Crane Rails Research Articles

Nominal stresses in continuous and intermittent rail welds of crane runway beams

Crane runway beams of hot-rolled I sections are frequently the supporting structures of top-running overhead bridge cranes. In case of light crane service, the crane rails are usually fastened to the top flange of the crane runway beams by fillet welds. A survey among steel construction companies revealed that continuous rail welds as well as intermittent rail welds are commonly used. The rail welds are subject to multiaxial fatigue since they are exposed to normal and shear stresses due to the local wheel load introduction and global bending. Currently, the design standards EN 1993-1-9 (2005) and EN 1993-6 (2007) neither provide an appropriate detail category nor a nominal stress formula for rail welds. The paper focuses on the calculation of the nominal stresses in rail welds as basis of the fatigue action effect within the nominal stress method. It describes the differences in the nominal stresses of continuous and intermittent rail welds because of the contact between rail and top flange that has to be assumed for intermittent rail welds. Based on work samples, the contact conditions of intermittent rail welds are characterized as ‚technical contact‘ (in contrast to ‚ideal contact‘) due to imperfections within the contact surfaces that are described in detail. A Finite Element model is presented that accounts for the ‚technical contact‘ between rail and flange. This model is analyzed in a parametric study to identify the decisive parameters on the nominal stresses in intermittent rail welds.

Modeling of operational reliability of running wheels of overhead cranes of seaports

Overhead cranes are widely in operation in sea and river ports for cargo transshipment in open and closed storage areas. Since they are the main link in technological processes, the productivity of Port production lines depends on their reliable and continuous operation. It is known that during the operation of cranes, 90% of the running wheels fail and are replaced with new ones due to intensive wear of the edges, and 60-70% of crane rails due to wear of their side faces. Since the service life is the main indicator of the durability of parts and assemblies, therefore, increasing the installation of wheel life is an urgent task, which will reduce the cost of repair and operation of cranes. As the experience of operation shows, running wheels have the most worn elements of movement mechanisms. Thus, their service life ranges from several months to 2-3 years. This is due to the fact that replacing the wheels is cheaper compared to replacing the crane track. Since the service life is the main indicator of the durability of parts and assemblies, therefore, increasing the installation of wheel life is an urgent task, which will reduce the cost of repair and operation of cranes. Analysis of studies of complex technical systems shows that the reliability of overhead crane mechanisms operated for more than 30 years in the Seaport is not fully understood, the nature of wheel damage depends on the operating conditions. For research, 4 identical overhead cranes with a lifting capacity of 10 tons were selected, which operate in Hook mode in seaports. Crane wheels are made of 65g steel by casting. Crane mechanisms were visually examined and wheel wear was measured after 3 months during 4 years of operation. Based on the research results, the parameters of the Wear model from time to time in the form of a step function are calculated. The obtained values of the correlation coefficient indicate that there is a fairly tight relationship between wear and operating time. The average error value for the proposed model does not exceed 6.1%, which is quite acceptable for engineering calculations. It is established that the service life of Crane wheels does not exceed 3.3...3.4 years of operation, which is less than 4 years specified by the manufacturer.

Stress increases in crane runway girders due to rail joints

AbstractVertically acting wheel loads from overhead bridge cranes and potential additional horizontal crane loads induce two types of stresses in crane runway girders: i) global stresses due to bi‐axial bending and torsion and ii) local stresses which mainly affect the girder's web. The latter typically represent one of the most decisive criteria for the fatigue design check of welded girders and are the focus of this paper. Crane rails with foot flange are typically connected to the top flange with rail clips. These clips maintain the position of the rail in vertical and horizontal transverse direction, but they generally allow for longitudinal movement of the rail. Rails with foot flange are used with and without elastomeric bearing pads between the rail and the top flange of the girder. The local stresses in the webs of crane runway girders are strongly affected by discontinuities of the crane rails. Such discontinuities can originate from unplanned rail cracks as well as planned rail expansion joints. The current mechanical models for concentric as well as eccentric wheel loading in relevant design standards assume continuous crane rails. However, rail joints are expected to significantly increase the local stresses in the region beneath rail joints. The present paper focuses on the impact of rail joints on the local stresses in crane runway girders. The research activities comprise experimental tests as well as finite element calculations. The aim of the investigations is to develop a better understanding of the mechanical behaviour in order to avoid future fatigue damage due to an unexpected increase of local stresses at a rail joint.

