This page has only limited features, please log in for full access.
This paper presents a combined experimental and numerical investigation of the behavior of glued laminated timber beams when exposed to fire. The influence on the time variation of charring rates based on the evolution of temperature profiles is examined for different fire scenarios and durations as well as different beam’s cross-section sizes. Predictions of charring depths provided by numerical simulations of heat transfer and simplified charring rate models are compared. In the absence of a mass transport representation, a Bayesian inference is introduced to identify the temperature-dependent material parameters for the conventional heat transfer model. A similar approach is adopted when adjusting the selected parameters of the charring rate models to account for variations in actual fire scenarios, which potentially depart from standard fire exposure. When compared to experimental results, both approaches confirmed their predictive capabilities, particularly in the stage of initial design. Since presented in the framework of Bayesian statistics, they open the door to fully stochastic analysis with an emphasis on the load bearing capacity of the studied beams.
Lucie Kucíková; Tomáš Janda; Jan Sýkora; Michal Šejnoha; Guido Marseglia. Experimental and numerical investigation of the response of GLT beams exposed to fire. Construction and Building Materials 2021, 299, 123846 .
AMA StyleLucie Kucíková, Tomáš Janda, Jan Sýkora, Michal Šejnoha, Guido Marseglia. Experimental and numerical investigation of the response of GLT beams exposed to fire. Construction and Building Materials. 2021; 299 ():123846.
Chicago/Turabian StyleLucie Kucíková; Tomáš Janda; Jan Sýkora; Michal Šejnoha; Guido Marseglia. 2021. "Experimental and numerical investigation of the response of GLT beams exposed to fire." Construction and Building Materials 299, no. : 123846.
Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section,
Lucie Kucíková; Michal Šejnoha; Tomáš Janda; Jan Sýkora; Pavel Padevět; Guido Marseglia. Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire. Sustainability 2021, 13, 5494 .
AMA StyleLucie Kucíková, Michal Šejnoha, Tomáš Janda, Jan Sýkora, Pavel Padevět, Guido Marseglia. Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire. Sustainability. 2021; 13 (10):5494.
Chicago/Turabian StyleLucie Kucíková; Michal Šejnoha; Tomáš Janda; Jan Sýkora; Pavel Padevět; Guido Marseglia. 2021. "Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire." Sustainability 13, no. 10: 5494.
This article concerns numerical simulations of glass plates loaded by a force impulse caused by a low velocity impact. Three types of numerical models of different complexity – the spring-mass system, the modal decomposition based model, and the conventional finite element method – all exploiting the Hertz contact law are compared and their advantages and limitations are discussed. Their performance is verified against the results provided by the commercial software LS-DYNA and validated by two full scale experiments. It is observed that the accuracy of the spring-based model decreases with increasing dimension of the plate and increasing stiffness of the impactor. Nevertheless, the models based on modal decomposition and finite element methods deliver results reasonably close to experimental measurements.
Tomáš Janda; Jaroslav Schmidt; Petr Hála; Petr Konrád; Alena Zemanová; Radoslav Sovják; Jan Zeman; Michal Šejnoha. Reduced order models of elastic glass plate under low velocity impact. Computers & Structures 2020, 244, 106430 .
AMA StyleTomáš Janda, Jaroslav Schmidt, Petr Hála, Petr Konrád, Alena Zemanová, Radoslav Sovják, Jan Zeman, Michal Šejnoha. Reduced order models of elastic glass plate under low velocity impact. Computers & Structures. 2020; 244 ():106430.
Chicago/Turabian StyleTomáš Janda; Jaroslav Schmidt; Petr Hála; Petr Konrád; Alena Zemanová; Radoslav Sovják; Jan Zeman; Michal Šejnoha. 2020. "Reduced order models of elastic glass plate under low velocity impact." Computers & Structures 244, no. : 106430.
An accurate material representation of polymeric interlayers in laminated glass panes has proved fundamental for a reliable prediction of their response in both static and dynamic loading regimes. This issue is addressed in the present contribution by examining the time–temperature sensitivity of the shear stiffness of two widely used interlayers made of polyvinyl butyral (TROSIFOL BG R20) and ethylene-vinyl acetate (EVALAM 80-120). To that end, an experimental program has been executed to compare the applicability of two experimental techniques, (i) dynamic torsional tests and (ii) dynamic single-lap shear tests, in providing data needed in a subsequent calibration of a suitable material model. Herein, attention is limited to the identification of material parameters of the generalized Maxwell chain model through the combination of linear regression and the Nelder–Mead method. The choice of the viscoelastic material model has also been supported experimentally. The resulting model parameters confirmed a strong material variability of both interlayers with temperature and time. While higher initial shear stiffness was observed for the polyvinyl butyral interlayer in general, the ethylene-vinyl acetate interlayer exhibited a less pronounced decay of stiffness over time and a stiffer response in long-term loading.
