基于拉伸型限位键的牺牲装置与性能试验

减、隔震支座中的剪切牺牲销钉,其脆性破坏模式易导致群钉共同承载时发生先后断裂,而产生难以协同的问题,销钉截面削弱部位也因应力集中而易导致正常使用状态下的疲劳问题.提出一种基于拉伸型限位键的水平限位牺牲装置,通过力转向块将水平限位力转变为作用在拉伸型限位键上的拉力,拉伸型限位键通过采用具有一定长度的截面削弱段使其具有有限的延性能力以防止脆性断裂,并通过大弧度光滑过渡减小应力集中,提高其抗疲劳性能.开展不同类型限位键和基于拉伸型限位键的限位牺牲装置静载性能试验,结果表明,拉伸型限位键具有更高的极限变形能力,延性变形能力可通过改变截面削弱段长度进行调节;限位装置整体承载性能与理论预期值符合较好,重复试验下的承载力离散性小,满足群钉协同承载要求.开展了拉伸型限位键和剪切型限位键的疲劳性能对比试验,结果表明新型拉伸限位键比剪切型限位键具有更优的抗疲劳性能.

Protection Retainer Based on Tensile Fusing Units and Performance Tests

Protection retainer with fusing pins used in isolators often lead to asynchronous failure owing to the brittle fracture when a group of pins are employed. Stress concentration in the necked zone may cause fatigue failure under functional loads. A protection retainer with tensile fusing units was presented in the study, in which the external lateral load was transferred as tensile force exerted on the fusing units by a deviator. The tensile fusing units had certain length of necked section that provides essential ductility to prevent brittle fracture. Smooth section transition with relatively large radius was used to enhance the capacity in resisting fatigue loads. Static tests on shear pins, tensile fusing units and the new retainer with multiple tensile fusing units were conducted. The results showed that the tensile fusing units have much larger ultimate deformation capacity than the shear pins and the ductile capacity of the tensile fusing units can be adjusted with different length of the necked zone. The tested retainers exhibited consistent ultimate loading capacity as predicted by the theoretical equations and small discreteness with repeatability tests. This indicates that the tensile fusing units in the retainers can work in sync. Furthermore, fatigue tests on the shear pins and the tensile fusing units were conducted and the results showed evidently higher fatigue resistance of the tensile fusing units.