Stiffness evolution of jet grouting columns performed under port caissons using PS suspension logging

AbstractJet grouting is one of the ground improvement techniques that are currently more widely used for upgrading gravity quays, especially to increase their berth depth. Irregular columns are formed because of a rotating high‐pressure injection of a cementitious fluid in the ground that mixes with the natural soil. Despite its popularity, there is hardly any field experimentation on the stiffness gain of the mixture, especially under the base of port caissons. As fresh columns behave like a dense fluid with an excess of pore pressure, the evolution of mixture stiffness, especially at early ages after injection, is a key aspect when programming working windows for ground improvement, drill locations, sequencing and timing. Otherwise, crane rails, pavement and other services are at risk of undergoing undesirable local movements. One of the upgrading programs of the Port Authority of Valencia, Spain, is the increase of the berth depth of its quays, many engineered as concrete caissons. The concern about the temporary local loss of the foundation stiffness during the execution of each jet grouting column prompted research to find an in situ procedure capable of measuring the stiffness evolution of the jet grouting columns at early ages. This paper presents a successful procedure using PS suspension logging, expanding its scope of geotechnical engineering applicability in an innovative way. The use of the technique for the intended purpose and the execution process itself stands out as a novelty, with the insertion of the borehole casing pipe through the axis of the recently executed column. The key outcomes of this research are: (1) the novelty of studying the evolution of the stiffness in the early ages of the jet grouting columns executed under port caissons, where it is not possible to execute test columns; and (2) to propose an adequate and reliable method at the beginning of the works to plan the injection sequence of the next columns of jet grouting.

Impact of rail joints on the local stresses in crane runway girders

Vertically acting wheel loads from overhead bridge cranes and potential additional horizontal crane loads induce global stresses due to bi-axial bending and torsion and local stresses in crane runway girders which mainly affect the girder’s web. The latter typically represent one of the most decisive criteria for the fatigue design check of welded girders and are the focus of this paper. Crane rails with foot flange are typically used for moderate to high wheel loads. They are usually connected to the top flange with rail clips. Rails with foot flange are used with and without elastomeric bearing pads between the rail and the top flange of the girder. The local stresses in the webs of crane runway girders are strongly affected by discontinuities of the crane rails. Such discontinuities can originate from unplanned rail cracks as well as planned rail expansion joints. The current mechanical models for concentric as well as eccentric wheel loading in relevant design standards assume continuous crane rails. However, rail joints are expected to significantly increase the local stresses in the region beneath rail joints. The present paper focuses on the impact of rail joints on the local stresses in crane runway girders. The research activities comprise experimental tests as well as numerical parametric studies based on finite element calculations, both for rails with and without elastomeric bearing pads. The aim of the investigations is to develop a better understanding of the mechanical behaviour and to quantify the increase factor for maximum local stresses in order to avoid future fatigue damage due to an unexpected increase of local stresses at a rail joint.

Metodologija kontrole geometrije kranskih šina geodetskim merenjima

In the new hall of the Institute for Materials and Structures, there was a need to control the geometry of the existing crane rails. In this paper, the methodology for determining the geometry of such a complex structure is presented, and the results of the applied method are also presented. The final product, i.e. the examined geometry of crane rails included numerical and graphical analysis of straightness, analysis of parallelism and analysis of horizontality of crane rails.

Numerical Back-analysis of Caisson Quay Walls in the Yeong-il Bay Port during the 2017 Pohang Earthquake

The performance of nonlinear response history analysis was analyzed based on the historic case of the 2017 Pohang earthquake in Korea. The Yeong-il bay container terminal stopped operations for a period after the Pohang earthquake and intensive site and hazard investigations were conducted. Nonlinear response history analyses using various soil constitutive models, including sophisticated liquefaction models, were performed on the caisson quay wall under two-dimensional plane strain condition. The results of analysis were compared to the hazard investigation results. The analysis results exhibit reasonable agreement with the field measurement data for the earthquake-induced permanent displacement of the quay wall and quay crane rails.

