Mobile Elevating Work Platforms Research Articles

Risk Analysis in Civil Construction Services Using Mobile Elevating Work Platforms

The use of vertical transportation equipment in Civil Construction, such as Mobile Elevating Work Platforms - MEWP had optimized activities, avoiding wasted time and simplifying. However, brings in addiction to risks inherent to mechanical equipment, the height factor, increasing the probability of accidents occurrences. The aim of this work was to identify the risks of accidents and nonconformities with the Brazilian legislation present in the activities using MEWP, in order to propose measures of control and systematization of the actions, to integrate accident prevention in construction sites. For this purpose, a checklist was developed and applied in a large Construction workplace located in the Metropolitan Region of Recife-Brazil. According to the data obtained, a list of control guidelines and safety measures was elaborated, identifying the responsibilities of users and operators in services using MEWP. It was observed that the irregularities found are due factors related to operation, maintenance and use inspection of the equipment and significant occurrence of irregularities such as absence of work area isolation, daily inspections and electrical grounding in motorized MEWP. These facts need for improvements making improvements on training and inspections to ensure the fulfillment of the safety standards and an accident-free work environment.

Numerical and Experimental Determination of the Wind Speed Value Causing Catastrophe of the Scissor Lift

The current work is devoted to the numerical determination of the wind speed value, which can cause the overturning of the mobile elevating work platform of the scissor lift type. In the first step of the analysis, the scaled model of the real vehicle is prepared. In the second step, the model is used in the aerodynamic tunnel to determine the aerodynamic force values and moment, which act on the vehicle. The three different configurations of the work platform are considered, namely: (a) The work platform raised to the maximum height with an additional bridge extended, (b) the work platform raised to the maximum height, and (c) the work platform half raised. In each position, the direction of the wind is changed from the range from 0° to 180° with an increment equal to 15°. In the next step of the analysis, the CFD simulations are carried out. The ANSYS Fluent R22 software is used. As a model of turbulent airflow, the standard k-ε with standard wall function is adopted. The obtained experimental results are used to verify the numerical model. A very good agreement between the results of the experiment and the results of numerical simulations is obtained. As the main result of the numerical study, the values of the tipping moment and corresponding wind speed that cause the overturning of the analyzed real scissor lift are determined. It occurred that the lowest value of the wind speed is obtained for the first variant of the vehicle configuration V1crt = 22.315 m/s for the angle of the wind speed direction β = 30° and the highest one for the third variant V3crt = 34.534 m/s and β = 15°, without any persons on the work platform. The presence of human beings on the work platform is also considered.

Evaluation of Two Proximity Warning Devices on a Mobile Elevating Work Platform

Contact between a mobile elevating work platform (MEWP) and an energized overhead powerline (OHPL) is a warned-against event that is associated with damage to property as well as injury or death. The objective of this project was to evaluate the effectiveness of two different proximity warning devices (PWDs) installed on an MEWP operated near OHPLs. The general procedure used was to rotate the MEWP work platform horizontally away from, then toward, the OHPL from each side of the MEWP (at various platform heights), noting the distance between the MEWP and the OHPL when an alarm occurred. PWD2 allowed violation of the simulated OSHA boundary on 74.3% of the total rotations without initiating a warning alarm and was too sensitive to be practical as a startup alarm system. PWD1 did not allow operation of the MEWP within 20 feet of the actual OSHA minimum approach distance. The results of the startup test for PWD1 were no-where near consistent.

Use of mixed reality for the training of operators of mobile elevating work platforms with the aim of increasing the level of health and safety at work and reducing training costs

The article presents an immersive multisensory simulator developed in a project co-financed by INAIL (the Italian Workers' Compensation Authority) as part of a collaborative research program for the application of innovative technologies and systems to the management of health and safety at work. Specifically, the program provides for the development of simulators for the structuring of skills qualification paths for operators in charge of running and maintaining the most dangerous work equipment. The simulator we present reproduces all the aspects that contribute to a complete driving experience of the simulated machine in an artificial working environment that replicates typical and atypical operations and hazards involved in the use of self-propelled mobile elevating work platforms (MEWPs) with an extendable articulated boom. The simulator has been designed following the analysis of the most critical working routines with aerial work platforms and using physical components of a real MEWP combined with immersive Virtual Reality technologies. The use of Extended Reality technologies to simulate challenging work scenarios makes it possible to train operators by confronting them with very risky situations without any real danger, both in terms of damage to machinery, and above all in terms of user’s safety. The presented simulation system has been designed as a high-TRL prototype to demonstrate the feasibility of developing training programs in the context of occupational safety and health, based on a mixed-reality simulator targeting MEWP operators and verifiers.

