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Book chapter(2022)
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Bruno A.S. Pedrosa, Carlos Rebelo, José A. Fonseca de Oliveira Correia, Milan Veljkovic, Luís A. P. S. Silva
There is a significant number of old metallic bridges with high levels of structural degradation due to their long service period. Fatigue problems are especially important in these structures since the majority of them were not designed taking into account this phenomenon. Several investigations showed that riveted joints are critical details since several fatigue cracks were found in these joints. In this sense, strengthening methodologies need to be studied. The strategy that has been considered a good solution is the implementation of injection bolts to replace faulty rivets. The structural performance of injection bolts has been demonstrated essentially under quasi-static conditions presenting good results. This paper intends to contribute to the scientific knowledge regarding the fatigue behavior of connections with preloaded injection bolts in the context of a bridge strengthening scenario. An experimental investigation was conducted to compare the fatigue performance of connections with preloaded injection bolts and preloaded standard bolts. Single and double shear connections were tested. New S–N design curves were proposed based on a statistical analysis of the results and compared with the S–N curves proposed in EC3-1–9. The obtained results showed that the use of injection bolts lead to lower scatter and improvement of fatigue life. It was verified that the Eurocode 3 is not able to represent the fatigue strength of connections whose performance is influenced by old metallic materials. Additionally, the fatigue behavior of these connections was assessed by numerical analysis. The relevance of the fatigue crack initiation was evident.
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There is a significant number of old metallic bridges with high levels of structural degradation due to their long service period. Fatigue problems are especially important in these structures since the majority of them were not designed taking into account this phenomenon. Several investigations showed that riveted joints are critical details since several fatigue cracks were found in these joints. In this sense, strengthening methodologies need to be studied. The strategy that has been considered a good solution is the implementation of injection bolts to replace faulty rivets. The structural performance of injection bolts has been demonstrated essentially under quasi-static conditions presenting good results. This paper intends to contribute to the scientific knowledge regarding the fatigue behavior of connections with preloaded injection bolts in the context of a bridge strengthening scenario. An experimental investigation was conducted to compare the fatigue performance of connections with preloaded injection bolts and preloaded standard bolts. Single and double shear connections were tested. New S–N design curves were proposed based on a statistical analysis of the results and compared with the S–N curves proposed in EC3-1–9. The obtained results showed that the use of injection bolts lead to lower scatter and improvement of fatigue life. It was verified that the Eurocode 3 is not able to represent the fatigue strength of connections whose performance is influenced by old metallic materials. Additionally, the fatigue behavior of these connections was assessed by numerical analysis. The relevance of the fatigue crack initiation was evident.
Journal article(2018)
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M.E. Pritchard, S.L. de Silva, G. Michelfelder, G. Zandt, S.R. McNutt, J. Gottsmann, M.E. West, J. Blundy, M.J. Comeau, More authors...
The Central Andes is a key global location to study the enigmatic relation between volcanism and plutonism because it has been the site of large ignimbrite-forming eruptions during the past several million years and currently hosts the world’s largest zone of silicic partial melt in the form of the Altiplano-Puna Magma (or Mush) Body (APMB) and the Southern Puna Magma Body (SPMB). In this themed issue, results from the recently completed PLUTONS project are synthesized. This project focused an interdisciplinary study on two regions of large-scale surface uplift that have been found to represent ongoing movement of magmatic fluids in the middle to upper crust. The locations are Uturuncu in Bolivia near the center of the APMB and Lazufre on the Chile-Argentina border, on the edge of the SPMB. These studies use a suite of geological, geochemical, geophysical (seismology, gravity, surface deformation, and electromagnetic methods), petrological, and geomorphological techniques with numerical modeling to infer the subsurface distribution, quantity, and movements of magmatic fluids, as well as the past history of eruptions. Both Uturuncu and Lazufre show separate geophysical anomalies in the upper, middle, and lower crust (e.g., low seismic velocity, low resistivity, etc.) indicating multiple distinct reservoirs of magma and/or hydrothermal fluids with different physical properties. The characteristics of the geophysical anomalies differ somewhat depending on the technique used—reflecting the different sensitivity of each method to subsurface melt (or fluid) of different compositions, connectivity, and volatile content and highlight the need for integrated, multidisciplinary studies. While the PLUTONS project has led to significant progress, many unresolved issues remain and new questions have been raised.
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The Central Andes is a key global location to study the enigmatic relation between volcanism and plutonism because it has been the site of large ignimbrite-forming eruptions during the past several million years and currently hosts the world’s largest zone of silicic partial melt in the form of the Altiplano-Puna Magma (or Mush) Body (APMB) and the Southern Puna Magma Body (SPMB). In this themed issue, results from the recently completed PLUTONS project are synthesized. This project focused an interdisciplinary study on two regions of large-scale surface uplift that have been found to represent ongoing movement of magmatic fluids in the middle to upper crust. The locations are Uturuncu in Bolivia near the center of the APMB and Lazufre on the Chile-Argentina border, on the edge of the SPMB. These studies use a suite of geological, geochemical, geophysical (seismology, gravity, surface deformation, and electromagnetic methods), petrological, and geomorphological techniques with numerical modeling to infer the subsurface distribution, quantity, and movements of magmatic fluids, as well as the past history of eruptions. Both Uturuncu and Lazufre show separate geophysical anomalies in the upper, middle, and lower crust (e.g., low seismic velocity, low resistivity, etc.) indicating multiple distinct reservoirs of magma and/or hydrothermal fluids with different physical properties. The characteristics of the geophysical anomalies differ somewhat depending on the technique used—reflecting the different sensitivity of each method to subsurface melt (or fluid) of different compositions, connectivity, and volatile content and highlight the need for integrated, multidisciplinary studies. While the PLUTONS project has led to significant progress, many unresolved issues remain and new questions have been raised.
