采用低屈服点金属的可置换式钢节点减震分析

Seismic Analysis of Replaceable Steel Connection with Low Yield Point Metal

传统钢结构节点设计通常不能充分达到预期抗震要求,而以梁端削弱型梁柱节点虽然能够初步实现"强柱弱梁",但可能在削弱区产生局部屈曲和整体侧移,在强震下安全储备不足。针对此问题,基于可恢复功能减震结构的理念,提出采用低屈服点金属的梁端削弱更换式梁柱节点。该节点利用低屈服点材料对翼缘和腹板的削弱处进行填补,在地震中低屈服点金属率先屈服并充分耗能,可降低节点主体的损伤,并可在震后对低屈服点金属进行更换。选取低屈服点钢材作为置换材料,通过材料性能试验获得相应的材料本构。在此基础上,对比分析低周往复加载下不同的抗震减震性能和损伤特征。采用多尺度有限元建模方式对采用不同类型节点的钢框架进行弹塑性时程分析。结果表明,可置换式节点能够将主要损伤控制在置换材料内,并具有更强的耗能能力、可恢复能力和安全储备。

The design for traditional steel rigid connections cannot fully meet the desired seismic requirements, though beam-column connections with weakened beam end can approximately realize the concept of “strong column-weak beam”, in which the local buckling in the weakened zone and the overall lateral may occur in strong earthquakes and have insufficient capacity. A replaceable steel connection with low yield point metal was proposed, based on the concept of earthquake-resilient structures. In this connection, the weakened parts in the flange slab and web plate were filled with low yield point metal, which yields then dissipates sufficient energy in earthquakes. Thus, damage to the main parts in the connection was slight, and the yield point metal could be replaced after the earthquake. The low yield point steel was selected as the replacement material, and the material constitutive relationship was obtained by a performance test. The seismic performance of the three types of connections, which include the traditional connection, beam end weaken connection, and replaceable connection under low cycle reciprocating load, were studied using the finite element method. In addition, the energy dissipation capacity and damage characteristics of different connections were compared. The multi-scale finite element models for the steel frames with different connections were analyzed by the inelastic time-history method. Both the computational efficiency and accuracy were assured. The analysis results approve that the replaceable connection can confine major damage in the replacement material and have better energy dissipation ability, safety reserves and resilience. © 2016, Editorial Department of JVMD. All right reserved.