Machine Foundations Research Articles

Load Effect Impact on the Exploitation of Concrete Machine Foundations Used in the Gas and Oil Industry

Load Effect Impact on the Exploitation of Concrete Machine Foundations Used in the Gas and Oil Industry

A Review of Fiber Synergy in Hybrid Fiber Reinforced Concrete

Abstract Fibre reinforced concrete (FRC) presently utilized as a part of special structures subjected to dynamic loads for example airport pavements, expressways overlays, bridge decks and machine foundations. In most cases, FRC contains just a single kind of fibre. The utilization of at least two kinds of fibres in an appropriate mix can possibly improve the mechanical properties of concrete and result in performance synergy. The audit demonstrates that the blend of fibre allows a more powerful control of the dynamic crack development. This review analyses the components for synergistic impacts that gives direction on the fiber and matrix choice.

Bearing deformation of heavy-duty machine tool-foundation systems and deformation detection methods

Because of the characteristics of heavy-duty machine tools such as large self-weight and heavy load, the working precision and service life of their lathe beds, columns, and other large structural parts are all directly influenced by the foundation. In view of the considerable influence of joint surfaces on system characteristics, this study involved obtaining joint surface parameter values from a microscopic perspective, deriving a static joint surface parameter model from Reynolds equation, adopting fractal theory to develop a bolted joint surface parameter model, and thus completing the embedding of joint surface parameters under uneven loads; a simulation model for a heavy-duty machine tool-foundation system was also devised considering the influence of joint surfaces. To identify the structural micro-deformation status of heavy-duty numerical control machine tool-foundation systems, the authors constructed a fiber grating technology-based experimental platform for detecting the deformation of structural parts, verified the correctness of the above simulation model via experiments, and proposed a method for detecting the deformation of heavy-duty machine tool-foundation systems using fiber grating technology. Based on the above simulation model, the influence of reinforced layer position, foundation outline specifications and soil properties around the foundation on the bearing deformation of heavy-duty machine tool-foundation systems were studied, and some guidelines on the construction of concrete foundations were formulated. This model and the related detection method laid a theoretical foundation for guiding the design and optimization of heavy-duty machine tool structure and foundation.

Closed form solutions for response of machine foundations under accidental blast loads

An attempt has been made in this study to analyze and predict the response of machine foundations under operating conditions subjected to accidental blast loads. Three cases of machine foundations subjected to combined sinusoidal and blast loads have been analyzed, namely- i) response of soil remains elastic during the blast, and maximum displacement also occurs in the elastic state, ii) blast takes place in elastic state but maximum response is obtained in plastic state, and iii) during the blast, the state of soil-foundation system changes from elastic to plastic and the maximum response is obtained in plastic state. Closed form solutions have been obtained for predicting the displacement-time history of machine foundations for all these three cases. Parametric study has also been carried out to understand the influence of parameters like mass of machine and the foundation, stiffness of soil, damping ratio, frequency ratio, and the ultimate bearing resistance of soil on displacement-time history of machine foundations. Results of parametric study would be helpful in designing the machine foundations in the presence of combined harmonic and blast loads.

Experimental Investigation of Toughness Enhancement in Cement Mortar

This paper presents the results of investigation carried out to improve the mechanical toughness of cement mortar. Toughness is a basic parameter which has to be improved in brick walls, concrete roads, machine foundations, dams etc. Materials fails due to an impact force and vibrations resulting in minor cracks and bonding failure between bricks, it leads to failure of the structure. In order to avoid the failure toughness has to be enhanced and this can be done by modifying the cement mortar. In this project recycled glass is used in the form of powder less than 45 µm as replacement of cement. Also natural rubber latex is added as 20% replacement of water. Three mortar mix are considered, namely 1:3, 1:4, 1:5. The compressive strength of mortar cubes, and flexural strength are done to determine the strength and toughness of the mortar. Results showed that fracture toughness increased to considerable amount.

