Raid Karoumi

Some modeling aspects in the nonlinear finite element analysis of cable supported bridges

Abstract This paper presents a method for modeling cable supported bridges for nonlinear finite element analysis. A two-node catenary cable element, derived using exact analytical expressions for the elastic catenary, is proposed for the modeling of cables. The cable element tangent stiffness matrix and internal force vector are evaluated accurately and efficiently using an iterative procedure. The reliability and efficiency of the formulations used are demonstrated by studying the behavior of the Great Belt suspension bridge during girder erection and the behavior of a cable-stayed bridge. Eigenfrequency analyses are also conducted and the results show good agreement when compared with previously published data.

Energy Harvesting from Train-Induced Response in Bridges

The integration of large infrastructure with energy-harvesting systems is a growing field with potentially new and important applications. The possibility of energy harvesting from ambient vibratio ...

Life cycle assessment as a decision support tool for bridge procurement: environmental impact comparison among five bridge designs

PurposeThe conventional decision-making for bridges is mostly focusing on technical, economical, and safety perspectives. Nowadays, the society devotes an ever-increased effort to the construction sector regarding their environmental performance. However, considering the complexity of the environmental problems and the diverse character of bridges, the related research for bridge as a whole system is very rare. Most existing studies were only conducted for a single indicator, part of the structure components, or a specific life stage.MethodsLife Cycle Assessment (LCA) is an internationally standardized method for quantifying the environmental impact of a product, asset, or service throughout its whole life cycle. However, in the construction sector, LCA is usually applied in the procurement of buildings, but not bridges as yet. This paper presents a comprehensive LCA framework for road bridges, complied with LCA ReCiPe (H) methodology. The framework enables identification of the key structural components and life cycle stages of bridges, followed by aggregation of the environmental impacts into monetary values. The utility of the framework is illustrated by a practical case study comparing five designs for the Karlsnäs Bridge in Sweden, which is currently under construction.Results and discussionThis paper comprehensively analyzed 20 types of environmental indicators among five proposed bridge designs, which remedies the absence of full spectrum of environmental indicators in the current state of the art. The results show that the monetary weighting system and uncertainties in key variables such as the steel recycling rate and cement content may highly affect the LCA outcome. The materials, structural elements, and overall designs also have varying influences in different impact categories. The result can be largely affected by the system boundaries, surrounding environment, input uncertainties, considered impact indicators, and the weighting systems applied; thus, no general conclusions can be drawn without specifying such issues.ConclusionsRobustly evaluating and ranking the environmental impact of various bridge designs is far from straightforward. This paper is an important attempt to evaluate various designs from full dimensions. The results show that the indicators and weighting systems must be clearly specified to be applicable in a transparent procurement. This paper provides vital knowledge guiding the decision maker to select the most LCA-feasible proposal and mitigate the environmental burden in the early stage.

Train–bridge interaction – a review and discussion of key model parameters

Research in the field of train–bridge interaction is reviewed, with a particular focus on the vertical dynamic response of the bridge. The most influential system parameters are identified and discussed, providing a basis from which to establish an appropriate degree of complexity in train and track modelling. A two-level factorial experiment is presented. This is used to highlight the relative influence of train–bridge interaction in the train–bridge model, compared with variations in other key parameters. We distinguish those parameter combinations in the train–bridge system that lead to a significant reduction in bridge response due to the train–bridge interaction. The present survey fills an important gap in our existing knowledge by synthesising conclusions from the vast literature on train–bridge interaction. Moreover, the knowledge is related to the European design code’s guidelines for dynamic bridge analysis. The conclusions are summarised to give a rough guidance on modelling choices for train–bridge interaction systems.

Life cycle assessment of a railway bridge: comparison of two superstructure designs

Railway bridges currently encounter the challenges of increasing the load capacity while the environmental sustainability should be achieved. However, it has been realised that the environmental assessment of railway bridges has not been integrated into the decision-making process, the standard guideline and criterion is still missing in this field. Therefore, the implementation of life cycle assessment (LCA) method is introduced into railway bridges. This article provides a systematic bridge LCA model as a guideline to quantify the environmental burdens for the railway bridge structures. A comparison case study between two alternative designs of Banafjäl Bridge is further carried out through the whole life cycle, with the consideration of several key maintenance and end-of-life scenarios. Six impact categories are investigated by using the LCA CML 2001 method and the known life cycle inventory database. Results show that the fixed-slab bridge option has a better environmental performance than the ballasted design due to the ease of maintenances. The initial material manufacture stage is responsible for the largest environmental burden, while the impacts from the construction machinery and material transportations are ignorable. Sensitivity analysis illustrates the maintenance scenario planning and steel recycling have the significant influence on the final results other than the traffic disturbances.

