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Prof. Dr. Bohumil Kasal
1. Department of Organic and Wood-Based Construction Materials, Technische Universität Braunschweig, Hopfengarten 20, 38102 Braunschweig, Germany;

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Research Keywords & Expertise

0 Timber
0 wood science
0 Organic materials
0 seismic engineering
0 FRP-reinforced wood, in-situ assessment

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Timber
wood science

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Journal article
Published: 06 November 2020 in Colloids and Surfaces A: Physicochemical and Engineering Aspects
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Wood aging is a topic of great interest due to its impact on wood performance and durability as a construction material. Therefore, it is important to develop accurate methods to monitor aging and understand its mechanisms. Atomic force microscopy (AFM) is a powerful tool to study the changes in materials properties in the nanoscale. We aim in this paper at developing an accurate AFM-based method to understand the wood aging phenomenon by studying the surface changes of wood pits as they are the most susceptible wood structures to aging. For this objective, surface adhesion measurements were performed to detect any chemical changes on the surface of wood structures by estimating the relative adhesion force (RAF). The results showed that unfunctionalized AFM tips should not be used for monitoring aging as they fail to simply differentiate between the different wood structures (cell wall, lumen, pit torus and pit margo) as the RAF values were around 10 for the four structures. With a focus on pit structures (torus and margo), AFM tips functionalized with hydroxyl groups showed significantly different RAF values for torus and margo suggesting the ability of these tips in detecting possible chemical changes. The RAF values of torus and margo were around 216 and 530 for unaged wood, respectively. This indicates that, for the first time, the use of functionalized tips does not only improve the interaction between the tips and wood in general but also improves the sensitivity to its different structures. This also allowed monitoring wood aging as the RAF values for torus and margo dropped to 152 and 301 upon aging, respectively. This work suggests that using AFM tips with different functional groups, such as carboxyl, acetyl, methoxyl, and hydroxyl groups can bring a more thorough understanding of wood aging.

ACS Style

Jia Mao; Hatem Abushammala; Bohumil Kasal. Monitoring the surface aging of wood through its pits using atomic force microscopy with functionalized tips. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2020, 609, 125871 .

AMA Style

Jia Mao, Hatem Abushammala, Bohumil Kasal. Monitoring the surface aging of wood through its pits using atomic force microscopy with functionalized tips. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2020; 609 ():125871.

Chicago/Turabian Style

Jia Mao; Hatem Abushammala; Bohumil Kasal. 2020. "Monitoring the surface aging of wood through its pits using atomic force microscopy with functionalized tips." Colloids and Surfaces A: Physicochemical and Engineering Aspects 609, no. : 125871.

Journal article
Published: 16 April 2019 in Polymers
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In this study, ammonium polyphosphate (APP) and aluminum hydroxide (ALH) with different mass contents were used as fire retardants (FRs) on plant-based natural flax fabric-reinforced polymer (FFRP) composites. Thermogravimetric analysis (TGA), limited oxygen index (LOI), and the Underwriters Laboratories (UL)-94 horizontal and vertical tests were carried out for evaluating the effectiveness of these FR treatments. Flat-coupon tensile test was performed to evaluate the effects of FR treatment on the mechanical properties of the FFRP composites. For both fire retardants, the results showed that the temperature of the thermal decomposition and the LOI values of the composites increased as the FR content increases. Under the UL-94 vertical test, the FFRP composites with 20% and 30% APP (i.e., by mass content of epoxy polymer matrix) were self-extinguished within 30 and 10 s following the removal of the flame without any burning drops, respectively. However, the mechanical tensile tests showed that the APP treated FFRP composites reduced their elastic modulus and strength up to 24% and 18%, respectively. Scanning electronic microscopic (SEM) for morphology examination showed an effective coating of the flax fibres with the FRs, which improved the flame retardancy of the treated composites.

ACS Style

Erik Valentine Bachtiar; Katarzyna Kurkowiak; Libo Yan; Bohumil Kasal; Torsten Kolb. Thermal Stability, Fire Performance, and Mechanical Properties of Natural Fibre Fabric-Reinforced Polymer Composites with Different Fire Retardants. Polymers 2019, 11, 699 .

AMA Style

Erik Valentine Bachtiar, Katarzyna Kurkowiak, Libo Yan, Bohumil Kasal, Torsten Kolb. Thermal Stability, Fire Performance, and Mechanical Properties of Natural Fibre Fabric-Reinforced Polymer Composites with Different Fire Retardants. Polymers. 2019; 11 (4):699.

Chicago/Turabian Style

Erik Valentine Bachtiar; Katarzyna Kurkowiak; Libo Yan; Bohumil Kasal; Torsten Kolb. 2019. "Thermal Stability, Fire Performance, and Mechanical Properties of Natural Fibre Fabric-Reinforced Polymer Composites with Different Fire Retardants." Polymers 11, no. 4: 699.

