Engineering June 2002 Vol 8/2 []

CONTENTS & ABSTRACTS

InEnglish. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.

Engineering



Volume 8 No. 2June 2002



Specialissue on prestressed suspension structures

Preface; 67

Jüri Engelbrecht

Investigations of prestressed cable structuresat Tallinn Technical University; 68–83

Valdek Kulbach

Abstract. The paper presents a summary of research activities of theDepartment of Structural Design at TTU in the field of suspension structuresagainst the background of the world developments in this field.

Key words: cable, cable network, girder-stiffened structure, hanging roof,hypar-network.

Investigation and design of shallow wooden andcomposite shell-cable roofs; 84–100

Karl Õiger

Abstract. The paper gives a review of the investigations on thebehaviour of shell roofs, carried out at the Tallinn Technical University. Theroof structures examined consisted of a board shell or of a prestressed cablenetwork and timber or steel cladding. Edge beams were made from blanks, glulam,or steel tube. Main attention is paid to the influence of the roof cladding(panels) on the behaviour of square and elliptical saddle-shaped suspensionroofs.

Key words: suspension roof, shell-cable roof, hypar.

Analysis of saddle-shaped cable networks withdifferent contour structures; 101–113

Valdek Kulbach, Juhan Idnurm, and Ivar Talvik

Abstract. Usually the cable network of a saddle-shaped roof is formedinside a contour of two inclined plane arches which are supported by massivecounterforts at lower ends. In the present paper advantages of hypar-networksencircled by a spatial contour beam with elliptical layout and without anyexternal horizontal supports have been presented. Both discrete and continuouscalculation methods can be used for the analysis of the stress-strain state ofthose networks. A system of nondimensional parameters is used to study theeffect of variable geometrical and stiffness properties on the behaviour of anelliptical roof structure. Comparison of the behaviour of cable networks withdifferent contour beams is given.

Key words: cable structure, continuous analysis, discrete analysis,geometric nonlinearity, hanging roof, suspended roof, prestressed cablenetwork, suspension structure.

Experimental investigation of the Saaremaa suspensionbridge model; 114–120

Valdek Kulbach and Egon Kivi

Abstract. A model of the bridge across the Suur Strait between the Estonianmainland and Muhu Island has been erected and tested. The main problem bydesigning of a self-anchored bridge is evaluation of the stability of thebended and compressed stiffening girder. In spite of a very slender box girderthe approximate analysis and experimental investigation demonstrated itssufficient stability. The investigation proved also some advantages of the modelwith unloaded anchor cables as compared to the model with the loaded ones.

Key words: suspension bridge, cable structure, box girder, bridge model, girderstability, self-anchored system.

Discrete and continuous modelling of suspensionbridges; 121–133

Valdek Kulbach, Siim Idnurm, and Juhan Idnurm

Abstract. In the calculation of suspension bridges, the main problem isthe geometrically non-linear behaviour of the cable. Linear methods of analysisare suitable only for very small spans. A geometrically non-linear continuousmodel is especially useful for classical loading cases as for the uniformlydistributed load on the whole or half span. However, traffic generates bothconcentrated and uniformly distributed loads. The discrete model of asuspension bridge allows one to apply all kinds of loads, such as thedistributed and the concentrated ones. In this paper, application of bothdiscrete and continuous models for the calculation of the suspension bridges isconsidered. Linear elastic strain-stress dependence of the material and absenceof the inclination of hangers is assumed. Hanger elongation may be taken intoaccount. Some comparative numerical examples are presented.

Key words: suspension bridge, cable systems, continuous modelling, discretemodelling, geometric non-linearity, girder-stiffened structures.

Challenges for tensile stresses; 134–142

Jüri Engelbrecht

Abstract. This essay describes some interesting phenomena related toflexible (hanging) structures in nature and engineering. Despite of the seemingsimplicity, the behaviour of such structures may be complicated due tonon-linear effects.

Key words: tension, hanging structures, spider’s web.



CHRONICLE

Valdek Kulbach 75; 143