| 1. |
- Andersson, Andreas, 1980-, et al.
(författare)
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Attenuating resonant behavior of a tied arch railway bridge using increased hanger damping
- 2012
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Ingår i: Bridge Maintenance, Safety, Management, Resilience and Sustainability - Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management. - : Taylor & Francis Group. - 9780415621243 ; , s. 2572-2577
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Konferensbidrag (refereegranskat)abstract
- In this paper, dynamic analyses and field measurements of a tied arch railway bridge is presented. Excessive vibrations of the hangers were obtained, caused by resonance during train passages. The resulting increase of the stress level and number of stress cycles were shown to decrease the fatigue service life significantly. The most critical section is a threaded turnbuckle connection of the hangers. Due to low damping of the hangers, more than 50 % of the cumulative fatigue damage was related to free vibrations after train passage. Passive dampers were installed to attenuate the vibrations by means of increased damping. A combination of field measurements and numerical models are used to investigate the behavior of the bridge and the impact of increased hanger damping.
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| 2. |
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| 3. |
- Ekholm, Kristoffer K J, 1982, et al.
(författare)
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Non-linear analysis of a stress-laminated-timber bridge loaded to failure
- 2012
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Ingår i: Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management, IABMAS 2012, Stresa, Lake Maggiore, 8-12 July 2012. - : CRC Press. - 9780415621243 ; , s. 1879-1886
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Konferensbidrag (refereegranskat)abstract
- The general assumption in stress-laminated-timber (SLT) bridge design is that the structural response is linear both in the serviceability limit state (SLS) and in the ultimate limit state (ULS). However, this has been shown not to be the case according to a full-scale test performed in Sweden where the SLT deck was subjected to a failure load. When an SLT deck is loaded to failure, non-linear behaviour must be considered when a structure of this kind is analysed. Both horizontal and vertical slip occur in the interlaminar interface between the stressed glulam laminations. This behaviour does not occur in a solid timber plate. Once slip has occurred, the stresses are redistributed between the laminations. Interlaminar slip is of great importance and is affected by several factors such as the pre-stress level, surface roughness and surface moisture content. A rectangular SLT deck, 5.00 × 7.98 × 0.27 m 3 (length, width and thickness), with two patch loads positioned close to the edge, was tested. The deflection values for both ultimate and non-destructive loads were compared with finite element (FE) models of the SLT deck in order to evaluate the behaviour of the deck. The results from the experiments were compared with both linear and non-linear FE models.
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| 4. |
- Gonzàlez, Ignacio, et al.
(författare)
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Improved bridge response evaluation based on dynamic testing
- 2012
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Ingår i: Bridge Maintenance, Safety, Management, Resilience and Sustainability - Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management. - : Taylor & Francis Group. - 9780415621243 ; , s. 2584-2588
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Konferensbidrag (refereegranskat)abstract
- Dynamic analysis of the Rössjö railway bridge, located on the new Swedish high speed line, is carried out. A simple 2D finite element model is developed and the dynamic response to passing trains is studied. The model is updated by modifying the support stiffness and comparing the predicted response with measurements. Results show that measured deck accelerations are in good agreement with what was predicted from the updated model. To further increase the accuracy in the predicted response, a method based on Bayesian updating is proposed.
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| 5. |
- Guadagnini, M., et al.
(författare)
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Bond of FRP strengthening systems for concrete structures : A Round Robin Test
- 2012
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Ingår i: Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management. - Boca Raton : CRC Press. - 9780415621243 - 9780203103388 ; , s. 1179-1186
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Konferensbidrag (refereegranskat)abstract
- Although various test methods to examine the local bond behaviour of FRP strengthening systems to concrete have been proposed thus far, their implementation can lead to a wide range of results and a standard methodology has yet to be generally accepted. With these issues in mind, a Round Robin Testing (RRT) programme was carried out to assess the performance and reliability of small scale testing on various FRP strengthening systems, including both externally bonded laminates and near surface mounted reinforcement. Ten laboratories and eight manufacturers and suppliers participated in this extensive international exercise, which was initiated within the framework of the European funded Marie Curie Research Training Network, EN-CORE, with the support of Task Group 9.3 of the International Federation for Structural Concrete (fib). This paper describes the proposed testing programme and summarized some of the results obtained by the participating laboratories.
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| 6. |
- Heshmati, Mohsen, 1987, et al.
