This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use...This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.展开更多
In this paper, the behavior of barrel-vaulted structures undergoing rocking of the abutments and the effectiveness of a few retrofit solutions are discussed. The comprehension of the structural performance of vault-ab...In this paper, the behavior of barrel-vaulted structures undergoing rocking of the abutments and the effectiveness of a few retrofit solutions are discussed. The comprehension of the structural performance of vault-abutment systems is fundamental for their seismic vulnerability assessment, and for the design of efficient strengthening techniques. In the paper, traditional techniques such as extrados thin concrete slab or masonry spandrel walls as well as an innovative solution with an extrados thin improved lime mortar slab reinforced by means of glass fiber mesh are considered. The different strengthening solutions are studied and compared on the basis of the results of non linear numerical analyses and by reference to a simplified analytical approach. Numerical and analytical models are validated through comparison with the results of a recent experimental study focusing on the behavior of vaulted masonry structures subjected to rocking of the abutments. The validated models can be used by engineers for the seismic vulnerability assessment of masonry vaulted structures as well as for the proportioning of possible extrados strengthening solutions, and will be used in the future to explore different structural system configurations.展开更多
为推动大跨度部分斜拉桥在曲线和低纵断面桥址的应用,研究其在地震工况下的合理约束体系,结合某高速铁路跨越引江河、芒稻河和马汊河的工程实践,采用调查研究、有限元分析、对比分析、归纳总结等方法,在传统部分斜拉桥的基础上开展一系...为推动大跨度部分斜拉桥在曲线和低纵断面桥址的应用,研究其在地震工况下的合理约束体系,结合某高速铁路跨越引江河、芒稻河和马汊河的工程实践,采用调查研究、有限元分析、对比分析、归纳总结等方法,在传统部分斜拉桥的基础上开展一系列的设计研究。结果表明:采用竖琴式索面布置,并与外倾牛角式桥塔结合,有效提升了桥梁整体景观性和轨道平顺性,并可改善索塔锚固区的受力性能;采用梁端配跨设计,在保证结构刚度的同时降低梁高1.0~1.5 m,有效提升了部分斜拉桥对低纵断面桥址的适应性;针对平曲线上的工点,通过BIM(Building Information Modeling)技术和局部坐标的应用可确保拉索系统的精确定位;采用新型支承约束体系,大幅提升了桥梁结构的抗震性能,与常规连续梁约束体系和连续梁+双固定约束体系相比,分别减小主墩底部弯矩66%和53%。展开更多
文摘This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.
文摘In this paper, the behavior of barrel-vaulted structures undergoing rocking of the abutments and the effectiveness of a few retrofit solutions are discussed. The comprehension of the structural performance of vault-abutment systems is fundamental for their seismic vulnerability assessment, and for the design of efficient strengthening techniques. In the paper, traditional techniques such as extrados thin concrete slab or masonry spandrel walls as well as an innovative solution with an extrados thin improved lime mortar slab reinforced by means of glass fiber mesh are considered. The different strengthening solutions are studied and compared on the basis of the results of non linear numerical analyses and by reference to a simplified analytical approach. Numerical and analytical models are validated through comparison with the results of a recent experimental study focusing on the behavior of vaulted masonry structures subjected to rocking of the abutments. The validated models can be used by engineers for the seismic vulnerability assessment of masonry vaulted structures as well as for the proportioning of possible extrados strengthening solutions, and will be used in the future to explore different structural system configurations.
文摘为推动大跨度部分斜拉桥在曲线和低纵断面桥址的应用,研究其在地震工况下的合理约束体系,结合某高速铁路跨越引江河、芒稻河和马汊河的工程实践,采用调查研究、有限元分析、对比分析、归纳总结等方法,在传统部分斜拉桥的基础上开展一系列的设计研究。结果表明:采用竖琴式索面布置,并与外倾牛角式桥塔结合,有效提升了桥梁整体景观性和轨道平顺性,并可改善索塔锚固区的受力性能;采用梁端配跨设计,在保证结构刚度的同时降低梁高1.0~1.5 m,有效提升了部分斜拉桥对低纵断面桥址的适应性;针对平曲线上的工点,通过BIM(Building Information Modeling)技术和局部坐标的应用可确保拉索系统的精确定位;采用新型支承约束体系,大幅提升了桥梁结构的抗震性能,与常规连续梁约束体系和连续梁+双固定约束体系相比,分别减小主墩底部弯矩66%和53%。
