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The problem of limited the size of the cross-section and span of the timber can be overcome through lamination technology. Timber with a small cross-sectional size and short-span and also timber waste can be optimized the used through this technology. This study aims to determine the failure behavior of glue laminated timber beams made of timber planks. The research was conducted on meranti and mahogany timber. Standard specimen and test based on ASTM D-198-15. The laminated timber is made from pieces of timber planks (the varian is 40 cm, 50 cm, 60 cm and full length) as much as 4 layers which are arranged into lamina timber with a size of mahogany is 6.5 x 9.2 cm, meranti is 5.5 x 9.5 cm. Each span is 150 cm long. The span between supports is 130 cm. The beam is tested center-point loading. The analysis results show that the beam failure starts from the disconnection of the joints between the boards on the outer layer of the laminated beam that is subjected to tensile stress. The connection between the planks in the outer tensile layer can cause the beam to weaken. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of load-bearing capacity and deformability of wood-steel hybrid systems, depending on the selected system constellation, and the possibility of increasing system efficiency and in real conditions by applying pre-stress, in accordance with modern principles of structural conceptual design. The subject of the research is the behaviour of pre-stressed glued laminated beams with external polygonal ropes, different researched constellations, i.e. strut type hybrid systems, in real conditions. The paper is practically divided into three methodological units: theoretical and numerical analysis, and examples of practical applications, and on the theoretical basis of urban transformations of historical units. Theoretical assumptions, as well as the current and own approach to the analysis of parameters, set the theoretical basis for the analysis of these systems and the possibility of applying numerical methods in practice. Parametric analysis of the hybrid system obtained practical expressions and diagrams for use in practice, needed to determine suitable constellations of strut type hybrid system by different geometric characteristics and pre-stressed hybrid system, and for different percentages of wooden girder moisture. In order to compare these systems, the same assumptions were used for the calculation, namely: plane behaviour of the system, and to determine the effective pre-stressing, the condition of annulment of vertical deflection in characteristic cross-sections was used, i.e. achieving the effect of vertical immobility of the struts, from which the measure of pre-stressing of the deformable system was obtained. A hybrid system with a wooden girder, which has bending stiffness, is often used in construction, and the main disadvantage of such a system is the expressed deformability in real operating conditions. The basic thesis of this paper is that by external pre-stressing of glued laminated girder achieves less deformability and increases bearing capacity, while saving base material in real conditions, and is confirmed by our own parametric analysis and laboratory testing of pre-stressed hybrid systems of different constellations. The attached parametric analysis diagrams provide a sufficiently accurate orientation for finding the correct constellations of wood-steel hybrid systems and the possibility of estimating the efficiency of hybrids in real conditions, as well as the necessary pre-stressing applications. The derived expressions of the approximate procedure and the expressions for finding the effective pre-stressing force, assuming the linear behaviour of the system, give sufficiently accurate results for the design of pre-stressed hybrid systems in practice. Also, with this or similar methodology it is possible to qualitatively investigate hybrid systems with different combinations of materials. The presented conceptual solutions for the integration of hybrid systems and modern materials in specific localities represent a contribution to the development of a methodological approach to the transformation of historical urban units. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of load-bearing capacity and deformability of wood-steel hybrid systems, depending on the selected system constellation, and the possibility of increasing system efficiency and in real conditions by applying pre-stress, in accordance with modern principles of structural conceptual design. The subject of the research is the behaviour of pre-stressed glued laminated beams with external polygonal ropes, different researched constellations, i.e. strut type hybrid systems, in real conditions. The paper is practically divided into three methodological units: theoretical and numerical analysis, and examples of practical applications, and on the theoretical basis of urban transformations of historical units. Theoretical assumptions, as well as the current and own approach to the analysis of parameters, set the theoretical basis for the analysis of these systems and the possibility of applying numerical methods in practice. Parametric analysis of the hybrid system obtained practical expressions and diagrams for use in practice, needed to determine suitable constellations of strut type hybrid system by different geometric characteristics and pre-stressed hybrid system, and for different percentages of wooden girder moisture. In order to compare these systems, the same assumptions were used for the calculation, namely: plane behaviour of the system, and to determine the effective pre-stressing, the condition of annulment of vertical deflection in characteristic cross-sections was used, i.e. achieving the effect of vertical immobility of the struts, from which the measure of pre-stressing of the deformable system was obtained. A hybrid system with a wooden girder, which has bending stiffness, is often used in construction, and the main disadvantage of such a system is the expressed deformability in real operating conditions. The basic thesis of this paper is that by external pre-stressing of glued laminated girder achieves less deformability and increases bearing capacity, while saving base material in real conditions, and is confirmed by our own parametric analysis and laboratory testing of pre-stressed hybrid systems of different constellations. The attached parametric analysis diagrams provide a sufficiently accurate orientation for finding the correct constellations of wood-steel hybrid systems and the possibility of estimating the efficiency of hybrids in real conditions, as well as the necessary pre-stressing applications. The derived expressions of the approximate procedure and the expressions for finding the effective pre-stressing force, assuming the linear behaviour of the system, give sufficiently accurate results for the design of pre-stressed hybrid systems in practice. Also, with this or similar methodology it is possible to qualitatively investigate hybrid systems with different combinations of materials. The presented conceptual solutions for the integration of hybrid systems and modern materials in specific localities represent a contribution to the development of a methodological approach to the transformation of historical urban units. [ABSTRACT FROM AUTHOR]

