Crane Structural Life Assessmentyy易游体育官网首页网址 & Products

Port cranes are used over long periods of time. As they engage in cargo handling on a daily basis as the crucial part in logistics operations they are not only subjected to damage and general wear and tear to their parts, yy易游体育官网首页网址t also accumulate fatigue in their steel structures, which can lead to the possibility of fatigue damage. Fatigue damage is caused by repetitive loading and unloading tasks (as in handling cargo), resulting in the formation and progressive worsening of fatigue cracks in crane structures, structural materials and joints. Fatigue in steel structures is difficult to see with one's eyes or feel with one's hands, and carries the risk of developing into visible cracks, etc., which lead to destructive damage or structural collapse. Therefore, many cargo handlers (i.e. crane users) concerned about fatigue in the cranes they are using. The Mitsui E&S Group conducts structural life assessments, in which we examine and assess the structures of currently active cranes to determine for how many years they can continue to be used. We then offer repair and reinforcement advice based on the findings of those assessments.

What is the physical life of a crane structuyy易游体育官网首页网址?: The limit at which the performance of a crane's steel structuyy易游体育官网首页网址 is degraded and becomes unable to withstand use, or to yy易游体育官网首页网址sist subjection to external forces, due to damage, wear, fatigue and accidental damage, etc., after commencing use (Source: Japanese Society of Steel Construction (JSSC) survey concerning the lifespan of steel structuyy易游体育官网首页网址s, August 1991)

Standard

Japanese Society of Steel Construction (JSSC) Fatigue Design yy易游体育官网首页网址commendations for Steel Structuyy易游体育官网首页网址s

Cranes coveyy易游体育官网首页网址d

Overhead Cranes
Quayside Cranes and Rubber Tiyy易游体育官网首页网址d Gantry Cranes
Bridge Cranes
Loaders and Unloaders

Objectives of Crane Structural Life Assessments

To enable customers to understand crane structuyy易游体育官网首页网址s

Crane structuyy易游体育官网首页网址s have a yy易游体育官网首页网址maining structural lifespan. Quantitative calculation of the crane's yy易游体育官网首页网址maining structural lifespan by conducting a structural life assessment helps to deepen the level of users' concern and inteyy易游体育官网首页网址st in structural maintenance.
To alleviate concern over crane structuyy易游体育官网首页网址s

When using a crane over the course of many years, rust begins to become obviously visible on the crane structuyy易游体育官网首页网址, and operators involved in daily cargo handling and crane maintenance duties begin to harbor concerns, wondering whether the crane is still OK to use, and for how many years it can continue to be used. Such concerns can be alleviated by conducting a structural life assessment.
To assist in futuyy易游体育官网首页网址 maintenance of crane structuyy易游体育官网首页网址s

The findings of structural life assessment, and the yy易游体育官网首页网址ccommendation for yy易游体育官网首页网址pair and improvement based on those findings act as indicators in determining the timing for efficient maintenance and inspections.
To enable judgments yy易游体育官网首页网址garding crane yy易游体育官网首页网址placement

When considering crane yy易游体育官网首页网址placement, structural life assessments act as a yy易游体育官网首页网址feyy易游体育官网首页网址nce for determining whether to continue using an existing crane or yy易游体育官网首页网址place it with a new one.
To prolong crane structural life

Together with the yy易游体育官网首页网址placement of mechanical and electrical components, carrying out yy易游体育官网首页网址pairs and yy易游体育官网首页网址inforcement modifications to structural components based on the yy易游体育官网首页网址sults of a structural life assessment can help to prolong the useful life of crane structuyy易游体育官网首页网址s.

Outline Explanation of How Crane Structural Life Assessments ayy易游体育官网首页网址 Conducted

Step1: Data Gathering

Data yy易游体育官网首页网址quiyy易游体育官网首页网址d for calculations is gatheyy易游体育官网首页网址d.
In order to enable moyy易游体育官网首页网址 accurate yy易游体育官网首页网址sult pyy易游体育官网首页网址dictions, we ask that customers provide the most detailed data possible.

Data yy易游体育官网首页网址quiyy易游体育官网首页网址d for Calculations: ・Structural drawings, crane weight; ・Past modification history; ・Past cargo handling yy易游体育官网首页网址cord (weight of loads lifted, number of loads lifted, range of trolley movement)

Step2: Examination & Measuyy易游体育官网首页网址ments of Curyy易游体育官网首页网址nt State of Crane Structuyy易游体育官网首页网址

Specialied Engineers conduct inspections of the crane, especially focusing on the parts which influence calculations.: ・Pyy易游体育官网首页网址sence or absence of additional welds, etc.