Strain measurements on rails of crane runway girders to predict accurate wheel loads

AbstractIn existing crane runways, data on the actual wheel loads acting on the crane rail are often missing. Therefore, approximated wheel loads have often to be assumed for static calculations of the crane runway girder. Within this paper, a method is presented that allows to calculate the actual wheel loads based on strain measurements on the crane rail. The idea is to measure strains on the rail at certain pre‐defined locations, while the crane is passing and calculate the wheel load from the measured strains. The correlation between the strains in the rail and the wheel load is determined in a numerical finite element study and in laboratory tests.The numerical studies also comprise several different geometries of crane runway girders. The objective is to verify the influences of them on the calculated strains in the rail. The results of the numeric calculations show, that the strains in the rail generally depend on the stiffness of the crane runway girder. The thickness of the upper flange and the web as well were identified as the main parameters. This behavior is also verified in laboratory tests.For the contact between the rail and the crane runway girder, two different cases have been investigated. The first analysis refers to a hard contact under compression which allows separation under tension. This configuration corresponds to cases with steel wearing plates beneath the crane rails. The second case considers an elastomeric rail pad between the rail and the crane runway girder.

Experimental Analysis of Frictional Characteristics of the Interface between Gantry Crane Wheels and Rails under Submerged Rail Conditions

The purpose of this paper is to clarify the influence of rail submergence that occurs at the quay on the frictional characteristics of the interface between gantry crane wheels and rails. The characteristics serve as a basis for the dynamic simulation analysis of cranes that run away due to wind and crane designs. An experimental analysis system developed uniquely by the authors was used to carry out this research. Wheel was pressed to submerged rail, then the rail was slid. The friction force generated between the wheel and the rail was measured. This experimental analysis was conducted for contact pressure conditions that the ratios of the maximum Hertzian contact pressure to the yield stress of the material of the rail are approximately 1.76, 2.12 and 2.39. Under these various contact pressures, the ratio of the maximum static friction force under submergence conditions to the same friction force under dry conditions increased slightly. In contrast, when contact pressure conditions were nearly identical, the dynamic friction force under submergence and dry conditions was about same. Finally, the ratio of the dynamic friction coefficient to the static friction coefficient as a reference for designing cranes was shown and discussed.

СТАТИСТИЧНИЙ АНАЛІЗ РЕЗУЛЬТАТІВ ГЕОДЕЗИЧНИХ ЗЙОМОК КОЛІЙ МОСТОВИХ КРАНІВ У ВИРОБНИЧИХ БУДІВЛЯХ

Abstract. The studies were carried out in order to develop effective methodology for the statistical analysis of the results of geodetic surveys of the rails of overhead cranes. The findings will provide generalization of the measurement results, demonstration of their changes over time, as well as comparison with the permissible values of deviations from the design position. The analysis includes the results of geodetic surveys of the position of the rails of overhead cranes in machine-building shops during four years. The position of the heads of the crane rails was determined using a level, a transit theodolite, and a laser sight. In accordance with the requirements of regulatory documents for the operation of overhead cranes, three parameters of the position of the crane rail heads were controlled: the height difference on adjacent pillars of the same row; height difference on pillars of different rows in one transverse frame; deviation of the distance between the rails from the design value. The controlled parameters are random variables that should be analyzed by statistical methods. Deviations of the distance between the axes of the crane rails from the design value are presented in the form of a random variable with the normal distribution law. The differences in the elevation marks of the heads of the crane rails, which are monitored without taking into account the sign, are described by the distribution law of the modulus of a random variable. As a generalized characteristic of the state of crane rails, it is proposed to use the probabilities of horizontal and vertical deviations of the crane rails beyond maximum permissible values established by the norms. Based on the results of the research, conclusions were drawn about the need for systematic control of the position of overhead crane rails by geodetic methods, the applicability of the above distributions for the probabilistic description of deviations of crane rails from the design position, as well as the feasibility of using the probability of deviations of the crane rails geometry beyond the permissible values established by the norms.

HIGH-PRECISION OBJECT DELINEATION WITH UAV – DEMONSTRATED ON A TRACK SYSTEM

Abstract. The proper function of rail-based transport networks relies on the accurate positioning of the tracks. Regular control and maintenance intervals are in place to guarantee safe and reliable operation. This also holds for the crane rails of the storage cranes in the container terminal in the Hamburg harbour. Especially in the terminal “Altenwerder” the geomorphological conditions of the soil lead to a permanent subsidence of the tracks and thus ask for intensive surveying and maintenance activities. The allowed tolerances are in the range of 10mm in the XY-plane on a stretch of 300m. In the daily practice, the measurements are done using traditional tachymetric survey, in combination with a rail car carrying a reflector. This method is reliable but comes with the disadvantage that the operation of cranes needs to be interrupted. In this paper we present an alternative, automatic approach which employs state-of-the-art UAV-based photogrammetry to measure the actual location of the rail. The mid-format camera system combined with a 150mm tele-lens results in a GSD of 0.9mm at 35m flying height. Challenges addressed concern the proper setup and installation of the ground control network, the flight planning and bundle adjustment. Furthermore, an automated rail delineation in the derived surface model was developed. First experiments show that an automatic workflow is possible, including the delineation task. Remaining obstacles concern, for instance, the compliance with the requirements regarding absolute positional accuracy, since the inner block geometry is theoretically much more accurate than the realised control point network.