(författare)
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Fatigue design of plated structures using structural hot spot stress approach
- 2012
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Ingår i: Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management, IABMAS 2012, Stresa, Lake Maggiore, 8-12 July 2012. - : CRC Press. - 9780415621243 ; , s. 3146-3153
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Konferensbidrag (refereegranskat)abstract
- In most fatigue design codes, the nominal stress method is the predominant approach for fatigue design of structures. However, the known limitations of this method along with new advanced computational possibilities, have paved the way to search for more accurate stress based fatigue design approaches. The structural hot spot stress approach (SHSS) is one of these methods which has drawn a wide-spread attention since its advent. The SHSS designates the basic stress by taking into account the geometrical variations of the detail at the location of expected fatigue crack initiation (hot spot). In this paper, the fatigue strength of several frequently used structural details is investigated using both nominal stress and SHSS approaches. The aim of this investigation is to establish an equivalency between these two approaches with reference to the fatigue strengths of the studied details. A large database including available fatigue test results (from 1950s till present) is built up and used to produce hot spot stress S-N curves for the studied details.
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| 7. |
- Kliger, Robert, 1950, et al.
(författare)
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Timber bridges in Sweden - On-going research and steadily expanding market
- 2012
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Ingår i: Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management, IABMAS 2012, Stresa, Lake Maggiore, 8-12 July 2012. - : CRC Press. - 9780415621243 ; , s. 1887-1894
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Konferensbidrag (refereegranskat)abstract
- In this paper, research on timber bridges both in the past in Scandinavia and on-going in Sweden is summarised. The on-going, more recent research at Chalmers University of Technology focuses on improving our understanding of the mechanical behaviour of stress-laminated-timber (SLT) decks loaded until failure. The experimental results from three full-scale tests on SLT decks are reported. All the SLT decks were made of glulam laminations. Developments in terms of strengthening the anchorage zone where the tension in the pre-stressed bars is applied are leading to a reduction in the structural efficiency of decks. Some results of laboratory tests conducted on SLT decks reinforced in the anchorage zones by means of self-tapping screws are presented. The loss of tension in the pre-stressed bars has been recorded both instantaneously and after a few months in a climate chamber where they were exposed to moisture variation. The schedule for the on-going field studies is presented. Two case-study bridges completed in 2011 are also reported as examples of innovative solutions when it comes to the industrialised production and assembly of very large sections as examples of more spectacular projects performed in Sweden.
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| 8. |
- Leander, John, 1976-, et al.
(författare)
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Rate of convergence of measured stress range spectra
- 2012
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Ingår i: Bridge Maintenance, Safety, Management, Resilience and Sustainability - Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management<em></em>. - : Taylor & Francis Group. - 9780415621243 ; , s. 3381-3386
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Konferensbidrag (refereegranskat)abstract
- A fatigue assessment is afflicted with several uncertain variables. Monitoring constitutes a mean to reduce or properly estimate some of them. The subject of this paper is the measured stress range spectrum and, the required duration of monitoring to obtain convergence. A theoretical model is presented based on the Palmgren–Miner damage rule and an assumed shape of progress. The long-term monitoring campaign of The Söderström Bridge located in Stockholm, Sweden, is used as a case study. It is an open deck bridge for railway traffic subjected to high traffic intensity. The required duration of monitoring differs between different structural parts in the bridge. Stress range spectra for members with a short influence line seem to converge faster than for members with a longer influence line. For some gauge locations, a diverging shape of the spectrum has been found due to non-linear behavior of the structure. The proposed model for convergence progress is shown to give reliable predictions of the required monitoring duration. By implementing the model in the routines for data acquisition, the end time could be a variable determined during operation of the monitoring system.
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| 9. |
- Ni Nuallain, Nora Aine, et al.
(författare)
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Optimal seismic retrofit strategy selection of deteriorating concrete structures
- 2012
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Ingår i: Bridge Maintenance, Safety, Management, Resilience and Sustainability - Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management. - : Taylor & Francis Group. - 9780415621243 ; , s. 3568-3575
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Konferensbidrag (refereegranskat)abstract
- This paper presents a robust/repeatable approach for identification of the optimal retrofit strategy for structures in seismic zones which is probabilistically based and ultimately objective. The approach addresses the issues of (i) computational complexity vs. efficiency in modeling structures in seismic zones, (ii) the formulation of the structures seismic vulnerability probabilistically through the use of fragility curves and (iii) the incorporation of varying seismic retrofit options into these fragility curves to identify the optimal rehabilitation strategy for a structure as a function of condition. The overall aim and result is the optimization of retrofit budgets.
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