Lightweight design method and application of MEWP bracket based on multi-level optimization

<abstract> <p>Mobile elevating work platform (MEWP) is a large-scale engineering machinery equipment that transports workers and tools to the designated height for operation. As the key supporting component of MEWP, the bracket simultaneously needs to meet the performances of high stiffness and strength. Furthermore, the mechanical performance of the bracket can be significantly influenced by its cross-sectional shape. However, the optimal cross-sectional shape of bracket is not easily to obtain owing to the lacking of lightweight design method. Thus, a lightweight design method of MEWP bracket based on multi-level optimization is proposed in this paper. Firstly, the multi-case topology optimization model of MEWP bracket is constructed by using the compromise programming method, and the optimal section configuration of MEWP bracket is obtained based on Solid Isotropic Material with Penalization (SIMP). Secondly, the parameterization of the cross-sectional shape of bracket is realized using the mesh deformation technology, and the multi-case optimization mathematical model of the MEWP bracket is established. Then, the cross-sectional shape and gauge of the bracket are optimized using multi-level optimization method. The optimized results show that weight reduction mass is 11.66 kg and the ratio is 52.4% under the premise that the stiffness of the bracket does not decrease. Furthermore, the weight of MEWP bracket optimized by the multi-level optimization method reduced by 1.27 kg compared with single gauge optimization method. Finally, a physical prototype is developed according to the optimization results.</p> </abstract>

Studying coefficient of increase of the support surface after deployment of a mobile hoist

Currently, there are about 150 manufacturers of mobile elevating work platforms (MEWP), which are constantly designing and implementing new machines with advanced capabilities. Along with the improvement of hoisting equipment, the support devices of the MEWP are also improved. Therefore, there is a need to investigate the coefficient of increase of the support surface area after the deployment of a mobile hoist for different types of support devices. Goal. The aim of this work is to study how the coefficient of increase of the support surface area after the deployment of the support device depends on the length of the support projecting for different designs of support devices used in MEWP. Methodology. Analytical methods of studying the designs with variable geometrical parameters were used in the work. To obtain the dependences of the coefficient of increase of the support surface area after the deployment of the support device on the length of the support projecting, the methods of mathematical modeling employing computer technology were used. Results. The analysis of the dependences of the coefficient of the support surface area increase after the deployment of the support device on the length of the support projecting showed that the use of the considered support devices enlarges the coefficient of increase of the support surface area from 1.9 with angular supports to 3.4 for Spider type support devices. Originality. It is proposed to consider the coefficient of increase of the support surface area, which enables to take into account the lengths and angles of the supports when determining the support surface area. Practical value. With the results of the study it is possible to choose the type of support device and its geometric parameters at the design stage which will

Experimental study of oscillatory processes taken place in the operation of the mobile elevating work platform

Experimental study of oscillatory processes taken place in the operation of the mobile elevating work platform

Dynamic stability analysis and Experiment of the Mobile Elevating Work Platforms

In order to calculate dynamic stability of the Mobile Elevating Work Platforms (MEWP) during driving across obstacles and operating on the slope, the analysis method based on mathematical models and simulation models of the MEWP was put forward, then the MEWP dynamic simulation models where the tires and booms were set as flexible bodies were made by ADAMS. Four kinds of the most dangerous working conditions were analyzed, and then the dynamic curves of tire loads and dynamic stability safety coefficient were obtained. Next, the dynamic stability of the MEWP during operating on the slope was verified by field experiments, and the results show that the minimum dynamic stability safety coefficient is 0.157. By comparison and analysis of dynamic stability safety coefficient between simulation analysis and field experiment, it can be seen that the deviations are all positive and less than 5%, therefore the results show that the dynamic stability of the MEWP during driving across obstacles are satisfied. At the same time, the analysis method combining dynamic simulation and some field experiments of the MEWP is proved reliability, accuracy and economy. In all, the dynamic stability of the MEWP can be calculated accurately by ADAMS, in the meantime, the overload operation test (1.5 times rated load) must be performed on the 5° cross slope before the MEWP are selled, and so long as the minimum dynamic stability safety coefficient is no less than 0.1, the MEWP are proved stability and safety.

Welding of mobile elevating work platforms


 
 
 The demand for new welding technologies in civil engineering and transport is increasing. An example of this is the tendency to increase the operating range of a mobile platform mounted on motor vehicles while maintaining the weight of the vehicle. The most commonly used material in the production of mobile platforms are AHSS steels due to their high tensile strength at the level of 1400 MPa. However, the joints created with their use are characterized by much lower strength than the native material. In this article, the most appropriate parameters for welding elements of a mobile platform from difficult-to-use steel AHSS were selected.
 
