带可替换剪切耗能连接的防屈曲偏心支撑钢框架抗震性能研究

In current design of steel eccentrically braced frames (EBFs), the yielding link is coupled with the floor beam. This often results in oversized link elements, which leads to over-designed structures and foundations. In addition, the beams are expected to sustain significant damage through repeated inelastic deformations under design level earthquakes, and thus the structure may require extensive repair or need to be replaced. These drawbacks can be mitigated by designing EBFs with replaceable shear links. Therefore an innovative approach consisting of designing EBFs with replaceable nonlinear shear links is suggested in this project. That is the de-coupling of the link beam from the remaining members of the EBF. This will not only provide for independent control of required strength, overall frame stiffness and ductility，but also quick inspect and replace yielded and damaged links following a major earthquake. Thus economically bringing the structure back to its original safety level, and facilitating re-positioning of the structure to its undeformed configuration by disconnecting the distorted replaceable links from the structure. Very limited research on the design of EBFs with replaceable links has been completed to date abroad, but there is a lack of domestic research on the issue to date. Especially study on the seismic performances of eccentrically braced frames with replaceable shear links are not reported. The seismic performances of eccentrically buckling-restrained braced frames with replaceable shear links will be studied in the project. Thruogh experimental study, the developing and distribution of plasticity, failure mode, stiffness degeneration law of the replaceable shear links will be attained, and horizontal resist lateral stiffness, capacity of energy dissipation, ductility and the collapse mechanism of corresponding new structure will be obtained first. Then the general command flow and computer code will be compiled to finish the modeling and calculation based on the secondary developing function of the existing finite element software, and the influence factors of the seismic performance will be analyzed. At last performance-based seismic design method and the details of eccentrically braced frames with replaceable shear links and buckling-restrained braces will be proposed. This research provides the important the theoretical basis for designing method and engineering applications of this kind of structure, and the research work has both theoretical significance and extensive application prospect.

可替换剪切耗能连接即将偏心支撑钢框架中的耗能梁段从框架梁中分离出来，作为独立耗能连接件，不仅实现了将结构非弹性变形集中于耗能梁段区域的目标，也能达到震后损坏耗能梁段易于替换和降低修复成本的目的。目前，国外在可替换剪切耗能连接方面的研究成果极少，而国内相关研究缺乏，特别是针对带可替换剪切耗能连接的偏心支撑钢框架体系抗震性能的研究尚未见文献。 该项目拟对带可替换剪切连接的防屈曲偏心支撑钢框架体系的抗震性能进行研究，试验得出剪切耗能连接塑性开展与分布、破坏机制、刚度退化规律和相应新型结构的水平抗侧刚度、耗能能力、延性性能、倒塌机理；基于现有有限元软件编制分析程序，建立剪切耗能连接与框架结构的分析模型，系列分析相关参数对其抗震性能的影响规律；基于结构性态提出带可替换剪切连接的防屈曲偏心支撑钢框架设计方法和抗震构造措施。研究成果为该类结构体系工程应用提供理论基础，有重要理论意义和良好的工程应用前景。

在偏心支撑钢框架结构（EBFs）设计过程中，耗能梁段的设计是关键。为研究带可替换连接件的EBFs结构的性能，项目完成了22个端板连接和11个腹板连接的可替换独立耗能连接件的试验；完成了4榀端板连接和10榀腹板连接的带可替换剪切耗能连接的偏心防屈曲支撑钢框架1/3缩尺试验。通过对端板连接和腹板连接的剪切连接件的试验和有限元分析发现，所有的剪切耗能连接件都满足并超过了延性验收标准。其中，可替换剪切连接件展示了较好的耗能性能和力学性能，端板连接的剪切耗能连接件最大塑性转角可达0.18rad；而腹板连接的剪切耗能连接件能够承受更大的塑性转角，最大可达0.36 rad。对不同参数的可替换剪切连接件进行循环往复加载试验，并对剪切连接件的承载力、刚度、塑性转角及耗能性能进行深入分析，结果表明：可替换剪切连接件具有很好的塑性变形能力，能够满足其在地震作用下的变形要求；滞回曲线饱满，具有良好的耗能能力；刚度退化明显，剪切连接件的耗能性能得以充分发挥；同时，经过参数分析得到了截面尺寸、长度比及加劲肋间距等几何参数对剪切连接件的抗震性能的影响规律。. 通过对带可替换剪切耗能连接的偏心防屈曲支撑钢框架结构的试验和有限元分析，得出相应新型结构的水平抗侧刚度、耗能能力、延性性能、破坏机理，并分析相关参数对其抗震性能的影响规律，给出了基于性能的带可替换剪切连接件的偏心防屈曲支撑钢框架抗震设计指标。结果表明结构具有良好的承载能力、刚度和延性，延性系数在2.9~3.9之间，且塑性主要集中在可替换耗能连接件上，塑性转角均超过了0.08rad，说明该结构具有良好的抗震性能。同时，在K型偏心支撑防屈曲钢框架上对可替换连接件进行了替换试验，验证了对耗能连接件进行替换是可行的。说明将偏心支撑钢框架中的耗能梁段从框架梁中分离出来，作为独立耗能连接件，不仅实现了将结构非弹性变形集中于耗能梁段区域的目标，也能达到震后损坏耗能梁段易于替换和降低修复成本的目的。.