Journal article
Published: 14 January 2018 in Advances in Structural Engineering
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The seismic performance of three-dimensional moment-resisting timber frames with frictional damping devices was investigated experimentally. This article describes a novel three-dimensional beam-to-column connection which was designed to behave rigidly up to moderate seismic intensities and to start the frictional dissipating behavior at higher intensities. The three-dimensional beam-to-column connection component was initially tested under cyclic loading, and then the connection was mounted in a three-level prototype frame and tested on a shake table. From the cyclic loading tests, the energy dissipation of the proposed beam-to-column connection was higher than the equivalent rigid connection. The frame demonstrated self-aligning capabilities without permanent drift at seismic intensities up to 1.4 g and maintained strength up to high seismic intensities of 2 g. Because wood frames allow for large elastic deflections and can exhibit excellent self-aligning capabilities ( i.e., connections tolerate large rotations within safe stress levels), the proposed frictional beam-to-column connection is a promising alternative for moment-resisting timber frames that can be used to prevent structural members from reaching critical stresses.

ACS Style

Tiberiu Polocoșer; Jonas Leimcke; Bohumil Kasal. Report on the seismic performance of three-dimensional moment-resisting timber frames with frictional damping in beam-to-column connections. Advances in Structural Engineering 2018, 21, 1652 -1663.

AMA Style

Tiberiu Polocoșer, Jonas Leimcke, Bohumil Kasal. Report on the seismic performance of three-dimensional moment-resisting timber frames with frictional damping in beam-to-column connections. Advances in Structural Engineering. 2018; 21 (11):1652-1663.

Chicago/Turabian Style

Tiberiu Polocoșer; Jonas Leimcke; Bohumil Kasal. 2018. "Report on the seismic performance of three-dimensional moment-resisting timber frames with frictional damping in beam-to-column connections." Advances in Structural Engineering 21, no. 11: 1652-1663.

Journal article
Published: 01 January 2018 in Composite Structures
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This study investigated the flexural behavior of U-shape hybrid FRP-RC composite beams. The composite beams consisted of U-shape hybrid G/CFRP profile and encased rectangular RC beams with or without inner GFRP tube confinement at concrete compression zone of the beams. A total of 15 medium-sized (i.e. 1800 mm in length, 100 mm in width and 160 mm in depth) beam specimens were constructed and tested under four-point bending, including one ordinary RC beam as reference, 10 hybrid beams with and four hybrid beams without inner GFRP tube confinement. The examined experimental variables included: (1) different arrangements of G/CFRP layer in U-shape FRP profile, (2) inner GFRP tube, (3) conventional steel rebar, and (4) different types of FRP profile and concrete interfacial bond. Based on the testing, the failure mode, load–deflection relationship, ductility, energy absorption capacity and load-strain relationship of the beams were analyzed. The results indicated that compared with the ordinary RC beam, all hybrid FRP-RC beams experienced significant enhancement in cracking, yielding and ultimate loads. The ductility and ultimate load of the composite beams increased with an increase in the thickness of the hybrid FRP profile. The use of GFRP tube at concrete compression zone had a slight increase in the ultimate load of the hybrid beams but resulted in a pronounced enhancement of their ductility. Compared with U-shape FRP profile and concrete interface with a wet-bond type, the gravel-bond type prevented the U-shape FRP profile debonding from the RC beam effectively and in turn improved the yielding load, ultimate load and ductility of the hybrid beams. The hybrid U-shape FRP profile-concrete beams without steel rebar showed the catastrophic brittle failure indicating the necessity of using internal steel rebar for such hybrid beams

ACS Style

Liang Huang; Chen Zhang; Libo Yan; Bohumil Kasal. Flexural behavior of U-shape FRP profile-RC composite beams with inner GFRP tube confinement at concrete compression zone. Composite Structures 2018, 184, 674 -687.

AMA Style

Liang Huang, Chen Zhang, Libo Yan, Bohumil Kasal. Flexural behavior of U-shape FRP profile-RC composite beams with inner GFRP tube confinement at concrete compression zone. Composite Structures. 2018; 184 ():674-687.

Chicago/Turabian Style

Liang Huang; Chen Zhang; Libo Yan; Bohumil Kasal. 2018. "Flexural behavior of U-shape FRP profile-RC composite beams with inner GFRP tube confinement at concrete compression zone." Composite Structures 184, no. : 674-687.

Journal article
Published: 01 November 2017 in Colloids and Surfaces A: Physicochemical and Engineering Aspects
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ACS Style

X. Jin; B. Kasal. Discussion about the data analysis and conclusion of the paper titled “Comparison of silicon and OH-modified AFM tips for adhesion force analysis on functionalised surfaces and natural polymers”. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017, 533, 354 -355.

