Effect of pre-tensioned rope tensions on a ladder structure of turntable ladders

Abstract

To expand the operating zone and control more precisely, it is vital to enhance the flexural stiffness of the ladder structures of turntable ladders. Based on one set of optimized 3-segment ladders, the author proposed a solution to increase the bending stiffness on each ladder while their mass hardly increases. Steel wire ropes are suggested to be added inside the handrails. They are pre-stretched and controlled to reduce the vertical displacement and rapidly quench oscillation at the ladder top. These benefits have been demonstrated in the dynamic aspect in other works. In this study, the effect of pre-tensioned rope tensions on ladder structure is investigated and evaluated according to current standards. The work includes modeling the ladder structure, defining loads, combining loads, investigating stresses and displacements according to the tension values. Afterward, the positive effects and negative influences, as well as the recommendations on tension load and tensile process, are presented. According to the obtained results, the structure still ensures the working conditions while the tension value reaches the maximum one. Most of the stress values in the structural elements decrease with increasing tension. The vertical displacement at the top decreases significantly.