The Deviated Bending – The State of Stress of Elevator Guide Rails and their Elastic Deformation Based on the Change in the Load Distribution on the Car Floor

The Italian regulation related to the construction, installation and operation of elevators prescribes that the guide rails must support the horizontal push transmitted by the car normally hanging, no matter what the position of its travel is, with a load which is the same as its capacity, evenly spread on any half of its floor. Within the same article the regulation provides that the elastic deformation arrow must not be higher than seven millimetres. As a hypothesis of constraint it provides that each part of guide must be considered simply leaning between two consecutive anchorages. In the past, when the great majority of elevators used to be electric traction type, the checking of the above qualifications was done assuming simplifying hypothesis on the distribution of the load in the car (F 1 a & b), with the conviction, affirmed but not proved, that to such distribution did correspond the maximum stresses on the guide rails. Through the coming and spreading on a large scale of hydraulic elevators with lateral suspension, it immediately appeared evident that the old practice of approximation was not reliable any longer. To overcome this difficulty some solutions have been proposed which develop to a long series of little formulas which on turn get to some results which can easily be objected. According to me the most correct way to behave consists of a detailed analysis which may branch to different analytic developments which take into account all implications involved, but finally synthesize into a few formulas taking to reasonable reliable results.