AMA Style

X. Jin, B. Kasal. Discussion about the data analysis and conclusion of the paper titled “Comparison of silicon and OH-modified AFM tips for adhesion force analysis on functionalised surfaces and natural polymers”. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2017; 533 ():354-355.

Chicago/Turabian Style

X. Jin; B. Kasal. 2017. "Discussion about the data analysis and conclusion of the paper titled “Comparison of silicon and OH-modified AFM tips for adhesion force analysis on functionalised surfaces and natural polymers”." Colloids and Surfaces A: Physicochemical and Engineering Aspects 533, no. : 354-355.

Journal article
Published: 01 November 2017 in Construction and Building Materials
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Compared with normal aggregate concrete, recycled aggregate concrete (RAC) containing recycled clay brick coarse aggregates (termed as RAC-RCBA) shows very lower compressive strength and larger variation in compressive strength, which hinder the application of RAC-RCBA as structural concrete. This study used polyester FRP (PFRP) as confining material of RAC-RCBA cylinders to improve the strength of RAC-RCBA. The axial compressive behavior of 42 PFRP tube encased RAC-RCBA cylinders (termed as PFRP confined RAC-RCBA) and 24 unconfined RAC-RCBA cylinders were investigated. Compared with conventional glass/carbon FRP (G/CFRP) materials, the main advantages to use PFRP are its much lower material cost and much larger tensile strain capacity. In this study, the experimental parameters considered were: (1) strength, (2) size, and (3) slenderness ratio of RAC-RCBA cylindrical specimens. Statistical analysis was also conducted to investigate the size effect and the slenderness ratio effect. The experimental results indicated that compared with conventional G/CFRP composites, the PFRP had a significantly lower tensile strength and modulus, but a much larger tensile strain at failure. The PFRP tube enhanced the ductility of the RAC-RCBA cylinders remarkably, while the enhancement on the compressive strength of RAC-RCBA by PFRP was not so pronounced as that by carbon/CFRP tubes. It was also found that the size and the slenderness ratio influenced the compressive strength of the RAC cylinders at the transitional point (fct) remarkably, and the fct decreased with the increase in size and slenderness ratio for middle, large and tall sized cylinders. In addition, a size-dependent model for fct was proposed and the predictions fitted well with the experimental results, the applicability of the proposed model for other weakly confined RAC-RCBA was also verified through the comparison with the experimental results of flax FRP tube confined RAC-RCBA

ACS Style

Liang Huang; Liuxin Chen; Libo Yan; Bohumil Kasal; Yuxin Jiang; Changyi Liu. Behavior of polyester FRP tube encased recycled aggregate concrete with recycled clay brick aggregate: Size and slenderness ratio effects. Construction and Building Materials 2017, 154, 123 -136.

AMA Style

Liang Huang, Liuxin Chen, Libo Yan, Bohumil Kasal, Yuxin Jiang, Changyi Liu. Behavior of polyester FRP tube encased recycled aggregate concrete with recycled clay brick aggregate: Size and slenderness ratio effects. Construction and Building Materials. 2017; 154 ():123-136.

Chicago/Turabian Style

Liang Huang; Liuxin Chen; Libo Yan; Bohumil Kasal; Yuxin Jiang; Changyi Liu. 2017. "Behavior of polyester FRP tube encased recycled aggregate concrete with recycled clay brick aggregate: Size and slenderness ratio effects." Construction and Building Materials 154, no. : 123-136.

Article
Published: 05 September 2017 in Mechanics of Composite Materials
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Numerical methods for simulating hollow and foam-filled flax-fabric-reinforced epoxy tubular energy absorbers subjected to lateral crashing are presented. The crashing characteristics, such as the progressive failure, load–displacement response, absorbed energy, peak load, and failure modes, of the tubes were simulated and calculated numerically. A 3D nonlinear finite-element model that allows for the plasticity of materials using an isotropic hardening model with strain rate dependence and failure is proposed. An explicit finite-element solver is used to address the lateral crashing of the tubes considering large displacements and strains, plasticity, and damage. The experimental nonlinear crashing load vs. displacement data are successfully described by using the finite-element model proposed. The simulated peak loads and absorbed energy of the tubes are also in good agreement with experimental results.

ACS Style

J. Sliseris; L. Yan; B. Kasal. Numerical Simulation and Experimental Verification of Hollow and Foam-Filled Flax-Fabric-Reinforced Epoxy Tubular Energy Absorbers Subjected to Crashing. Mechanics of Composite Materials 2017, 53, 487 -496.

AMA Style

J. Sliseris, L. Yan, B. Kasal. Numerical Simulation and Experimental Verification of Hollow and Foam-Filled Flax-Fabric-Reinforced Epoxy Tubular Energy Absorbers Subjected to Crashing. Mechanics of Composite Materials. 2017; 53 (4):487-496.