The work of wooden structures for complex types of stress-strain state, in particular oblique bend, is analyzed. It is substantiated, when there is oblique bend and in what structures. The method of experimental researches of wooden glued beams on a skew bent at angles of a slope of 100 and 250 is developed. The results of experimental studies of complete deflections of glued beams in the conditions of oblique bending under the influence of low cycle load are presented. [ABSTRACT FROM AUTHOR]

The methods and results of experimental studies of strength and deformability of solid and glued wood (pine) on compression along and across fibers under the action of repeated non-cyclic loads were presented. The analysis of the obtained results of wood behavior in 50 repetitive load cycles has been carried out. It is established that the behavior of wood for repeated loads essentially depends on the upper level of application of low cycle loads. [ABSTRACT FROM AUTHOR]

This paper presents an attempt of using a finite element method for predicting delamination of a glue laminated timber beam through a cohesive layer. There were used cohesive finite elements, quadratic stress damage initiation criterion and mixed mode energy release rate failure model. Finite element damage was equal to its complete stiffness degradation. Timber material was considered to be an orthotropic with plastic behaviour after reaching bending limit. [ABSTRACT FROM AUTHOR]

Portal frame structures, which are constituted of straight glulam beams and columns connected semi-rigidly by steel insert gusset plate with a lot of drift pins, were the first successful glulam structures widely used in Japan. In addition to this connection system, the author invented also a new type of jointing devise for glulam structures named as "Lagscrewbolt" which had a full threaded portion at inner part to grip wooden member as well as another thread part at the end of shank to connect with other member. The initial type of "Lagscrewbolt" was successfully applied to a various types of glulam buildings which could be rapidly built-up on construction site. Its strength performance, however, was rather brittle therefore the improvement of the ductility was a crucial research subject. In order to give a sufficient ductility on the "Lagscrewbolted joint system", so-called "Slotted Bolted Connection" concept was adopted for making use of large energy dissipation characteristics due to high-tension bolted steel connection with slotted bolt holes. Static & dynamic performance of glulam portal frame specimens was evaluated by static cyclic loading test as well as shaking table test. Current latest form of the jointing system can show very high ductility as well as stable hysteretic cyclic loops by inserting brass-shim between steel-to-steel friction interfaces. [ABSTRACT FROM AUTHOR]