1. Slip modeling in timber-framed walls with wood-based or fibre-plaster sheathing boardsMiroslav Premrov, Peter Dobrila, Branko Bedenik, Igor Špacapan, 2007, izvirni znanstveni članek Opis: The paper provides mathematical modelling for prefabricated timber-framed walls composed of a timber frame and two different types of sheathing boards. Since by wood-based boards (WBB) the tensile strength is similar to the compressive one, there are practically no cracks appearing in the boards. On the other hand, in case of fibre-plaster sheathing boards (FPB) the tensile strength is approximately 10-times lower than the compressive one and therefore cracks in the tensile diagonal boardćs direction usually appear. Based on analysis of experimental research results [1] special approximate mathematical models have been developed. The models enable simultaneously to consider the flexibility of mechanical fasteners in the connecting areas, as well as possible cracks appearing in the tensile area of the sheathing boards. Ključne besede: civil engineering, timber structures, walls, CFRP strips, carbon fibre-reinforced polymer, mathematical modelling Objavljeno: 31.05.2012; Ogledov: 1273; Prenosov: 26 Povezava na celotno besedilo |
2. Analysis of composite T beam composed of timber, concrete and carbon stripMatjaž Tajnik, Peter Dobrila, Miroslav Premrov, 2007, izvirni znanstveni članek Opis: This paper provides a mathematical model and numerical example of composite T-section composed of a concrete plate and a timber beam strengthened at the bottom tension side with a carbon fibre-reinforced polymer (CFRP) strip. Analysis is provided in accordance with the European standards for timber, steel and concrete structures. The tensile strength of the carbon strip as well as the compressive strength of the concrete plate are higher than the bending strength of the timber beam, therefore it is convenient to use such composition of material to gain a higher load bearing capacity. It has been shown that the inclusion of CFRP strip reinforcement on the increase of load carrying and bending stiffness capacity was not as high as expected. On the other hand, we realized the importance of variety of material grade and geometrical properties combinations between sub-components which can significantly improve load bearing capacity and stiffness of composed beam. Furthermore, the CFRP strip contribution to the bending resistance and stiffness of the element is presented as a function of the fastener spacing intervals between concrete plate and timber beam. Ključne besede: composite structures, timber structures, carbon strip, load bearing capacity, modeling Objavljeno: 31.05.2012; Ogledov: 1261; Prenosov: 51 Povezava na celotno besedilo |
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5. Optimum design of plane timber trusses considering joint flexibilitySimon Šilih, Miroslav Premrov, Stojan Kravanja, 2005, izvirni znanstveni članek Opis: The paper presents the optimization of metal-plate-connected plane timber trusses with special emphasis on joint flexibility. The optimization was performed by the non-linear programming approach. Since various truss design parameters such as type of truss configuration, span/depth ratio, number and type of diagonal and vertical members and type of joint connections simultaneously affect each other, it is proposed that all of these parameters should be considered simultaneously in a single mathematical model. An optimization model for cost optimization of timber trusses was thus developed. The economic objective function for minimizing the structure's self-manufacturing costs was defined, subjected to the design, stress and deflection (in)equality constraints. The finite element equations were as the equality constraints defined for the calculation of the internal forces and the deflections of the structure. The stiffness matrix of the structure was composed by considering fictitiously decreased cross-section areas of all the flexibly connected elements. Constraints for the dimensioning of the timber members were determined in accordance with Eurocode 5 in order to satisfy the requirements of both the ultimate and the serviceability limit states. The cross-section dimensions and the number of fasteners were defined as independent optimization variables. A numerical example demonstrates the applicability of the optimization approach presented as well as the influence of the fasteners' flexibility on the optimal self-manufacturing costs. Ključne besede: civil engineering, timber structures, trusses, fasteners, flexibility, optimization, non-linear programming Objavljeno: 01.06.2012; Ogledov: 1411; Prenosov: 78 Povezava na celotno besedilo |
6. Mathematical modelling of timber-framed walls strengthened with CFRP stripsMiroslav Premrov, Peter Dobrila, 2008, izvirni znanstveni članek Opis: This paper provides mathematical modelling for prefabricated timber-framed walls composed of a timber frame and fibre-plaster boards. Because the tensile strength of the fibre-plaster boards is approximately 10-times lower than the compressive one, it is convenient to strengthen the boards in their tensile diagonal direction with carbon fibre-reinforced polymer (CFRP) strips, which are glued to the boards. Based on analysis of experimental research results [7] special approximate mathematical models have been developed. The models enable simultaneously to consider the influence of inserted CFRP strips, flexibility of mechanical fasteners in the connecting areas and any appearing of tensile cracks in the coating boards. Ključne besede: civil engineering, timber structures, frame walls, fibre-plaster boards, steel reinforcement, CFRP strips, mathematical modelling Objavljeno: 01.06.2012; Ogledov: 1320; Prenosov: 62 Povezava na celotno besedilo |
