Publications by Alain Nussbaumer

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This paper quantitatively studies the influence of fiber orientation on the high cycle tensile fatigue resistance of ultra-high performance fiber reinforced cementitious composites (UHPFRC) within and beyond elastic domain. Eight tensile fatigue tests and ...

Many old riveted steel bridges remain operational and require retrofit to accommodate ever increasing demands. Complicating retrofit efforts, riveted steel bridges are often considered historical structures and as such structural modifications that affect ...

For the fatigue verification of railway bridges, European standards EN 1991-2, EN 1993-2, and EN 1992-2 provide a simplified procedure using a damage equivalence factor (lambda method). Engineers verify that the stress range from the LM71 load model does not exceed the reference fatigue resistance of the detail. These factors were established by correlating LM71 stress ranges with equivalent ranges from limited train simulations over selected influence lines, calculating cumulative damage with multi-linear

Fatigue tests were carried out on welded circular hollow section K-joints typical to bridges. The tests specimens were large-scale (approximately 9 m long and 2 m high) trusses loaded in the plane of the truss. Measured member stresses showed that a signif ...

Seeking light and transparent bridge designs, engineers and architects have found an efficient and artistic way to fulfill their requirements: steel tubular bridges. Like any other welded structure, the joints of this kind of bridge suffer from high tensile weld residual stresses. Combined with high stress concentrations, tensile residual stress is a relevant factor in fatigue crack development. Therefore, an experimental study has been carried out on tubular joints in order to characterize the 3D residual

In structures, where UHPFRC is subjected to a high number of fatigue stress cycles, the tensile fatigue behavior is critical and must be well understood. This paper studies the high cycle tensile fatigue behavior of UHPFRC utilizing four advanced measurement techniques. Sixteen fatigue specimens from a previous study are re-analyzed and eight specimens are tested. Prior to testing, the local fiber orientation and dosage are determined using a magnetic probe. During testing, specimen behavior is monitored by

Steel tubular truss are lightweight, aesthetical and used in many different applications. These structures are sensitive to fatigue and specific verification methods have been developed for them, in particular by CIDECT [2001]. Due to assembly and welding, these structures contain large internal self-balanced stresses. Since tensile residual stresses tend to open cracks, they have a detrimental influence on the fatigue crack propagating under cyclic traffic loadings. Different studies on the behaviour of tu

In this paper research work on welded butt weld connections between hot-rolled seamless tubes and steel castings are presented. Comparison is made between different weld preparations for the butt welds including different steel grades, repair methods, the ...

The design rules for the verification of civil engineering steel structures against fatigue are compiled in the European harmonized design standard Eurocode EN 1993-1-9 released in 2005. This design standard is currently under revision, together with all o ...

The influence of welding tensile residual stresses on fatigue crack growth in bridge tubular K-joints is investigated through experimental testing of large-scale specimens. Crack development is monitored using the alternating current potential drop method. ...

Real behavior of existing structures is usually associated with large uncertainty that is often covered by the use of conservative models and code practices for the evaluation of remaining fatigue lives. In order to make better decisions related to retrofi ...

The propagation of long cracks under constant amplitude cyclic loading is studied in complex welded box beams made of high strength low alloy (HSLA) steel. The 8 x 1 x 0.7 m box beams were designed to simulate the cellular structure of a double hull ship but the results of the experiments are equally applicable to other box systems such as bridges. These experiments were designed to evaluate the residual fatigue life after a significant fatigue crack has formed. After testing, residual stresses were measure

Tubular elements are used in steel structures not only for bracing of other members but also as cross girders diaphragms. They are a competitive solution both due to the lightweight and structural efficiency. Slotted tube-to-plate connections are the natur ...

An increasing number of existing steel structures are nowadays at the end of their service lives and most of them are subjected to fatigue loading. To tackle the fatigue problem, carbon fiber-reinforced polymer (CFRP) composites have been proposed and succ ...

In the design of tubular truss bridges, engineers have found the fatigue performance of the joints to be a critical aspect. In looking for ways to improve this performance, the use of residual stress-based post-weld treatments has been suggested. Although ...

Due to their aesthetic and structural advantages, tubular space truss structures are enjoying increasing popularity in modern bridge construction. The use of cast steel nodes for the joints between the circular hollow section members is also becoming incre ...

The fatigue provisions for bridge design in North America and Europe are highly simplified for the sake of practical implementation, in comparison with the state of the art in understanding of the true fatigue behavior. Historically, one significant simpli ...

Among different details in old riveted railway bridges throughout the world, connections such as stringer-to-floor-beam double-angle connections are one of the most fatigue-prone details. These connections are subjected to fatigue loadings due to the secon ...

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. With repeated cycles of uplift, these shell-to-base connections are susceptible to low-cyc ...

During the evaluation of an existing bridge, measurements at the site can be used to update the traffic load model. Measurements can be made with either temporary Weigh-In-Motion (WIM) sensors installed on the road surface or with strain gauges installed on the structure. The aim of updating a traffic load model is to avoid costly interventions on an existing bridge that are often proposed as a result of an assessment using a design traffic load model. This paper presents the measurement of traffic loads an

Alain Nussbaumer

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Influence of fiber orientation on the high cycle tensile fatigue resistance of Ultra-High Performance Fiber Reinforced Cementitious

Finite element modeling for fatigue strengthening of metallic riveted bridges using un-bonded pre-stressed CFRP plates

Development of Specific Damage Equivalence Factors for Fatigue Assessment of Railway Bridges in Europe

Experimental study on the fatigue behaviour of welded tubular K-joints for bridges

Residual stress effects in tubular K-joints crack growth

High cycle tensile fatigue behavior of UHPFRC

Alternative stress definition and residual stress effects in fatigue design of welded tubular structures

New experimental determination of fatigue strength of tubular truss joints in steel grades up to S690

New developments on fatigue in Eurocode on steel structures

Effect of tensile residual stresses on fatigue crack growth and S-N curves in tubular joints loaded in compression

Measurement, Data Interpretation, and Uncertainty Propagation for Fatigue Assessments of Structures

Behavior of long fatigue cracks in cellular box beam

Fatigue behaviour and detailing of slotted tubular connection

Computational Investigation of Mode-I Fatigue Crack Growth in CFRP-Strengthened Steel Plates with a Cohesive Zone Model

A probabilistic assessment of the effect of post-weld treatment on the fatigue performance of tubular truss bridges

Fatigue design of cast steel nodes in tubular bridge structures

A WIM-Based Assessment of Multiple Vehicle Presence Effects on Fatigue Damage of Highway Bridges

Development of a Strengthening System for Riveted/Bolted Steel Connections Using Prestressed CFRP Rods

Fatigue analysis of unanchored steel liquid storage tank shell-to-base connections during earthquake induced uplift

Traffic Load Models and Weigh-In-Motion Data