Chicago/Turabian Style

J. Sliseris; L. Yan; B. Kasal. 2017. "Numerical Simulation and Experimental Verification of Hollow and Foam-Filled Flax-Fabric-Reinforced Epoxy Tubular Energy Absorbers Subjected to Crashing." Mechanics of Composite Materials 53, no. 4: 487-496.

Article
Published: 05 July 2017 in Journal of Dynamic Behavior of Materials
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This article studies many of the geometric and dynamic aspects of low-velocity impact testing for obtaining material parameters. Predictive analytical models are developed for a sphere and pendulum impact of a spring–spring beam, while a numerical model of a pendulum impact with a spring–spring beam with overhangs is developed for comparison. The dynamic nature of collecting impact loads elicited interest in the validation of inverse analysis procedures for data correction. Using the measured loads and the corrected loads as forcing functions, certain assumptions about modes of vibrations and data correction or filtering were validated. Wood beam specimens were selected for the experiments to validate the analytical models and because there was a lack of experimental data for dynamic material properties of wood.

ACS Style

Tiberiu Polocoser; B. Kasal; X. Li. Design of Experiment and Pitfalls of Low-Velocity Pendulum Impact Testing. Journal of Dynamic Behavior of Materials 2017, 3, 436 -460.

AMA Style

Tiberiu Polocoser, B. Kasal, X. Li. Design of Experiment and Pitfalls of Low-Velocity Pendulum Impact Testing. Journal of Dynamic Behavior of Materials. 2017; 3 (3):436-460.

Chicago/Turabian Style

Tiberiu Polocoser; B. Kasal; X. Li. 2017. "Design of Experiment and Pitfalls of Low-Velocity Pendulum Impact Testing." Journal of Dynamic Behavior of Materials 3, no. 3: 436-460.

Original
Published: 09 June 2017 in Wood Science and Technology
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The following state-of-the-art report summarizes important work done in wood science concerning intermediate and high strain rate testing. Intermediate testing may be done with hydraulic machines, which are generally classified as rapid loading. Intermediate testing may also be done using a transverse impact of a beam specimen with a pendulum, drop mass, or toughness tester, whereas high strain rate testing is generally done with the Kolsky bar. The article analyzes the different experimental testing apparatuses, the conclusions past researchers have made about them, and the toughness and strength measurements which were usually done. The transverse impact test is examined in detail because of its adjustability for specimen sizes. The value of this research is it delves into certain impact mechanics principles which are missing from the analysis of impact testing in wood science, which must be included to validate previously held assumptions. The physical response of wood to a dynamic load is not any different from other materials such as metals or rigid foams and is governed by the same principles. Nevertheless, over the years the application of impact mechanics principles to wood testing has been scarce and “black box” experimental, where empirical approaches such as the duration-of-load were often preferred. An example of these principles is the influence of higher modes of vibration plays a greater role on the stress state in testing than its influence on deflections. This principle has been thoroughly investigated for small strain rate vibrations, however, not applied to impact testing. Presently, there is no consensus on a constitutive strain rate model for wood under intermediate and high strain rates. This article provides direction for obtaining dynamic Young’s modulus and yield strength, which can be normally expected in the design of structures subjected to dynamical loadings, for the future creation of applicable constitutive strain rate models.

ACS Style

Tiberiu Polocoșer; Bohumil Kasal; Frank Stöckel. State-of-the-art: intermediate and high strain rate testing of solid wood. Wood Science and Technology 2017, 51, 1479 -1534.

AMA Style

Tiberiu Polocoșer, Bohumil Kasal, Frank Stöckel. State-of-the-art: intermediate and high strain rate testing of solid wood. Wood Science and Technology. 2017; 51 (6):1479-1534.

Chicago/Turabian Style

Tiberiu Polocoșer; Bohumil Kasal; Frank Stöckel. 2017. "State-of-the-art: intermediate and high strain rate testing of solid wood." Wood Science and Technology 51, no. 6: 1479-1534.