Field testing of a long-span arch steel culvert during backfilling and in service

The paper presents the first part of the in-situ measurements and data analyses for the tests conducted during backfilling and during service of a long-span corrugated steel culvert railway bridge over Skivarpsån, Rydsgård, Sweden. Static and dynamic tests were carried out measuring strains and displacements. Temperature readings were taken along with the measurements. Comparisons of moments during compaction showed that there is good agreement between test results and theoretical values. The theoretical calculation of the rise of the crown during compaction and the crown moments due to live load seem to be conservative, while the theoretical axial forces agree reasonably with the measured axial forces.

Life cycle assessment framework for railway bridges: literature survey and critical issues

Currently, the whole world is confronted with great challenges related to environmental issues. As a fundamental infrastructure in transport networks, railway bridges are responsible for numerous material and energy consumption through their life cycle, which in turn leads to significant environmental burdens. However, present management of railway bridge infrastructures is mainly focused on the technical and financial aspects, whereas the environmental assessment is rarely integrated. Life cycle assessment (LCA) is deemed as a systematic method for also assessing the environmental impact of products and systems, but its application in railway bridge infrastructures is rare. Very limited literature and research studies are available in this area. In order to incorporate the implementation of LCA into railway bridges and set new design criteria, this article performs an elaborate literature survey and presents current developments regarding the LCA implementation for railway bridges. Several critical issues are discussed and highlighted in detail. The discussion is focused on the methodology, practical operational issues and data collections. Finally, a systematic LCA framework for quantifying environmental impacts for railway bridges is introduced and interpreted as a potential guideline.

Train–track–bridge modelling and review of parameters

Abstract This study gathers all necessary information to construct a model to calculate the coupled dynamic response of train–track–bridge systems. Each component of the model is presented in detail together with a review of possible sources for the parameter values, including a collection of vehicle models, a variety of track configurations and general railway bridge properties. Descriptions of the most important track irregularity representations are also included. The presented model is implemented in MATLAB and validated against a commercially available finite element package for a range of speeds, paying particular attention to a resonant speed. Finally, the potential of the described model is illustrated with two numerical studies that address interesting aspects of train and bridge dynamic responses. In particular, the effect of the presence of a vehicle on the bridge’s fundamental frequency is studied, as well as the influence of the wavelength of the rail irregularities on the dynamic effects of the bridge and the vehicle.

Modelling of Climatic Thermal Actions in Hollow Concrete Box Cross-Sections

Abstract The temperature distribution in concrete structures varies as a result of fluctuations in solar radiation, air temperature, wind speed and long-wave radiation. Variations in temperature may cause longitudinal and transverse movements. If these movements are restrained, stresses and strains can be induced, which may contribute to cracking in the structure. To predict such thermal actions in a hollow concrete section, a finite element (FE) model was developed. Hourly resolution of climatic input data was used in the FE model to capture the daily temperature variations in the structure. The FE model was validated against temperature measurements performed in the hollow concrete arch of the New Svinesund Bridge located at the border between Sweden and Norway. To be able to use the developed model for future studies of other structures, an iterative method to consider the inside cavity air was also developed. The results of the simulations show that the model can capture the daily temperature variations. In addition, the proposed model shows acceptable agreement with the measurements from the bridge, and the calculated linear temperature differences for the bridge show good agreement with the design values in the Eurocode. The model is well suited for predicting temperature distributions and can be used for further studies of bridges, including those with box cross-sections, as well as for other concrete structures.

Passive and Adaptive Damping Systems for Vibration Mitigation and Increased Fatigue Service Life of a Tied Arch Railway Bridge

In this paper, the use of external damping systems for vibration mitigation of railway bridge dynamics is studied. Theoretical analysis and numerical simulations are presented based on both passive and adaptive tuned mass dampers (TMD). Routines for a variable stiffness TMD in combination with incremental frequency estimates are developed and its performance under different loadings is studied. The potential of the dampers are studied on a tied arch railway bridge by means of numerical simulations. The bridge has earlier been the subject of extensive dynamic assessments and available field measurements of the response during train passage are reanalyzed and used for model calibration. Both field measurements and numerical simulations show resonant behavior of several hangers during train passage. Due to low structural damping, the resulting stresses are shown to significantly reduce the fatigue service life. A system of passive pendulum dampers was installed in 2005, proving an increased damping ratio due to free vibrations. Its performance during train passage was however not measured. The dynamic response is studied for different damping models based on a calibrated 3D finite element model. The response is highly sensitive to the train speed due to the risk of resonance. Fragility curves are adopted to estimate the extent of cumulative damage under mixed traffic loads at variable speeds.