Do mixed pier-to-deck connections alleviate irregularity of seismic response of bridges with unequal height piers?

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• 作者：M. G. Ishac ; S. S. F. Mehanny
• 关键词：Irregular bridges ; Unequal height piers ; Seismic response ; EC8
• 刊名：Bulletin of Earthquake Engineering
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：15
• 期：1
• 页码：97-121
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geotechnical Engineering & Applied Earth Sciences; Environmental Engineering/Biotechnology; Civil Engineering; Geophysics/Geodesy; Hydrogeology; Structural Geology;
• 出版者：Springer Netherlands
• ISSN：1573-1456
• 卷排序：15

文摘

Uniformity in seismic response of apparently irregular bridges has been an intensive topic of research. EuroCode proposes a force-based criterion that indicates whether such bridges under seismic ground motion are considered uniform or not. In this research, several case study three-span bridges with unequal pier heights and different pier-to-deck connection configurations are designed as per EC8 requirements for irregular bridges, then investigated for (a) seismic response uniformity up to collapse limit state, (b) intrinsic overstrength, and (c) material usage efficiency under inelastic static pushover as well as incremental dynamic analysis using a bin of seven real earthquakes. Design optimization targeting regular response is performed on each bridge scheme based on an enhanced curvature-based uniformity criterion, and the results are compared to the initial design complying with EuroCode requirements. Among the main conclusions of the current research is that irregular bridges under investigation complying with EuroCode uniformity index do not necessarily behave in a uniform manner under seismic loading. Response uniformity has been improved drastically by altering the steel reinforcement ratios of either the short or the long pier and/or by changing the types of pier-to-deck connection. Associated changes in the inherent overstrength of each scheme as well as the usage efficiency of piers reinforcement are also monitored and compared to the initial design. The current investigation hence emphasizes that it is the designer’s role to accentuate and delineate the main aspects of the design requirement of irregular bridges: either heading towards better uniformity in response and/or improved built-in overstrength, or targeting a more economically efficient design in terms of piers reinforcement ratio but with reduced, yet satisfactory, uniformity. All these aspects could however be more-or-less mutually accomplished but with certain limitations.