Experimental Analysis of Frictional Characteristics of the Interface between Gantry Crane Wheels and Rails under Dry Conditions - Effects of Wheel Load and Sliding Velocity on the Characteristics

Experimental Analysis of Frictional Characteristics of the Interface between Gantry Crane Wheels and Rails under Dry Conditions - Effects of Wheel Load and Sliding Velocity on the Characteristics

Failure analysis concerning causes of wear for bridge crane rails and wheels

Wear of the guiding structures is an undesirable phenomenon, which is occurring very often in the technical practice. This negative phenomenon also reduces reliability level of the hoisting machines and machinery. Taking into consideration the practical point of view it is possible to specify that wear of the crane guiding structures means wear of the crane rails and crane wheels. The guiding structure is defined in this case as a cinematic couple “wheel-rail”. There is presented in the article an experimental and calculation analysis, which was performed in order to investigate an excessive wear of the crane guiding structure, namely in the case of the hoisting equipment utilised in a real operation. There were experimentally researched two bridge slab tong cranes with the loading capacity 50 t and also their crane runways. It was determined, according to the performed analyses that in the case of one crane the geometry of its undercarriage is incorrect. The experimental measurements confirmed a fact that the real value of the horizontal force was approximately 3.8-times higher in comparison with the assumed force value obtained from a calculation. Another finding was that also the crane runway geometry exceeded values of the permitted deviations with regard to the valid technical standard. There is described in the chapter Conclusion a proposed short-term solution, which is able to eliminate wear of the crane rails and crane wheel flanges, however without prevention of the crane skewing.

Defects of steel crane beams and methods of their strengthening

Crane structures are the most vulnerable in buildings and structures because of their early wear in comparison with other building structures. The wear of crane structures is because of the appearance and the development of fatigue damage nature. The article presents the constructive solutions developed by the authors for strengthening the structures of steel crane beams with conventional and corrugated walls which allow to reduce the influence of the negative influence of installation, operation and technological processes on their operational durability. The most dangerous installation defect is the displacement of the crane rail axis relative to the axis of the crane beams wall. Value of this shift is exceeded several times in the cases considered below. It is proposed to use crane beams with corrugated walls to solve this problem. The authors have developed and implemented a project to restore the performance of steel crane beams by strengthening the walls of damaged beams without stopping production. Strengthening was performed on the outside of the eccentricities of the application of loads from crane rails by creating a truss structure parallel to the I-beam with chords of I-beams, which made it possible to significantly reduce the magnitude of local stresses from moments, the magnitude of transverse forces and consequently shear stresses, which are the main factors in the appearance and development of fatigue cracks in their walls.

Оценка точности комплексного метода геодезического контроля подкрановых путей мостовых кранов

The method of using the electronic total station for a complex method of geodetic controlling tracks of bridge cranes is explained. This technique provides for the direct determining the x, y, z coordinates of the crane rails axial points in the controlled section of the track from one point of the total station. The values of x and y can calculate the track width and control the straightness of the rails, and the values of z to find the excess between the rail points in the row and span. Estimating the accuracy of such control’s results by obtaining the covariance matrix of coordinate errors is shown. It is noted that this form of accuracy representation is not clear enough, depends on the orientation of the coordinate axes and is not informative. The article proposes a simple method of assessing the accuracy of survey points in the directions oriented relative to crane tracks. This technique is based on the geometric interpreting the error of the defined points’ position using the circles of mean square errors, which can be constructed in any plane of three-dimensional space. By the radius-vector of these circles the MSE point defined can be judged in any given direction. On the example of estimating the accuracy of the track crane’s track width the iconic modeling is made, which confirmed the simplicity, reliability, accessibility and meaningfulness of the proposed methodology.

