Publications by Alain Nussbaumer

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Large scale tubular truss beams, approximately of 9 m long and 2 m high, were tested under constant amplitude fatigue loading. The beams were made out of circular hollow sections of steel S355, welded to form a uni-planar truss with K-joints, in a shape common to bridge construction. The main goal of these tests was to focus on the fatigue behavior of the joints loaded in compression that is with chord in compression, one diagonal in compression and the remaining diagonal in tension. The tests showed, as in

This paper investigates the structural response of laminated glass beams under combined fire-exposure and sustained in-plane loading. This is done by means of experimental testing and Finite Element (FE) numerical modelling. Firstly, small-scale (1 m long) ...

The aim of this paper is to provide a fatigue-life assessment of an existing composite steel-concrete bridge within Switzerland. The Venoge bridge is a 219 meters length, four spans, four girder composite bridge, situ-ated on the Geneva-Lausanne Swiss moto ...

The promotion of tubular structures in bridge construction is a meaningful goal since these are aesthetic, lead to structurally efficient systems as well as sustainable ones. Good fatigue design of the tubular superstructure is a key factor to ensure safety of these bridges. The present paper present the results of several research studies carried out to determine the fatigue strength, i.e. S-N curves for design, of different welded joints and details typical in tubular trusses. The details considered are b

In this study, a mechanical anchorage for prestressed carbon fiber-reinforced polymer (CFRP) rods was proposed. The proposed anchorage consisted of a steel barrel with a conical hole and three separate aluminum wedges that are in direct contact with the CF ...

Quenched and self-tempered (QST) steel reinforcement bars (rebars) are manufactured by Thermex or Tempcore processes. Characterization studies of QST rebars are mostly limited to reveal the hardened outer layer and some improved mechanical properties compa ...

This paper presents a 3D thermo-mechanical model of arc-welding applied to tubular K-joints susceptible to fatigue cracking. The 3D torch trajectory is reproduced to simulate both temperatures and stresses during welding and ultimately the 3D residual stress distribution after cooling. The influence of latent heat, of the increase of thermal conductivity to simulate the fluid convection within the weld pool, the activation of finite elements to simulate the use of filler wire and the number of passes on as-

The fabrication procedure changes when changing the size of the structural components. For the weldments, the change of the welding procedure leads to the change in residual stresses which consequently affects the fatigue life of the structure. The weld size and number of welding passes are important factors which have considerable impact on the values and distribution of the welding residual stresses. This technological size effect is investigated in this study by simulating the welding process for tubular

Assessment of existing steel structures: recommendations for estimation of remaining fatigue life. The growing importance of sustainability affects new markets for the construction industry; the rehabilitation and refurbishment of existing buildings and civil engineering works is getting more and more into the focus of construction activities. This also applies to bridges as well where the quality management comprising the full life of a bridge has a long tradition. For bridges in particular the enormous in

During severe seismic events the base of unanchored steel liquid-storage tanks can uplift, causing large inelastic rotation demands at the shell-to-base connections and large multi-axial stresses (radial tension and circumferential compression) in the tank ...

Stringer-to-floor beam web-to-web double-angle connections are among the most fatigue-prone elements in old riveted bridges. These connections are often designed to carry only shear loads. However, in these elements, fatigue damage occurs because of the ou ...

The base of large steel liquid storage tanks can uplift during severe earthquakes, causing large inelastic rotations at the connection between the tank shell and tank base. While recent experimental studies indicate significantly higher connection rotation capacity than what is specified in the current Eurocode standard (set at 0.2 rad), additional radial base-plate welds (present in some tank connection details due to fabrication methods) have never been considered in tests. This study experimentally inves

Post-tensioned steel strands have been traditionally used in different prestressed structures such as concrete girders, post-tensioned concrete slabs, cable-stayed bridges, post-tensioned walls, etc. for a long time. However, due to the vulnerability of st ...

In many countries and regions, traffic infrastructure projects suffer from low funding. The budget is tight for new infrastructure building and, thus, the importance of inspection, maintenance and assessment of the existing traffic infrastructure increases ...

This study investigates the effect of high-peak loads on local relaxation of residual stress and fatigue damage in HFMI-treated high-strength steel welded joints. The finite element simulations are applied to consider the combined effect of geometry, mater ...

Fatigue strengthening of existing steel structures is of great importance and has attracted lots of interest recently. Apart from the conventional strengthening technique, i.e. utilizing bulky and heavy steel plates and its disadvantages, carbon fiber rein ...

Different failure criteria used to prevent fatigue crack initiation in metallic members are described. A series of closed-form analytical solutions were developed to predict the fatigue resistance of metallic beams after strengthening with carbon fiber-rei ...

In Eurocode standards, three verification schemes are proposed for fatigue design under variable amplitude loadings: 1) Based on constant amplitude fatigue limit; 2) Based on constant amplitude equivalent stress range at 2.10 cycles; 3) Based on accumulate ...

The use of glass material for structural components has drastically increased in the last decade. Among others, a laminated connection is a type of adhesive joint that makes use of foil interlayer adhesive to transfer forces between glass and metal parts. ...

This paper provides an original framework for the fatigue reliability analysis of a road bridge; the framework is applied to the Venoge bridge, a composite steel concrete bridge within the A1 Swiss highway. Two critical details are selected by inspection: a longitudinal weld attachment and a cover plate welded attachment. Weigh in Motion (WIM) data from Denges station (1 km far from the bridge) and a refined three-dimensional Finite Element (FE) model of the bridge are used to get realistic time-stress resp

Alain Nussbaumer

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Study on crack propagation in tubular joints under compressive fatigue loadings

Structural response of fire-exposed laminated glass beams under sustained loads; exploratory experiments and FE-Simulations

Fatigue Life Assessment of Existing Motorway Bridge

New S-N curves for details in bridges with steel truss tubular superstructure

Development of a Mechanical Wedge-Barrel Anchor for CFRP Rods: Static and Fatigue Behaviors

Geometrical and material characterisation of quenched and self-tempered steel reinforcement bars

Simulation of welding stresses for fatigue design of welded tubular connections

Investigation of technological size effects of welding on the residual stresses and fatigue life of tubular joints made of structural steels S355 and S690

Beurteilung bestehender Stahltragwerke : Empfehlungen zur Abschätzung der restnutzungsdauer

Fatigue analysis of liquid-storage tank shell-to-base connections under multi-axial loading

Development of Mechanical Strengthening System for Bridge Connections Using Prestressed CFRP Rods

Effect of radial base-plate welds on ULCF capacity of unanchored tank connections

Experimental Study on the Static and Fatigue Behaviour of a New Mechanical Wedge-Barrel Anchor

Assessment of existing steel structures. A guideline for estimation of the remaining fatigue life

Local relaxation of residual stress in HFMI-treated high-strength steel welded joints subjected to high-peak loads

Fatigue strengthening of cracked steel plates using prestressed unbonded CFRP reinforcements

Fatigue design criteria for strengthening metallic beams with bonded CFRP plates

New framework for calibration of partial safety factors for fatigue design

Laminated connections for structural glass components: a full-scale experimental study

Reliability based fatigue assessment of existing motorway bridge