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Abstract

This paper presents an approach based on NURBS (non-uniform rational B-splines) to achieve a seismic response surface (SRS) from a group of points obtained by using an analytical model of RC joints. NURBS based on the genetic algorithm is an important mathematical tool and consists of generalizations of Bezier curves and surfaces and B-splines. Generally, the accuracy of the design process of joints depends on the number of control points that are captured in the results of experimental research on real specimens. The values obtained from the specimens are the best tools to use in seismic analysis, though more expensive when compared to values simulated by SRSs. The SRS proposed in this paper can be applied to obtain surfaces that show site effect results on destructions of beam-column joint, taking into account different site conditions for a specific earthquake. The efficiency of this approach is demonstrated by the retrieval of simulated-versus-analytical results.
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Abstract

This paper presents a vibration analysis of a multi-link surgical micromanipulator joint, based on its detailed mathematical model. The manipulator’s prototype contains 6 links with the diameter of 8-10 [mm] and with the length of the modules of about 130 [mm]. It is driven by brushless servomotors with worm and planetary gears, for which the total transmission ratio is above 1/10000. Regarding the low efficiency of micro-robot drive systems and its vibrations, a reliable joint model and its performance is crucial for the development of a high-precision control system. To achieve the required accuracy, modelling framework has been enriched with an advanced model of friction. Simulation results are presented and discussed.
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Abstract

Based on the theory of heat transfer, the influence of expansion joints on the temperature and stress distribution of ladle lining is discussed. In view of the current expansion joint, the mathematical model of heat transfer and the three dimensional finite element model of ladle lining brick are established. By analyzing the temperature and stress distribution of ladle lining brick when the expansion joints are in different sizes, the thermal mechanical stress caused by the severe temperature difference can be reduced by the suitable expansion joint of the lining brick during the ladle baking and working process. The analysis results showed that the thermal mechanical stress which is caused by thermal expansion can be released through the 2 mm expansion joint, which is set in the building process. So we can effectively reduce the thermal mechanical stress of the ladle lining, and there is no risk of steel leakage, thus the service life of ladle can be effectively prolonged.
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Abstract

Beam-to-column end-plate joints can be classified as rigid (fully restrained), semi-rigid (partiallyrestrained) or pinned, depending on their type, configuration and the connector arrangement. Fullyrestrained joints are needed for rigid frames in which there is assumed that the frame joints havesufficient rigidity to maintain – under the service state – the angles between the intersecting mem-bers, ensuring the full moment transfer. In contrast in semi-continuous frames, partially restrainedjoints are characterized by relative rotations occurring between the intersecting members so thatthe bending moment can only be transferred partially. In recent years, the idea of using partiallyrestrained, unstiffened joints in building structures has gained momentum since this idea appearsto be more practical and economical. Semi-continuous frames can resist actions by the bendingmoment transfer in partially restrained joints, allowing in the same time for a certain degree ofrotation that enhances the overall ductile performance of these structures. One of the effective waysthat affects ductility of end-plate beam-to-column joints is to use thinner end-plates than those usednowadays in practical applications. In the current study, a certain class of steel-concrete compositejoints is examined in which the thickness of end-plates is to be equivalent to approximately 40-60% of the bolt diameter used in all the composite joints investigated in the considered joint class. Thispaper is an extension of the authors’ earlier investigation on numerical modelling of the behaviourof steel frame joints. The aim of current investigations is to develop as simple as possible andyet reliable three-dimensional (3D) FE model of the composite joint behaviour that is capable ofcapturing the important factors controlling the performance of steel-concrete end-plate joints inwhich the end-plate thickness is chosen to be lesser than that used nowadays in conventional jointdetailing. A 3D FE model constructed for composite joints of the considered joint class is reportedin this paper and numerical simulations using the ABAQUS computer code are validated againstexperimental investigations conducted at the Warsaw University of Technology. Comparison betwe-en the nonlinear FE analysis and full scale experimental results of the considered class of compositejoints is presented which conclusively allows for the accuracy assessment of the modelling tech-nique developed. Comparison between the FE results and test data shows a reasonable agreementbetween the numerical FE model developed and physical model of experimentally examined jointspecimens. Finally, practical conclusions for engineering applications are drawn.
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