Journal article
Published: 01 April 2017 in Construction and Building Materials
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The combined use of environmentally-friendly plant-based natural fibre reinforced polymer (FRP) composites and recycled aggregate concrete (RAC) will be beneficial for the development of sustainable concrete. In literature, a large amount of research has been conducted on unconfined RAC where the recycled aggregates (RAs) mainly came from concrete rubble, but the use of RAs from masonry rubble for RAC is very rare. This study reported the compressive behavior of flax FRP tube encased RAC containing partially clay brick aggregate (CBA), which was termed as FFRP-rAC-CBA. For the RAC, up to 70% of natural coarse aggregates was replaced by recycled aggregates (RAs). The RAs consisted mainly of 60% of recycled clay brick aggregates and 40% of recycled concrete and mortar aggregates. A total of36 cylindrical specimens including 24 FFRP-rAC-CBA and 12 unconfined rAC-CBA were tested under uni-axial compression. The testing variables included: (i) strength of rAC-CBA (i.e. 27.5 MPa and 32.8 MPa); (ii) thickness of FFRP tube (i.e. 3, 6, 9 and 12 FRP layers); and (iii)size of cylinder (i.e. 75 × 150, 150 × 300 and 300 × 600, unit of mm). Tests results indicated that the natural FFRP tube enhanced the ultimate strength and ductility of the confined rAC-CBA remarkably and the enhancement was more pronounced in specimens with higher concrete strength. Increasing FFRP thickness led to higher compressive stress and strain of the FFRP-rAC-CBA. In addition, stress and strain models were proposed to predict and compare with experimental results of FFRP-rAC-CBA. A size-dependent model was also used to predict the transitional strength and ultimate strength of FFRP-rAC-CBA

ACS Style

Bin Yan; Liang Huang; Libo Yan; Chang Gao; Bohumil Kasal. Behavior of flax FRP tube encased recycled aggregate concrete with clay brick aggregate. Construction and Building Materials 2017, 136, 265 -276.

AMA Style

Bin Yan, Liang Huang, Libo Yan, Chang Gao, Bohumil Kasal. Behavior of flax FRP tube encased recycled aggregate concrete with clay brick aggregate. Construction and Building Materials. 2017; 136 ():265-276.

Chicago/Turabian Style

Bin Yan; Liang Huang; Libo Yan; Chang Gao; Bohumil Kasal. 2017. "Behavior of flax FRP tube encased recycled aggregate concrete with clay brick aggregate." Construction and Building Materials 136, no. : 265-276.

Article
Published: 03 March 2017 in Journal of Dynamic Behavior of Materials
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This study reviews the article by Timoshenko (Z Angew Math Phys 62(1–4):198–209, 5), and how two other researchers have interpreted the numerical method he employed. The numerical method is then compared to some standard contemporary methods, showing the continuous historical development. Additional important contributions in the impact literature are systematically compared and then applied to the low-velocity impact prediction of a wood beam, which has not been done yet. How to obtain the material parameters needed for the prediction are discussed and also how the impact testing can be used to obtain dynamic material properties are discussed in detail. The predictions using the methods developed by past researchers for metals are qualitatively a good starting point, showing where areas in impact testing of wood can be improved.

ACS Style

Tiberiu Polocoşer; Bohumil Kasal; Aljoscha Hallermann; Xinyi Li. What was Timoshenko’s Small-Increment Method? With an Application to Low-Velocity Impact of a Wood Beam. Journal of Dynamic Behavior of Materials 2017, 3, 45 -63.

AMA Style

Tiberiu Polocoşer, Bohumil Kasal, Aljoscha Hallermann, Xinyi Li. What was Timoshenko’s Small-Increment Method? With an Application to Low-Velocity Impact of a Wood Beam. Journal of Dynamic Behavior of Materials. 2017; 3 (1):45-63.

Chicago/Turabian Style

Tiberiu Polocoşer; Bohumil Kasal; Aljoscha Hallermann; Xinyi Li. 2017. "What was Timoshenko’s Small-Increment Method? With an Application to Low-Velocity Impact of a Wood Beam." Journal of Dynamic Behavior of Materials 3, no. 1: 45-63.

Journal article
Published: 01 January 2017 in Construction and Building Materials
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Previous studies showed that concrete column confined by both glass fiber reinforced polymer (GFRP) tube and inner steel spiral reinforcement (termed as GFRP-SR-confined concrete) is a hybrid structure exhibiting much better static structural performance (e.g. load carrying capacity and ductility) compared with concrete column filled GFRP tube (CFFT) or conventional concrete column with inner steel spiral reinforcement (SR). To date, very few studies have considered the dynamic behavior of this hybrid structure. This research reports an experimental study on the dynamic behavior of GFRP-SR-confined concrete columns under impact loadings using a drop-hammer with large capacities (i.e. impact height up to 6.42 m and weight of hammer up to 588 kg). The test variables considered include the different levels of impact energy and strain rate, GFRP tube thickness and volumetric ratio of SR. The impact behavior of this hybrid structure is also compared with the CFFT and conventional SR column counterparts. The test results indicate that the failure pattern of this hybrid structure is highly dependent on the level of impact energy. Increasing the tube thickness and SR volumetric ratio enhances the impact-resistant capabilities of the structure remarkably. In addition, the impact results are compared with the quasi-static compressive results of the GFRP-SR-confined concrete

ACS Style

Liang Huang; Xiaoxun Sun; Libo Yan; Bohumil Kasal. Impact behavior of concrete columns confined by both GFRP tube and steel spiral reinforcement. Construction and Building Materials 2017, 131, 438 -448.