Tomáš Hána; Tomáš Janda; Jaroslav Schmidt; Alena Zemanová; Michal Šejnoha; Martina Eliášová; Miroslav Vokáč. Experimental and Numerical Study of Viscoelastic Properties of Polymeric Interlayers Used for Laminated Glass: Determination of Material Parameters. Materials 2019, 12, 2241 .
AMA StyleTomáš Hána, Tomáš Janda, Jaroslav Schmidt, Alena Zemanová, Michal Šejnoha, Martina Eliášová, Miroslav Vokáč. Experimental and Numerical Study of Viscoelastic Properties of Polymeric Interlayers Used for Laminated Glass: Determination of Material Parameters. Materials. 2019; 12 (14):2241.
Chicago/Turabian StyleTomáš Hána; Tomáš Janda; Jaroslav Schmidt; Alena Zemanová; Michal Šejnoha; Martina Eliášová; Miroslav Vokáč. 2019. "Experimental and Numerical Study of Viscoelastic Properties of Polymeric Interlayers Used for Laminated Glass: Determination of Material Parameters." Materials 12, no. 14: 2241.
A simple approach to the identification of geometrical and material uncertainties of wood is presented. This stochastic mechanics problem combines classical micromechanics, computational homogenization and experimental measurements with Bayesian inference to estimate the model parameters including the characteristics of errors in macroscopic elastic properties of wood caused by randomness of microstructural details on the one hand and the experimental errors on the other hand. The former source of uncertainty includes, for example, variability in microfibril angle and growth ring density. Even such limiting consideration of random input illustrates the need for combined computational and experimental approach in a reliable prediction of the desired material properties. Tying the two approaches in the framework of Bayesian statistical method proves useful when addressing their limitations and as such giving better notion on the credibility of the prediction. This is demonstrated here on one particular example of spruce wood.
Michal Šejnoha; Tomáš Janda; Jan Vorel; Lucie Kucíková; Pavel Padevět; Vladimír Hrbek. Bayesian inference as a tool for improving estimates of effective elastic parameters of wood. Computers & Structures 2019, 218, 94 -107.
AMA StyleMichal Šejnoha, Tomáš Janda, Jan Vorel, Lucie Kucíková, Pavel Padevět, Vladimír Hrbek. Bayesian inference as a tool for improving estimates of effective elastic parameters of wood. Computers & Structures. 2019; 218 ():94-107.
Chicago/Turabian StyleMichal Šejnoha; Tomáš Janda; Jan Vorel; Lucie Kucíková; Pavel Padevět; Vladimír Hrbek. 2019. "Bayesian inference as a tool for improving estimates of effective elastic parameters of wood." Computers & Structures 218, no. : 94-107.
This paper focuses on the modal analysis of laminated glass beams. In these multilayer elements, the stiff glass plates are connected by compliant interlayers with frequency and temperature-dependent behavior. The aim of our study is (i) to assess whether approximate techniques can accurately predict the behavior of laminated glass structures and (ii) to propose a simple tool for modal analysis based on the Enhanced Effective Thickness concept. For this purpose, we consider four approaches to the solution of the related nonlinear eigenvalue problem: a complex-eigenvalue solver based on the Newton method and three simplified approaches. In particular, we limit our attention to the modal strain energy method, the dynamic effective thickness method, and the Enhanced Effective Thickness method. A comparative study of free vibrating laminated glass beams is performed considering different geometries of cross-sections, boundary conditions, and material parameters for interlayers under two ambient temperatures. The viscoelastic response of polymer foils is represented by the generalized Maxwell model. We show that the simplified approaches predict natural frequencies with an acceptable accuracy for most of the examples. However, there is considerable scatter in predicted loss factors. The Enhanced Effective Thickness approach adjusted to modal analysis results in lower errors in both quantities compared to the other two simplified procedures. It reduces the extreme error in loss factors by half compared to the modal strain energy method and to one quarter compared to the original dynamic effective thickness method.
Alena Zemanová; Jan Zeman; Tomáš Janda; Jaroslav Schmidt; Michal Šejnoha. On modal analysis of laminated glass: Usability of simplified methods and Enhanced Effective Thickness. Composites Part B: Engineering 2018, 151, 92 -105.
