Papers by Keyword: Experimental Verification

Abstract: Modern fasteners offer new options for the design of timber load-bearing structures. In the design, the traditional hinged connections are increasingly being replaced with semi-rigid connections. Nevertheless, there is no feedback from the actual structures with this kind of connection regarding the accuracy of static calculations. The authors therefore decided to test one connection and compare the results with those obtained from calculation models. The paper presents the experimental verification of the frame connection in which the semi-rigid action was achieved by combining the aluminium Sherpa connector and total thread Rothoblaas screws. The timber samples were provided by Latti Extra.

Abstract: Thermal deformations of machine tool are among the most significant error source of machining errors. Most of current thermal error modeling researches is about 3-axies machine tool, highly reliant on collected date, which could not predict thermal errors in design stage. In This paper, in order to estimate the thermal error of a 4-axise horizontal machining center. A thermal error prediction method in machine tool design stage is proposed. Thermal errors in workspace in different working condition are illustrated through numerical simulation and volumetric error model. Verification experiments shows the outcomes of this prediction method are basically correct.

Abstract: Mechanical properties of high performance concrete (HPC) enable design of subtle structural elements. Subtle HPC frame concept comes from the effort to integrate load bearing elements into building envelope in order to reduce risks of thermal bridges. Substantial advantages of subtle structural elements are material and energy savings during production, transportation, manipulation and assembling. Paper presents implementation of construction of experimental frame at University Centre UCEEB in Buštěhrad. Individual structural elements were made in prefa plant ŽPSV a.s. in Litice nad Orlicí and Čerčany, the company also assembled the experimental frame. The frame was built from February to April 2016. Within June and July, the construction was tested by static loading test, which partial results are presented in the paper. Accomplished calculations, experimental verification and analysis show that subtle HPC frame is the effective solution from reliability aspects as well as from environmental and economical parameters.

Abstract: Originally open balconies and loggias of high-rise residential building showed a significant aerodynamic load - discomfort for users. Subject of the contract cooperation with the investor was therefore development, experimental verification and optimization of the strength and functional parameters of sliding elements of transparent loggia enclosures from the effect of the dynamically changing wind pressure (pressure - suction), as well as the elimination of undesirable acoustic expressions. This paper introduces the aerodynamic study of the building with the objective of quantifying the maximum load on sliding elements from the effects of wind as the boundary condition for their dimensioning. It describes the final design of transparent sliding elements and their experimental verification in a large pressure chamber in laboratory. The elimination of undesirable acoustic expressions was successfully implemented through design optimization with use of acoustic camera.

Abstract: Mechanical properties of high performance concrete (HPC) enable design of subtle structural elements. Subtle HPC frame concept comes from the effort to integrate load bearing elements into building envelope in order to reduce risks of thermal bridges. Substantial advantages of subtle structural elements are material and energy savings during production, transportation, manipulation and assembling. Paper presents preparation and implementation of construction of experimental frame at University Centre UCEEB in Buštěhrad. Individual structural elements were made in prefa plant ŽPSV a.s. in Litice nad Orlicí. Construction of frame prototype is the result of long term research when the vertical and horizontal structural elements and their connections were successively designed and experimentally verified. This article shows experimental results of horizontal load bearing structures - floor panels and beams - in detail. Samples were tested by four-point bending test and also creep of floor panels was measured. Accomplished calculations, experimental verification and analysis have showed that subtle HPC frame is the effective solution from reliability aspects as well as from environmental and economical parameters. Minimal columns cross sections enable their complete implementation into building envelope and they also contribute to high quality architectonic solution of buildings interiors.

Abstract: This paper presents a new energy approach based on the concept of a volume stain-energy-density factor useful to deal with the general problem of brittle fracture for sharp V-notches under mixed-mode I and II. The basic assumption is that the fracture occurs when the volume strain energy density factor arrive at its critical value in the direction of crack initiation where the deviator strain energy density factor is minimum. The method is validated taking into account experiment data already reported in the literature and the analytical predictions are in good agreement with experiment data. It indicates that the accuracy of the new approach is undoubtedly very satisfactory and can be applied in engineering.

Abstract: Footbridge over the Labe River in Celakovice is a cable stayed structure with the main span 156 m long. It is designed for pedestrians, cyclists and also a light utility vehicle may pass over the footbridge. Until now, the footbridge has a record span of the cable stayed structure in the Czech Republic. The ultra high performance concrete (UHPC) was first applied for the load carrying structure on the footbridge at the Czech Republic. The pylons are made of steel and the stays are made of locked coil strands. Since no obligatory codes were available for the design of structures made of UHPC, the extensive experimental verification of material parameters and structural elements was necessary.

Abstract: Paper presents some results of long-term research of a new optimized subtle precast construction system based on high performance silicate composites. The system is particularly aimed for building construction in passive or zero-energy standard. Subtle structural elements from high performance concrete (HPC) can be integrated into building envelope of energy efficient buildings with significant reduction of envelope structure and avoiding risk of thermal bridges. Significant advantages of subtle elements are material and energy savings during production, transport, manipulation and construction on building site.Paper presents experimental verification of connection between columns and beams ensured by Peikko ́s PCs corbels. Moreover, production of two prototypes of high performance fibre reinforced columns over two floors is presented. Prototypes were casted in ŽPSV a.s. plant, Litice nad Orlicí in June 2014. Complex LCA analysis of three various reinforced concrete columns was performed. Analysis covers construction life phase. Consequently, environmental impacts of assessed variants were compared and evaluated. Results show that it is possible to reduce some impacts on the environment from 16 up to 65% in comparison with common solution of reinforced concrete columns due to the utilization of excellent mechanical properties of high performance concrete that enables the design of subtle structural elements.

Abstract: There is a close relationship between cold ring rolling product quality and ring diameter growth rate in cold rolling process, but the technological parameters are main factors in influencing ring diameter growth. The paper used both numerical simulation and experimental verification to study the effect of the core roller speed and wide-diameter ratio on increment of ring diameter in cold rolling process of deep groove ball bearing inner ring. It is found that the core roller has greater influence on diameter growth, and the faster the feeding speed of core roller is , the greater the increment of ring diameter is. Finally, it is verified that the agreement between numerical simulation and experiments is good.

Abstract: The finite element method and Component element method are widely used in modeling nowadays. Also the classical computing models especially discrete computing models give very good results. Often some assumptions must be adopted in the process of creation of computing models especially within creation of bridge computing models. In such a case the experimental tests are needed to verify the validity of adopted assumptions. The presented paper describes the adopted assumptions and methodology of their experimental verification. It mutually compares the experimentally and numerically obtained results and makes findings for practical applications.