Behaviour of machine foundations resting on saturated sand granular tire rubber mixtures

This study aims to investigate the behaviours of machine foundations resting on sand granular tire rubber mixtures after saturation. Kerbala sand with two relative densities, 35% and 60%, and granular rubber of sizes 0.07 to 3 mm, resulting from hashing scrap tires into small pieces, were used. A harmonic vertical mode of vibration was applied using a mechanical oscillator fixed on a square steel footing (200 × 200 × 20 mm). The footing was rested on sand inside a steel box of size 1200 × 1200 × 900 mm. Nine model tests were carried out on saturated sand to study the effects of 0, 8, and 12% mix ratios and 0.5 B and 1 B mixing depth for the two relative densities and two frequencies (69 Hz and 80 Hz) in terms of displacement amplitude, settlement, and excess pore water pressure generation in soil. The same number of models were tested for a comparison of dry sand under the effects of the same parameters. The results showed that, in general, the displacement amplitude decreased and the settlement increased for saturated sand compared to dry sand under the same conditions. Mixing granulated tire rubber with saturated sand decreased the displacement amplitude, settlement, and excess pore water pressure; the range of percentages of reduction were from 19% to 73%, 40% to 70%, and 24% to 60% respectively.

Effect of Anisotropy on Cyclic Properties of Chennai Marine Clay

Variations of normalized shear modulus (G/Gmax) and damping ratio (D) with strain are important for site response studies, analysis of machine foundation, etc. In this study, an attempt was made to investigate the effect of anisotropic consolidation on cyclic behaviour of the Chennai marine clay. The anisotropic consolidation on the specimens was represented through a parameter called stress ratio (Kc), which is defined as the ratio of radial stress to the axial stress on the specimen. A series of cyclic triaxial and resonant column tests were conducted on reconstituted marine clay specimens at three stress ratio (Kc) of 1.00, 0.67 and 0.55. In this study, all the tests were conducted on normally consolidated specimen, where stress ratio (Kc) is less than or equal to one. The test results show that the normalized shear modulus and damping ratio are affected by the stress ratio (Kc). Moreover, the effect of cyclic loading parameters such as loading cycles and loading frequency on normalized shear modulus (G/Gmax) and damping ratio curves with stress ratio (Kc) is also presented. Based on the cyclic test results, a hyperbolic model was proposed to predict the variation of normalized shear modulus curve (G/Gmax) with stress ratio (Kc).

Laboratory and numerical investigation of machine foundations reinforced with geogrids and geocells

The manuscript describes the results of large scale field tests and numerical studies conducted on geosynthetics reinforced soil beds supporting model machine foundation. A series of vertical mode block resonance tests are conducted over a rigid concrete footing resting on different reinforced soil conditions. The tests are performed in a test pit of size 2 m × 2 m × 0.5 m using a concrete footing of size 0.6 m × 0.6 m × 0.5 m. Four different conditions, namely, unreinforced, single layer geogrid reinforced, two layer geogrid reinforced and geocell reinforced conditions were considered. The tests are performed under six different dynamic force levels using a Lazen type mechanical oscillator. In total, 38 number of field tests are conducted. The dynamic response is studied in terms of reduction in resonant amplitude, peak particle velocity (PPV) and improvement in dynamic properties of the soil. Experimental results revealed that the displacement amplitude of vibration significantly reduced in the presence of geosynthetics. The maximum reduction is observed in the presence of geocell reinforcement as compared to the other conditions. In the presence of geocell reinforcement, resonant amplitude is decreased by 61% and the natural frequency of the soil system is increased by 1.38 times as compared to the unreinforced condition. In addition, the geocell reinforcement found to reduce the PPV by 48% at a distance of 0.5 m from the footing face. The elastic uniform compression of the foundation bed is improved by 91% in the presence of geocell reinforcement. Further, the experimental results are validated with the numerical studies conducted by using finite difference package FLAC3D. The encouraging agreement in the dynamic behavior of reinforced soil is observed between the numerical and experimental studies. The numerical results revealed that the lateral spreading of vibrations is significantly controlled in the presence of geocell reinforcement.