AMA Style

Liang Huang, Xiaoxun Sun, Libo Yan, Bohumil Kasal. Impact behavior of concrete columns confined by both GFRP tube and steel spiral reinforcement. Construction and Building Materials. 2017; 131 ():438-448.

Chicago/Turabian Style

Liang Huang; Xiaoxun Sun; Libo Yan; Bohumil Kasal. 2017. "Impact behavior of concrete columns confined by both GFRP tube and steel spiral reinforcement." Construction and Building Materials 131, no. : 438-448.

Research article
Published: 13 December 2016 in Journal of Reinforced Plastics and Composites
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Natural flax fabric-reinforced polymer (FFRP) tube encased coir fibre-reinforced concrete (CFRC) structure (termed as FFRP-CFRC) is steel-free hybrid structure that has shown its potential as axial, flexural and earthquake-resistant structural members. An FFRP plate with a CFRC overlay has great potential to be light and environmentally friendly wall panel or pedestrian bridge deck. The overall structural performance of this panel or deck is highly dependent on the bond at the FFRP and CFRC interface. Therefore, this study proposed a novel interlocking at their interface to improve the bond and thus the composite action of the hybrid structures composed of FFRP and CFRC components. This interlocking was generated by creating numbers of perforations on the FFRP component (tube and plate) surface. To evaluate the effectiveness of using this interlocking on the bond behaviour between FFRP and CFRC, two stages experimental studies were conducted. In the first stage, 18 FFRP-CFRC cylindrical specimens were constructed and tested under push-out bond, bending and axial compression. In the second stage, 30 FFRP plate and CFRC sandwich block specimens were constructed and tested under push-out bond considering different experimental parameters, i.e. depth, diameter and number of perforations. Additionally, numerical simulation was performed to verify the failure modes of FFRP plate and CFRC sandwich blocks under push-out. This study revealed that the presence of interlocking is an effective way to improve the interfacial bond and composite action between FFRP (either tube or plate) and CFRC components.

ACS Style

Libo Yan; Nawawi Chouw; Bohumil Kasal. Experimental study and numerical simulation on bond between FFRP and CFRC components. Journal of Reinforced Plastics and Composites 2016, 36, 305 -320.

AMA Style

Libo Yan, Nawawi Chouw, Bohumil Kasal. Experimental study and numerical simulation on bond between FFRP and CFRC components. Journal of Reinforced Plastics and Composites. 2016; 36 (4):305-320.

Chicago/Turabian Style

Libo Yan; Nawawi Chouw; Bohumil Kasal. 2016. "Experimental study and numerical simulation on bond between FFRP and CFRC components." Journal of Reinforced Plastics and Composites 36, no. 4: 305-320.

Book chapter
Published: 03 November 2016 in Structural Analysis of Historical Constructions: Anamnesis, Diagnosis, Therapy, Controls
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ACS Style

M. Drdácký; Bohumil Kasal. Testing historic materials for redesign purposes. Structural Analysis of Historical Constructions: Anamnesis, Diagnosis, Therapy, Controls 2016, 585 -591.

AMA Style

M. Drdácký, Bohumil Kasal. Testing historic materials for redesign purposes. Structural Analysis of Historical Constructions: Anamnesis, Diagnosis, Therapy, Controls. 2016; ():585-591.

Chicago/Turabian Style

M. Drdácký; Bohumil Kasal. 2016. "Testing historic materials for redesign purposes." Structural Analysis of Historical Constructions: Anamnesis, Diagnosis, Therapy, Controls , no. : 585-591.

Journal article
Published: 01 November 2016 in Construction and Building Materials
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Engineered bamboo scrimber has processed from the raw bamboo culm into a compressed or laminated product with thermosetting resin in the density range of 800–1200 kg/m3. The present work investigates the mechanical properties of commercially available engineered bamboo scrimber and compares the results of present work with the existing results in the literature. The main aim of this work is to investigate the influence of bamboo scrimber densities on the mechanical properties. The strength and modulus properties in tensile, compression, shear and flexural were evaluated using the specimens of three different densities. The dynamic modulus of elasticity of bamboo scrimber beams were evaluated using ultra-sonic pulse method. According to the present results it can be concluded that the density have significant influence on the mechanical properties of bamboo scrimber. The long term water absorption was also conducted to analysis the weight gained by the bamboo scrimber having different densities and the results revealed that density of specimen’s influences the water absorption

ACS Style

Anuj Kumar; Tomáš Vlach; Lenka Laiblova; Martin Hrouda; Bohumil Kasal; Jan Tywoniak; Petr Hajek. Engineered bamboo scrimber: Influence of density on the mechanical and water absorption properties. Construction and Building Materials 2016, 127, 815 -827.

