Mobile Crane Research Articles

DYNAMIC MODEL OF A RAILWAY LIFTING CRANE

Introduction: Currently, mobile boom cranes equipped with telescopic boom equipment are widely used in construction, loading and unloading, as well as installation. Purpose of the study: We aimed to develop a dynamic model for a railway lifting crane, taking into account the interaction of its structural elements with each other and the bearing soil surface in a three-dimensional formulation. Methods: In the course of the study, we used Simulation and Motion modules of the SolidWorks software package, Klepikov’s non-linearly deformable soil model, and Lagrange’s equation of the second kind. Results: As a result, we developed a numerical analytical 3D model describing dynamic loading and deformation of the “mobile boom crane – foundation” system in a three-dimensional formulation. The model takes into account the following: the internal bending deformation and the interaction of the mating structural elements of a crane (telescopic sections, telescoping hydraulic cylinders, and outriggers), hoist rope rigidity, grillage (framework of sleepers) influence, elastic and plastic properties of the base platform soil, and action of inertial loads on the structural elements of the lifting crane.

Analisis Kekuatan Pelat Lantai Dermaga di Pelabuhan Ciwandan Banten Terhadap Penambahan BMC

Pier 005B is located at Pelabuhan Indonesia II (Persero) Branch of Banten and has a length of 300meters and a width of 44 meters. It is planned that at Pier 005B, will be putted 1 (one) unit of Harbor MobileCrane (HMC) brand LHM 420 will be placed as a supporting tool for loading and unloading activities from andto ships. This HMC certainly has certain specifications and capacities, so it must be calculated properly againstthe additional load that can be accepted by the floor slab of Pier 005B. The research method used is descriptivequalitative. This HMC is capable of carrying a maximum load of 124 tons at a distance of 12 to 16 meters. Withthe HMC's own weight of 371 tons and the assumption of a human weight of 0.4 tons/meter2, the total weight ofHMC received by the floor slab is 22.68 tons/meter2. By using the SAP 2000 version 22 computer application,the ultimate internal forces due to the load on the floor slab are the ultimate moment of 7.27 ton.meter, theultimate shearing force of 7.61 tons and the limit of deflection of 7.17 mm. Then re-calculated the capacity ofthe existing floor slab in accordance with the Indonesian National Standard (SNI), obtained the internal forcesthat can be borne by the floor slab, namely the slab moment of 18.49 ton.meter, plate shear force of 22.38 tonand the deflection limit. plate by 14.58 mm. So it can be concluded that the floor slab of Pier 005B is capable ofcarrying the Harbor Mobile Crane (HMC) load.

Analysis of the Complex Causes of Death Accidents Due to Mobile Cranes Using a Modified MEPS Method: Focusing on South Korea

The convenience and efficiency of mobile cranes are expanding their applicability in industrial sites, but fatal accidents continue to occur as their use increases. There were 56 cases in South Korea from 2015 to 2019, killing 59 workers. To accurately investigate the cause of a fatal accident, accident investigation reports were used. Since they are used not only as the cause of the accident but also as a result of judicial treatment, only direct causes are mentioned. Thus, indirect causes in this study were separately analyzed to induce a complex cause analysis. The man-made, management, economic, physical, political, and social (MEPS) analysis method, developed by the National Institute of Disaster in South Korea, is a type of root cause analysis (RCA), used to derive the fundamental causes of various types of disasters, mainly social ones. The complex causes of fatal accidents were analyzed by applying a modified MEPS method to mobile cranes. The MEPS method investigated three categories, namely man-made, management, and physical factors, among six categories and a newly established level four, to find the root cause of fatal accidents. The analysis results showed that violations of procedures and regulations were the most frequent causes in the man-made factors. A lack of general and special safety education was the most common cause in the management factor, and the overturning, falling, and jamming of the mobile crane were the most frequent causes in the physical factor.

Noise Exposure Assessment in Construction Equipment Operators in Tehran, Iran.