Local stresses in webs of crane runway girders: Tests and numerical calculations

The design of crane runway girders is strongly affected by the local stresses due to wheel loads (mainly fatigue design, but also web buckling). A realistic approach of these local stresses, particularly the vertical direct stresses σz at the web top, is very important for economic design.In this paper firstly a summary of formulae in literature and in relevant international design standards is given. These formulae are based on very limited tests in the past, which are also mentioned.In the main part of this paper new test results for local stresses in webs due to vertical wheel loads for crane runway girders with I-section and box section are given, also including different connections with the crane rails (with/without welds between rail and girder flange and cases with no rail). Centric loading was tested, but also eccentric loading with different eccentricities, leading to additional web bending out of plane.For all tests, accompanying comprehensive Finite Element analyses were conducted. These FE-models are also presented and their results are compared with the test results and with the predictions of design formulae, used in practice. Finally, additional numerical investigations are presented, dealing with the effects of different contact properties between rail and girder flange.

05.02: Influence of rails on the stability of crane runway girders

ABSTRACTDue to the stressing of crane runway girders, they are usually susceptible to lateral torsional buckling. In this paper, the contribution of crane rails to bending stiffness, torsional rigidity and load bearing capacity of crane runway girders is presented. The torsional and warping stiffness of the combined cross section is being determined by numerical approaches, i.e. two‐dimensional isoparametric finite elements for cross sections. The influence of the increased stiffness and cross sectional capacity is then considered for stability verifications based on an application of equivalent initial geometric imperfections. The corresponding non‐linear member analyses are performed using finite beam elements with seven degrees of freedom. In addition, the influence of the rails on the stress states of the total cross sections is evaluated and presented.

Control Measurements of Crane Rails Performed by Terrestrial Laser Scanning

This article presents a method for measuring the geometry of crane rails with terrestrial laser scanning (TLS). Two sets of crane rails were divided into segments, their planes were adjusted, and the characteristic rail lines were defined. We used their profiles to define the positional and altitude deviations of the rails, the span and height difference between the two rails, and we also verified that they complied with the Eurocode 3 standard. We tested the method on crane rails at the hydroelectric power plant in Krško and the thermal power plant in Brestanica. We used two scanning techniques: “pure” TLS (Riegel VZ-400) and “hybrid” TLS (Leica MS50) scanning. This article’s original contribution lies in the detailed presentation of the computations used to define the characteristic lines of the rails without using the numeric procedures from existing software packages. We also analysed the influence of segment length and point density on the rail geometry results, and compared the two laser scanning techniques. We also compared the results obtained by terrestrial laser scanning with the results obtained from the classic polar method, which served as a reference point for its precision.

Fatigue hazards in welded plate crane runway girders – Locations, causes and calculations

Steel crane runway beams compared with other building structures are exposed to extremely complex load-stress conditions. It turns out, that significant from the point of view of the resistance of the crane runway beams is a cyclic nature of fluctuating loads, which leads to formation of numerous cracks and damages. This effect is especially characteristic for webs in plate I – cross sections of crane runway beams. The complex state of stresses is generated by overall bending that causes normal and shear stresses – σx, τxz, and by crane wheel eccentric load that produces respectively stresses – σz,x, σo,x, τo,xz. Stress components produced by overall bending are determined as I kind stress, whereas the stress components from the crane wheel load are introduced as II kind stress. Such a combination of stresses lowers the fatigue strength of the web, which is ignored by many rules specified in standards. Limited fatigue strength is observable, among others, in crane rails splices. The results of numerical analyses obtained as II kind stresses in the web located directly beneath the crane rails splices that occur as: orthogonal contact, bevel contact and stepped bevel contact as well, confirmed the complexity of the issue. Following that, other factors, not being defined yet, but affecting the stress state of the both crane rail and crane runway beam are scheduled to be studied, as for instance, the eccentric load induced by crane trolley in mentioned above elements.

Increasing the Moment of Inertia of Crane Rails Torsional

This article is devoted to extreme increase in the moments of inertia of crane rails torsional strongly influence the endurance of crane girders. We investigate increase in moment of inertia of the rail under torsion with increasing thickness of the walls and shelves of thick-walled I-section profile in the square until its transformation into a square profile. It was found that the transformation of the profile of a monolithic solid square increases the moment of inertia of the torsion Jkr, cm4 to 3,1075 times and reaches its extreme. A cross-sectional area remains constant (const). Crane rails with a high moment of inertia for torsion provides significant economic benefits, and significantly reduces the operating costs of the enterprise.