AMA StyleAlena Zemanová, Jan Zeman, Tomáš Janda, Jaroslav Schmidt, Michal Šejnoha. On modal analysis of laminated glass: Usability of simplified methods and Enhanced Effective Thickness. Composites Part B: Engineering. 2018; 151 ():92-105.
Chicago/Turabian StyleAlena Zemanová; Jan Zeman; Tomáš Janda; Jaroslav Schmidt; Michal Šejnoha. 2018. "On modal analysis of laminated glass: Usability of simplified methods and Enhanced Effective Thickness." Composites Part B: Engineering 151, no. : 92-105.
This paper presents a numerical and experimental modal analysis of laminated glass beams, i.e. a multilayer composite structure made of glass panes bonded to an interlayer foil. These polymer foils provide shear coupling of glass layers, damping of vibrations, and play a key role in post-breakage performance. In this contribution, three-layer beams with ethylene-vinyl acetate interlayer are investigated. Using a finite element discretization and the Newton method, we solve numerically a complex eigenvalue problem which is nonlinear due to the frequency/temperature-sensitive viscoelastic behavior of the interlayer. In our experimental investigations, a roving hammer test was carried out to identify the mode shapes, natural frequencies, and modal damping. The validation shows that there is a good agreement between the numerical predictions and experimental data in natural frequencies. However, the errors in loss factors can be high, because these values are very sensitive to the material properties of polymer, frequency, temperature, and boundary conditions. These effects are discussed in the concluding part of our study.
Alena Zemanová; Tomáš Plachý; Jaroslav Schmidt; Tomáš Janda; Jan Zeman; Michal Šejnoha. Numerical and Experimental Modal Analysis of Laminated Glass Beams. Springer Texts in Business and Economics 2018, 485 -495.
AMA StyleAlena Zemanová, Tomáš Plachý, Jaroslav Schmidt, Tomáš Janda, Jan Zeman, Michal Šejnoha. Numerical and Experimental Modal Analysis of Laminated Glass Beams. Springer Texts in Business and Economics. 2018; ():485-495.
Chicago/Turabian StyleAlena Zemanová; Tomáš Plachý; Jaroslav Schmidt; Tomáš Janda; Jan Zeman; Michal Šejnoha. 2018. "Numerical and Experimental Modal Analysis of Laminated Glass Beams." Springer Texts in Business and Economics , no. : 485-495.
In this paper a fully probabilistic approach based on the Bayesian statistical method is presented to predict ground settlements in both transverse and longitudinal directions during gradual excavation of a tunnel. To that end, the convergence confinement method is adopted to give estimates of ground deformation numerically. Together with in situ measurements of the evolution of vertical deflections at selected points along the tunnel line, it allows for the construction of a likelihood function and consequently in the framework of Bayesian inference to provide posterior improved knowledge of model parameters entering the numerical analysis. In this regard, the Bayesian updating is first exploited in the material identification step and next used to yield predictions of ground settlement in sections along the tunnel line ahead of the tunnel face. This methodology thus makes it possible to improve original designs by utilizing an increasing number of data (measurements) collected in the course of tunnel construction.
Tomáš Janda; Michal Šejnoha; Jiří Šejnoha. Applying Bayesian approach to predict deformations during tunnel construction. International Journal for Numerical and Analytical Methods in Geomechanics 2018, 42, 1765 -1784.
AMA StyleTomáš Janda, Michal Šejnoha, Jiří Šejnoha. Applying Bayesian approach to predict deformations during tunnel construction. International Journal for Numerical and Analytical Methods in Geomechanics. 2018; 42 (15):1765-1784.
Chicago/Turabian StyleTomáš Janda; Michal Šejnoha; Jiří Šejnoha. 2018. "Applying Bayesian approach to predict deformations during tunnel construction." International Journal for Numerical and Analytical Methods in Geomechanics 42, no. 15: 1765-1784.
This paper focuses on the modal analysis of laminated glass beams. In these multilayer elements, the stiff glass plates are connected by compliant interlayers with frequency/temperature-dependent behavior. The aim of our study is (i) to assess whether approximate techniques can accurately predict the behavior of laminated glass structures and (ii) to propose an easy tool for modal analysis based on the enhanced effective thickness concept by Galuppi and Royer-Carfagni. To this purpose, we consider four approaches to the solution of the related nonlinear eigenvalue problem: a complex-eigenvalue solver based on the Newton method, the modal strain energy method, and two effective thickness concepts. A comparative study of free vibrating laminated glass beams is performed considering different geometries of cross-sections, boundary conditions, and material parameters for interlayers under two ambient temperatures. The viscoelastic response of polymer foils is represented by the generalized Maxwell model. We show that the simplified approaches predict natural frequencies with an acceptable accuracy for most of the examples. However, there is a considerable scatter in predicted loss factors. The enhanced effective thickness approach adjusted for modal analysis leads to lower errors in both quantities compared to the other two simplified procedures, reducing the extreme error in loss factors to one half compared to the modal strain energy method or to one quarter compared to the original dynamic effective thickness method.