Occupational hearing loss is a common complication among construction workers, especially those working with heavy machinery and construction equipment. This research measured the noise that construction operators are exposed to, and proves that most of the construction equipment operators that we studied have a potential risk of hearing impairment. We examined 22 types of construction machinery that are commonly used in various stages of construction projects in Tehran (demolition, excavation, and execution). The noise that construction operators were exposed to was measured with a dosimeter during 8 working hours, and the Time-Weighted Average (TWA) was calculated for each operator according to OSHA standards. Finally, a suitable hearing protection device (HPD) was suggested. The results indicated that the operators of D8N (opened-cab) and CAT D8L SA (closed-cab) bulldozers were exposed to more noise than other operators in this study. Hand-saw, Caterpillar 943, and Komatsu 470 loader operators were also exposed to significant noise levels. Other operators, such as drivers of older Benz and Volvo trucks, the Backhoe HLB95, the Soosan mobile crane, and the Bobcat were also exposed to heavy noise that put them at risk of occupational hearing loss.

Availability Optimization of the Mobile Crane Using Approach Reliability Engineering at Oil and Gas Company

Reliability engineering is needed for scheduling maintenance to improve system or equipment performance. The purpose of this paper is to provide recommendations for maintenance schedules based on reliability, availability, and maintainability (RAM) analysis that optimizes the availability of mobile cranes operating in Indonesian oil and gas companies. This paper begins with searching for a critical system using the Pareto principle. The critical system is then made a reliability block diagram to facilitate the analysis. However, before conducting the analysis, it is necessary to know the characteristics of the probability distribution of the data so that the analysis results are accurate and stable. Analysis of reliability, availability, and maintainability (RAM) is then carried out in the probability distribution equation for each system. The analysis results show that the implementation of maintenance at the time of reliability reaches the mean time between failure, and the maximum maintainability time is 240 minutes. The result is an increase in the availability of the lower structure (LS) system by 0.53% (98.78% to 99.31%), electrical and safety equipment (ESE) by 0.19% (99.02% to 99.21%), upper structure (US) was 0.07% (99.32% to 99.39), and overall system availability was 0.07% (99.31% to 99.38%).

A MATHEMATICAL MODEL AND SOLUTION METHOD FOR THE BERTH ALLOCATION PROBLEM WITH VARIABLE HANDLING TIME AND CONTINUOUS TIME HORIZON

In this paper, we present the integration of two problems related to the operations in a port terminal: the Berth Allocation Problem (BAP) integrated with the Machine Assignment Problem. We present a mixed-integer linear programming (MILP) formulation, capable of assigning and scheduling incoming vessels to berthing positions and the assignment of machines for handling the vessels. The machines can be quay cranes, mobile cranes, straddle carriers, forklifts, trucks, and any other machine. The problem aims to minimize the waiting time plus the handling time of the vessels. To solve the problem, we developed a heuristic algorithm, capable of solving a problem instance in seconds. To compare the results, we generate several instance problems based on real data and solve them with our MILP formulation implemented in a solver, our heuristic, and a First In First Out (FIFO) algorithm. The solver was able to find solutions only in small-scale instances, and the heuristic was able to find good solutions for all instances.

State Estimation in a Hydraulically Actuated Log Crane Using Unscented Kalman Filter

Multibody system dynamics approaches together with state estimation methods can reduce the need for a large number of sensors, especially in the digital twin of working mobile machinery. To demonstrate this, a hydraulically actuated machine was modeled using the double-step semi-recursive multibody formulation and lumped fluid theory in terms of system independent states. Next, because of the high non-linearity of the modeled system and with respect to the reported performance degradation of the Extended Kalman Filters (EKF), which are mostly related to the linearization procedure of this filter, the Unscented Kalman Filter (UKF) was implemented to achieve high accuracy and performance. The methodology of the proposed approaches was applied to a mobile log crane model PATU 655. The implementation of the proposed estimation algorithms is demonstrated with three different multibody based simulation models: the synthetic real system producing the artificial measurements, the simulation model, and the estimation model. Encoders and pressure sensors, installed on the synthetic real system, provided synthetic sensor measurement data. To mimic real-world conditions, the estimation and simulation models used in the processing of the state estimation algorithm were assumed to have errors in the initial conditions and force model. The proposed UKF was applied to the estimation model with the synthetic sensor measurement data. The minimum percent normalized root mean square errors in the associated measured and unmeasured states of case example were 0.11% and 1.86%, respectively. The UKF using the multibody system dynamics formulations is able to estimate the case example states despite 15% and 60% errors in mass and inertial properties of bodies and Payload, respectively, confirming the accuracy and performance of the algorithm

Reference Architecture for Running Computationally Intensive Physics-Based Digital Twins of Heavy Equipment in a Heterogeneous Execution Environment