DETERMINANTS OF GROWTH AND DEVELOPMENT OF COMPANIES FROM ELECTRO ENGINEERING INDUSTRY

Purpose: High employment costs caused by current legal-formal regulations in Poland are to be blamed by many entrepreneurs for the unsatisfactory dynamics of growth and development of their companies. They are also blamed for such short histories of the companies. Is that a right accusation? If yes then what impact would labour cost reduction have on growth and development of companies? This paper includes results of research on this issue. Methodology: The opinion poll was conveyed with the use of questionnaires which were given to entrepreneurs, their employees and representatives of trade unions from enterprises which exist on the area of Warmia and Masuria Voivodship, who participated in seminars that are a part of program “The exchange of good practices in CSR in machinery industry in Poland and Bulgaria”. The program was organized by Bulgarian Branch Chamber of Machine Building and Foundation “Institute of Corporate Social Responsibility in Olsztyn”. Findings: The results of the research show that labour cost reduction in enterprises would not lead to any significant changes in decision making nor it would result in activity that would enable growth and development of the company. Originality/value: The importance of this paper is to verify the thesis claimed by many entrepreneurs, that labour costs imposed by the government are too high and they prevent growth and development of their enterprises. It has been shown that the thesis is not true, and that the entrepreneurs themselves are to be blamed for lack of growth and development of their enterprises, as it is caused by lack financial liquidity which results from belated payment of due amounts and obligations which also affects continuity of their businesses.

Analysis of the absolute and the relative transmissibility on the centrifugal pump

In this paper, we proposed a new technique on the relative transmissibility which are generally only known as the absolute transmissibility or transmissibility. Relative transmissibility is ratio of the relative deflection amplitude of the isolator to the displacement amplitude imposed at the foundation. Absolute transmissibility is ratio of the vibration amplitude of the equipment to the vibration amplitude of the foundation. Centrifugal pump system which is supported by foundation in the form of A36 steel hollow rectangular has one degree of freedom. This method lead to calculate absolute and relative transmissibility ratio both normal pump and damage pump with variation of spring stiffnes and coefficient damping. Relative transmissibility is significant only in an isolator used to reduce vibration transmitted from a vibrating foundation. It is proven theoretically and experimentally that pump with the A36 steel as the foundation has relative transmissibility less than one, which means that system has a good isolation. The minimum value of spring stiffness which is used of isolation system to have a good isolation is 107 N/m. This research opens opportunities for industry in determining type of material used for machine foundation which is related to the value of spring stiffness.

Optimization for Upgradation of Small Hydropower Plant in Nepal: A Case Study of Sundarijal Hydropower Plant

Efficiencies of electro-mechanical components of the Sundarijal Hydropower Plant in Nepal has been decreased and the plant has been generating less energy than design generation. The study shows that the plant can be upgraded to 1.1 MW capacity at Q60 design with rehabilitation. Main objective of the plant rehabilitation is to improve operational stability and reliability of power supply by increasing capacity, efficiency, and safety of the plant. The research is based on the Residual Life Assessment of hydro-mechanical components. Minimum thickness of existing penstock obtained from measurement is six mm which is sufficient for upgradation at Q60 design. Mechanical and chemical properties of penstock is found to be acceptable for upgradation. Machine foundations are tested to be safe for upgradation. Upgradation can be carried out for two scenarios: i) using two generating units system ii) using three generating units system. Energy generation per annum from two generating units system is 65.92 MWh lower than three generating units system. The difference in annual revenue between two systems is 3.93 thousand USD. Capital cost estimation shows that cost for three generating three generating units system is higher than two generating units system by 152 thousands USD. Cash flow analysis shows that IRR ratio for two generating units system is higher than three generating units system by three percentage. Upgradation with two generating units system is more suitable and beneficial than three generating units system. Optimization of turbine units is also carried out using nonlinear gradient reduction method in excel solver. Journal of the Institute of Engineering, 2018, 14(1): 82-95

