SGER: Soil-Structure Interaction of Bridge Columns in Frozen Environmenmts

SGER：冰冻环境中桥柱的土-结构相互作用

• 批准号: 0502117
• 负责人: Sri Sritharan
• 金额: --
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2006-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0502117&HistoricalAwards=false
• 关键词: SGER; Soil; Structure; Interaction; Bridge

Abstract for: SGER: Soil-Structure Interaction of Bridge Columns in Frozen Environments, CMS-0502117 PI: Sritharan, Iowa State UniversityThe seasonal freezing that occurs in much of the U.S. is expected to significantly influence the lateral behavior of civil structures, especially bridges. Research on material behavior shows that at temperatures near -20 degrees C concrete properties are altered by 20 to 50 percent, ductility of steel may be completely lost, and soil properties are enhanced by up to two orders of magnitudes. Consequently, the lateral load response of structures, which is dictated by soil-foundation-structure interaction and the ductility capacity of structural members, is dependent on environmental conditions. With the potential for large seismic events in various states that experience seasonal freezing, an investigation of the temperature effects on the lateral load response of soil-foundation-structure systems becomes of paramount importance. This project explores temperature effects on soil-foundation-structure systems by studying bridge Columns supported on cast-in-drilled-hole (CIDH) pile shafts. Through a large-scale outdoor Experimentation, lateral load responses of three bridge columns in warm and frozen ground conditions will be studied to understand the seasonal temperature effects on soil-structure interaction as well as system ductility. A preliminary analytical investigation revealed that freezing conditions at a ground temperature near -20 degrees C may reduce structure displacement capacity by 70% and increase column shear demand by 35%, due to relocation and reduction in spread of plasticity in the pile shaft. An analytical study utilizing the measured material properties and in-situ soil test data will be performed to characterize the responses of the three bridge column systems. Comparing the analytical and experimental results, seismic design implications of the effects of seasonal freezing on soil-foundation-structure systems will be presented. In addition, a plan for detailed investigation on this subject area will be developed. The results of the proposed exploratory study are expected to improve design of soil-foundation-structure systems under extreme lateral loads such as those induced by earthquakes, thus contributing to construction of safer, more reliable structures in regions that experience seasonal freezing.

摘要：SGER：冰冻环境中桥梁柱的土壤-结构相互作用，CMS-0502117 PI：斯里塔兰，爱荷华州立大学美国大部分地区发生的季节性冰冻预计将显着影响土木结构（尤其是桥梁）的横向行为。材料行为研究表明，在接近 -20 摄氏度的温度下，混凝土性能会发生 20% 至 50% 的改变，钢的延展性可能会完全丧失，而土壤性能会增强多达两个数量级。因此，结构的横向荷载响应由土壤-基础-结构相互作用和结构构件的延性能力决定，并且取决于环境条件。由于在经历季节性冰冻的各个州都可能发生大型地震事件，因此研究温度对土壤-基础-结构系统横向荷载响应的影响变得至关重要。该项目通过研究钻孔灌注桩 (CIDH) 桩轴支撑的桥梁柱，探讨温度对土壤基础结构系统的影响。通过大型室外实验，研究三个桥柱在温暖和冰冻地面条件下的横向荷载响应，以了解季节温度对土壤-结构相互作用以及系统延性的影响。初步分析调查显示，地温接近-20℃的冻结条件可能会导致结构位移能力降低70%，柱剪力需求增加35%，因为桩身的重新定位和塑性扩散的减少。将利用测量的材料特性和现场土壤测试数据进行分析研究，以表征三个桥柱系统的响应。通过比较分析和实验结果，将提出季节性冻结对土壤-地基-结构系统影响的抗震设计意义。此外，还将制定针对该主题领域的详细调查计划。 拟议的探索性研究的结果预计将改善极端横向荷载（例如地震引起的荷载）下的土壤基础结构系统的设计，从而有助于在经历季节性冰冻的地区建造更安全、更可靠的结构。