Physics-based digital twins for heavy equipment provide a powerful tool for improving operation and maintenance activities. In contrast to data-driven models, they present more explainable and confident results but require more computational power. Besides the problem of physics-based digital twins creation, there is a task of managing their lifecycle, including their execution, maintenance, storage, and updating. The features distinguishing this kind of digital twins are the mobility of the real counterpart, operation in remote locations, long lifecycle, information sensitivity, and gaps in information technology awareness among the equipment owners and users. This paper presents a methodology and reference architecture for a set of interconnected systems capable of running digital twins of heavy equipment in such conditions. A data model for preserving digital twin-related information for decades of machine operation is described. Operating-system-level virtualization technologies are used to run digital twins in a heterogeneous execution environment. An example of the reference architecture implementation is presented for the physics-based digital twins of a mobile log crane. The experimental part of the paper includes a comparison of computing time for different types of digital twins in different execution environments. It highlights the peculiarities related to running physics-based digital twins in containers. Experiments were performed using the Amazon cloud platform, an edge computing system represented by a single-board microcomputer based on ARM architecture, and a virtual machine on a desktop personal computer. Experimental results show that physics-based digital twins for the analysis of the multi-body dynamics can be run within the proposed architecture with real-time performance in all three types of execution environments. The paper demonstrates the practical implementation of physics-based digital twins for heavy equipment and defines directions for future research in this field.

Optimizing Heavy Lift Plans for Industrial Construction Sites Using Dijkstra’s Algorithm

AbstractPlanning lift activities of mobile cranes for a modular project can raise productivity and improve safety. An optimized lift plan is essential for multiple lifts due to high rental cost of ...

An integrated decision support system for mobile crane selection

This research presents a novel computer-based system for the selection of mobile cranes in building construction. The proposed system integrates four main modules: an algorithm known as the analytical hierarchy process (AHP), the simple multi-attribute ranking technique (SMART), an experience-based algorithm, and a system database. The AHP module assesses the importance of the selection criteria, while SMART applies multi-attribute utility theory. The experience-based algorithm completes the calculations necessary for selecting the best and most technically appropriate crane alternative, and the database module hosts information about 37 different mobile cranes. The methodology followed to achieve the research objective consisted of three main phases. The first involved conducting a comprehensive literature review to identify selection criteria for mobile cranes, as well as a number of face-to-face interviews with experts to finalize the list of selection criteria considered. Face-to-face interviews were also conducted with local experts to obtain a framework for the current practice of crane selection and identify areas in need of improvement. Phase two involved using AHP for data collection in order to assess the importance of the identified criteria. The final phase included an analysis of the collected information and development of a computer application. The system was tested on a hypothetical project and validated using a real-world endeavor to demonstrate its effectiveness for a number of construction management functions, including project planning, scheduling, cost estimation, and the efficient use of available resources. This study determined the most significant selection criteria to be rental cost, crane availability, and safety considerations. The results show the capabilities of the proposed system, as well as its flexibility when working with a wide range of inputs.

Optimization of valve plate applied in secondary unit and noise reduction

Secondary unit, in term of application, is the combination of pump and motor, the valve plate specifically designed for pump or motor may not be suitable for a secondary unit. This paper mainly discusses design of valve plate of secondary unit applied in mobile crane, several critical points needed to be noticed during design have been discussed, furthermore, by adopting the proposed method to optimize a valve plate, which originates from closed-loop pump and now is used in opened-loop system, noise reduction was realized. Firstly, 1D simulation models, including pump condition and motor condition, were established in AMESim to obtain cylinder pressure, flow ripple and other critical parameters; secondly, by using Pumplinx, 3D numerical simulation was conducted to evaluate the cavitation risk; finally, a test bed was set up to validate the simulation result. Simulation result agreed well with the tested one. Both of them verified practicability of the proposed method. This research may provide a guidance for engineers and scholars who are interested in pump and motor.