AMA Style

Anuj Kumar, Tomáš Vlach, Lenka Laiblova, Martin Hrouda, Bohumil Kasal, Jan Tywoniak, Petr Hajek. Engineered bamboo scrimber: Influence of density on the mechanical and water absorption properties. Construction and Building Materials. 2016; 127 ():815-827.

Chicago/Turabian Style

Anuj Kumar; Tomáš Vlach; Lenka Laiblova; Martin Hrouda; Bohumil Kasal; Jan Tywoniak; Petr Hajek. 2016. "Engineered bamboo scrimber: Influence of density on the mechanical and water absorption properties." Construction and Building Materials 127, no. : 815-827.

Journal article
Published: 01 November 2016 in Composite Structures
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In literature, there are few studies which investigated compressive behavior of fibre reinforced polymer (FRP) tube confined recycled aggregate concrete (RAC) where the recycled aggregates (RAs) mainly came from demolished old concrete components. Study which considered FRP tube confined RAC using recycled clay brick aggregates (RCBA) originating from demolished brick masonry components is rare. Thus, this paper reports a systematic study on axial compressive behavior of FRP tube encased RAC containing RCBA (termed as FRP-confined RAC-RCBA). The experimental variables considered are, i.e., replacement ratio of RCBA (r = 0, 50, 70 and 100%), FRP tube thickness (nf=2, 4 and 6 layers) and type of fibre material (GFRP and CFRP). This study shows that both GFRP and CFRP tubes enhanced strength and deformation of the confined RAC-RCBA specimens remarkably. The ultimate compressive stress of the confined specimens decreased with an increase of RCBA replacement ratio but their axial deformation kept approximately constant. Failure mode and the compressive stress-strain behavior of G/CFRP-confined RAC-RCBA were similar to these tube confined normal aggregate concrete (NAC) and the ultimate compressive strength of G/CFRP tube confined RAC-RCBA specimens enhanced with an increase in FRP tube thickness. The CFRP-confined specimens showed higher ultimate strength but lower ultimate axial strain than those of GFRP-confined specimens. The applicability of eight widely used confinement models, i.e., 5 design-oriented and 2 analysis-oriented models, for FRP-confined NAC to FRP-confined RAC-RCBA was also evaluated

ACS Style

Chang Gao; Liang Huang; Libo Yan; Bohumil Kasal; Wengui Li. Behavior of glass and carbon FRP tube encased recycled aggregate concrete with recycled clay brick aggregate. Composite Structures 2016, 155, 245 -254.

AMA Style

Chang Gao, Liang Huang, Libo Yan, Bohumil Kasal, Wengui Li. Behavior of glass and carbon FRP tube encased recycled aggregate concrete with recycled clay brick aggregate. Composite Structures. 2016; 155 ():245-254.

Chicago/Turabian Style

Chang Gao; Liang Huang; Libo Yan; Bohumil Kasal; Wengui Li. 2016. "Behavior of glass and carbon FRP tube encased recycled aggregate concrete with recycled clay brick aggregate." Composite Structures 155, no. : 245-254.

Journal article
Published: 01 October 2016 in Royal Society Open Science
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This study attempts to address the interpretation of atomic force microscopy (AFM) adhesion force measurements conducted on the heterogeneous rough surface of wood and natural fibre materials. The influences of wood surface roughness, tip geometry and wear on the adhesion force distribution are examined by cyclic measurements conducted on wood surface under dry inert conditions. It was found that both the variation of tip and surface roughness of wood can widen the distribution of adhesion forces, which are essential for data interpretation. When a common Si AFM tip with nanometre size is used, the influence of tip wear can be significant. Therefore, control experiments should take the sequence of measurements into consideration, e.g. repeated experiments with used tip. In comparison, colloidal tips provide highly reproducible results. Similar average values but different distributions are shown for the adhesion measured on two major components of wood surface (cell wall and lumen). Evidence supports the hypothesis that the difference of the adhesion force distribution on these two locations was mainly induced by their surface roughness.

ACS Style

X. Jin; Bohumil Kasal. Adhesion force mapping on wood by atomic force microscopy: influence of surface roughness and tip geometry. Royal Society Open Science 2016, 3, 160248 .

AMA Style

X. Jin, Bohumil Kasal. Adhesion force mapping on wood by atomic force microscopy: influence of surface roughness and tip geometry. Royal Society Open Science. 2016; 3 (10):160248.

Chicago/Turabian Style

X. Jin; Bohumil Kasal. 2016. "Adhesion force mapping on wood by atomic force microscopy: influence of surface roughness and tip geometry." Royal Society Open Science 3, no. 10: 160248.

Journal article
Published: 01 September 2016 in Materials and Structures
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ACS Style

Gao Ma; Bohumil Kasal; Chengzhi Tao; Libo Yan; Liang Huang; Liang Chen. Experimental performance of reinforced double H-block masonry shear walls under cyclic loading. Materials and Structures 2016, 50, 1 .

