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1

Fatigue testing of a bolted connection for buried flexible steel culverts

Leander J., Wadi A., Pettersson L.

Archiwum Instytutu Inżynierii Lądowej

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2017

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Nr 23

153--162

EN

A fatigue assessment of steel structures based on the safe life approach requires a detail category representing the fatigue strength. For flexible culverts there are no matching details in the governing regulations. In this paper the testing and evaluation of the fatigue strength of a standardized bolted connection for steel culverts are presented. A test rig was designed to mimic the in-service conditions with a combination of bending moment and axial force. A total of ten specimens was tested to failure. The failure was governed cracks initiating at the indentations from the bolt heads and propagated towards the nearest edge. From the test results, an S-N curve has been derived suggesting a characteristic fatigue strength of 124 MPa at 2 million cycles and a slope of 5 in log-log scale.

2

Fatigue design of soil steel composite Bridges

Pettersson L., Leander J., Hansing L.

Archiwum Instytutu Inżynierii Lądowej

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2012

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Nr 12

237-242

EN

Soil steel composite bridges are used more and more often in road and railroad bridge construction. Spans have increased and structures with spans over 20 m have been built. At the same time road designers call for lower heights of cover. At lower heights of cover the effect of concentrated loads will increase and therefore checking of the fatigue capacity is becoming more important. The paper presents the on-going project involving fatigue testing of bolted connections used to lap corrugated steel plates in Soil Steel Composite Bridges together with an evaluation of the detail category. The project also includes the development of a design procedure for the fatigue design of a Soil Steel Composite Bridge with low height of cover according to the Eurocode.

PL

Kompozytowe konstrukcje gruntowo-stalowe są wykorzystywane coraz częściej w roli mostów drogowych i kolejowych. Rozpiętość tych konstrukcji wzrasta; powstają nawet konstrukcje o rozpiętości przekraczającej 20 m. Jednocześnie projektanci dróg wymagają coraz mniejszej wysokości naziomu. Przy mniejszej wysokości naziomu wzrasta oddziaływanie skupionych obciążeń, co zwiększa znaczenie kontroli wytrzymałości zmęczeniowej. Praca przedstawia prowadzony aktualnie projekt badawczy, obejmujący próby zmęczeniowe połączeń śrubowych służących do łączenia na zakładkę blach w mostach gruntowo-stalowych ze stali falistej wraz z oceną kategorii. Projekt obejmuje również opracowanie procedury projektowania wytrzymałości zmęczeniowej mostów gruntowo- stalowych z niskim naziomem zgodnie z Eurocode.

3

Transient underwater bubble sound

Leander J.

Hydroacoustics

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1997

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Vol. 1

179--179

EN

Gas bubbles in the sea may act as separate sound sources and thus contribute to the overall ambient noise level. Some examples of natural gas bubble generation in the sea are wind induced breaking waves, capillary-gravity waves and rain drops falling on the surface. Due to these processes, gas bubbles can be brought into or generated in the sea surface layer and then set into transient motion. The resulting scattered sound pulses and in particular the induced acoustic power have been of major concern in a number of recent investigations. From the vast amount of experimental data it is found that to a first approximation, the gas bubbles act as linear spherical sound sources oscillating at the fundamental mode. Due to the interaction with the sea surface, the overall acoustic field has the character of a transient dipole. By modelling a gas bubble as a linear oscillator, one can extract information from experimentally obtained pulses. Typical examples are the equilibrium radius, transient frequency, damping constant, source strength and power spectrum. In these investigations, free linear oscillations are assumed which is relevant in looking for the parameters mentioned. In this work, however, we consider driven oscillations and thus consider the full transient problem also including the finite time of excitation. As a result, we also model the wave front of the scattered pulses including information about the excitation. This means that a time-scale related to the excitation enters into our analysis. By means of this model we are able to simulate scattered pulses which to a great extent agree with experimentally obtained data. Although the model presented is here used in order to simulate sound from wind, capillary- gravity and rain drop induced bubbles it can also be used in studying wave propagation in bubbly fluids in general. It is finally suggested that the time-scale of duration of the excitation that enters into our analysis can be used in a further understanding of gas bubble generation and excitation in the sea.