Экспериментальные исследования колебаний груза при перемещении грузоподъёмного крана ДЭК-251

Measurement of the parameters of vibrations of the load moved by a self-propelled crane with a flexible rope suspension when the crane moves along an unprepared construction site with irregularities is an urgent task, since it will allow using the obtained numerical values of the vibration parameters to improve the accuracy of the crane’s operation in terms of moving loads. Based on the solution of this problem, it is possible to create systems for automatic damping of cargo vibrations. This will reduce the time spent on performing a work step when moving a load. This also solves the problem of reducing the dynamic loads on the elements of the crane. The article discusses one of the methods for determining the angles of deviations of the point of the load and the point of suspension of the load on the boom when moving the DEK-251 mobile crane along the unevenness of the construction site using the projection-polynomial mathematical model of the optoelectronic system. As an example, the article presents a number of graphs of time dependences of changes in the values of the angles of deviations of the load and the point of suspension of the load when moving over the unevenness of the site of a crane with a boom length of 22 meters and an angle of inclination of the boom of 48 degrees. The cargo was at a height of 4.8 meters, the weight of the cargo was 200 kilograms. The graphical time dependences of the load fluctuations and the load suspension point in the longitudinal plane are given in the form of angles of deviations from the lens center, taking into account the microrelief. The data allows you to calculate the linear coordinates of objects in space. Moreover, the results were obtained taking into account the camera errors.

Lifting path planning of mobile cranes based on an improved RRT algorithm

Lifting operations of mobile cranes are one of the commonly-seen and most important activities for prefabrication housing production (PHP) on sites. However, relevant operations are normally based on the experience of operators or project managers, this often leads to low efficiency as well as high accident rate due to dynamic and complex construction sites. Thus, it is important and necessary to develop an appropriate approach to the lifting planning of mobile cranes so as to guide on-site operations. This paper proposes an improved Rapidly-exploring Random Tree (RRT) algorithm for lifting path planning of mobile cranes. Considering the critical role of Nearest Neighbor Search (NNS) in the implementation of RRT algorithm, a novel strategy for searching the nearest neighbor is developed, i.e., Generalized Distance Method and Cell Method. Both methods are tested in simulation-based experiments. The results show that 1) the Generalized distance method not only reduces the search time, but also unifies the unit of distance measurement and clarifies the physical meaning of distance; 2) the Cell method dramatically reduces the traversal range as well as the search time; and 3) both methods improve the quality of lifting path planning of mobile cranes. This improved RRT algorithm enables rapid path planning of mobile cranes in a dynamic and complex construction environment. The outcomes of this research not only contribute to the body of knowledge in spatial path planning of crane lifting operations, but also have the potential of significantly improving efficiency and safety in crane lifting practices.

Study on Overturn Proof Monitoring System of Mobile Crane

While up-right build structures are under construction, an over-hung crane has a major role in efficient lifting and transporting heavy materials from one point to another. There are several types of cranes for a variety of construction sites, such as bridge/overhead, barge lift, tower crane, etc. The mobile crane is one of the most widely used types of construction equipment due to its mobility. Unfortunately, the number of crane accidents including casualties and deaths has increased over the last decade. In order to reduce these fatal tragedies, a dynamic simulator of mobile cranes based on analyzed overturn limit data has been developed and analysis results have been applied to site tests. The test bench is formulated to simulate the actual construction field and some practical experiments have been performed in realistic manners of operation. Moreover, wireless network communication systems are applied for monitoring the status of the crane from a distance where visibility is not secure. Consequently, the applicability in the field derived from operating the simulator and actual vehicle testing confirmed the feasibility of applying it to construction sites.

GA-Based Optimization Method for Mobile Crane Repositioning Route Planning

Mobile cranes have been used extensively as essential equipment at construction sites. The productivity improvement of the mobile crane affects the overall productivity of the construction project. Hence, various studies have been conducted regarding mobile crane operation planning. However, studies on solving RCP (the repositioning mobile crane problem) are insufficient. This article presents a mobile crane reposition route planning optimization method (RPOS) that minimizes the total operating time of mobile crane. It converts the construction site into a mathematical model, determines feasible locations of the mobile crane, and identifies near-global optimal solution (s) (i.e., the placement point sequences of mobile crane) by implementing genetic algorithm and dijkstra’s algorithm. The study is of value to practitioners because RPOS provides an easy-to-use computerized tool that reduces the lengthy computations relative to data processing and Genetic Algorithms (GAs). Test cases verify the validity of the computational method.

BIM-based 4D mobile crane simulation and onsite operation management

Heavy industrial construction, particularly when modularization is adopted, requires thorough heavy-lift studies to manage the extensive use of mobile cranes in congested and dynamic site layouts. This study introduces an integrated 4D crane simulation and onsite operation management framework for multiple concurrent mobile crane operations in the BIM environment with the support of a comprehensive database. Unlike similar recent efforts, the proposed framework is built upon previously developed crane planning and optimization systems, which enables generating accurate operation plans both in micro (objects) and macro scales (site). This framework addresses five different components regarding onsite crane operation management, including BIM-based multi-crane lift animation, scheduling and cost analyses, motion controlling in the BIM environment, safety monitoring and clash detection, and spatiotemporal site analyses. The developed framework's functionality is validated by implementing it into a portion of a real project in Alberta, Canada, through three different cases.