AMA Style

Gao Ma, Bohumil Kasal, Chengzhi Tao, Libo Yan, Liang Huang, Liang Chen. Experimental performance of reinforced double H-block masonry shear walls under cyclic loading. Materials and Structures. 2016; 50 (1):1.

Chicago/Turabian Style

Gao Ma; Bohumil Kasal; Chengzhi Tao; Libo Yan; Liang Huang; Liang Chen. 2016. "Experimental performance of reinforced double H-block masonry shear walls under cyclic loading." Materials and Structures 50, no. 1: 1.

Journal article
Published: 01 August 2016 in Journal of Materials in Civil Engineering
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Single-blow impact testing of spruce and pine specimens were done to assess the effects of additional E-glass reinforcing on the tension face of a beam along with a rubber lamina adhered to the impact face. Comparisons between classic three-point static bending and dynamic pendulum tests proved the wood specimens did not absorb more energy in a dynamic loading; conversely, when reinforced with E-glass the spruce specimens absorbed about 2.5 times more energy, and the pine specimens absorbed 1.4 times more energy. The pine specimens treated with rubber and E-glass absorbed only about 1.5 times more energy, indicating a minimal positive effect by adding rubber. The most critical aspect of testing was the strain rate sensitivity of the E-glass.

ACS Style

Tiberiu Polocoşer; Frank Stöckel; Bohumil Kasal. Low-Velocity Transverse Impact of Small, Clear Spruce and Pine Specimens with Additional Energy Absorbing Treatments. Journal of Materials in Civil Engineering 2016, 28, 04016048 .

AMA Style

Tiberiu Polocoşer, Frank Stöckel, Bohumil Kasal. Low-Velocity Transverse Impact of Small, Clear Spruce and Pine Specimens with Additional Energy Absorbing Treatments. Journal of Materials in Civil Engineering. 2016; 28 (8):04016048.

Chicago/Turabian Style

Tiberiu Polocoşer; Frank Stöckel; Bohumil Kasal. 2016. "Low-Velocity Transverse Impact of Small, Clear Spruce and Pine Specimens with Additional Energy Absorbing Treatments." Journal of Materials in Civil Engineering 28, no. 8: 04016048.

Journal article
Published: 01 June 2016 in Construction and Building Materials
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In this study, coir fibres were studied for use as reinforcement materials for polymer and cementitious composites. The effect of fibre treatment (i.e. 5 wt.% NaOH solution at 20 °C for 30 min) on microstructure and mechanical properties of coir fibre, coir fibre reinforced epoxy (CFRE) and coir fibre reinforced cementitious (CFRC) composites were investigated. Scanning electronic microscope (SEM) studies were carried out to examine the microstructures of untreated and treated coir fibres, fibre/epoxy and fibre/cement interfaces. Mechanical properties of CFRE were determined by vibration, tensile and flexure tests and mechanical properties of CFRC were determined by compression and four-point bending tests, respectively. The test results show that coir fibre had a much cleaner and rougher fibre surface after the alkali treatment. Compared with the untreated CFRE, treatment improved the tensile and flexural properties of composites, i.e. 17.8% and 16.7% growth in tensile and flexural strength, respectively. However, the treatment also reduced the damping ratio of the CFRE. The increase in tensile and flexural properties and reduction in damping ratio are attributed to the improvement of fibre and epoxy matrix interfacial adhesion due to the treatment, as displayed by SEM micrographs. Compared with the plain concrete, coir fibre improved the compressive strength, flexural strength and toughness effectively. The treatment can further improve these properties of CFRC. SEM studies clearly confirmed that the failure modes of coir fibres in cement matrix are fibre breakage, fibre pull-out and fibre debonding from the cement matrix. The microstructure of coir fibre, CFRE and CFRC were correlated with their mechanical properties.

ACS Style

Libo Yan; Nawawi Chouw; Liang Huang; Bohumil Kasal. Effect of alkali treatment on microstructure and mechanical properties of coir fibres, coir fibre reinforced-polymer composites and reinforced-cementitious composites. Construction and Building Materials 2016, 112, 168 -182.

AMA Style

Libo Yan, Nawawi Chouw, Liang Huang, Bohumil Kasal. Effect of alkali treatment on microstructure and mechanical properties of coir fibres, coir fibre reinforced-polymer composites and reinforced-cementitious composites. Construction and Building Materials. 2016; 112 ():168-182.

Chicago/Turabian Style

Libo Yan; Nawawi Chouw; Liang Huang; Bohumil Kasal. 2016. "Effect of alkali treatment on microstructure and mechanical properties of coir fibres, coir fibre reinforced-polymer composites and reinforced-cementitious composites." Construction and Building Materials 112, no. : 168-182.