Table of Contents
The created scheme of appropriate port loads with the impact of wind load is made to take into account maximum wind speed for crane operation. The design diagram of a crane with a load, as a material system with five degrees of freedom, is represented in a cylindrical coordinate system that directly characterizes the parameters of the crane’s working process.
Wind speed formula is represented as the sum of its two components:
- static – the corresponding wind speed averaged over a 2-minute time interval
- dynamic – the corresponding pulsation component represented by trigonometric functions – sinusoids with random amplitudes and periods of pulsations.
A statistical relationship between the duration of pulsations and the coefficients of gustiness of the wind is established. Calculated analytical dependences of the wind load on the loaded crane are taken into account, considering its dynamic component, changes in the speed of the wind along the crane height and the own speeds of the mechanisms movement as a function of the generalized coordinates – the angle of rotation and the crane boom to indicate the crane wind speed limits that the crane can withstand.
Purpose of the crane calculator
The existing methodology for calculating wind load doesn’t take into account the dynamic nature of the abovementioned loads. In such case, calculations for the operating state of the crane are performed for certain positions, and the drag coefficients are determined for each individual part of the crane according to its typical elements, depending on the angle of attack of the wind flow. The absence of analytical dependencies of the wind load as a function of the generalized coordinates of the movement of crane mechanisms does not allow to carry out studies of the influence of wind loads on the main performance indicators of cranes and really determine the permissible wind speeds for their operating state, depending on the type of crane, technology of handling operations with cargo. The existing contradiction applied to the crane is adopted in the calculations by the nature of its impact and the method of measuring the speed of the wind in seaports (the average and max gusts in the weather reports do not allow to reveal the available reserves of the cranes when they are used in high wind loads and ensure safety of their work.
Considered aspects
For the wind load on the crane in the non-working state, the maximum wind load is taken, to which the crane elements must be calculated.
The wind load on the crane in working condition must be taken into account when calculating metal structures and mechanisms, brakes, when determining engine power, own and cargo stability of the crane.
For the wind load on the crane in working condition, the max wind load is accepted, at which the operation of the crane with nominal load is ensured.
The wind load must be determined as the sum of the static and dynamic components. The static component corresponding to the steady wind speed should be taken into account in all cases. The dynamic component caused by the pulsation of the speed of wind is to be taken into account only when calculating the strength of metal structures and when testing the stability of tipping cranes.