7. Modelling of fastener flexibility in CFRP strengthened timber-framed walls using modified [gamma]-methodMiroslav Premrov, Peter Dobrila, 2008, izvirni znanstveni članek Opis: The paper provides semi-analytical modelling for prefabricated timber-framed walls using the modified ▫$/gamma$▫-method. The walls are composed of a timber frame and gypsum plasterboards (GPB) which are flexibly connected to the timber frame. Because the tensile strength of the GPB is approximately 10-times lower than the compressive one, it is convenient to strengthen the boards in their tensile diagonal direction with carbon fibre-reinforced polymer (CFRP) strips, which are glued to the boards. Additionally, in the proposed mathematical model the classical beam theory is used taking into account a fasteners' flexibility in the timber frame - GPB connecting area, as well as crack appearing in the GPB and an influence of the inserted CFRP strips. Therefore the CFRP strip contribution is considered with a modified slip modulus which results in the fictive increased stiffness coefficient of the fasteners. Ključne besede: civil engineering, timber structures, frame walls, fibre-plaster boards, steel reinforcement, CFRP strips, carbon fibre-reinforced polymer, mathematical modelling Objavljeno: 01.06.2012; Ogledov: 1392; Prenosov: 16 Povezava na celotno besedilo |
8. Approximate analytical solutions for diagonal reinforced timber-framed walls with fibre-plaster coating materialMiroslav Premrov, Peter Dobrila, Branko Bedenik, 2004, izvirni znanstveni članek Opis: This paper provides approximate analytical solutions for diagonally reinforced timber-framed panel walls usually used as main bearing capacity elements in the construction of prefabricated timber structures. These walls can be mathematically treated as composite elements made of a timber frame and fibre-plaster boards as a coating material. As boards are the weakest part of the system they are reinforced with steel diagonals. The proposed approximate analytical models with the fictitious thickness and width of fibre-plaster boards enable simultaneously to consider the influence of inserted steel diagonals, flexibility of mechanical fasteners between the boards and the timber frame and any appearing cracks in the tensile area of the fibre-plaster boards. The obtained numerical results show good agreement with the measured experimental results. Ključne besede: civil engineering, timber structures, panel walls, fibre-plaster boards, steel reinforcement, steel diagonals, mathematical modelling Objavljeno: 01.06.2012; Ogledov: 1378; Prenosov: 56 Povezava na celotno besedilo |
9. Analysis of timber-framed walls coated with CFRP strips strengthened fibre-plaster boardsMiroslav Premrov, Peter Dobrila, Branko Bedenik, 2004, izvirni znanstveni članek Opis: This paper provides an experimental analysis of timber-framed walls, coated with carbon fibre-reinforced polymers (CFRP) strengthened fibre-plaster boards, usually used as main bearing capacity elements in the construction of prefabricated timber structures. The tensile strength of the fibre-plaster boards is lower than the strength of timber frame, therefore it is convenient to strengthen boards with high-strength materials in order to gain a higher capacity. It has been shown that the inclusion of CFRP diagonal strip reinforcement on the load-carrying capacity can be quite high and that it is maximized when the carbon strips are connected to the timber frame. On the other hand, the ductility itself was not significantly improved. The test samples proved an important distinction in behaviour in timber frame-fibreboard connecting area, dependant on the boundary conditions between inserted CFRP strips and timber frame. It has been shown that proposed simplified Eurocode 5 methods, applicable for wood-based sheathing boards, could be unsuitable for the problems presented. Ključne besede: civil engineering, timber structures, panel walls, fibre-plaster boards, steel reinforcement, carbon fibres Objavljeno: 01.06.2012; Ogledov: 1657; Prenosov: 68 Povezava na celotno besedilo |
10. Reinforcing methods for composite timber frame-fiberboard wall panelsPeter Dobrila, Miroslav Premrov, 2003, izvirni znanstveni članek Opis: This paper presents different possibilities on how to reinforce timber frame wall panels, which are mainly used as load-carrying capacity elements in the construction of prefabricated timber structures. These walls can be treated as composite elements composed of a timber frame and fiber-plaster boards. As the boards are the weaker part of the system they need to be somehow reinforced in order to assure the resistance and ductility of the elements especially in multi-level buildings located in seismic or windy areas. The aim of this research is to determine the differences in resistance and ductility between elements, reinforced using two different methods. Whilst the first, using additional fiberboards, does not improve the resistance and especially the ductility in the contended sense, it is more convenient for finding a solution when inserting diagonal steel strips, which are fixed to the timber frame. Ključne besede: timber structures, stene, fiber-plaster boards, steel diagonals, mathematical models Objavljeno: 01.06.2012; Ogledov: 1389; Prenosov: 73 Povezava na celotno besedilo |