 

Accuracy of incidental dynamic analysis of mobile elevating work platforms

This paper presents the results of a study into the dynamic behaviour of a support structure of a mobile elevating work platform. The vibrations of the mechanical system of the observed structure are examined analytically, numerically, and experimentally. Within the analytical examination, a simple mathematical model is developed to describe free and forced vibrations. The dynamic analysis of the mechanical system is conducted using a discrete dynamic model with a reduced number of vibrational degrees of freedom. On the basis of the expression for the system energy, and by applying Lagrange\'s equations of the second kind, differential equations are derived for system vibrations, frequencies are determined, and the laws of forced platform vibration are established. At the same time, a nonlinear FEM model is developed and the laws of free and forced vibration are determined. The experimental and numerical part of the study deal with the examination of the real structure in extreme conditions, taking into account: the lowest eigenfrequency, forced actions that could endanger the general stability, the maximal amplitudes, and the acceleration of the work platform. The obtained analytical and numerical results are compared with the experiments. The experimental verification points to the adverse behaviour of the platform in excitation cases – swaying. In such a situation, even a relatively small physical force can lead to unacceptably high amplitudes of displacement and acceleration – exceeding the usual work values.

Safety I–II, resilience and antifragility engineering: a debate explained through an accident occurring on a mobile elevating work platform

Occupational health and safety (OHS) represents an important field of exploration for the research community: in spite of the growth of technological innovations, the increasing complexity of systems involves critical issues in terms of degradation of the safety levels. In such a situation, new safety management approaches are now mandatory in order to face the safety implications of the current technological evolutions. Along these lines, performing risk-based analysis alone seems not to be enough anymore. The evaluation of robustness, antifragility and resilience of a socio-technical system is now indispensable in order to face unforeseen events. This article will briefly introduce the topics of Safety I and Safety II, resilience engineering and antifragility engineering, explaining correlations, overlapping aspects and synergies. Secondly, the article will discuss the applications of those paradigms to a real accident, highlighting how they can challenge, stimulate and inspire research for improving OHS conditions.

Experimental and analytical study on elevating working platform

This paper describes the research performed about the dynamical behavior on the mobile elevating work platform (MEWP). In particular, this research was inspired by that accident happened during a pruning operation. A big branch of three fell down and bumped the basket of MEWP. The consequent dynamical actions have made the operator jump out of the basket of MEWP. The main object of this work is to characterize the dynamic behavior of this machine (height=34 m, working load limit =200 kg) in order to estimate the actions induced by the branch on the MEWP. This load condition is not contemplated in the standards used for the design of this machine. For this purpose many experimental, analytical and numerical analyses were performed. In order to characterize the dynamical behavior of the machine (real damping, stiffness of the global arm and the sliding blocks positioned between each arms, etc.), on the similar MWEP, about 20 accelerometers and strain gauges were applied; subsequently the machine was subjected to different movements (extension and rotation the arms and the jib). The MEWP was subjected to geometrical relief with the aim to carry out the solid model necessary for finite element model (f.e.m.) analyses; which are performed using the parameters acquired in the previous step. The f.e.m. results were compared with the values obtained from the strain gauges. A lumped parameter model was created in order to apply the load condition induced by the branch to the jib. Numerical and analytical results show that in the geometrical configuration of MEWP (when the accident occurred), the acceleration of the basket is greater than gravity and it justifies the operator jumping out of the basket. The results achieved led to a revision of the standards (in a specific technical committee) both for designing this machine in order to consider this exceptional load condition and for designing the safety equipment for MWEPs operators.

Simulation Analysis and Experiment for the Articulating Booms of the Mobile Elevating Work Platforms

In order to analysize the dynamic characteristic of the articulating booms in the Mobile Elevating Work Platforms (MEWP), the dynamic models of the articulating booms were made by software ADAMS and the dynamic operation performance was analyzed. Lastly, the field experiments were carried out and the results show that the dynamic operation performance of the articulating booms is stable in the condition of 300 kg load. The maximum loading capacity errors of the different oil cylinders between the test results and simulation calculation data are less than 10%.

Urban green spaces activities: A preparatory groundwork for a safety management system

IntroductionUrban green spaces works and maintenance are high-risk activities and usually represent possible sources of injuries. The management issues are complex and strongly influenced by companies' policies in terms of safety management and human factor. A high number of tasks—including protecting public health and safety and safe working procedures—need to be faced by professional arborists or gardeners. MethodThe present paper provides a preparatory groundwork for modeling and describing the real risk levels during the abovementioned activities. The methodology represents a useful tool for decision making both for group leaders and safety coordinators. This goal is reached by collecting data emerging from several workplaces located in North East Italy regarding the frequency and severity of injuries. ResultsThe preliminary results point out that the most frequent injuries in green maintenance activities are represented by cuts, contusions, and ocular lesions, but none of them have lead to particularly serious consequences for the operators; indeed, the high levels of severity are related to traumas, fractures, and acute lumbar herniated discs. The riskiest activities are related to pruning, especially using mobile elevating work platforms, and grass cutting, especially when operated in escarpments and banks. Workers' behavior and companies' safety policies are key elements for a correct safety management system.