Cyclic response of coir fibre-reinforced sand

The reinforcement technique is a better choice to the conventional ground improvement technique under appropriate conditions to enhance the bearing capacity of soil. The behaviour of reinforced earth was studied by considering generally static loads. In some situations, structures are also subjected to cyclic loads; such as those occurred by the machine foundations, traffic loads, earthquake, etc. Review of earlier studies has indicated that very few literatures are available with regard to performance of coir reinforcement under cyclic loading. The objective of the present study is to assess the behaviour in terms of load-carrying capacity and cyclic settlement using coir fibres as reinforcement and by conducting cyclic load settlement tests using model footings resting on sand reinforced with coir fibres. The present experimental study indicated that, coir reinforcement shows decrease in cyclic resistance ratio as well as cyclic stiffness with increase in u/B ratio. In the present study, better cyclic resistance of sand was observed in coir fiber-reinforced sand compared to unreinforced sand under all excitation parameters tested.

Response of circular footing on dry dense sand to impact load with different embedment depths

Machine foundations with impact loads are common powerful sources of industrial vibrations. These foundations are generally transferring vertical dynamic loads to the soil and generate ground vibrations which may harmfully affect the surrounding structures or buildings. Dynamic effects range from severe trouble of working conditions for some sensitive instruments or devices to visible structural damage. This work includes an experimental study on the behavior of dry dense sand under the action of a single impulsive load. The objective of this research is to predict the dry sand response under impact loads. Emphasis will be made on attenuation of waves induced by impact loads through the soil. The research also includes studying the effect of footing embedment, and footing area on the soil behavior and its dynamic response. Different falling masses from different heights were conducted using the falling weight deflectometer (FWD) to provide the single pulse energy. The responses of different soils were evaluated at different locations (vertically below the impact plate and horizontally away from it). These responses include; displacements, velocities, and accelerations that are developed due to the impact acting at top and different depths within the soil using the falling weight deflectometer (FWD) and accelerometers (ARH-500A Waterproof, and Low capacity Acceleration Transducer) that are embedded in the soil in addition to soil pressure gauges. It was concluded that increasing the footing embedment depth results in increase in the amplitude of the force-time history by about 10-30% due to increase in the degree of confinement. This is accompanied by a decrease in the displacement response of the soil by about 40- 50% due to increase in the overburden pressure when the embedment depth increased which leads to increasing the stiffness of sandy soil. There is also increase in the natural frequency of the soil-foundation system by about 20-45%. For surface foundation, the foundation is free to oscillate in vertical, horizontal and rocking modes. But, when embedding a footing, the surrounding soil restricts oscillation due to confinement which leads to increasing the natural frequency. Moreover, the soil density increases with depth because of compaction, which makes the soil behave as a solid medium. Increasing the footing embedment depth results in an increase in the damping ratio by about 50-150% due to the increase of soil density as D/B increases, hence the soil tends to behave as a solid medium which activates both viscous and strain damping.

Cost, Risk Management, Planning and Scheduling of Industrial Machine Foundation

Cost, Risk Management, Planning and Scheduling of Industrial Machine Foundation

Liquefaction Potential of Sandy Soil from Small Laboratory Machine Foundation Model

Liquefaction Potential of Sandy Soil from Small Laboratory Machine Foundation Model

Effect of soil stabilized by cement on dynamic response of machine foundations

Machine foundations require significant attention from designers. The main goal of the design of machine foundation is to limit the amplitude displacement and not disturb the people who work near the machine. In some cases, if the design of machine foundations does not satisfy the acceptable value of the dynamic response (such as maximum amplitude of displacement), the stabilization of soil under the machine foundation may be used to decrease the amplitude of displacement. This paper outlines effect of stabilized soil under the foundation by cement on the displacement response of machine foundations. Three-dimensional analyses by using finite element method are carried out to investigate the effect of depth of stabilized layer with different percentage of cement content on the dynamic response of the machine foundation. In addition, the effect of area stabilized by cement material on the dynamic response of machine foundation is investigated. The results shown that, the dynamic response of machine foundations generally decreases with increasing the depth of soil layer stabilized with cement. A significant decrease in the displacement of machine foundations is occurred for the stabilized soil layer with a depth of two times of the width of foundation, and the optimum percentage of cement for stabilizing is 6%.

