed in rope ends, at where energy dissipating devices are also attached, to avoid movement interference with net or post end during large sliding process. The measured force value actually reflects the working force of the attached energy-dissipating device rather than the maximum internal force of the whole rope. To investigate the correlation between the measured force and the maximum internal force, a validated numerical model was employed to investigate the spatial distribution characteristics of internal force along support rope firstly. Second, the relationships between the internal force of upper and lower support ropes at both sides of the middle and border post ends were built based on geometrical relationships and equilibrium conditions, respectively. Subsequently, parametric simulations were carried out to study the effect of transmission attenuation, including the friction coefficient between support rope and post end, as well as transmission length represented by span number of flexible barriers. Finally, a variable named cable force ratio was defined and an applicable calculation formula was built comprehensively considering geometrical relationship and transmission attenuation. The results provides a basis for the optimum design of support ropes of flexible rockfall barriers.