Failure analysis of the mobile elevating work platform

This paper presents an investigation of the accident which occurred during startup of the extending structure from the transport position. In order to clarify the causes of crack occurrence along almost the entire surface of the lever cross-section, the authors performed visual, experimental (chemical composition, tensile properties, microhardness) as well as metallographic examinations. Stress states in the critical zone are defined by applying the finite element method (FEM). Based on the investigation results it was concluded that the lever breakdown is predominantly caused by both the ‘operating-in’ defect (the malfunction of the limit switch) and the ‘manufacturing-in’ defect (poor weld quality). The investigation results presented in this paper are important because same or similar problems could arise in supporting structures of various types of transportation, construction and mining machines.

Wind Action on a Mobile Elevating Work Platform (MEWP) in Operational Conditions

The paper presents a brief presentation of researches done on a mobile elevating work platform model in a wind tunnel. The major aim of the tests was to define aerodynamic coefficients of the platform in different conditions of operation and for a variable angle of wind attack. The results may be useful in the designing process of the mobile elevating work platform.

Dynamic Characteristics for Leveling System of Mobile Elevating Work Platforms

Focused on revealing variations of dynamic characteristics of an auto-leveling system used in mobile elevating work platforms (MEWP) at large height, a unified mathematical model composited of a series of sub-models was built for the leveling systems. An effect on dynamic characteristics including the fast response and relative stability from varying-parameters was investigated. Results displayed the displacement-angle factor changing with work-conditions tended to cause fluctuations of the stability, while enlarging the amplifier gain would accelerate system response. Increasing the area ratio was conducive to leveling stability to be reinforced, but lead a different response speed for forward process or reverse leveling, which was harmful to overall stability. The findings would provide essential theory guidance for the design and manufacture of the leveling system devices of high altitude platform. DOI : http://dx.doi.org/10.11591/telkomnika.v12i5.4914

A survey of safety issues in tree-climbing applications for forestry management

Topping, trimming, consolidation, securing and felling are very common operations in arboriculture, in city park as well as in forests. In case of very large trees, these operations are often not possible from ground level using ladders or Mobile Elevating Work Platforms (MEWPs) because of excessive height or uneven/inaccessible terrain. In past years, different people start applying techniques, materials and procedures normally used in mountaineering and caving, to climb trees and these techniques start to be applied to forestry management operations; these techniques are now worldwide used. Work activities at height, as tree-climbing for forestry management purpose, are regulated in Italy by Legislative Decree 81/08 about safety in the workplace, as this activity expose operators to fall from height and many other risks. Moreover, as this activity involves the use of specific tools, operators must be trained (with periodic refreshment) and tools must been periodically checked by authorised operators. The objective of this work is to present and synthesise regulations and some technical aspects in order to allow operators to better understand different issues and general principles related to this activity.

A survey of safety issues in tree-climbing applications for forestry management

Topping, trimming, consolidation, securing and felling are very common operations in arboriculture, in city park as well as in forests. In case of very large trees, these operations are often not possible from ground level using ladders or Mobile Elevating Work Platforms (MEWPs) because of excessive height or uneven/inaccessible terrain. In past years, different people start applying techniques, materials and procedures normally used in mountaineering and caving, to climb trees and these techniques start to be applied to forestry management operations; these techniques are now worldwide used. Work activities at height, as tree-climbing for forestry management purpose, are regulated in Italy by Legislative Decree 81/08 about safety in the workplace, as this activity expose operators to fall from height and many other risks. Moreover, as this activity involves the use of specific tools, operators must be trained (with periodic refreshment) and tools must been periodically checked by authorised operators. The objective of this work is to present and synthesise regulations and some technical aspects in order to allow operators to better understand different issues and general principles related to this activity.

Dynamic Responses of Mobile Elevating Work Platform and Mega Container Crane Structures

The modern design methods lead to the objectivisation of the process of thinking, which is important for the new system development. The aim of objectivisation and decomposition of the design is obvious: it should enable a new approach in the problem solving and thinking of the designer, enriches the large quantity of new information, facts and ideas, which are important for the system designing. The first part of this paper gives a brief presentation of mobile elevating work platform structure response to the wind excitation in possible resonant states. The second part is dedicated to the dynamic analysis of the mega container crane structure subjected to the moving load.