Engine Isolation Angular Mount with Different Types Elastomers

This article was focused on engine isolation elastomeric angular mounts. In ships, submarines heavy machinery is in continuous operations generate massive vibrations and noise. These vibrations and noise will transmit to sea water via machine foundation and will be a passive target for enemies. So it has to be reduced by providing isolation mounts or damping between machines and foundation or source and receiver. For this mounting systems should isolate engine vibrations caused by engine transmits forces in engine speed and prevent engine from shock excitation. This represents that dynamic stiffness and damping of the engine mount supposed to be frequency and amplitude reliant. So making of engine mount has been concerted on developing of frequency and amplitude properties. So different types of elastomeric shock and vibration mounts compounds are developed for two different hardness (45&55) all the mechanical properties ageing properties has been studied and compound with developed NBR, PU& CR compounds of same hardness. In all the cases PU elastomers based compounds are giving better results than NBR & CR. One angular mount is developed its static loads and deflection test at different rated loads has been carried out it gives satisfactory results

Vibration isolating plate with quasi-zero effect

The Paper is devoted to vibrating isolating plate with quasi-zero stiffness. It based on dome type cells with quasi-zero stiffness, that provide low natural frequency about 1 Hz. The general scheme of the plate is presented. Dimension, efficiency and other parameters of the plate were discussed. The effect of plate's application has been estimated. The plate allows to reduce vibration level. It also allows to reduce size of foundation of machines almost two times.

Dynamic response of machine foundation resting on sand-granulated tyre rubber mixtures

This paper examines the dynamic response of machine foundation resting on sand mixed with granular rubber of sizes (0.07-3) mm to improve the vibration attenuation and to reduce the settlement of the foundation. Granular rubber used is the product of hashing scrap tyres to small pieces in a tyre factory of Babylon in Iraq. Forty Model tests were carried out in a steel box of size (1200x1200x900) mm using a steel square footing of size (200x200x20) mm and a vertically acting rotating-mass type mechanical oscillator to apply a harmonic vertical mode of vibration. Karbala sand was used in this study with two relative densities (loose and medium) mixed with granular rubber ratios of (4%, 8% and 12%) of dry sand for different depths of mixing of (0.25 B, 0.5 B and 1B). The effect of relative density, frequency, depth of mixing and mixing ratio were studied. The results showed that the displacement amplitude and the settlement of machine foundation resting on dry sand granular rubber mixtures decreased with increasing mixing ratio and mixing depth. The optimum mixing ratio and mixing depth for loose state are (8% and 0.5B) at 69 Hz frequency while they are (12% and 1B) at 80 Hz frequency. For medium state they are (8% and 1B) for both frequencies. The settlement became constant after few seconds of vibration application when the foundation resting on sand mixed with optimum granular rubber content.

Glass transition temperature-cure temperature-transformation (TgTT) diagram for EPY epoxy system

The EPY® epoxy system applied for the production of machine foundation chocks was isothermally cured at varying cure temperatures and times. The thermal behavior during the curing of the system was monitored by means of the glass transition temperature (Tg) and conversion degree (α) measured using differential scanning calorimetry (DSC) and rotational viscometry (ARES). Also, the thermal decomposition was measured by thermogravimetry and differential thermal analysis ­(TG-DTA). The results were analyzed and summarized in the generalized phase diagram, as well as in the Tg-cure temperature-transformation (TgTT) cure diagram. The phase diagram has reference to the transformations (in liquid, ungelled glass, gelled glass and rubber state) encountered at time to gelation and vitrification. Whereas the TgTT diagram shows that there are three types of behavior related to the temperature of cure and makes a useful framework for understanding and analyzing the relations and interdependencies during the curing process of the epoxy system.