可恢复功能的装配式门式钢桥墩抗震机理与设计理论

Traditional portal bridge piers are mainly reinforced concrete structures. Because of the heavy self-weight and poor ductility of the traditional reinforced concrete piers, the piers tend to damage under severely seismic action and the repairing of the piers is very difficult. The earthquake-resilient prefabricated portal steel bridge piers will be developed, which agree with the guide of state policy and the concept of constructing green buildings. The new prefabricated portal steel piers will improve the capacity of urban earthquake relief, and the adverse impacts on urban ecological environment and transportation during field construction will be significantly reduced. The seismic performance of the energy dissipative components will be tested. The effects of construction measures and design parameters on replaceable performance and buckling mechanism of the energy dissipative components will be discussed. The mechanical model of the replaceable components will be established. The pseudo-static experiment, pseudo-dynamic test and numerical simulation of the new prefabricated portal steel piers will be conducted. The interactive buckling mechanism and extremely low cycle fatigue mechanism of the new portal steel piers will be investigated. The rules of plastic damage evolution and characteristics of hysteresis curves of the new portal steel piers will be revealed. The influence rules of construction measures of the replaceable components, stiffness ratio between pier column and lateral beam, axial compression ratio, slenderness ratio and width-to-thickness ratio of plate on the seismic behavior of the new portal steel piers will be analyzed. Based on experimental study and theoretical analysis, the quantitative relation between evaluation index of seismic performance and damage grade of the new portal steel piers will be proposed. The allowable values of performance index for earthquake resilience of steel bridge piers will be suggested. The study results will provide scientific basis on resilience-based seismic design theory and application in actual structures of the new prefabricated steel bridge piers.

传统的门式桥墩多采用钢筋混凝土结构形式，但其自重大、延性差，在较强地震下易损坏，且修复困难。研发可恢复功能的装配式门式钢桥墩契合国家政策导向，符合发展绿色建筑理念；可提升城市抗震救灾能力，能显著降低施工对城市生态环境和交通的不利影响。本项目拟开展可更换耗能部件抗震性能试验，研究不同构造细节和设计参数对可更换性能和屈曲耗能机理的影响规律，并建立力学模型。进行新型钢桥墩的拟静力、拟动力试验和数值模拟，研究新型钢桥墩的相关屈曲机理和超低周疲劳破坏机理，揭示新型钢桥墩的塑性损伤演化规律和滞回特性。同时分析可更换部件的构造形式、墩柱和横梁线刚度比值、墩柱长细比和轴压比、板件宽厚比等对抗震性能的影响规律。基于试验和理论分析结果，建立新型钢桥墩性能评价指标与损伤等级的定量关系，提出基于震后可恢复功能的性能指标限值。研究成果可为钢桥墩基于可修复功能的性能化抗震理论提供依据，促进新型装配式钢桥墩的推广应用。

传统的钢筋混凝土墩柱在地震作用下容易发生严重的剪切破坏和弯曲破坏，甚至倒塌，震后难以快速修复。基于损伤控制理论，引入可恢复功能和装配式结构设计理念，研发出多种新型门式钢墩柱结构，可提升城市抗震救灾能力，并能显著降低施工对城市生态环境和交通的不利影响。.为研究新型门式钢桥墩的抗震性能，选取新型门式钢桥墩根部可更换耗能墩柱为重点研究对象。开展了新型箱形钢桥墩的轴压试验、数值模拟和理论分析工作。分析了探讨了设置无加劲肋和3种不同加劲肋、低屈服点耗能钢板的高度、宽度及厚度、设置耗能壳板等构造对新型桥墩抗震性能的影响规律。同时探讨了新型箱形钢桥墩根部耗能区的轴压屈曲机理和变形性能。在试验研究和理论分析的基础上，提出了新型箱形钢桥墩变形及其承载能力的简化计算公式。研究得出以下主要结论：.（1）在反复轴向拉压作用下，设置十字形或井字形加劲肋能增大箱形钢墩柱的延性和耗能能力，而设置X字形加劲肋减小了箱形钢墩柱的延性。.（2）低屈服点钢板的宽度和厚度对箱形钢墩柱的承载力影响较大。箱形钢墩柱承载力随着低屈服点钢板宽度的减小或低屈服点钢板厚度的增大而增大。.（3）改变低屈服点耗能钢板高度、宽度及厚度，对箱形钢墩柱的耗能能力均有影响。低屈服点钢板高度在(1/3～5/7)试件高度范围内，增大低屈服点钢板高度，箱形钢墩柱耗能能力随其提高。.（4）箱形钢桥墩根部耗能区设置内嵌防屈曲耗能钢板后，耗能钢板充分发挥了约束壁板屈曲变形的作用，其承载能力和抗震性能得到较大提升。.（5）在拟静力试验中，7根试件损伤主要集中在根部可更换的耗能区，而上部墩柱和刚性支座无明显破坏，可重复使用，实现了震后可恢复性能的设计理念。.（6）焊接接头和孔洞对材性试件的破坏有不利影响，带焊接接头的试件容易发生脆性破坏，延性变差；开孔试件在孔洞周围出现明显的应力集中现象。.本项目获得了新型装配式钢桥墩的屈曲机理、抗震性能和设计方法，为此类新型装配式钢墩柱的推广应用提供了科学依据。