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1

Deformations and decrease of load-carrying capacity of welded structures due to residual welding stresses

Farkas J., Jarmai K.

Foundations of Civil and Environmental Engineering

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2006

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No. 7

117-126

EN

Residual deflection due to restrained shrinkage of longitudinal welds is calculated in the case of an asymmetric I-section crane runway girder. The residual welding compression stresses decrease the load-carrying capacity of a welded I-section compression strut in a significant measure. The effective width of a welded stiffened plate should be calculated considering residual welding stresses. The fatigue strength of welded joints is influenced by residual welding stresses significantly. These effects are illustrated by numerical examples.

2

Minimum Cost Design of a Square Plate Stiffened by Edge-Parallel or Diagonal Grid of Welded Ribs.

Farkas J.

Zeszyty Naukowe Politechniki Gdańskiej. Budownictwo Lądowe

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2001

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nr 56

49-56

EN

A square plate stiffened by edge-parallel orthogonal grid of open-section ribs can be calculated as an orthotropic torsionless plate. On the contrary, a diagonally stiffened plate is calculated as an isotropic one, therefore its maximum bending moment is smaller than that of edge-parallel stiffened one. The thickness of the face plate as well as the height and thickness of flat stiffeners are determined using the constraints on maximum stresses in ribs and face plate and on the local buckling of ribs. The cost function includes the material and fabrication (welding) costs. The calculation is performed for different numbers of stiffeners. The investigated numerical example shows that the diaginally stiffened plate of n=4 is the cheapest one.

PL

Kwadratowa płyta usztywniona rónoległą do brzegów siatką żeber o przekroju otwartym może być obliczana jak ortotropowa bez skręcania. Płyta usztywniona siatką diagonaną obliczania jest jako płyta izotropowa, co prowadzi do miejszych momentów zginających. Grubość płyty oraz wysokość i grubość żeber wyznacza się na podstawie stanu naprężeń w żebrach i w płycie. Uwzględnia się również lokalną stateczność żeber. Analizę przeprowadzono dla różnych liczb żeber. Funkcja celu obejmuje koszty materiału i wykonanie (spawanie). Przykład numeryczny wskazuje, że płyta usztywniona diagonalnie o podziale n=4 jest najtańsza.

3

Minimum cost design of ring and stringer stiffened cylindrical shells

Liszkai T., Farkas J.

Computer Assisted Mechanics and Engineering Sciences

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1999

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Vol. 6, No. 3-4

425-437

EN

In this paper the optimum design of bent cylindrical shells with welded ring or stringer stiffeners are treated. The objective function is the cost of the structure and the constraints are related to overall and local stability. The problem is solved by MathCad 7.plus software and presented also graphically for ring stiffened cylinders and by CFSQP optimization software for stringer stiffened cylinders.