Alena Zemanová; Jan Zeman; Tomáš Janda; Jaroslav Schmidt; Michal Šejnoha. On modal analysis of laminated glass: Usability of simplified methods and enhanced effective thickness. 2018, 1 .
AMA StyleAlena Zemanová, Jan Zeman, Tomáš Janda, Jaroslav Schmidt, Michal Šejnoha. On modal analysis of laminated glass: Usability of simplified methods and enhanced effective thickness. . 2018; ():1.
Chicago/Turabian StyleAlena Zemanová; Jan Zeman; Tomáš Janda; Jaroslav Schmidt; Michal Šejnoha. 2018. "On modal analysis of laminated glass: Usability of simplified methods and enhanced effective thickness." , no. : 1.
In this contribution the Bayesian statistical method is applied to assess the expected probability distribution of the terrain subsidence in the course of tunnel excavation. The approach utilizes a number of simplifying assumptions regarding the system kinematics to arrive at a very simple model with just a few degrees of freedom. This deterministic model together with the intrinsic uncertainties of its parameters and measurement inaccuracies are used to formulate the stochastic model which defines a distribution of the predicted values of terrain subsidence. Assuming the measured data to be fixed, the stochastic model thus defines the likelihood function of the model parameters which is directly used for updating their prior distribution. This way the model parameters can be incrementally updated with each excavation step and the prediction of the model refined.
Tomáš Janda; Jiří Šejnoha; Michal Šejnoha. Hierarchical stochastic model of terrain subsidence during tunnel excavation. IOP Conference Series: Materials Science and Engineering 2017, 236, 12076 .
AMA StyleTomáš Janda, Jiří Šejnoha, Michal Šejnoha. Hierarchical stochastic model of terrain subsidence during tunnel excavation. IOP Conference Series: Materials Science and Engineering. 2017; 236 ():12076.
Chicago/Turabian StyleTomáš Janda; Jiří Šejnoha; Michal Šejnoha. 2017. "Hierarchical stochastic model of terrain subsidence during tunnel excavation." IOP Conference Series: Materials Science and Engineering 236, no. : 12076.
Michal Šejnoha; Tomáš Janda; Lenka Melzerová; Václav Nežerka; Jiří Šejnoha. Modeling glulams in linear range with parameters updated using Bayesian inference. Engineering Structures 2017, 138, 293 -307.
AMA StyleMichal Šejnoha, Tomáš Janda, Lenka Melzerová, Václav Nežerka, Jiří Šejnoha. Modeling glulams in linear range with parameters updated using Bayesian inference. Engineering Structures. 2017; 138 ():293-307.
Chicago/Turabian StyleMichal Šejnoha; Tomáš Janda; Lenka Melzerová; Václav Nežerka; Jiří Šejnoha. 2017. "Modeling glulams in linear range with parameters updated using Bayesian inference." Engineering Structures 138, no. : 293-307.
Michal Šejnoha; Tomáš Janda; Jan Vorel; Lucie Kucíková; Pavel Padevěd. Combining Homogenization, Indentation and Bayesian Inference in Estimating the Microfibril Angle of Spruce. Procedia Engineering 2017, 190, 310 -317.
AMA StyleMichal Šejnoha, Tomáš Janda, Jan Vorel, Lucie Kucíková, Pavel Padevěd. Combining Homogenization, Indentation and Bayesian Inference in Estimating the Microfibril Angle of Spruce. Procedia Engineering. 2017; 190 ():310-317.
Chicago/Turabian StyleMichal Šejnoha; Tomáš Janda; Jan Vorel; Lucie Kucíková; Pavel Padevěd. 2017. "Combining Homogenization, Indentation and Bayesian Inference in Estimating the Microfibril Angle of Spruce." Procedia Engineering 190, no. : 310-317.
Tomáš Janda; David Mašín. General method for simulating laboratory tests with constitutive models for geomechanics. International Journal for Numerical and Analytical Methods in Geomechanics 2016, 41, 304 -312.