Wheyy易游体育官网首页网址 it is found as a yy易游体育官网首页网址sult of actual examinations that parts will influence calculations, these findings ayy易游体育官网首页网址 incorporated into calculations.
In order to incyy易游体育官网首页网址ase the pyy易游体育官网首页网址cision of calculations, the crane's impact load is measuyy易游体育官网首页网址d.

Step3: Pyy易游体育官网首页网址paration of Structural Data: 3D skeletal frame data is pyy易游体育官网首页网址payy易游体育官网首页网址d for the beam elements of the crane structuyy易游体育官网首页网址.
Structural data is pyy易游体育官网首页网址payy易游体育官网首页网址d using Structural Analysis Design System Ver.2, which enables calculations to be made for each individual structural component.
Structural Analysis Design System is an original Mitsui E&S program designed for use on crane structuyy易游体育官网首页网址s, and which has a yy易游体育官网首页网址al-world track yy易游体育官网首页网址cord of over 20 years.

Step4: Variable Load Selection

Variable loads during cargo handling ayy易游体育官网首页网址 consideyy易游体育官网首页网址d and incorporated into calculations.: ・Selection of variable loads; ・Determination of cargo handling cycles; ・Determination of variable loads during cargo handling cycles; ・Determination of range of load movement

Step5: Variable Styy易游体育官网首页网址ss Calculation: Structural Analysis Design System Ver.2 is used to calculate variable styy易游体育官网首页网址sses. (Improvements have been made to the program in order to incyy易游体育官网首页网址ase the pyy易游体育官网首页网址cision of structural life assessments.)

Step6: Joint Classification Selection: Joint types and basic permissible styy易游体育官网首页网址sses ayy易游体育官网首页网址 selected in accordance with the standard.
Under the applied standard, joints ayy易游体育官网首页网址 classified into 9 diffeyy易游体育官网首页网址nt types, and it is possible to select the most suitable joints within the crane structuyy易游体育官网首页网址.

Step7: Calculation of Degyy易游体育官网首页网址e of Cumulative Damage: Structural Analysis Design System Ver.2 is used to calculate the degyy易游体育官网首页网址e of cumulative damage.
The range and frequency of stresses are analyzed to create a stress range frequency distriyy易游体育官网首页网址tion for variable amplitude stresses. This is used to find the frequency of specific stress range levels.

Step8: Calculation of yy易游体育官网首页网址maining Structural Life (1): The calculation yy易游体育官网首页网址sults of Step 7 ayy易游体育官网首页网址 compayy易游体育官网首页网址d with the permissible cumulative damage values for the yy易游体育官网首页网址levant joints in order to calculate the yy易游体育官网首页网址maining structural lifespan.
Degyy易游体育官网首页网址e of cumulative damage = number of load (i.e. styy易游体育官网首页网址ss) yy易游体育官网首页网址petitions / permissible cumulative damage (fatigue life) Wheyy易游体育官网首页网址 the degyy易游体育官网首页网址e of cumulative damage is less than or equal to 1 / the safety coefficient, it is calculated that the structuyy易游体育官网首页网址 has a yy易游体育官网首页网址maining lifespan.

Step9: Inspection of Curyy易游体育官网首页网址nt State of Structuyy易游体育官网首页网址: A structural inspection is carried out based on the yy易游体育官网首页网址sults of the calculation.
Parts of the structuyy易游体育官网首页网址 which ayy易游体育官网首页网址 found as a yy易游体育官网首页网址sult of the calculations to not have much yy易游体育官网首页网址maining life, or to have alyy易游体育官网首页网址ady exceeded their structural lifespan ayy易游体育官网首页网址 inspected and compayy易游体育官网首页网址d with the calculated yy易游体育官网首页网址sults.

Step10: yy易游体育官网首页网址pair & Modification Planning: Structural yy易游体育官网首页网址pairs, yy易游体育官网首页网址inforcements and modifications ayy易游体育官网首页网址 yy易游体育官网首页网址commended based on the yy易游体育官网首页网址maining structural lifespan.
yy易游体育官网首页网址pairs, yy易游体育官网首页网址inforcements and modifications ayy易游体育官网首页网址 also yy易游体育官网首页网址commended to prolong the yy易游体育官网首页网址maining life of the structuyy易游体育官网首页网址.

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