Optimized Mobile Crane Path Planning in Discretized Polar Space

Improper planning and management of heavy lifts is a major cause of cost overruns, delays, and, more importantly, safety incidents in industrial megaprojects. Automated lift planning is widely acknowledged as an effective solution. This research presents an automated lift path planning system for mobile cranes leveraging space discretization and an obstacle-avoidance technique from robotics. The proposed method treats the lifted object as a three-degree-of-freedom convex traveling through the surrounding environment [a given two-dimensional (2D) elevation] with discretized rotational and translational motions in polar coordinates. It efficiently finds the best feasible pick location and optimized collision-free lift path in the polar coordinate system to the set location. This system is a state-of-the art advancement in crane path planning because it mimics the crane’s intrinsic behavior and generates paths considering cost functions for safety, practicality, and economic objectives to enable its implementation in real practice settings. Illustrative examples are presented to verify the proposed approach and demonstrate its superiority over past similar path planning systems in terms of optimality and operational ease.

Suitability Confirmation for Welding Ultra-High Strength Steel S1100QL Using the RapidWeld Method

This experiment assesses the suitability of square-welding high strength steel using the deep penetra-tion welding method, RapidWeld. The aim of this method suitability assessment was to compare the final material properties of three welds, welded accordingly to identical welding procedures. High strength, ultra-fine-grain steel S1100QL (XABO 1100) was used as a parent metal. The suitability con-firmation was based on the achievement of requested mechanical properties of ISO 15614-1 and mo-bile crane manufactures standards. The hardness, strength properties and impact energy measure-ment and evaluatioon of the joint was performed during the experiment. The joint was welded re-peatedly with the use of the same welding parameters for the confirmation of process stability. The achieved mechanical properties fulfill all the requirements. The hardness value deviation is caused by different properties in the heat affected zone. The root cause of the impact energy deviaton was not fully investigated, but the minimal measured values are above requirement. The deviation of the strength characteristics is mininal. The performed experiment has confirmed that the selected weld-ing method is suitable to ensure that the requested material properties of welded high strength, ultra-fine-grained steel are achieved.

Assessment of Musculoskeletal discomfort for mobile crane operators

Workers seated in mobile cranes and operating for a prolonged period with an awkward posture are facing various ergonomic problems in the different body parts and particularly in the lower back. The research study purpose is to find an association of discomfort with the mobile crane operations. A discomfort study was carried out in a heavy equipment manufacturing industry where most of the mobile crane operators are continuously suffering from musculoskeletal discomfort in different body parts. Discomfort information was obtained with the help of a body part discomfort questionnaire during the various shift intervals from the start to the end of the shift. A total of 30 mobile crane operators of age from 21 to 59 years were made to participate. The study results reveals that, among the 30 mobile crane operators, 83.3% of operators reported discomfort in the lower back, and 20.0% reported in the upper back. In other parts, 23.3% to 63.3% of operators reported discomfort. Considering the severity level of discomfort reported by the operators, the highest discomfort is seen in the lower back and neck region. The operator’s age also has a significant influence on body discomfort sensed by mobile crane operators. Concluded that the main effected body parts are lower back and neck and the risk factors that may cause this discomfort are an awkward posture and whole-body vibration.

Simulation of ground bearing pressure profile under hydraulic crane outrigger mats for the verification of 16-point combined loading

The modular construction approach relies heavily on mobile cranes. With the increase in weight of modules, the ground bearing pressure (GBP) applied by the hydraulic crane also increases. To avoid ground failure, the primary technique is to determine the GBP by calculating the resulting force at each outrigger and assuming it is distributed uniformly over the surface area of the mat under the outrigger. Finite element analysis (FEA) indicates that the pressure profile beneath the crane mat is not uniform in nature, which means the traditional method of calculating the GBP is inaccurate. In this study, a new method is proposed to determine the GBP profile. The proposed methodology can determine the GBP at 16 points, the four corners of each of the four outriggers. For a theoretical case study, a hydraulic crane Grove GMK 7550 with three different payloads is examined and the results are verified by using FEA.