AMA StyleTomáš Janda, David Mašín. General method for simulating laboratory tests with constitutive models for geomechanics. International Journal for Numerical and Analytical Methods in Geomechanics. 2016; 41 (2):304-312.
Chicago/Turabian StyleTomáš Janda; David Mašín. 2016. "General method for simulating laboratory tests with constitutive models for geomechanics." International Journal for Numerical and Analytical Methods in Geomechanics 41, no. 2: 304-312.
The paper is concerned with hypoplastic models for both coarse and fine grained soils. It concentrates on the description of models parameters and presents procedures for their evaluation based on actual laboratory tests. The sample of sand for the calibration of the hypoplastic model for coarse grained soil comes from the Třeboň basin. The sample was classified as Sa. The second sample was classified as saCl. This sample comes from the street Evropská in Prague and was used for the calibration of the hypoplastic model for fine grained soils. The classification was performed according to ČSN EN ISO 14688-2. Keywords: hypoplasticity, fine grained soils, coarse grained soils, calibration, parameters.
Tomas Kadlicek; Tomáš Janda; Michal Šejnoha. Calibration of Hypoplastic Models for Soils. Applied Mechanics and Materials 2016, 821, 503 -511.
AMA StyleTomas Kadlicek, Tomáš Janda, Michal Šejnoha. Calibration of Hypoplastic Models for Soils. Applied Mechanics and Materials. 2016; 821 ():503-511.
Chicago/Turabian StyleTomas Kadlicek; Tomáš Janda; Michal Šejnoha. 2016. "Calibration of Hypoplastic Models for Soils." Applied Mechanics and Materials 821, no. : 503-511.
Several advancements in the modeling of soil structure interaction in the light of tunnel excavation are discussed. The theoretical formulation as well as numerical implementation are presented such as to meet the following requirements: simplicity, reliability and practical applicability to make the resulting software product available for a direct use on the construction site. To that end a recently introduced 2D3D modeling of tunnel excavation incorporating the in situ measurements is effectively combined with a fully three-dimensional (3D) beam-like representation of a typical urban structure made of masonry or precast concrete. Both standard and advanced non-linear constitutive models can be adopted to account for a potential shear failure of a subsoil material during excavation consequently triggering the evolution of damage of an above-ground (upper) structure. A simple example is provided to illustrate the proposed approach.
T. Janda; M. Šejnoha. Modeling of soil structure interaction during tunnel excavation: An engineering approach. Advances in Engineering Software 2013, 62-63, 51 -60.
AMA StyleT. Janda, M. Šejnoha. Modeling of soil structure interaction during tunnel excavation: An engineering approach. Advances in Engineering Software. 2013; 62-63 ():51-60.
Chicago/Turabian StyleT. Janda; M. Šejnoha. 2013. "Modeling of soil structure interaction during tunnel excavation: An engineering approach." Advances in Engineering Software 62-63, no. : 51-60.
The present contribution reports on a mixed numerical experimental study of the time dependent processes in saturated soils with reference to isotropic consolidation. Owing to its relative simplicity, isotropic consolidation is often viewed as a basic tool for inferring the material parameters of various constitutive models. Within this modeling framework, the paper advocates the use of critical state models for an accurate description of the time dependent deformation of clayey soils. Material models, in which the critical state model applies only to the subcritical region, have been also addressed. Examples include models where the supercritical region is cut off, e.g., by a Mohr–Coulomb surface. Starting with the modified Cam clay model, as a classical representative, the paper revisits a simple isotropic consolidation test. It is suggested that such a conventional laboratory experiment, when combined with a suitable optimization procedure, is sufficient in deriving the desired material parameters, including the initial void ratio, deformation dependent variation of the coefficient of permeability and the preconsolidation pressure representing here an important measure of the structural strength of soils. Several numerical and experimental results are presented to support the theoretical grounds.
Tomáš Janda; Pavel Kuklík; Michal Šejnoha. Mixed Experimental and Numerical Approach to Evaluation of Material Parameters of Clayey Soils. International Journal of Geomechanics 2004, 4, 199 -206.
AMA StyleTomáš Janda, Pavel Kuklík, Michal Šejnoha. Mixed Experimental and Numerical Approach to Evaluation of Material Parameters of Clayey Soils. International Journal of Geomechanics. 2004; 4 (3):199-206.
Chicago/Turabian StyleTomáš Janda; Pavel Kuklík; Michal Šejnoha. 2004. "Mixed Experimental and Numerical Approach to Evaluation of Material Parameters of Clayey Soils." International Journal of Geomechanics 4, no. 3: 199-206.