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2.
Evaluation of Green`s function for vertical point-load excitation applied to the surface of a semi-infinite elastic medium
Andrej Štrukelj, Tomaž Pliberšek, Andrej Umek, 2006, izvirni znanstveni članek

Opis: The topic of this paper is to show that the integrals of infinite extent representing the surface displacements of a layered half-space loaded by a harmonic, vertical point load can be reduced to integrals with finite integration range. The displacements are first expressed through wave potentials and the Hankel integral transform in the radial coordinate is applied to the governing equations and boundary conditions, leading to the solutions in the transformed domain. After the application of the inverse Hankel transform it is shown that the inversion integrands are symmetric/antimetric in the transformation parameter and that this characteristic is preserved for any number of layers. Based on this fact the infinite inversion integrals are reduced to integrals with finite range by choosing the suitable representation of the Bessel function and use of the fundamental rules of contour integration, permitting simpler analytical or numerical evaluation. A numerical example is presented and the results are compared to those obtained by the CLASSI program.
Ključne besede: civil engineering, soil mechanics, Green`s function, layered half-space, vertical point load
Objavljeno: 31.05.2012; Ogledov: 1292; Prenosov: 7
URL Celotno besedilo (0,00 KB)

3.
Slip modeling in timber-framed walls with wood-based or fibre-plaster sheathing boards
Miroslav 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: 1030; Prenosov: 13
URL Celotno besedilo (0,00 KB)

4.
MINLP optimization of a single-storey industrial steel building
Tomaž Žula, Zdravko Kravanja, Stojan Kravanja, 2008, izvirni znanstveni članek

Opis: The paper presents the topology and standard sizes optimization of a single-storey industrial steel building, made from standard hot rolled I sections. The structure consists of main portal frames, connected with purlins. The structural optimization is performed by the Mixed-Integer Non-linear programming approach (MINLP). The MINLP performs a discrete topology and standard dimension optimization simultaneously with continuous parameters. Since the discrete/continuous optimization problem of the industrial building is non-convex and highly non-linear, the Modified Outer- Approximation/Equality-Relaxation (OA/ER) algorithm has been used for the optimization. Alongside the optimum structure mass, the optimum topology with the optimum number of portal frames and purlins as well as all standard cross-section sizes have been obtained. The paper includes the theoretical basis and a practical example with the results of the optimization.
Ključne besede: civil engineering, topology optimization, sizing optimization, nonlinear programming, MINLP
Objavljeno: 31.05.2012; Ogledov: 1161; Prenosov: 25
URL Celotno besedilo (0,00 KB)

5.
Optimum design of plane timber trusses considering joint flexibility
Simon 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: 1020; Prenosov: 23
URL Celotno besedilo (0,00 KB)

6.
Mathematical modelling of timber-framed walls strengthened with CFRP strips
Miroslav 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: 998; Prenosov: 13
URL Celotno besedilo (0,00 KB)

7.
Modelling of fastener flexibility in CFRP strengthened timber-framed walls using modified [gamma]-method
Miroslav 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: 1109; Prenosov: 11
URL Celotno besedilo (0,00 KB)

8.
Approximate analytical solutions for diagonal reinforced timber-framed walls with fibre-plaster coating material
Miroslav 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: 1065; Prenosov: 6
URL Celotno besedilo (0,00 KB)

9.
Analysis of timber-framed walls coated with CFRP strips strengthened fibre-plaster boards
Miroslav 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: 1253; Prenosov: 19
URL Celotno besedilo (0,00 KB)

10.
Mobile computing in construction
Danijel Rebolj, Karsten Menzel, 2004, predgovor, spremna beseda

Ključne besede: civil engineering, mobile computing
Objavljeno: 01.06.2012; Ogledov: 656; Prenosov: 17
URL Celotno besedilo (0,00 KB)

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